Piston Slap: A Self-defeating Technology Disorder?

Sajeev Mehta
by Sajeev Mehta
piston slap a self defeating technology disorder

Felix writes:

Got a Mazda 3 hatch to replace my 29-year-old MR2, and while it’s no MR2, it has its own benefits. But I detest Hill Launch Assist, and the power steering is the biggest reminder that it’s no MR2.

The Mazda power steering is better than I expected, but it’s still the first thing I notice when I start it up and always makes me want the MR2 back, three years later. I tried turning the engine off on a private road with just enough slope to keep moving, and it’s kind of scary to imagine that happening on a freeway, it’s so stiff and jerky. Is there any way to disable it and having just plain manual steering, to see what it’s like?

As for Hill Assist, what annoys me the most is not knowing if a slope is enough to trigger it or not; if I expect it, and it didn’t engage, there’s a tire chirp for no reason, and if I don’t expect it but it did engage, I sometimes kill the engine unless I’m paying attention. I can understand its attraction for weenies who are just learning stick, but I don’t need it and don’t want it.

Sajeev answers:

Calling this a disorder is a bit much, so perhaps let’s just do it, to it.

Regarding the (intrusive?) Hill Launch Assist, considering these links ( here, here) and what little I know about SCT’s tuning parameters, there’s a slim chance a performance tune could disable Hill Launch Assist while giving you a few more ponies. Better ask SCT, as I had the opportunity to 100 percent kill AdvanceTrac on my 2011 Ranger. But my tail-happy little rig should default to implementing mindless, stress-free control on slick roads. I am rather surprised you’d defeat Hill Launch Assist for similar reasons.

But hey, I live in a flat city so who cares what I think?

As previously mentioned, you can probably pull a fuse/disconnect the plug at the steering motor to experience manual steering on a car with big-ish wheels and a small tiller. I suspect you will regret it the minute you take a low speed, high steering input, parking maneuver.

[Image: Mazda]

Send your queries to sajeev@thetruthaboutcars.com. 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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  • Burgersandbeer Burgersandbeer on Jan 06, 2018

    My '08 5 series has hill assist. I had no idea when I bought it. The first time I expected it to roll and it didn't I thought I left the parking brake engaged or something else was wrong. Definitely a weird feeling. After 19 years in manuals I don't need it, but I can see it being convenient in some of the steeper areas of the SF area. Hopefully having it doesn't completely erode the hill start skill.

  • NG5 NG5 on Jan 06, 2018

    Surprising that there isn't a menu option to disable Hill Assist. There is on the Ford I drive. I curbed a wheel the first time I experienced it because I was parallel parking on a hill and didn't want to shift into reverse. I didn't realize what the car was doing. The system completely fooled me about where the clutch catch point was, and as soon as you touched the throttle the brake would drop entirely. Very disorienting first experience. I turned it off for months, but now I leave it on because I think it's better for clutch wear on hills. I hate having to move quick to avoid rolling back in traffic, and the temptation to ride the clutch if traffic is creeping uphill is too great. I'd recommend learning the system and getting used to it for those reasons.

  • Nrd515 I bought an '88 S10 Blazer with the 4.3. We had it 4 years and put just about 48K on it with a bunch of trips to Nebraska and S. Dakota to see relatives. It had a couple of minor issues when new, a piece of trim fell off the first day, and it had a seriously big oil leak soon after we got it. The amazinly tiny starter failed at about 40K, it was fixed under some sort of secret warranty and we got a new Silverado as a loaner. Other than that, and a couple of tires that blew when I ran over some junk on the road, it was a rock. I hated the dash instrumentation, and being built like a gorilla, it was about an inch and a half too narrow for my giant shoulders, but it drove fine, and was my second most trouble free vehicle ever, only beaten by my '82 K5 Blazer, which had zero issues for nearly 50K miles. We sold the S10 to a friend, who had it over 20 years and over 400,000 miles on the original short block! It had a couple of transmissions, a couple of valve jobs, a rear end rebuild at 300K, was stolen and vandalized twice, cut open like a tin can when a diabetic truck driver passed out(We were all impressed at the lack of rust inside the rear quarters at almost 10 years old, and it just went on and on. Ziebart did a good job on that Blazer. All three of his sons learned to drive in it, and it was only sent to the boneyard when the area above the windshield had rusted to the point it was like taking a shower when it rained. He now has a Jeep that he's put a ton of money into. He says he misses the S10's reliablity a lot these days, the Jeep is in the shop a lot.
  • Jeff S Most densely populated areas have emission testing and removing catalytic converters and altering pollution devices will cause your vehicle to fail emission testing which could effect renewing license plates. In less populated areas where emission testing is not done there would probably not be any legal consequences and the converter could either be removed or gutted both without having to buy specific parts for bypassing emissions. Tampering with emission systems would make it harder to resell a vehicle but if you plan on keeping the vehicle and literally running it till the wheels fall off there is not much that can be done if there is no emission testing. I did have a cat removed on a car long before mandatory emission testing and it did get better mpgs and it ran better. Also had a cat gutted on my S-10 which was close to 20 years old which increased performance and efficiency but that was in a state that did not require emission testing just that reformulated gas be sold during the Summer months. I would probably not do it again because after market converters are not that expensive on older S-10s compared to many of the newer vehicles. On newer vehicles it can effect other systems that are related to the operating and the running of the vehicle. A little harder to defeat pollution devices on newer vehicles with all the systems run by microprocessors but if someone wants to do it they can. This law could be addressing the modified diesels that are made into coal rollers just as much as the gasoline powered vehicles with cats. You probably will still be able to buy equipment that would modify the performance of a vehicles as long as the emission equipment is not altered.
  • ToolGuy I wonder if Vin Diesel requires DEF.(Does he have issues with Sulfur in concentrations above 15ppm?)
  • ToolGuy Presented for discussion: https://xroads.virginia.edu/~Hyper2/thoreau/civil.html
  • Kevin Ford can do what it's always done. Offer buyouts to retirement age employees, and transfers to operating facilities to those who aren't retirement age. Plus, the transition to electric isn't going to be a finger snap one time event. It's going to occur over a few model years. What's a more interesting question is: Where will today's youth find jobs in the auto industry given the lower employment levels?