By on February 16, 2016

2nd_Volkswagen_R32

Nick writes:

I bought a used 2008 Volkswagen Golf R32 with 48,000 miles in January 2010 (5,000 only in the U.S., 3.2-liter NA V6). Every summer since then I’ve had issues as the weather warms up. Basically, it starts to act up when driving at around 85+ miles-per-hour or so, and it gets even worse if I’m stuck in any kind of stop-and-go traffic. The only sure fix is letting it sit and cool off for 30 minutes or longer.

Typically, right after starting off at a light, I’ll get a second or two of power before the power suddenly drops off and the car kinda burbles and burps. The tach will start to jump if I mash the throttle, but otherwise the revs stay on the low end of the gauge. When forced to drive in this condition, the computed mileage doesn’t seem to suffer, but going something like 20 miles once drained a quarter of a tank. More recently, for the first time ever, it actually died in an intersection and the battery light came on. Once I got it stopped and in park, it restarted fine.

I don’t get backfires. Others said they’ve noticed a strong gas smell at the car’s rear but I don’t think they observed drips.

I love the car except for this problem no one can figure out. The only theory others have offered is a fried fuel flow sensor. With the gas and recent engine stall, I wonder if it’s just flooding the engine or something.

Sajeev answers:

This has to be vapor lock!

Considering how jammed in that motor is in a VW Golf, the comments on this forum and the extensive diagnosis (?) time you’ve spent with mechanics — man, it’s gotta be vapor lock.

But how do you fix it?

You must protect the fuel line(s) from engine heat. Odds are that the area shown in the forum link needs said protective shielding, but there’s a chance that shielding isn’t enough: it can only do so much in an cramped compartment so thoroughly heat soaked. Cooling down a heat soaked shield could be worse than the initial problem, but try shielding the fuel rail first.

If that fails…dare I say it? It’s time for a boy-racer aftermarket hood with scoops, vents or something — anything to expose the engine to outside air. Maybe you can get a carbon fiber one if you like that look. I personally dig this unit if painted to match the rest of the car, but maybe it’s not vented aggressively enough for the VR6 motor.

Regardless, it’s certainly better than the stock hood, though you can also cut holes in your hood and install any sort of vent you wish. Hmm, the scoops from the 1987 Ford Thunderbird Turbo Coupe would look pretty sweet.

Off to you, Best and Brightest!

[Photo Courtesy: Wikimedia Commons]

Send your queries to [email protected]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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72 Comments on “Piston Slap: Vapor Lock and the Hot R32?...”


  • avatar
    CoreyDL

    “I bought a used 2008 Volkswagen Golf R32”

    Well there’s your main problem.

    • 0 avatar
      Nick_515

      Nope. Says bought in 2010 – that was 5 yrs ago – and no other problems.

      I know, I know… VW amirite.

    • 0 avatar
      RHD

      “…it starts to act up when driving at around 85+ miles-per-hour or so…”
      We would think a German-engineered VW would be designed to cruise at Autobahn speeds for hours, but apparently not!

    • 0 avatar
      28-Cars-Later

      PTVAGD

    • 0 avatar
      ihbase

      That is so helpful… because only VW cars ever have any mechanical issues.

      The owner states that starvation occurs both in moving traffic at 80+MPH and in stop and go traffic. This would suggest that the cause is not related to a lack of airflow over fuel components. Therefore, hood cops and additional ventilation will not yield any benefit. It is not a 351/400M. Additional airflow past the carb is not exactly applicable here.

      The proper way to diagnose the issue is to check fuel pressure, including monitoring pressure while driving. If you observe a pressure drop correlated to starvation, you can begin to address the cause.

      1. Filter restriction, or
      2. Defective fuel pressure sensor, or
      3. Bad fuel pump- I’m guessing that there is a lift pump and a rail pressure pump- but I am not familiar with the R32 motor.

      It is an interesting car and worth fixing. Start with a fuel pressure test.

      -Mike

      • 0 avatar
        EAF

        I would have a similar opinion; HPFP or cam follower, low pressure in-tank fuel pump, or an associated sensor. Before today I had not heard of a case of “vapor lock” in +20 years. It goes to show you that VW always lets down with their POS vehicles.

        O.P. take BBAll’s suggestion and dump it!!!

