nater321

First off my car, 1999 Audi A4 1.8t Q AEB Tiptronic Automatic.

My car has about 153,000 miles on it. I have replaced alot of parts in the last month/year. Just the past month, I replaced all four coils because I was getting two codes for coils. I also replaced the ICM oem hugo. As well as the Up stream o2 and Down stream o2. I have had a 3" test pipe in but never had these symptoms before so I can't say I think it's that. I also purchased NGK Double Platinum Plugs. Also I replaced the Fuel Filter, Breather hose, Coolant Temp sensor, Coolant Flange and all Orings, As well as exhaust manifold and exhaust gasket. Followed by a transmission fluid change as well as filter and gasket.

I have Vag Com as well as a Chilton and Bentley manual and im stumped. To get to the symptoms.. I can drive the car and be light on it and really no issue for the most part. Now when I give it full throttle or a good amount it will go up to about 3500 or so and then start to almost cut out or just start bogging/jerking. During the first week this happened, I was two miles from work and went to accelerate from 45 to 55 and it started to chug and jerk so bad that I had to let off the gas because it felt like it was going to stall. I tried to disconnect the MAF, then start my car and that only seemed worse and I could barley keep the car running yet alone drive to test it. I did buy replacement coils off ebay but im showing no codes for bad coils or misfires.


Any help or suggestions would be greatly appreciated, I have been throwing money at this problem and scratching my head on solutions or if it is some how the transmission for weeks. I need my car for a new job, and have time to check anything or diagnose with Vag Com or my Bentley. I also saw that I had a vacuum hose off on the fuel pressure regulator for a long time. I put a new hose on but could this have messed the regulator up for the time it was off?

njohnson88@student.cvtc.edu if you can help me or have any sort or tips or advice on where to start or how to narrow something down.

Thanks a lot,

Nate.

David.Norton

Hi Nate;
Never had that happen on my A4, but I had an old 5KTQ with exactly that problem. So my experience may or may not help you, but mine turned out to be a torn boot on the pressure side of the turbo. As the boost built it would push the tear open, venting a bunch of air off. The fuel injection would still supply the fuel called for by the inlet to the turbo, but the mixture went way rich as a lot of the air was venting, The car would flood, start chugging, and sometimes stall, after which it was very hard to start. On the 5K I had to flex the boots to see the tear, it would close up tight otherwise, so it took me weeks to find it. I too replaced a bunch of parts I didn't need to. So I hope that helps, and good luck with it.

turbo510

Ah, yes, the old flex boot! And they weren't cheap either. I realized that mine had a split after making a fast stop, which made the engine tilt a little, opening the split and stalling the engine. On Nate's car I'd suspect fuel delivery, bad MAF, or fuel pressure (regulator or even pump).

4Driver4

You only mention that you aren't seeing for coils or misfires...what codes are you seeing? Anything?

nater321

The only code I seem to be throwing now or even getting is a Cat below efficiency thrush hold. Or something of the sort, which I believe is coming from the 3" test pipe. I want to say it feels like some kind of fuel issue. Could I have damaged my fuel pressure reg with that vacuum line off for so long? Is there anyway of testing that? Also when testing the MAF, do I unplug after the car has been started?

Thanks for the replies guys!

nater321

I think I have narrowed down the problem guys. I just need some help figuring what this means... Well after doing the plugs, o2's, coolant temp sensor, trans fluid etc also including the throttle alignment. I now only get this code:

17963 - Charge Pressure: Maximum Limit Exceeded
P1555 - 35-10 - - - Intermittent

It's odd, I don't get this code until I really get on the throttle or after driving it for a while when the symptoms start to show up. I would almost say it goes into a limp or shutter, but it feel's like fuel or something because it almost wants to cut out or the more gas you give it the more hesitation. I hope this kind of makes sense. During the drive I brought with the laptop and vagcom. I started getting the symptoms so I pulled the code's and only got the Charge Pressure Code. I cleared the code and got on the throttle and it took off nice, no shutter or chugging/cutout. I don't know where else to go with this. I am hoping someone can explain to me what this might be or where I could start.

Thanks.

dusted

I'm new here, and I don't really have much professional experience with VW/Audi's, but I would think that whatever controls your wastegate/BOV might be causing issues. Check whatever mechanical implements are in place that control boost pressure, and make sure they function properly, then check whatever sensors relay this info to the pcm. Either your mechanical controls have fudged up, of the sensor is telling the pcm that there is too much boost when there's not. Just my .02.

Edwardo

Someone correct me if I'm wrong, but 99s have a MAF sensor not a MAP sensor, so it shouldn't be throwing that code. The fact that it's fine after he clears the code it means that his wastegate actuator is mechanically fine.

xsrfsno225x

MAF was the culprit on the same exact problem for me. I even unplugged it to test.