Hi everyone,

I have a 99 A4 1.8T 2WD, 95000 miles.

Any help would be GREATLY Appreciated I've been searching all of the Audi forums and haven't found the solution to my problem..

My car is making a weird noise that sounds like someone blowing their nose or passing gas.. (for lack of better words!)

This only happens between 2200 rpm to 3500 rpm.

Once I hit about 4000 rpm in any gear, my engine chokes and can't go past 4000 rpm at all!

Also, if I try to accelerate a little harder than normal, my engine surges.

I have already changed out my ignition coils, ignition module, air filter.

I don't know what it could be. It's not burning any oil or anything..

I removed the throttle body once to clean out the carbon build up and put it back but didn't have a VAG-COM so I just unplugged the battery for a while to reset the ECU and changed out the ignition coils and module at the same time but it's still happening.

Anyone have the same problem and was able to fix it?

Thank you in advance!

 

I've not had this issue in our Audi, but my t-bird's cat plugged up and these were the symptoms.

We had our cats (the back two) replaced this spring as they were partially plugged. Power picked up when she crushed the flex pipes on a snow pie she drive over (snow that fell off teh roof and she did not notice as she came into the garage). Took it to a shop and he said the rear cats were part way plugged. I had not mentioned a pickup in power until AFTER he said that (not wanting to give him a reason to charge us for unnecessary work).

I hope it is not that however. Is it throwing any codes at all?

 

youve had your TB done??

 

My guess is a worn out diverter valve.

 

Will it like not go above it at all? Becuase if i remember right, when in neutral the govenor is set at 4k rpm so something there may be tweaked

 

surges like turbo surge? (do you know what that is?) do you have a boost gauge?

it would help a great deal if you bought/ stole from a friend a boost gauge and saw what is happening to your pressure when you experience this "surge"

sounds like a vacuum hose is split/poped off or a bad n75 valve possibly though that doesnt have much to do with limiting the rpms to 4k


does the needle hit exactly 4k and stop dead, will not move? does it bounce around a little like its hitting a governer? if you have it at like 3900 rpms in say 3rd gear, if you drop it down to second to get above 4k rpms what happens?

 

Does the farting happen when you goose the throttle or is it constant? If you have a mighty-vac, you can check the diverter valve.

Vibrations? Bucking? Misfires? Codes? MIL?

 

Thanks for the reply everyone, please see my responses below..

I was thinking it could be the diverter valve, but didn't know how to check if it's still working.

Mlaubach - The guy that had the car before me drove it for a while with a bad thermostat sensor which showed the engine temp as cold all the time. I guess this could have dumped extra fuel and caused the cat to get clogged. If this was the case, I would think the O2 sensors would catch it and correct it. Anyways, I hope it's not my cat.. I know that it's "recommended" by most people to change it by 90K.

01afour - I just took it out to clean the carbon build up on it and then put it back in. I didn't change the gasket though but if there's a vacuum leak from there, I don't think it would cause my car to perform this bad.

AudiCross - It goes to maybe 4100-4200 and then just gets stuck there even though the pedal is down to the floor. During that time, it sounds like I'm totally stressing the motor out and it won't go any faster.

ghost6303 - I don't know what turbo surge feels like and I don't have a boost gauge (I will go get one though and tap into one of the lines off of the manifold). I checked all of the lines and it seems like everything is connected. I wanted to do a vacuum leak test but don't know how to do it. When I'm "trying" to accelerate hard, the car surges it's way up to 4K or sometimes feels like the power gets cut off and on and if I don't ease off of the gas, it seems like it won't even reach 4K. I haven't tried downshifting to lower gears when that happens because I'm afraid I'll blow my engine or turbo..

Tweaked - I'll look into the Mighty-vac but how would you go about checking the diverter valve? No vibrations. The bucking is the surging feeling I'm talking about I guess.. and it makes like a buzzing noise..? My car misfires sometimes only during start-up (cold or hot but happens more often on hot days). I get a MIL once in a while but it clears itself out on its own, I forgot which code exactly and it usually happens during heat waves or when it's hot out. I'm using 91 octane which is the highest grade we have here in here in California..

 

** Update **

So I tried going past 4K rpm and it goes.. but it's just surging the whole time. This happens when I'm hard on the pedal. If I try to accelerate normally past 4K, it seems to hesitate and doesn't surge as much.

The deep buzzing noise that comes and goes as I accelerate (in any gear) seems to be coming from the driver side..

 

this sounds like a misfire to me, it happened to me. Any Check engine light? If it's a misfire, it's probably the ICM. Read the codes and tell us. Good luck.