HELP!: rough idle, hesitation on acceleration, lack of power

[mlishn]

I have a 1988 325iC (5MT).

I've been having a strange problem with my e30 for a little while.
I've researched on what it could be based on the symptoms, but am unsure which tests/ cleanings/ replacements to perform first.

Here are the symptoms:
- CEL is on (will do stomp test for code)
- the car drives great until it warms up. once it warms up and roughly 10 minutes after driving it feels like the car is losing power, the throttle is unresponsive and the rpm's stutter (bounce around) from 500 to 1500. this happens both when the car is standing still (clutch engaged), or placed into neutral.
- once this happens, if I turn off the car for about 15min and drive again, the problems will not reappear immediately, but will appear roughly 5-10 minutes after.
- if I try to turn on the car immediately after turning it off, the car does not turn over unless I pump the gas pedal.
- also not sure if this is related: the throttle cable has a little big of slack. (will tighten or replace)

Based on reading some forum posts:
- need to check for a vacuum leak?
- need to clean the ICV?
- check if the fuel pump is working?
- check if the fuel relay is working?

If you've had an experience with this, or have had a similar problem, let me know what steps you took to fix it.

Any help would be appreciated.
Thanks!

[bloodsnot]

Yes, check for vacuum leaks and clean your ICV. Then you can at least eliminate them from your list of possible culprits. Do these first.

The relay and pump wouldn't necessarily be my first hunch because this problem seems to relate to engine temperature. Be sure to test your coolant temperature sensor (one of the two sensors on the thermostat housing) which could be failing to let your DME know when the car is warmed up. If your car has a CSV - cold start valve, essentially a seventh injector that sits on the passenger side end of the intake manifold - test that it is getting voltage when the car is cold but not when hot and test that it actually squirts fuel when voltage is applied.

Does your car have trouble starting when cold? You mention that it doesn't like to start when hot unless you open the throttle - howabout when it's just warm? Does it crank over a bit more than when cold (after sitting overnight)?

It is possible that your fuel pump isn't up to snuff, but check there after you've ruled out the temperature dependent functions.

[mlishn]

Yes, check for vacuum leaks and clean your ICV. Then you can at least eliminate them from your list of possible culprits. Do these first.

The relay and pump wouldn't necessarily be my first hunch because this problem seems to relate to engine temperature. Be sure to test your coolant temperature sensor (one of the two sensors on the thermostat housing) which could be failing to let your DME know when the car is warmed up. If your car has a CSV - cold start valve, essentially a seventh injector that sits on the passenger side end of the intake manifold - test that it is getting voltage when the car is cold but not when hot and test that it actually squirts fuel when voltage is applied.

Does your car have trouble starting when cold? You mention that it doesn't like to start when hot unless you open the throttle - howabout when it's just warm? Does it crank over a bit more than when cold (after sitting overnight)?

It is possible that your fuel pump isn't up to snuff, but check there after you've ruled out the temperature dependent functions.

I will clean my ICV either today or tomorrow and check for vacuum leaks at that time as well.

The car starts right up after standing overnight or when it is cold. It only has that problem after it has warmed up (roughly past the half way mark).

[paperplane94]

Shot in the dark: Fuel Pressure Regulator

It's easy. Check for fuel smells or even fuel in the vacuum hose of the FPR. There shouldn't be any in there.