so i have an occasional problem with my 90 n/a gxl.
when driving it suddenly has no power and rpm's drop...fast.
take it out of gear rev and it bounces up and down but never goes over 3k.
let go of gas and idle is normal.
but then it always goes away after a few minutes or so.
seems like its becoming more prominent and lasts longer each time.
so far...3 times.

just have exhaust and a air control valve with a vacuum leak.

 

Have you checked for codes yet?

 

lol.
its a 1990, obdii didnt come out until 95-96.

sounds like it could be a fuel issue?
have you done any work on the fuel system lately?

 

There are about 60 or so error codes on the S5.

 

@ ineedfc - Do some research before you shoot down someone elses suggestion.

When you say exhaust, be more specific. Does it have a cat? Could possibly be clogged/getting clogged.

 

no cat.
no work done to the fuel system.
currently in a parking lot waiting for it to stop
so I can go home.
so far 4 times.
and first time 2 in one day.

 

You wrote in the original post you had a vacuum leak. Well, go fix it.

It could also be the fuel pump or the wiring to it getting finicky. Hard to say.

 

Your car might be in limp mode so this is why you need to check for codes. Until then it would be best to keep the rpm level as low as possible and actually not drive the car for that matter until you can verify whether the car is actually in limp mode or not.

 

i dont have the tools, space, or time to replaced the acv, although i have already found a replacement.


the only thing ive done recently is replaced a broken vacuum solenoid.
it was the 6pi one.
seriously need to figure this out though.
no certain situations or anything seem to trigger it.
just seems random.

 

im thinking something fuel related.
like pump, filter, injectors, etc.
might do a fuel pressure test if i can rent one.
not sure how im going to induce the problem though.

 

I'm with Satch on this one.
Most s5's are prone to limp mode.and that is from the OMP going Gaga!..it could be telling you something.

 

how do you test the omp?

 

You would like, pull codes, oh my God!

Code #20, #26, #27 and #37 are OMP related.

http://www.banzai-racing.com/FD&S5_error_codes.htm

 

haha, forgot s5's are electrical.