Greetings All,
I have a 2016 Volkswagen Passat that experiences shaking and hesitation when accelerating after slowing down to low speeds or full stop. I have the 1.8L 4-cylinder turbo with 96,000 miles.
I scanned my computer and it came back with 3 codes: P2336, P2339 (cylinders above knock threshold), and P102F (torque limitation due to fuel pressure) - Supposedly the dealer "fixed" this with the new fuel pump but I guess not!
Any ideas? Thanks.
You are most likely experiencing low speed pre-ignition, and it happens exactly at the situation you just described...low engine speed with high load. It is VERY common on turbocharged engines. Further supporting this are the knock codes you are getting. What oil rating are you using? Any oil rated below API SN+ will cause super-knocking due to the high calcium content from the additives. When oil vapors from the PCV are sent into the engine, they ignite the air fuel mixture prematurely, causing detonation. Oil has a low octane rating and will easily ignite due to the higher compression from the turbocharger. For your next oil change, make sure you use this new oil. API SN+ was specifically introduced to address this issue. Trust me, I had this issue before on my BMW. I had no idea what was wrong until I did some research on all this. When I switched to SN+, the issue disappeared.
The fuel system on the car is just fine. The low fuel pressure code is most likely part of the safety feature turbocharged engines have when they sense super-knocking. It's to stop the injectors from spraying gas for a few cycles to prevent the premature ignition and protect the engine. Loose carbon deposits that enter the chamber will also cause this, so if you haven't done a carbon cleaning yet, now is the time.
@razmigb
Thanks. Three questions: 1) Would using the wrong oil also contribute to excessive oil consumption (like 1 qt every 1000 miles)?
2) Would it be a good idea to have the PCV valve replaced?
3) Would the oil issue have anything to do wit the shaky/jerky acceleration at low speed?
Thanks.
1) using the wrong oil doesn't necessarily contribute to oil consumption. There are more factors that need to be taken into account like worn out piston rings, how much oil vapor is being sent into the intake by the PCV system, etc. Do you do your own oil changes? Maybe it was overfilled with oil. Overfilling the oil causes a lot more oil vapors and can also cause some oil to "splash" near the ventilation tube and will send liquid oil into the intake. You can take off your turbo inlet pipe and check if there is an extreme amount of oil on the sides of the tube.
2) Again, check to see how much oil there is inside of the intake pipes. If you see too much oil and the oil was not overfilled, then the PCV valve might be stuck open. That might explain your high oil consumption.
3) Yes, I explained this in my answer. Oil that is not rated API SN+ contain high calcium content, which makes the oil ignite in the cylinder and prematurely ignites the air/fuel mixture causing the super-knock.
@razmigb
When you switched to API SN+ oil how quickly did you notice the LSPI go away/ EPC light not show anymore, right away? Sorry if this question doesn't make sense.
It took a day or two before everything started working normally again. I did not have a check engine light at all; I had to do lots of research. On BMWs, it stores a shadow code for which cylinders super-knocking occured and it can only be seen using dealer level tools (Bimmerlink, Bavarian Technic, etc.) I'm wondering if VW stores shadow codes for super-knocking other than regular knock codes and if the dealer saw them? Liquimoly has great oils for VW and other Euro cars with SN+ ratings.
@razmigb
Thanks! Any opinion on Mobil 1 - 123843 Extended Performance High Mileage?
@floridachris
As long as it is a European formula with Volkswagen's approval (can find on the back) and SN+ rated. Pennzoil Platinum Euro 5w-40 is API SN+ rated as well as VW approved. Pennzoil is good too. I did not find any Mobil 1 oil that is API SN+ for Euro cars. But you can do more research on which oil you want to use.
@razmigb
I checked my VW's engine bay and all I see is "Use only oil that expressly complies with VW 502 00". I do not see a viscosity rating (i.e. 5W-30, etc.) For instance, my mechanic has always put in 5W-30 but according to a Mobil 1 datasheet, their 0W-40 oil conforms to the VW spec. So does this mean I can use 0W-40 instead?
Volkswagen typically uses 0w-40 or 5w-40. 5w-30 is fine too. If you have cold days where you live like below 50 degrees F, I would use 0w. If it's rarely cold below 50 degrees F, then 5w is good. You want oil to be as light as possible on really cold days (0w). And you want oil to be as thick as possible when it gets hot (30-40 and 5w if rarely freezing temperatures).
Change the fuel filter and then pressure test the fuel pump. Also, load test the battery and alternator.
