Ok i have an s5 (1991) t2

mods:
greddy front mount
hks evc4

thats really it right now.
anyway... when i bought the car, starting was weird. i would crank, it would start right up, then immediately die. i had to hold the throttle for a minute or so for it to be steady, but it was very steady at about 1000 rpms. very smooth.

as of recently, when i start up, its the same thing. instant death. but i have to hold the throttle much longer now until it keeps an idle. now, it idles at about 800 rpms, but its REALLY rough... the car shakes a lot.

the engine has about 3000 miles on it (rotary ressurection rebuild), and when its moving, its perfect. smooth and fast. when its idling, its complete crap. its idling so bad that i dont have power steering any more at a stop, i dont think its turning the belt fast enough.

any ideas?

p.s. no smoke or anything.

 

have you checked plugs and wires? Also check for any vacuum leaks.

 

yea i totally checked for leaks, not - a - one. i checked ALL vac. lines, did the ol' starting fluid trick, etc.

ill swap wires from my n/a right now (racing beat) but i dont think that will help. new plugs about a week ago (AFTER this starting happening)

 

absolutely no change. i used a timing light to check spark from all wires and they are all good. bac is hooked up.

 

oop vac. leak maybe
when i spray to the right of the turbo, my rpms fly up...
what is over there that can be leaking? i dont see any vacuum lines, just omp lines

 

does anybody have ANY ideas?? im thinking maybe TPS but would that cause the engine to shake so bad?

 

could it be injectors? or my leading coil ground? i dont even know where to look at this point, ill be setting the tps tommorrow...

good thing i have the n/a to drive

 

Dude, I have the EXACT same problem as you! Help us both out!

 

It's probably had the factory cold start fucked with or removed, just use the idle adjustment screw underneath the top mount (not sure if american fcs came with it, have a look, it connects to the throttle cable/butterflys etc etc bit)

 

But our problem is that, the engine doesn't idle COLD, but idles rough when when warm...

I was told that this could mean that the fuel being sent to the engine could be too rich... forgot what could 'cause that though.. but yeah... I don't think it's the screw.

 

? You said you sprayed the right of the turbo and the rpms fly. Doesn't that mean you have a vacuum leak there? Check the vacuum line for the turbo itself, its' a metal line a bit to the right of the turbo, under the airpump. Just recently fixed a bunch of leaks for more car and just redid/block off everything. Let me know if it works.

 

turn the idle stop screw up and re-calibrate the TPS and i guarantee it will smooth out.

 

that wouldn't explain raising rpms when spraying to the right of the turbo. Try to localize where it is you are spraying when the rpms jump. It could be the LIM gasket, UIM gasket (both are to the right of the turbo and you might not hear those leaks.).

Also check to make sure you are getting the right voltage across the MAF at idle, just in case that has decided to crap on you. My buddies MAF went out and he could start the car and keep it running with the lightest of throttle inputs. But that whole rpm raising when you spray around the turbo screams vacuum leak.

 

How and what, exactly, are you spraying?

 

is it at full operating temperature?

i wouldn't worry about it not idling cold, but what about fully warmed up, (not half arsed, i mean up to 80 degrees) does it still run jumpy?

 

yea its still crap when hot.
i was actually spraying ZEP (someone knows what that is) because im out of carb cleaner. it could be tps im trying that today, maybe im running pig rich?

 

you'll know if it's running rich, just put it in a garage if it fills up with smoke, it's rich :P


nah seriously, if you're running so rich it's a problem, you'd know it

 

I keep thinking TID vac leak.

 

i have no TID, i have a frontmount and an intake on it :/
i checked all the hoseclamps on the intake, its all square, i put new couplers and clamps on everything too