The Truth About Cars » automatic The Truth About Cars is dedicated to providing candid, unbiased automobile reviews and the latest in auto industry news. Mon, 28 Jul 2014 18:32:39 +0000 en-US hourly 1 The Truth About Cars is dedicated to providing candid, unbiased automobile reviews and the latest in auto industry news. The Truth About Cars no The Truth About Cars (The Truth About Cars) 2006-2009 The Truth About Cars The Truth About Cars is dedicated to providing candid, unbiased automobile reviews and the latest in auto industry news. The Truth About Cars » automatic Piston Slap: Crystal Ballin’ With Yo Tranny! (Part II) Wed, 09 Apr 2014 12:24:30 +0000 Anything is Possible... (photo courtesy:

Aaron writes:

Hey Sajeev,

Huge fan of TTAC and the piston slap articles. My problem is that I noticed my car(2007 honda civic)would shudder, under light throttle and low rpms especially when going up a slight slope. This usually happens at 30km/hr or 40km/hr. I took it to the honda dealer(4 months ago) and he said the torque converter(tc) needs to be replaced(300 for tc plus 900 for labour and stuff).

My university got a bit busy and I took some time to think about it. The problem might be slightly worse now so I recently went back to the dealer to get more details about the cost and now they are saying the price of the tc has increased to 800 plus another 800 for labour. The guy suggested maybe just changing the transmission fluid(because it is starting to get dark) and driving the car until it fails and getting a new transmission for $3000 because the transmission will probably go out soon anyway.

I’m not sure what to do now. I’m considering going to a transmission shop and see if they can change the tc, but I’m worried about going to a random mechanic. I know a small time mechanic whom I go to for small stuff but I’m not sure if his shop is capable of swapping the tc(is it that complicated?). I have also looked online and found other people saying that if the torque converter is failing, the transmission is probably going to go soon. Some other people have said that if the torque converter fails, it could take out the rest of the transmission which might have been working fine otherwise. I then found another group of people saying that I should just drive the car without changing the transmission fluid because even changing the fluid could cause the transmission to fail sooner.

I just want to know which of these are actually true and what should my next course of action be. If the torque converter can be changed for a reasonable price and my transmission keeps working, I would like to do that. Or maybe I should see if I can get the entire transmission rebuilt or replaced.

Thank you,

P.S: Not sure if this matters, but the car once overheated severely (about 3 years ago) and about half the engine had to be replaced under warranty. The engine has been running smoothly since then and the only other problem is that recently(2 months ago) my engine starter and battery had to be replaced. The battery connectors also look pretty bad so I’m going to replace that soon. Hmmm maybe I should just sell my car.

Sajeev answers:

Oh great, another mystery box transaxle/crystal ballin’ yo tranny problem: one day the B&B will string me up for these blind guesses.

That said, on a more serious note, how many miles are on the Civic?

Aaron responds:

Hey Sajeev,

Thanks for the quick reply. It has 156,000 km(96,000 miles). Admittedly, the car has been driven pretty hard. I just did a quick stall speed test(mashing the brake and hitting the throttle) and the revs went up to 2,500rpm in both drive and reverse. That seems pretty normal. I drove around trying to recreate the problem(Light throttle and flat roads or slight inclines).

It happens at:

  • 15 or 20km/h (9 or 12mph)
  • 30ish km/h (18mph)
  • 40ish km/h (25mph)
  • And at 55ish km/h (34.18mph), the shuddering is only minor at this speed

There is also a sound when this happens, it sounds like metal spinning against metal in a liquid. However, this sound can only be heard if the shuddering is not too violent. If it is violent, it just sounds like the car kind of wants to stall. I checked the transmission fluid and it looks pretty brown and has a slight burning smell. If the car is accelerating faster( atleast above 2000rpm), it feels like there is no problem. Also no problem when slowing down.
Thank you,

Sajeev concludes:

Great assessment!  At this age (under 100k miles) odds are new and correct fluid will solve it: flush the old fluid out of the converter and also drop the pan to change the filter. Which might be asking a lot for many shops, but I’d want all the old ATF out of the system. So will this cure the problem?  Will thoroughly removing varnished ATF cause even more problems than a shudder?