@yaser
Thanks for the advice. I just have the low-pressure fuel pump in the tank replaced at the dealer. Still hesitating, more often than not when I DON'T come to a complete stop, such as when I'm coming up on a red light that then turns green so I start to accelerate again. If I accelerate slowly it seems to work fine. It's if I really press the petal (not to the floor but just give it "normal" gas) that it hesitates for a second or two. Does that change anything?
@floridaChris
I know that this comment is old but did you ever find out what the root problem is with your car? I am having exactly the same issue with my 2016 VW Passat and it has about 100,000 miles on it. I have an independent local mechanic that works on VWs but he can never seem to completely replicate the problem so I am going on 1 year with this issue.
@iwanttokeepthispassatgoing welcome to the forum! I appreciate that you tried to search for similar questions first before posting. If you don't get a reply from the topic starter, I suggest you create a new topic for your question. That way you will get better help. Good luck!
It may be that dreaded DSG transmission starting to go out. Do you feel it misfiring at all?
Do you have any check engine light or any saved trouble codes?
@inthrustwetrust
It had a low fuel pressure code (dealer fixed with the new fuel pump) and a cylinder knock above threshold code (EPC light would come on randomly) which the dealer analyzed the gas and said it had too much ethanol. The dealer said just drive the gas out and fill up elsewhere which I did and haven't seen the EPC light yet (knock on wood). No other lights on the dash though. How do I know if I have a DSG transmission and if it's going out?
@FloridaChris
Most Passats are fitted with the DSG dual clutch transmission. Does your transmission shift hard at all? This may be of some use to you - https://www.youcanic.com/guide/volkswagen-transmission-problems
If you don’t have codes, you’ll need to visit a mechanic who specialises in VAG vehicles and who has a dealer level scan tool (VCDS) to look at what’s going on.
What’s your car’s mileage & engine?
@inthrustwetrust
Umm, I wouldn't say it shifts hard. I have the 1.8L 4-cylinder turbo with 96,000 miles.
As mentioned in the other answer, load test your battery & alternator.
@inthrustwetrust
Will do. And scratch what I said about the EPC light not coming on anymore. I just gave a friend of mine a ride home and it came on twice in the space of 2 hours. (If I turn my car off, wait 10 seconds, and start it again it goes away and drives like normal)
I scanned my computer and it came back with 3 codes: P2336, P2339 (cylinders above knock threshold), and P102F (torque limitation due to fuel pressure) - Supposedly the dealer "fixed" this with the new fuel pump but I guess not!
Any ideas?
@FloridaChris
Goddamn VWs and their dashboard warning lights!!
It didn’t cross my mind earlier, but is your car still under warranty by any chance? If it is, I’d make them fix it for free & not take no for an answer.
Your new fuel pump should still be under warranty since they just changed it. I’d go back to the dealer & demand my money back since I’m sure it a big chunk of $$$ for a fuel pump on a Passat.
Unfortunately, 5 yrs is still too early for a VW to turn into an endless money pit.
@inthrustwetrust
I agree, the veh itself isn't under warranty but the fuel pump has 12 months/ 12,000 miles. I just concerned they are going to keep blaming the cylinder knock on "bad gas". Sounds like BS to me.
@FloridaChris
The trouble is, if a new O2 sensor & a new knock sensor fixes it, great! If not, the dealer sounds like they haven’t got any idea how to diagnose it. In that case, you’re better going to an independent mechanic who specialises in VAG vehicles & who has good reviews from the people you trust.
@inthrustwetrust
Why do you say a new O2 sensor? And as far as the jerky shifting from low speeds, could that be the tranny valve body?
@FloridaChris
Sometimes it may mean that the sensor is detecting a too rich air/fuel ratio.
Jerky shifting in the lower gears is a classic sign of problems in the DSG transmission. Maybe something to do with the mechantronic unit of the transmission - just do a simple google search for ‘DSG jerky low speed’.
@inthrustwetrust
Would the too rich air/fuel ratio cause the cylinder knock sensor to fire off the code?
I googled DSG jerky low speed and from what I'm reading it seems normal for that kind of transmission. How do I know the difference between normal jerky and "my tranny is dying" jerky?
@FloridaChris
An independent mechanic who specialises in DSG transmissions should be able to easily tell the difference with a dealer level scan tool.
Take a second opinion, from an independent mechanic who specialises in VAG cars, on the other codes before you spend any more money at the dealer.