  • avatar
    bball40dtw

    Former MkV R32 owner here. It’s vaporlock. My R32 had it. I bought the car new, in Michigan. Then I moved to Tucson and it vaporlocked all the [email protected] time. I ended up selling it a guy that didn’t live in the desert Southwest. I made sure to inform him of the vapor lock issue before the sale.

    Get rid of it.

  • avatar
    CoreyDL

    I experienced vapor lock too, in an equal-to-VW reliable Dodge Dynasty. It went without diagnosis until my parents dumped it. Oh pre-Internet times.

    It’s almost hard to believe someone has a problem with an MKIV VW, or any VW for that matter. They’re the most reliable, luxurious, and sporty’s car’s available today. Regularly I have seen a Sirocco’s trounce M3’s at stop lights and also 911’s. VW is an honest company building good car’s.

  • avatar
    Pch101

    It sounds like vapor lock, but fuel lines, fuel pump and/or fuel filter could be the cause. Have those been checked?

  • avatar
    seth1065

    if it is vapor lock , can you do something with the grill to open it up to get more air in? I think Corey must have been cut off by a VW today as he is more angry at VW than usual.

  • avatar
    abracc

    I had an ’08 R32…died on me coming out of a turn and wouldn’t restart. If I remember correctly it was the fuel pump that needed to be replaced. Also, if I remember correctly, prior to it dying on me, it was replaced due to a recall by VW. When they performed the recall work, they accidentally did something to the new pump…that is why it died on me. Might check to see if there are any open recalls…..

  • avatar
    bludragon

    I think you just diagnosed the undiagnosable problem my very first car had. 3 different mechanics didn’t get there at the time and in the end I sold it for scrap.

  • avatar
    SCE to AUX

    “…it starts to act up when driving at around 85+ miles-per-hour…”

    The proposed ODB-III protocol will prevent vapor lock by stopping scofflaws.

    • 0 avatar
      rehposolihp

      What? Texas has toll roads that have 85 mph speed limits. So 85 plus or minus the 2.5% means you could be going as fast as 87.125 completely legally in Texas.

      Also, honestly you could be going more like 95 before any cop is going to even consider doing anything about the discrepancy.

  • avatar
    Sobro

    I’d go with fuel pump issues also. I just read a Car Talk forum reply that said if the fuel pump isn’t delivering pressure way above the vapor pressure of the fuel, then at high temps the fuel will evaporate. E-10’s vapor pressure is 15 psi at some standard temp, while straight gasoline’s is 6-10 psi.

    I also wonder about fuel pump cooling. Does the vapor lock ever occur with a full tank of nice, cool gasoline?

  • avatar
    JMII

    I’m 99% sure the vwvortex.com has the answer you seek.

  • avatar
    28-Cars-Later

    BART’S THOUGHTS: Remember what I told you… Just one thing… My car broke down… I’m Joe Namath… My car broke down… It was just vapor lock… vapor lock… vapor lock…

  • avatar
    Nick_515

    I think I have a similar problem, but I am not sure.

    I have a well-loved, reasonably well-maintained 2005.5 Audi A4. It has a similar powertrain to yours (unless you drive stick) which is the 3.2l (well 3.1 but who’s counting) na di and 6AT.

    I have had it for 40k miles (currently 123k) and love it dearly.

    It has done what your R32 does exactly twice. Both in the dead of winter, both after 300 miles of highway driving (65-90 mph), followed by stop-and-go approaching either Holland Tunnel or GWB in NYC. First time freaked me out as I could see the tunnel when it started burbling, unable to maintain RPM at 800. I was worried it would damage the transmission. 30 minutes later problem disappeared. Second time around I knew what it was, didn’t sweat it, managed it in 2nd gear, stopped doing it. Long story short – looks like some sort of vaporlock, and maybe more common in the V6es.

    On a side note, something now makes noise in cold mornings, especially when turning the wheel. Let’s see if TTAC is right and vdub monsters are coming to get me finally.

  • avatar
    dtmcdani

    Has this recall been performed?

