Tdi ALH cutting power/jerking on acceleration

[blah-kay]

Hey guys, my problem is that my car is jerking or stuttering for a better term only during acceleration. It's not a motor mount shake or anything, it feels like the car is cutting boost or fuel entirely. The jerks are violent but don't happen in rapid succession. It happens randomly so I can't diagnose it properly, which makes it frustrating. I managed to get a vag-com graph when it was happening (will post it below). I graphed IQ, the n75 %, rpm, boost, and throttle petal %. For the disclaimer, was afraid I wouldn't be able to figure out how to turn Exel into a graph (I couldn't figure it out) so I took a screenshot of the live graph. Only look at the beginning of the graph right before I let off the throttle. You can see there is a random cut in fuel and a slight cut in the n75 valve %. After this, I changed my n75 valve and still have the problem but seeming less prominent or as often. I have a boost gauge in the car and when the jerking happens, the boost drops, this would make sense if fuel is cutting. But, when the car is running properly boost is nominal and the wastegate works as it should keeping me around 14 psi, with no abnormalitys. I have an EGR delete for reference. I have not done a boost leak test. But within the past year, I have changed all the vacuum lines to silicon ones. Not sure where to start, I didn't want to start throwing piles of parts at it. I think it's either a fuel or boost issue, maybe both. Seeing what you guys think, and where I should start.

http://imgur.com/a/mobydkU

 

[Gothmolly]

JSRMonster told me once there's a "smoke map" - where the car knows how much fuel to use based on the airflow. (Tuning involves fiddling with this). So maybe its a flaky MAF? If you disconnect the MAF, the car runs on a basic RPM mode where it knows that at X RPM it should be ingesting Y fuel. It won't run as powerfully or efficiently, but it should run solid and be consistent that way. Unplug the MAF and take it for a drive?

 

[blah-kay]

JSRMonster told me once there's a "smoke map" - where the car knows how much fuel to use based on the airflow. (Tuning involves fiddling with this). So maybe its a flaky MAF? If you disconnect the MAF, the car runs on a basic RPM mode where it knows that at X RPM it should be ingesting Y fuel. It won't run as powerfully or efficiently, but it should run solid and be consistent that way. Unplug the MAF and take it for a drive?

Okay, the problem hasn't been happening the last couple of days, but it's only a matter of time. Once I catch it, I'll unplug the MAF and get back to you

 

[BobnOH]

Malone Tuning has a routine on their site that will plot your data, but I like to do it myownself using
Dropbox link - LogPlottingApplication.zip
No stored codes? Could mean it's mechanical, like a failing DMF. Does not present as a MAF error.

 

[blah-kay]

Malone Tuning has a routine on their site that will plot your data, but I like to do it myownself using
Dropbox link - LogPlottingApplication.zip
No stored codes? Could mean it's mechanical, like a failing DMF. Does not present as a MAF error.

No codes besides my usual EGR, and no air bubbles in the lines anymore. I just changed the IP main head O-ring and the plastic T on the fuel filter.

 

[shoebear]

I wonder if it's an electrical fault of some kind, like the wiring to your IP or the relay (can't remember, but it's infamous) that powers your ECU? Or some other electrical problem. Got squirrels? They like to chew wiring (I know from personal experience). Maybe take a good look at all your wiring and connectors, including under the cowl where the ECU is.

 

[blah-kay]

I wonder if it's an electrical fault of some kind, like the wiring to your IP or the relay (can't remember, but it's infamous) that powers your ECU? Or some other electrical problem. Got squirrels? They like to chew wiring (I know from personal experience). Maybe take a good look at all your wiring and connectors, including under the cowl where the ECU is.

I checked the wires nothing that stands out, everything seems connected.

 

[blah-kay]

JSRMonster told me once there's a "smoke map" - where the car knows how much fuel to use based on the airflow. (Tuning involves fiddling with this). So maybe its a flaky MAF? If you disconnect the MAF, the car runs on a basic RPM mode where it knows that at X RPM it should be ingesting Y fuel. It won't run as powerfully or efficiently, but it should run solid and be consistent that way. Unplug the MAF and take it for a drive?

It was just happening, I pulled over and unplugged the MAF, and it still happened. When it cuts at a low rpm I can hear the wastegate open through the exhaust(boost issue? just changed my n75 ). When looking at the wiring tho, I noticed my idle wasn't entirely smooth, kinda shakey, which isn't out of the ordinary for my motor, it picks and chooses when it wants to have a smooth idle. Any recommendations on how I should graph it to see exactly what is happening? I've been graphing blocks 1, 2, and 11.

 

[blah-kay]

Update: I have a new code P0216 which is an Injection Timing circuit malfunction! I checked the timing and it's within spec. I'm going to check the transfer pump in the tank soon for restrictions. I already replaced the fuel filter. I don't think it's injector #3 for within the last year I got an entirely new set of injectors from Xmanturbos, I also run the grey diesel Kleen to keep them happy. If that's not it, I think when I was having my head seal problem where the pump would go dry every day for a while, it might have damaged the pump, so I may need a new IP entirely. Which sucks because they are so much $$$ , and I'm a broke college kid. If anyone has any other recommendations or ideas, I would appreciate them greatly.

 

[CanadianALH]

The VE cars don't have in tank lift pump unless it was added by a PO. I would try a IP reseal first.

 

[jmodge]

I would start with adjusting the IQ to see if it goes away. Also check the resistance of the #3 injector

 

[Gothmolly]

Isnt there a way with vagcom to track fuel injected PER injector? Maybe you have 1 that is flaky or has a piece of junk in it?

 

[CanadianALH]

Isnt there a way with vagcom to track fuel injected PER injector? Maybe you have 1 that is flaky or has a piece of junk in it?