Maybe on both counts.  Or maybe one and not the other.  See how much fun this is for me?

My best guess: do as the dealer said, change the fluid. If it fails, get a rebuilt transaxle from a Honda savvy shop.  Because opening up a transaxle for anything and not doing a rebuild is likely a waste of time, labor and money.

It’s usually best to prolong that moment with anything…including a fluid change. Even if the fluid change actually shortens the tranny’s lifespan. So much fun!

Send your queries to Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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Twincharging Is Volvo’s Replacement For Displacement Wed, 29 Jan 2014 14:00:53 +0000 Volvo Drive-E Engine, 2.0L twincharged, Picturre courtesy of Volvo

Engine downsizing is all the rage. Making the engine smaller increases fuel efficiency, reduces emissions and cuts vehicle weight. With ever tightening fuel economy legislation in the United States and CO2 emissions regulation in the European Union, mainline manufacturers are turning to turbochargers like never before. In 2009 just 5% of cars sold in America sported turbos, and that 5% consisted largely of European brands like Volvo and BMW with a long history of forced induction. By 2013 that number had more than doubled to 13%. Honeywell expects the number to rise to 25% in the next four years and the EPA tells me that by 2025 they expect 90% of cars sold in America to sport a turbo engine. With turbos becoming so ordinary, what’s a turbo pioneer like Volvo do to keep a competitive edge? Add a supercharger of course.

I recently had the opportunity to sample the new Volvo V60 (expect a first drive review shortly) but the star of the show wasn’t the car itself, it’s what’s under the hood. New engine designs are truly a rarity in the automotive world with engines being tweaked over time to keep them fresh. Volvo’s own modular engine found under the hood of most Swedish cars (and the occasional Focus RS) turned 24 years old this year, but it’s a spring chicken compared to the Rolls Royce L series 6.75L engine that dates back to 1952. Being the engine nerd I am, I spent a new hours with Volvo’s powertrain engineer discussing their new “Drive E” engine family.

Volvo’s new engine family is primarily a clean sheet design, although many design components are descendants of the old “modular” engine family. The line consists of four different variants dubbed T3, T4, T5 and T6. As before, T indicates turbocharged but now the number represents power output rather than the number of cylinders involved. Yes, this is the death knell for Volvo’s funky 5-cylinder because this is a strict four-cylinder lineup. Volvo has said the 149 horsepower T3 and the 188 horsepower T4 won’t be headed to America at the moment, so don’t expect to see a direct competitor for BMW’s downsized 320i from Sweden this year. Instead we get the 241 horsepower T5 and the 302 horsepower T6 under the hood of everything except the XC90.

Volvo Drive-E engine, 2.0L, picture courtesy of Volvo

All engines share a common block design, but what changes is the boost. T3, T4 and T5 engines use a single turbo while T6 adds a Roots-type supercharger in addition to the turbocharger. VW and others have dabbled with twincharging in the past, with VW’s 1.4L twincharged engine finding a home under the hoods of Euro models and putting down 140-180 horsepower. Volvo is taking things to the next step by calling their 2.0L engine the replacement for not just the 3.0L twin-scroll turbo but also the recently departed 4.4L V8.

While supercharging and turbocharging sounds excessive, there is a logic to the madness. While peak torque on the turbo-only T5 just 15 lb-ft lower than the T6 (when in overboost), the supercharger allows the T6 to deliver approximately 140 lb-ft more torque just off idle. The torque curves converge around 1,500-1,600 RPM when the T6 switches over to the turbocharger. From approximately 2,000 RPM to 3,500 RPM torque remains flat on both engines but the larger turbo on the T6 allows it to maintain peak torque all the way past 4,500 RPM. When torque does start to wane it does so more gradually than turbo-only engines.

