Hello guys, definitely a new guy here and I'm aware of the proper introduction post that's the norm with online forums. However, my time is short on this issue, and any and all help is greatly appreciated.

First of all, the car is a 2004 A4 1.8T engine code AMB with the CVT trans and about 80k miles. It recently had the transmission replaced with a brand new unit from Audi directly due to a bad sensor destroying the entire thing (gotta love these cars right?)

Anyway, the problem existed before the transmission issue, however it has progressively worsened over the past few weeks after getting the car back.


Here it is:

Under any acceleration (light, mild, WOT) between 2k and 3k rpm, the entire car will shudder, as if it's struggling to accelerate. Then, as suddenly as the problem arises, it goes away and the car runs smooth, but has a significant power loss above this RPM until redline.

There is no problem at idle, it does just fine under moderate driving, but in those RPM ranges is where it is having trouble.

any leads we can start on? thanks in advance guys.

-david

 

heh heh, my car might be your cars little brother

I exhibited somewhat similar symptoms, and found out that the Cam Follower was shot...yours sounds like it acting up worse than mine did...I would check it right away, as continued failure will cause much more major damage. I found out the first time that it was a known failure point, but I found out from this site, that just because it's been replaced once, it's still a failure point...at 80k I'd say you are right in that second failure range. Search "follower" in the DIY section...it's not a terribly difficult process.

I could be wrong about all that, but it's worth a look.

Shortly after I replaced the cam follower, I blew up my CVT as well welcome to the board.

 

Yea.... problem's still there.


any help guys? computer was throwing P0300, P0301 and P0304 codes as a misfire in cylinders 1 and 4. however, i switched the coils with cylinders 2 and 3, but the problem still exists and the PCM is still showing misfires in cylinders 1 and 4.

any insight on this problem? ordered an OEM check valve and replaced the one i'd rigged up, still the same problem.

i'm pulling my hair out because of this issue, so any help would be appreciated

 

Slack jaw, you really think its the cam follower?

(2003 A4 1.8T [AMB]). I have replaced coils and plugs less than 10kmi ago. Also, replaced fuel pump along with fuel filter less than 8k mi. Fuel pressure fine at rail. New CVT [trans] recently installed (3 weeks ago).

Vehicle has been suffering mostly light stumbling at all stages of power, however on occasion there will be a violent misfire. Low boost as well. Flashing CEL. Ran codes: P0300, P0301, and P302 and P0304. (General/Random misfire + Misfires on cyl 1, 2, and 4). Figured that since the coils were so new (latest revision, as well), it was likely a vacuum leak. Checked. Replaced two vacuum check valves. Engine develops boost now. Cleared codes. Ran Audi recommended Road Test. No CEL. Returned home. Let car sit over night. Drove to work in the morning. Car is running great. Feels as if it did the day I bought it.

Driving home, 70 mph, vehicle begins violent misfire. Pull off fwy. Run codes. P0304 (misfire cyl 4). Swap coils with cyl 3. Clear code. Vehicle still feels like misfire in one of the cyl. Run codes. misfire has moved to P0303 (cyl 3). Must be the coil pack - $26 at Kragen (lifetime warranty too). Replace coil in cyl 3. Clear code. Drive vehicle. FLASHING CEL. Run codes: P0304 (misfire on cyl 4). Swap with cyl 4 with new pack in cyl 3. Clear code. Drive car. Runs fine. Light stutter on heavy acceleration.

The problem is still there. I know it is. The car feels heavy on acceleration. It stutters b/t 2k - 2.8k rpm - which points to vacuum issue (this is where the vacuum lines have made transition to full boost.) Any ideas on how to identify a vacuum leak????

IF NOT VACUUM, then what? Replace the other 3 coils and see what happens? Maybe the plugs again (gap is good, btw)?? If the coils are generating spark, that leaves only two other sources of issue: air and fuel. So, vacuum/boost line leak could be issue or an injector could be the source of this problem. However, either of these do not explain the migration in misfires from various cylinders.

Could a ruined CAT cause such a series of events to occur, and also cause a coil to fail?

Please help if you can.

thank you!

 

found a port on the top of the transmission (GGT code trans) which looks to be where a speed sensor would plug into. it's at about the 1 o'clock position if you're looking coaxially at the transmission from the front, and is visible after removing the coolant reservoir from the top of the engine.

anyway, seeing as how i recently had the transmission replaced, i just thought i'd ask around to see what that is.

it has a threaded hole for a bolt to secure (whatever plugs into there) to the trans, and you can see the straight cut teeth of the flywheel very close to that opening. my guess is some kind of electronic speed sensor. can anybody identify what i'm talking about? thanks in advance.

 

neh man, I think I mis-read your OP a bit, and after having read around here a lot more lately, I think mine was simply going into limp mode....but it WAS happening at certain rpm/mph under certain types of loads...that's why I thought it might be similar.

I would think if they replaced your fuel pump that a new follower would have been part of that :idk:

You have that CVT replaced by dealer? if so, you should have a 2 year warranty on that. Mine was bucking right before it gave out...I wonder if possibly they simply don't have the fluid topped off on it. That don't explain your misfire codes though...

You got a lot of different symptoms and indicators though, I couldn't begin to diagnose...side story, I seen a couple guys have problems with their ESP and dudes are swearing left and right that a faulty brake light switch is the culprit...so I mean, how do you begin to make logical sense of it all?

You replaced one of the coils? Have they ever been in for the recall? Might as well replace all 4?

 

Hi, I had a question, when you started your car did it make a struggling noise almost puttering, and did your check engine light start blinking?

 

When I start my car after it's been sitting a couple hours it makes a struggling puttering noise and it's like my engine is vibrating. It does it for about 15 seconds and then runs normal. Took it in and they can't find anything wrong w/it any thoughts?