    Recall Number: 09V093000
    Recall Date: 03/20/2009
    Component: FUEL SYSTEM, GASOLINE:STORAGE:TANK ASSEMBLY

    Problem Summary: VOLKSWAGEN IS RECALLING APPROXIMATELY 5,000 MY 2008 R32 (5TH GENERATION) VEHICLES. WHEN CERTAIN DRIVING CONDITIONS ARE ACCOMPANIED BY HIGH AMBIENT TEMPERATURES, THE FUEL TANK VENTILATION VALVE MAY NOT REMAIN FULLY CLOSED. IF THIS HAPPENS, LIQUID FUEL MAY ENTER THE FUEL TANK VENTING SYSTEM AND MIGRATE INTO THE EVAPORATIVE SYSTEM, SATURATING THE CARBON CANISTER. SHOULD THIS OCCUR WHILE DRIVING, THE VEHICLE MAY EXPERIENCE PERFORMANCE ISSUES (I.E., VEHICLE JERKING) AND THE MALFUNCTION INDICATOR LAMP (MIL) IN THE INSTRUMENT CLUSTER COULD ILLUMINATE. FUEL COULD LEAK FROM THE EVAPORATIVE SYSTEM LEAK DETECTION PUMP FILTER.

    Consequence: A FUEL LEAK, IN THE PRESENCE OF AN IGNITION SOURCE, COULD LEAD TO A VEHICLE FIRE.

    What Owners Should Do: DEALERS WILL REPLACE THE FUEL TANK VENTILATION VALVE WITH AN IMPROVED VALVE FREE OF CHARGE. THE RECALL IS EXPECTED TO BEGIN DURING MAY 2009. OWNER MAY CONTACT VOLKSWAGEN AT 1-800-822-8987.

    Read more at http://www.cars.com/recalls/volkswagen/r32/#mwbMtKOuXvYk3pgq.99

    • 0 avatar
      redmondjp

      Ahhhh – now this makes sense.

      So it’s NOT vapor lock in the traditional sense, where the liquid fuel turns to a vapor inside the system prior to the point of air mixture.

      This is an over-rich mixture situation, where rogue fuel vapors are swamping the engine via the charcoal canister vacuum purge line, to the point that the engine can barely run if at all.

      So it shouldn’t be called vapor lock because it isn’t.

    • 0 avatar
      Fordson

      “I love the car except for this problem no one can figure out. The only theory others have offered is a fried fuel flow sensor. With the gas and recent engine stall, I wonder if it’s just flooding the engine or something.”

      So “no one” can figure out how to search TSBs or recalls or service campaigns, but put up with a problem like this for five years?

      Yes, it’s a VW and it’s a problem…but they had this sussed out by the time these cars were a year old…had it figured out before this guy even bought the car. Moral of the story…regardless of the make or model of the car, new or used…you have to do your legwork and your homework.

    • 0 avatar
      bball40dtw

      I had that recall done and still had the vapor lock issue. Phoenix and Tucson are outliers though. There is a reason auto companies do testing down there.

  • avatar

    vapor lock ? Is that even possible with FI ?

    Last time I saw that, it was a 1979 Turbo Mustang with the horrid first attempt turbo. Problem was a “draw through” design with non pressurized carb, which on hot summer days (Black car, NYC pavement, stop and go traffic) fuel would pool in the long intake runners. (no intercooler here). boom boom stall.

  • avatar
    qfrog

    Step 1 is always buy a VCDS because you will need it again remember you bought a VW.

    Step 2 is pull fault codes

    Step 3 is post fault codes

  • avatar
    TDIGuy

    Can’t get this URL thing working properly, but there is a Simpsons quote to go with any subject.

    https://frinkiac.com/?p=caption&q=vapor+lock&e=S09E06&t=1300815&m=+BUT+THERE%27S+NOTHING+FUNNY+ABOUT…+VAPOR+LOCK.+IT%27S%0A+THE+THIRD+MOST+COMMON%0A+CAUSE+OF+CAR+STALLINGS.

  • avatar
    carguy67

    Definitely sounds like fuel vaporization–aka ‘vapor lock’–in the fuel lines. Cars with side-draft carburettors located above the exhaust manifold, like my Healeys, often have this problem. When I shut down a Healey engine for a brief period–long enough to, say, get lunch–then restart I get hesitation and stumbling until airflow through the engine compartment has cooled things down a bit. It may be ‘correlation without causation,’ but this problem only started when I had to start using E10, as pumps with real gasoline are getting scarce. I suspect the ethanol in fuel contributes to this.