Aisin AWF8F35 8-speed transaxle, picture courtesy of Aisin

Why not stick with a supercharger alone like Jaguar and other auto makers? The reason is two-fold. Turbochargers operate off of “waste energy” from the exhaust. Exhaust gases spin the turbine which in turn spins the compressor forcing more air into the engine. In truth “waste energy” is a misnomer because there is a horsepower toll for having the turbo interfering with the exhaust stream, but in general this toll is smaller than the power required to operate a supercharger. The downside to a turbo is well known: turbo lag. Turbo lag is the time it takes the turbo to start “boosting.” Although the turbo is spinning at idle, it’s creating little positive pressure. Step on the gas and it takes a while for things to start humming along and boost to be created. That’s why the T5 has a lower torque rating off idle.

Superchargers are typically driven off the accessory belt. Because of the “direct” connection to the engine, they are always creating boost. Because this boost happens in sync with engine RPMs, the response is immediate. On the down side superchargers can consume up to 20% of an engine’s total power output according to Honeywell. This is considered a good trade since they can boot power up to 50%. Because of design trade offs, factory supercharged engines tend to “run out of breath” at higher RPMs which explains why Jaguar’s 5.0L supercharged engine lags the 4.4L and 4.7L twin-turbo German engines by a wide margin in peak torque.

Volvo’s answer to both problems was to use a supercharger for immediate response at the low end. From idle air flows into the supercharger then through the turbo into the engine. This not only improves low end response but it also helps get the turbo up to speed faster. At some point determined by the car’s computer (around 3,500 RPM) the engine opens a butterfly valve to bypass the supercharger and then de-clutches the supercharger to eliminate the inherent loss. This process allows a supercharger tuned for low end response and a turbo tuned for higher RPM running to be joined to the same engine. The result is a horsepower and torque curve superior to Volvo or BMW’s 3.0L twin-scroll turbos in every way, from torque at idle, length of the torque plateau, to high-RPM torque. To further increase efficiency Volvo relies on a variable speed electric water pump for cooling, direct-injection for combustion efficiency and low friction bearings and rings. Volvo’s marketing literature hails this as the answer to the V8.

But is it really? Yes and no. The pint-sized engine allows the XC60 to deliver 29 MPG on the highway in 304 horsepower T6 trim which is a 50% increase over Volvo’s 2009 XC90 V8. Score one for Drive-E. Out on the road, the 2.0L engine delivers more low end torque than any other 2.0L four-banger sold in America giving the XC60 more punch off idle than I expected. The T6′s torque curve may be flatter than Volvo’s sort lived 4.4L V8, but it’s not quite as robust at the top end or at idle. The broad torque band and the Aisin 8-speed auto allowed the XC60 T6 to tie an XC90 V8 to 60 MPH.  Aurally, Volvo’s “burbly” V8 is the clear winner. The Drive-E engine has a distinct (but muted) supercharger whine under 3,500, a definite four-cylinder exhaust note and an eerie silence at idle. Volvo was cagey about any Polestar tunes for their new engine, but I suspect considerable work will need to be done to best Volvo’s own Polestar I6.

My inner engineer is excited by the possibilities of modern forced induction technologies and small displacement engines. I suspect that the vast majority of American shoppers would be hard pressed to notice the difference between Volvo’s twin-charged 2.0L engine and a V8 in the 4L range in terms of power delivery and drive-ability. The constant march towards fuel economy also fills me with sadness. No matter how you slice it, a naturally aspirated V8 has a sound that we’ve grown up associating with performance and luxury. This association is so strong that BMW pipes V8 sounds into the cabins of their turbo V8s because the turbos interfere with the exhaust notes. As our pocketbooks rejoice, join me as I shed a tear for the naturally aspirated inline-6 and V8.

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Piston Slap: Sealed for an Infinite Life? Mon, 14 Oct 2013 12:11:58 +0000 Jerry writes:


Thank you and the rest of the TTAC staff for providing the community with an entertaining and genuinely informative automotive website. I’m a long-time reader, and hope you can answer some questions I had about my wife’s 2009 G37 S 7AT.

We purchased the car new in 2009 and love it. It’s paid off and we see no reason to replace it anytime in the foreseeable future. It’s a keeper.

We carpool and thus only have accumulated 29,xxx miles in the years we’ve owned it. I try to be diligent with my vehicle servicing, and prefer to do my own maintenance. When preparing for the upcoming 30,000 mile service, I noticed something peculiar in the maintenance schedule provided by Infiniti:

‘Replace automatic transmission fluid(except 7 speed automatic transmission).’

