well...this thread is actually pretty old...as is the problem I'm still having. The car starts great, idles great, drives great the first 5 minutes. As it warms up, it starts to miss, then the tach needle starts to jump wildly if not drop to the 0 and stay there for a few seconds, and it wants to die. BUT...if you can save it...it will idle just fine. Bit of a miss but it will sit there and idle fine. Course, you can't drive it anymore as you need more than idle to really do that with much efficiency and ANY revs over about 1200-1500 and it starts the now severe mis/backfire/startin to piss me off stuff.

 

So far...:

new wires, new coil (OEM Hitachi had to order it in), new rotor, friends cap from his running 88XT (that I still need to give back...but his car is running just fine on mine), new plugs (NGK), new fuel filter (we're reachin at straws now folks)....

 

any other ideas?

My wag is the problem lies somewhere in the distributor. The tach and the ECU both reqiure signals from the distributor. No signal to the tach probably means the ECU isn/t getting one either.

any check engine lights or recent work? if the CEL is on, the ECU is flashing the code for you in the trunk.

 

the coolant temperature sensors are common. the sensor isn't the problem it's the wiring harness connector that plugs into it, they get corroded and cause a bad connection. check that connector - green, dirty, nasty is bad.

 

if this is an 87.5 XT Turbo the MAF sensor (by the air filter) is another possibility. i had one once that had a broken wire inside of it. remove it and looking very delicately through it as the wires are very, very thin, make sure none of the strands are broken. they are very fine strands of wire running through the air flow. before i found it the car did just as you said.

had this problem with my 86/87/88 (all one car. 86 body, 87 spfi motor, 88 sedan inter.) the disty has a ir pick up if you get ANY water in ther if fogs the ir lens and you get a Missfire. clean out Under the metel plate under the roter with Starting fluid and caned air (computer air duster) and that should work.

Sounds like once the ECU enters closed loop operation it's not getting proper information from the sensors.

 

Coolant temp, and O2 sensors come to mind. Both can fail in ways that will result in the symptoms such as you describe.

 

GD

I agree with GD

 

but

 

Have you ever heard any wierd noises from the fuel pump?

Could it possibly be getting warm and not making

the output the engine needs to run above idle.

 

 

Can you swap the coil bracket and or the CAS (dist) from your

buddy's ride?