I have a1999 A4 1.8T with 120k miles.Since about mid December, I'vebeen having a problem during normal acceleration. When I roll on the throttle,it feels like something is hitting or jerking or stuttering during a certain RPM range (2,000 and 3,000 RPM). After 3,000 RPM, everything is smooth.

I took it to a dealer who diagnoised it as a transmission problem. The dealer said there were no failure codes showing. I replaced the transmission (ouch!!!) thinking that would fix the problem; however, it didn't. I had the throttle body cleaned also, but that didn't help either. The problem is worse after the car is warmed up. It is persistent!!! Someone told me it could be the turbo by-pass valve, butthis problem occurswhile accelerating, not after letting off the throttle. Help please.

 

when was the last time you changed the plugs and what plugs do you use.. tranny change.. man if it didnt grind or have any problems shifting why would you change it?

is it a 99.5 or a real 99.. meaning pre face lift.. its probibly a misfire, I would say get someone in your area to run some logs could be a bunch of things.. ICM, bad coil pack, needs new plugs.. all of which cost alot and you should try and find the problem.. where are you from?

 

I changed the trany because the dealer told me that was the problem. I know, it was a mistake. The same person who told me it could be the turbo by-pass valve, also said it could be the spark plugs. I haven't changed them for probably 3+ years. I think I have a true '99 A4. I live in Newport Beach, CA.

 

well go buy yourself some NGK BKR6E's about 2 bucks a peace.. (also find a new dealer) gap them to .28-.32.. If someone has a link to the Vag-Com locator chime in.. I have it at my house computer you should email some of the people that have a Vag-Com in your area and have them run some logs.. its hard to fix a problem you cant see, even though you dont throw a code dosent mean there is not a problem..
there are alot of things you can do once you know you have a misfire and where it is.. most comon probems are the coil packs, and the ICM.. both are expensive to replace i woudnt want you to spend a butt load of moeny with out first having a better grasp on the problem..
any mods? tip or manual..

 

I'm going to a guy tomorrow (the one who thinks it's the by-pass valve) and he said he will try to diagnosis the problem. I'll put new spark plugs in for sure. But, how would faulty spark plugs cause a problem only during a certain RPM range (2-3,000)? Wouldn't faulty spark plugs cause problems all the time? At any RPM.

No mods. (bone stock) and it has Tip.

 

it could be alot of things, but thats good your going to someone.. it is my understanding bad plugs can cause problems in any RPM range but I could be wrong have been b4.. i didnt say if was your plugs but if they are old its worth a shot being as it the cheepest fix and really easy to do.. also check the stems on the coil packs they are replacealbe on the AEB motors..

 

Thanks for your help. I appreciate it!!

 

Thanks for your help.

 

it really soulds liek the spark plugs to me. i had the same kinda problem in my jeep. it got so bad that i couldent go over 4500rpm and the car would get all jerky and it would feel liek the transmission was stuck and couldent go any more. changed the plugs and the truck drove liek a dream again

 

ouch, new tranny.. i hope you atlest kept the old one