Even more curious, the 7 speed automatic is not recommended for servicing at any point in the published maintenance schedule (which terminates at 120,000 miles). I’ve always thought 30,000-40,000 mile transmission services were optimal. There is no dip-stick, which I know is becoming more typical of luxury cars, so I can’t visually assess the condition of the fluid. Visiting some Infiniti forums reveals the transmission is effectively sealed to shade tree mechanics, and requires a visit to the dealership if you’re inclined to have it serviced.

I’d love your insight. I know there is no such thing as transmission fluid that never needs changed. I know any dealership I call will disagree with the literature and recommend it needs changed as frequently as I can afford it(~$350 for a flush and fill at the local dealership). What I don’t know is: When does this fluid really need changed, and why is Infiniti keeping it a secret?

Sajeev answers:

The 7-speed Infiniti angle adds a new twist to one of the quandaries that’s been around since the early days of the Piston Slap series.  My first recollection of these “sealed for life” automatic transmissions was the 1997 Chevy Malibu, and the universal truth hasn’t really changed: change the ATF at regular intervals (being vague for a reason) and make sure to use the correct fluid.

Why be vague? Because while most folks wouldn’t go past 100k-150k on transmission fluid if they knew the benefits–and if they kept a car that long–the actual life of transmission fluid varies by owner. If you carry/tow heavy loads in a minivan that idles in traffic to and from school/work in brutally hot weather, consider a more aggressive ATF replacement schedule.  But if you are one person traveling mostly rural highways in cooler parts of the country, you may never need to change the fluid at all.  (slight exaggeration)

So what’s the right move for you?

The path of least resistance is to visit the dealer and have them do the deed, perhaps every 75k or 100k.  Which isn’t a bad idea, and considering your low mileage…when will you reach 100,000 miles? So don’t sweat it!

Send your queries to Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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Piston Slap: Not Totally Enamored with E39 Upkeep? Mon, 12 Aug 2013 11:54:01 +0000 Will writes:


I was recently greeted with the warm, orange glow of a check engine light on my 2002 BMW 530iA with 93,000 miles. I took the car to AutoZone and had the code read. It’s a P0741, which indicates a failing torque converter. This is apparently a common issue on E39s with the ZF 5 speed automatic, as the seals in the torque converters tend to deteriorate.

Although it could also indicate other problems, I think this code probably means I have a transmission problem, as I’ve been experiencing some strange lock up behavior, especially on the interstate where the car will lurch and the revs will jump when I accelerate in fifth gear. I have an appointment at a local independent mechanic in a few days, but I’m not looking forward to hearing the diagnosis. Here’s the question: should I bite the bullet and spend $1200-$1800+ for a new/rebuilt torque converter to be installed, or do I sell the car and spend ten grand or so on a mid 2000s Honda with 80,000-100,000 miles?

I do like the Bimmer quite a bit, but it’s an expensive car to maintain, and I’m not totally enamored with the idea of spending so much time at the mechanic in the future. I’d be perfectly happy with a less luxurious Honda, but I would take a hit on the money I’ve put into this car already (new cooling system, some new suspension components, new MAF sensor, etc.)

Sajeev answers:

Can it really indicate other problems?  I always thought P0741 is about ye olde torque converter…or a bad circuit between the lock up solenoid and engine computer. Plus, your “strange lock up behavior” on the highway proves my point.

Odds are you need a new converter, maybe the solenoid plus miscellaneous bits your mechanic will spot when the E39 is on the lift. And since you aren’t especially thrilled with owning a fantastic car with Germanic levels of wallet molesting…well…

Enjoy your new Honda. You’ll be far better off, even if us car peeps wish you’d keep the E39.


Send your queries to Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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Piston Slap: A New (Wave Plate) Sensation? Mon, 03 Jun 2013 11:00:16 +0000

Keith writes:

Mr. Mehta,

My apologies if this has been covered, but I’m looking for advice on my soon-to-be out of warranty 2008 GMC Acadia. I’m at 64K and 4.8 years, so bumper to bumper is gone but power train is still good for a few months.

