mysterious engine problems

[ridgeracer]

A friend of mine has bought a -94 UR S4 with an engine that will not exeed 2500rpm no matter what.
The car has had a small water leak on to the ecu so this one is changed with a used but suposedly good one.
The coilpacks are changed but the engine still behaves the same.
It sounds like the turbo is spooling also, but once the engine hits 2500 rpm it starts to stutter and bang..

Any ideas ???

[volcano rs]

A friend of mine has bought a -94 UR S4 with an engine that will not exeed 2500rpm no matter what.
The car has had a small water leak on to the ecu so this one is changed with a used but suposedly good one.
The coilpacks are changed but the engine still behaves the same.
It sounds like the turbo is spooling also, but once the engine hits 2500 rpm it starts to stutter and bang..

Any ideas ???

i had a similar problem once and it turned out to be a bent con rod

[mdm]

if it's not reving then it tends to be to do with fuel, so check for air lecks, fuel pump, pressure etc it's usual something really simple.

[UrS4boy]

It sounds like the turbo is spooling also, but once the engine hits 2500 rpm it starts to stutter and bang.. Any ideas ???

Assuming that the ignition is fine (and it might not be), it definitely could be fuel, i.e weak fuel pump, clogged fuel filter, etc.

I would start with a fuel pump function test (and a clean filter):

http://forums.audiworld.com/s4s6/msgs/89799.phtml

If that test shows the fuel pump is fine, then I would move on to testing the ignition components:

http://forums.audiworld.com/s4s6/msgs/115408.phtml

HTH.

[caterpillar]

have a audi 200 tqa: the fuelpump was gone; i have the pedal to the floor, and have only 51km/h....

[ridgeracer]

But did it stutter and missfire on 2500 rpm even at standstill ?
The car can do 2500 in 6. gear but not under any condition does it rew above 2500rpm.
No oil smell or fuel smell.
It idles fine..

[caterpillar]

the fuelpump are gone i think... in tank pump ( borsch 040) or extern pump ( borsch 044)