Measuring block 13. Injection quantity deviation. That would be a good one to look at. According to older threads +-1.5 is good.

 

[burpod]

checking the pump timing graph isn't enough to verify timing is behaving. take an 004 only log. or 001-004 together

 

[sisyphus]

Try a different pedal?

 

[blah-kay]

My IQ is sitting around 3.7, and I checked my #3 resistance, it was 115 ohms. Haven't graphed blocks 13 and 4, will do it when the problem comes back.

 

[blah-kay]

I'm officially losing my mind. The intermittent cutting and jerking stopped for an entire month. Then yesterday it happened, only once. Then today twice. I can't get a measuring blocks log on it because of the sporadicness and scarcity. I'm truly at a loss.

 

[jmodge]

Did you raise your IQ?

 

[CanadianALH]

Maybe its a alternator pulley had a similar issue when I would step on it it would stuble and flash a battery light, did it like once without the light. Felt like it was a fuel cut but it was the pulley slipping, changed alternator pulley, tensioner, idler and belt and it fixed it.

 

[IndigoBlueWagon]

I have two thoughts. My car was cutting out on the highway earlier this year, but only intermittently. Seemed it happened when the cruise was set and I was going down a hill. For the life of me it felt like a fuel cutout. Turns out it was the N239 which operates the anti-shudder valve. It was shutting randomly and choking the engine for air. But I did get a code for it.

The other thought that occurs to me is maybe you have a failing injection pump shutoff solenoid. That could, I suppose, trigger a pump timing code. Not sure how to test that. I know you should be able to hear thes solenoid click when you turn on the ignition key, but if it's only an intermittent failure that might not help.

 

[CanadianALH]

Have you checked relay 109? A local auto parts store should have a relay tester. Have you looked at the wiring maybe it's a bad ground or a wire that is warn out and it shorting out from time to time.

 

[blah-kay]

I did lower my IQ, it sits around 1.6-2.3ish. I have the 11mm pump, bigger injectors, and other supporting mods, so it can handle the rich mixture. It can't be the N239 because I have an EGR delete. I have tested the solenoid cut-off in the past and have heard the clicking. Not sure it's the alternator pulley since it happens at low RMP with little throttle, also the battery light doesn't flash. ( it has also been changed within the past year.). I'll definitely check relay 109. Thanks for everyone's input! I was feeling pretty crappy about the issue.

 

[burpod]

I did lower my IQ, it sits around 1.6-2.3ish. I have the 11mm pump, bigger injectors, and other supporting mods, so it can handle the rich mixture. It can't be the N239 because I have an EGR delete. I have tested the solenoid cut-off in the past and have heard the clicking. Not sure it's the alternator pulley since it happens at low RMP with little throttle, also the battery light doesn't flash. ( it has also been changed within the past year.). I'll definitely check relay 109. Thanks for everyone's input! I was feeling pretty crappy about the issue.

running like that, with 11mm + big injectors, i can tell you from a lot of first hand experience and testing, a lot of tunes will have a lot of odd issues especially in sensitive areas of lower rpm/light throttle (usually from too much advance). that said, from the randomness of the symptoms it sounds likely it is more of a hardware issues. however, things can compound in odd ways. it could easily be a hardware issue that has also mixed in with tuning problems.

"rich" is very relative, and a blanket statement, especially since you really don't have any idea what the maps are doing. if you have big injectors, you really shouldn't be running rich any of time time, if the tune is good. you would only run "rich" under heavy fuel if you're trying to push more fuel/power than the turbo can handle boostwise. larger injector/pump car can (and should) run just as clean and efficient as a stock weak fueled 10mm/.185 - if anything, imo, it can run cleaner with such short injection durations.... if it done right.

you shold take a full driving log somewhere - commute, grocery store - of 011-001 and post up the log data. a little graph pic is fairly meaningless and has no context.

and boost dropping -really doesn't necessarily mean fuel is being cut (although it might ultimately be), there can be a lot of reasons for that. timing problems (internal to pump), boost control problems... things affect each other very quickly

 

[J_dude]

I did lower my IQ, it sits around 1.6-2.3ish.

Remember, IQ numbers are backwards, smaller number actually means you raised the IQ.

 

[blah-kay]

Ok, so I've had a good 3 months of mostly uninterrupted driving; until today. I was door dashing when my car suddenly started doing the power cutting issue, but this time it was multitudes worse than it ever was. It was so bad that I couldn't even accelerate to the speed limit much rather get out of first gear without the motor killing. It didn't even want to rev past 3k in neutral. I barely limped the car back to my house and did some research. When I got back in my car to get logs and diagnose the problem was gone; no symptoms whatsoever and the car only sat for around an hour or so. I wish I was able to log the issue. Anyway, I got the logs that were recommended to me. I'll link them below.
Here is blocks 01, and 11 that @burpod asked for LOG-01-001-011-xxx(blocks 01^J11).xlsx
And these are blocks 01, 04, and 13 that @CanadianALH and burped asked for regarding timing and IQ LOG-01-001-004-013 (blocks 01^J04^J13).xlsx

 

[csstevej]

Maybe you have a flaky crank shaft position sensor……they usually don’t set a code….. and can give you those symptoms .

 

[IndigoBlueWagon]

They also can lose internal connections when they get hot. So it would make sense if it runs OK after sitting a while.

 

[blah-kay]

I replaced it within the past year with the rebuild, is it common for them to fail? Also, I'm going to start carrying my laptop with me when I drive so if I get the symptoms I can at least get a log. What blocks do you guys recommend I record?

 

[IndigoBlueWagon]

Not common. If it was original to the car it would be reasonable to have had it fail. But not if it's a year old, unless the part is faulty.

 

[csstevej]

Was it OEM or aftermarket ?