Two fellow Acadia owners I know have reported tranny problems at roughly 60k and the forums seem to indicate numerous others with similar issues. Most often its an issue with the wave plate, particularly with the 07-09 models. Within the last few weeks I’m also starting to get an intermittent stabilitrak warning light promoting me to get the brakes serviced.

My question for you is should I 1) hope the tranny drops in the next two months 2) shell out $3k for a 4/48 extended service contract or 3) trade it in on something similar.

I love the car(truck) and was hoping to get 8-10 years out of it, so maybe #2. Or I could take the $3k and couple that with what I think is still pretty good resale value and get a new ride.

I’m generally pretty cynical about extended service contracts/warranties, but I have no experience on those for automotive.

Any thoughts, advice or general musings would be greatly appreciated. TTAC is wonderful resource. Keep up the good work!

Sajeev answers:

Now’s a good time to remind my dear readers that I am not a mechanic by trade, I’ve just been in “your shoes” in the past. Perhaps an oversimplification, but let’s do this thang and dig into your tranny.

This is the first I’ve heard of this problem, ditto the “wave plate.”  I suspect most of you are in my shoes, so a little research: this thread points to the wave plate vs. conventional clutch plate of the 3rd gear drum (i.e. direct drive, 1:1 ratio) of an older GM 4-speed.  Which I then recalled while hunting for a good rebuilt-upgrade for my Ford AOD. I learned about an upgrade to 3rd gear, choosing an aftermarket Blue Plate Special (yes, really) clutch pack for mine. With that in mind, reading one of the comments in the LS1 Tech link said it all:

“The waved steel keeps the splines from taking a hard hit by pre-loading it. In other words, the waved steel takes up the slack before the clutches are completely applied.”

So if the waved steel clutches aren’t the right “wave dimensions”, there could be a problem shifting into that gear. The problem might look like this. Note how the speedometer never slows down as the rpms fluctuate: indicating that the transmission is slipping that frickin’ hard on the upshift:

Click here to view the embedded video.

FINALLY: a transmission almost as horrible as the one in the Smart Car, without the need for Smart Car ownership! (childish giggling)

Unfortunately we don’t know if this video is indicative of your problem. Or if this thread on the Saturn forums also applies. Or if you have a problem yet…is nothing ever easy in this world???

My advice?  If/when the wave plates start ruining your ride, see if your homework (including the stuff I posted) can get you a little credit with GM service: pleasant, level-headed customers can easily get their out-of-warranty work covered under the blanket term of “goodwill.” Because nobody wants to lose a good customer, if possible.  If not, get a reman transmission that specifically addresses this problem. I suspect both GM and big name rebuilders (like Jasper) will have you covered. Even if it’s gonna happen after the warranty expires.

Perhaps you should just give up and get a Crown Vic Best of luck, as always.


Send your queries to Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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Piston Slap: Automatic Decisions, Manual Trannies Tue, 12 Mar 2013 17:16:09 +0000 TTAC commentator hidrotule2001 writes:

Hey Sajeev,

A few months back you helped me sort out a plan of action for my Ford Fiesta transmission problems, and I have another stick-shift quandary I thought you might have some insight on.

My second vehicle is a 2003 Ram 1500 (bare bones work-truck, standard cab, manual everything), which I’ve recently been doing a lot of maintenance on (new plugs, pads, rotors, u-joints, carrier bearing, and a few other things). One issue I haven’t been able to sort out is an odd grinding/squealing I get when the car is in gear at high rpms (3000+) with the clutch peddle fully depressed (on the floor), something akin to what you hear if you come off the clutch with the shifter only part-way into gear.

