M20B27 Engine Hesitation After Gear Shift

[nny403]

***12/2/2012 Issue has been resolved see last post***

I have a bogging down issue when the car will be sluggish even with the gas fully depressed then after about 5 seconds start running again. I have changed the following parts:

Plugs, Wires, Cap, Rotor, Fuel Pressure Regulator, rebuilt AFM.

What's driving me most crazy is all the things that I've replaced have been tested to be out of specification but still aren't solving the original symptoms of severe sluggish behavior from 2000-3000RPMS. The engine revs but the car doesn't move.

I'm down to replacing the Coolant Temp sensor because that's the last item on the list that might cause symptoms like this along with a slight cold startup erratic idle (maybe 100RPMS)

If it helps brainstorm ideas I've also have the clutch replaced about a year ago with a new Sachs one including all the seals, pilot bearing, throwout bearing the whole nine yards.

Would love some ideas of what to test next beyond these things. Throttle position sensor, fuel pressure et all? I've got electrical testing equipment but not fuel and it's a 40 minute drive to "rent" one from a parts store.

In exchange photo of sad children that want to drive in car in question (on the right, the rusty one)

[dnguyen1963]

Beautiful family...I would check for vacuum leaks.

[VAE30FTW]

I would test the DME CTS using a potentiometer and making sure it's within spec. should be about 270ohms at operating temp and 1200-1400 cold start IIRC.

[nny403]

For fun going to try this: http://www.fiero.nl/forum/Forum1/HTML/081547.html

[nny403]

Smoke test was unrevealing, which is good and bad because a year ago I paid to have it smoke tested and fixed all vacuum leaks.

Have coolant temp sensor, will need to get a collar to make it fit as for some reason the openings on the thermostat housing are unusually large. Will report on success or failure at that point.

[jlevie]

In your post you state that "The engine revs but the car doesn't move." That can only be a slipping clutch.

[nny403]

In your post you state that "The engine revs but the car doesn't move." That can only be a slipping clutch.

I reread and you're correct that's what I said, however it was a mistake of words. The engine will not rev and takes several seconds of full throttle before it will begin to accelerate at all. However, it seems the early cars have a different coolant temp sensor so I either try to locate one or get a collar to make it fit.

[gearheadE30]

A bad o2 seonsor could cause it to run excessively lean, which would cause this. AFM trace could also be worn.

[efficient]

sounds like what my car did. i have an 86 eta i would give it gas and it wouldnt go and felt sluggish. never solved the problem but i pulled the head and found water in my head and oil.

[nny403]

Resolved. Cleaned TPS and replaced coolant temp sensor. Thanks for suggestions guys. Temp sensor was slightly out of specification. For the record, I had replaced the oxygen sensor this summer and the mass air flow was rebuilt by a great guy on this forum, PM him if you want to have it done. Makes a lot of difference in throttle response.

Gregs///M

is his user name. It's well worth the $100 you'll pay.

[VAE30FTW]

Resolved. Cleaned TPS and replaced coolant temp sensor. Thanks for suggestions guys. Temp sensor was slightly out of specification. For the record, I had replaced the oxygen sensor this summer and the mass air flow was rebuilt by a great guy on this forum, PM him if you want to have it done. Makes a lot of difference in throttle response.

Gregs///M

is his user name. It's well worth the $100 you'll pay.

Good to haear!