    The hot engine start procedure for fuel-injected piston aircraft engines usually requires a ‘purge’ of the fuel system; which entails running the electric boost pump with full rich mixture for several minutes to both push the bubbles through, and to cool the lines. A stumbling engine on take-off is a bit unnerving.

    If the exhaust manifold is located anywhere near a fuel system component a wrap or ceramic coating–e.g. ‘Jet Hot’–might help.

  • avatar
    Duaney

    I had vapor lock with a 1996 Olds Ciera, fuel injected engine. Hot summer days after it was parked at various shopping stops. Cure was to pop the hood and let it cool. If the VW is vapor locking, the cures are to avoid ethanol if at all possible, run a cooler thermostat, and as well opening the hood when parked to cool it off.

  • avatar
    bubbajet

    Could this be a missing/damaged under-the-engine cowling causing poor airflow? I had a mid-2000s bug for a while and it had a really tight cowling below the engine. And, it had been damaged. I could see one of these forcing airflow around the upper parts of the engine compartment. More specifically, I can see where if this was missing you’d lose airflow out the bottom of the engine compartment.

    Seems like if it’s an airflow thing that developed later in life this could have gone missing or gotten damaged.

    Or I could be making ~***} up.

  • avatar
    Jgwag1985

    My brother has a 2010 Taurus SHO. He was experiencing a stumble problem, fuel starvation. They traced it to fuel line close enough to exhaust to cause problem. They (Ford dealer) put insulation/heat shield over fuel line. Problem went away and has never come back (3+ years later).

  • avatar
    turbobrick

    I’d blame the fuel pump. The Bosch pumps on my old Volvos get really cranky when the weather gets hot, you can hear them groaning. When one of them started going bad, the failure mode was inability to maintain fuel pressure when accelerating leading to engine cutting out for half a second as it kept gasping air. Eventually it would just stop running until the pump cooled off.

  • avatar
    Wade.Moeller

    You can’t get vaporlock in a fuel injected engine unless the fuel pressure is below specifications. Carbureted cars get vaporlock because they only use 8 PSI. More then that and the float valve won’t close. Fuel pressure in a Fuel injected system is much higher.

    Something is restricting the fuel flow and causing low pressure in high demand situations. Filter, blocked line, bad fuel pump(s), or a partially failed fuel pressure sender. Get a mechanical fuel pressure test set from Harbor Freight and go for a spirited drive with a buddy to watch the gauge. It should drop significantly from the reading at idle.

  • avatar
    luvmybeama

    dtmcdani called it. All lot of owners reviewing the car on Edmunds.com say they have had stalling and hesitation issues due to a saturated charcoal cannister/ faulty purge valve.

  • avatar
    Dgaylor72

    I’m sorry, but I don’t actually see how it could be true vapor lock. All fi cars have a return line back to there tank so there is constantly a flow of fresh cool fuel. I could see the possibility of the vapor canister saturated with raw fuel possibly. Or a weak fuel pump or regulator causing low fuel pressure.

    • 0 avatar
      JuniperBug

      Just because I love being pedantic, (and don’t have any specific knowledge on the R32), not all fuel injected systems use a return fuel line. Though considerably less common, there are cars that use a returnless system where the fuel pressure regulator is located at the tank, bleeding off excess fuel pressure right at the pump.

    • 0 avatar
      ahintofpepperjack

      Modern fuel injected cars have a single fuel line. There is no longer a return line.

      • 0 avatar
        JuniperBug

        Right you are.

        That’s what I get for focusing more on late-nineties designs and therefore presuming that returnless was an outlier. Sure enough, it seems that most, if not all, of the major manufacturers have gone returnless.

  • avatar
    Adub

    I hope you read this because it is probably NOT vapor lock. This is a fuel pump problem. The in-tank pump overheats and fails. Once it cools down, it’ll restart and run fine. The pump will diagnostic test just fine in the shop, but it will strand the dealer mechanic five miles down the road on a hot summer day. Once the pump was swapped out, no more problems.

    Not sure what causes the pump to fail the first time, but most of the cars I’ve seen with that problem either got gas with water (premium in low traffic areas) or had a high ethanol content.

    In every case, replacing the pump solved the problem. Believe me, when customers say they can only drive their car at night or when it is cold, you pay attention.


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