Everything I can find on forums seems to indicate this is a worn throw-out bearing, but there seem to be a few things that suggest otherwise:
1) it only happens above a certain RPM (3000+), and makes 0 noise if the clutch is put in at lower revs
2) it only happens when in 1st gear, and occasionally in 2nd or 3rd (but much quieter in these cases)

I’ve had two local shops take a look at it, and neither was able to say more than it might be the throw-out bearing, or possibly some other bearing in the transmission, and they wouldn’t be able to say for sure unless they pulled the transmission out. I figure if it’s to the point that the transmission needs to be pulled, I should look at replacing the clutch (since it’s still on it’s first one, with 120k miles), and possibly some other transmission components, but that’s going to set me back a pretty penny (and it seems like throwing parts at a transmission problem is a good way to lighten you wallet quickly). I’ve also noticed that first and second gear are “clingy” and that when I shift back to neutral and/or have the clutch engaged, it takes substantially longer for the RPMs to return to idle than it does in higher gears, on the order of 2 full seconds(I’ve never noticed this in other M/T vehicles I’ve had, or if there was a difference it wasn’t noticeable). I’ve got a video where you can see the difference in time it takes to return to idle, as well as hear the grinding noise, here.  I’ve also found that the problem is worst when the engine is cold, for the first 10-15 minutes of driving after starting.

At the advice of some DodgeForum members I recently took the truck into my local independent shop to have the clutch, throw-out bearing, transmission fluid, and pilot bearing replaced, but my mechanic called back to say he was pretty sure those weren’t the cause of the issue. He’s convinced the issue is coming from something within the trans, possibly the counter shaft bearing, and was hesitant to replace components he didn’t think were causing the issue. His quote for a rebuilt transmission was 1700, with shipping and labor and a new clutch, that would end up around 2700, which is right about what the truck’s worth.

So now the question is, do I…

-Wait things out and see if they get any worse?
-Have the clutch components replaced anyway and see if that improves things?
-Have them pull the trans and hope it’s something easy to replace/fix?
-Look for a used trans and have that installed instead of a rebuilt one?
-Bite the bullet and have a rebuilt trans installed?
-Try my hand at a tranny-pull and see what trouble I can get into?

Thoughts/suggestion/voodoo-cures welcome. Thanks!

Sajeev answers:

You covered all the bases, short of learning how to rebuild gearboxes yourself.  Which is usually the big problem here: nobody knows what the hell is failing until a rebuilder takes it apart and assesses the situation. I consider transmissions (of all types) to be magic boxes of horror that you must never tear apart unless you are ready for a complete rebuild.  Obviously that doesn’t include accessible fail points like the clutch, torque converter, etc that aren’t encased within the gearbox itself.

Maybe you need a new clutch/throwout bearing/pressure plate/pilot bearing, but if your mechanic says no, I revert to my “magic box of horror” tranny theory.

Don’t worry about RPM hanging between gears, that’s part of the engine computer’s tuning. Not sure why it would hang more gears than others, but make sure you are driving the same way (intensity of throttle input, RPM speed before going into neutral, etc) in all gears to see if there actually is a problem. The hang in my Ranger was super annoying in all situations, so an SCT tune cured it…among other things. But I digress.

Back to your mechanic’s recommendation: let the transmission die, don’t change it immediately.  Just make sure you buy a good replacement from a trusted rebuilder.  If your local searches fail, get one from Jasper or a similar national distributor with a good reputation.


Send your queries to Spare no details and ask for a speedy resolution if you’re in a hurry.

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Piston Slap: Of Power Curves and Turbo Boost… Mon, 17 Dec 2012 12:32:47 +0000 Chris writes:


In a couple recent Piston Slap articles you’ve mentioned that when driving car with a manual transmission its most efficient to accelerate with the engine near its torque peak, then cruise in the highest gear possible. This raised two questions in my mind:

1. Does the engine’s torque peak vary based on throttle position? From what I understand, power and torque curves are generated at wide open throttle. But would the torque curve look different at, say, 50% throttle? I’ve heard that exhaust backpressure can affect the torque curve (maybe this is a myth). Could throttle position have the same effect via intake vacuum? Speaking of intake pressure, that leads me to my real question:

2. How does your strategy of accelerating with the engine near its torque peak apply to a turbocharged vehicle? My car has a turbo and according to the manufacturer the torque peak is 2000 rpm. But clearly it’s not always capable of generating max torque at 2000. If I’m loafing along at 1800 rpm and floor the throttle it takes a very laggy second or so for the boost to build and its definitely past 2000 rpm by the time it starts really generating power. I’m thinking there must be a different torque curve for part-throttle acceleration, when the engine is either off-boost or not making full boost. I think this would also apply to an engine like Audi’s supercharged V6, where the supercharger can de-clutch from the engine under low load. Any thoughts on the most efficient way of accelerating in a turbo? Better to accelerate “on boost” at relatively low rpm and relatively wide throttle? Or accelerate with less throttle, keeping it out of the boost (but probably winding the tach up more to avoid moving at a snail’s pace)? Or just forget the whole thing, floor it and enjoy the wild turbo-torque surge?

If these are stupid questions, please disregard. These are just things I ponder while sitting in traffic… Keep up the great work!

Sajeev answers:

This is a fantastic question that I am totally not qualified to answer…but that hasn’t stopped me before, and it hasn’t stopped you lovely people from reading, so let’s do this thang!

Point #1: Yes, throttle position will affect the torque peak. Because an engine is basically just an air pump, if you have less throttle you have less air, less fuel and therefore less power.  Thankfully, with the advent of electronic fuel injection there are multiple mappings: older systems have a full and a part throttle program, and newer systems probably have several.  So I betcha you can maximize an engine’s efficiency at just about any throttle opening. Every application is a little different, and many are tuned to maximize performance with a computer reflash from an aftermarket programmer.

As a rule of thumb, and I’m ready to get slammed by engineers for saying this, backpressure (or a lack thereof) does indeed affect the torque output of an engine.  More importantly: backpressure isn’t a good thing, finding the ideal exhaust velocity to minimize backpressure while keeping the speed “slow” enough to not hurt torque output is crucial.  That’s why, in the past 10-15 years, we see far higher quality exhaust systems in all OEM applications: no crush bends in the tubes, cast iron manifolds that are shaped more like aftermarket tubular headers, and mufflers/catalytic converters that aren’t a significant restriction.**

Point #2: turbocharged motors are just like point #1 when it comes to power in part throttle applications. And every boosted application out there is different. Once again, and even more so, tuning makes ALL the difference in the world.  Because the turbo is a muffler/restrictor in the exhaust system, you want as little restriction behind it to ensure maximum efficiency: hence why the Dodge SRT-4 is muffler-less from the factory.

My gut feeling is that with any modern car, turbo or not, you need to give it more gas to cut through the slop of electronic throttle control/torque management to get into your torque peak quicker.  Spend less time accelerating and more time cruising, with traffic conditions in mind of course. That doesn’t mean you run wide-open throttle, either. There’s a happy medium out there, somewhere.

Off to you, Best and Brightest: I’m ready, I’m wearing my flame suit.

**Grab a catalytic converter from the 1970s-early 1990s. They neck down, restrict air flow, etc far more than the goodies I see today in cut-away diagrams at the auto shows.  We have come a long way, baby.




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QOTD: Pick Your Poison- A CVT Or A 4-Speed Automatic Thu, 19 Jul 2012 15:04:11 +0000

For 2013, America’s cheapest car will get another bit of unloved technology to go along with its continuously variable transmission.

The 2013 Nissan Versa sedan, currently available with a CVT or a 5-speed manual, will also get a 4-speed automatic option for the base model S trim. With the CVT adding $2,130 over the 5-speed manual, the 4-speed unit should command a lower premium than the CVT, albeit with an arguably cruder, less pleasant driving experience.

The hate for the CVT and 4-speed auto here at TTAC is about evenly matched, but if I had to pick, I’d come down on the side of the 4AT being more popular. Prove me wrong.

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Piston Slap: Justy-fied Freestylin’ over CVTs, Part II Wed, 19 Oct 2011 19:06:23 +0000  


Brian writes:

Not sure if this would be appropriate “piston slap” fodder or not, but here goes:
Our blossoming family recently expanded to five. My wife and I, and a three year old, a 20 month old and now a 2 month old fill up the house. We occasionally travel with our 75 lb dog. Knowing the Volvo Turbobrick would not handle the cargo/dog/people, and the PT Cruiser remains the most reliable vehicle ever built (even if the timing belt changes are a big pain) we decided to sell the Volvo for something more appropriate, if a lot slower and FWD.

Enter the Freestyle. We routinely get 28 mpg on trips, parts are cheap, we have lots of cubbies for kid’s junk and the car seats fit easily. I purchased a high mileage (150k) example that was a one owner (ish) with all receipts. It was a fleet car for some guy who then bought it when his company was done with it. It had the CVT replaced at 118k miles with a remanufactured transmission from Ford, installed at a dealer.

A few weeks ago the CVT died on us. At 153k miles. There was just over 1,000 miles left on the warranty. We all got home safe and sound, and the transmission was replaced. Again. With a remanufactured unit. Again. It’s apparently the only thing available. No new ones exist and nobody rebuilds them. I have a connection with the transmission rebuild world. I’ve called transmission parts suppliers and they don’t even sell a manual for it.

I’m not what you’d call ‘shy’. I do all my own work on my cars with the exception of this, flashing the ECU for a TSB on the aforementioned PT Cruiser, putting tires on wheels and replacing windshields. I’ve done a fair amount, but I’ve never owned anything this expensive. I fully expect this remanufactured transmission to die in roughly the same amount of time. My theory is that while the original certainly seemed to fare decently (118K on a conventional transmission is not terrible for a heavier people mover), the reman probably was rebuilt by the same folks who do the $34.99 starters for small block chevies that seem to last just a day over the one year warranty that you find in the local pep-advanced-zone’s. The choices are basically as follows:

Take a big depreciation hit and attempt to sell it (we bought it in March) and buy a Taurus X with the conventional automatic and the better 3.5L engine. We cannot afford this now, but I have a few years to see that mileage on the reman CVT.

Replace the CVT in the Freestyle with the 6F in the Taurus X. I know this isn’t easy. The engine should bolt right up, and the mounts should be pretty close (I have a welder and a hammer) but the ECU is the tricky part. This is not a slam dunk.

Replace the CVT in the Freestyle with the Aisian in the 500. This is only slightly more of a slam dunk, because it’s probably the same ECU. I just need to find out how to flash it.

Learn to rebuild the CVT myself and build a great one and keep it onhand as a spare. My neighbor has a lathe and Bridgeport in his basement. I am a degreed engineer. It would take a while, but it could work.

Sajeev answers:

Oh yeah, this is totally a Piston Slap worthy article. Not like we haven’t done this before, ya know. And while I am (a little) surprised that a Ford Reman transmission does this poorly, who knows who actually did the rebuild! It’s an orphan design, which is never good. The ideal transmission for the long haul of ownership is something with tons of support, and GM transmissions have usually done the best for decades, for this reason. And if you can’t procure a 100% new, never rebuilt CVT assembly, I agree with you.

Having done transmission swaps before (and truly hating myself during that time) and knowing a bit about Ford electronics, here’s my recommendation: do that 6-speed swap. Get a Hollander Interchange manual to find out which Fords used the same vintage 6-speed as the same year of your Freestyle. If you can easily snag that gearbox from the same vintage Five Hundred, you are set. But who knows, maybe there’s a cheap wrecked Fusion nearby that has the same part for much less! It all depends on the market and availability.

From there you will need to see what’s different in the mounting and wiring of the transaxle on the subframe. Maybe you need a different mount, maybe not. Perhaps there’s an extra wiring harness, or a completely different one! Maybe a new shifter in the console too. Hopefully not, and a factory shop manual with wiring diagrams will help.

Once you clear that hurdle, the final part is easy. The ECU’s are pretty simple, as Ford hasn’t made a significant change in them during this era. Odds are you can take any one of them and re-flash the correct transmission logic with a brilliant person and an SCT tuner in his pocket. Which will set you back up to $500, I suspect. That’s your fallback, because I suspect getting a matching computer from a donor Ford Five Hundred will make it all work great…but if not, the SCT-tune is the way to go.

It will be a ton of work, both in research and sweat equity. But I suspect a smart dude like yourself can get this done for under $1500, if you get lucky with the cost and quantity of parts needed for the swap.

Best of luck.

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