1990 2.3 NA problem

[Racingboy532]

Looking for some suggestions....

My 2.3 tends to run quite well when cold but picks up a misfire as it hits operating temperature. The misfire is not bad, just annoying. It really seems to sap the life out of the car though!

I replaced the wires, cap, rotor and plugs when I got the car 1 year ago.
Any ideas?

 

[white1989]

A couple of questions:

How many miles on the engine?

Does it "misfire" or bog at certain rpm ranges?

Have you a OBD1 code scanner?

 

[Racingboy532]

The motor is at 152,000.
It seems to both bog and misfire from 2000-3500 or so.
I do not have a scanner.

The tach doesn't appear to jump around and the car idles smoothly. It seems the miss is load based, although when it is fully warmed it will sometimes miss while just revving the motor. It really comes down on power when the car is fully warmed up. It runs quite nicely when cold.

 

[white1989]

Any mods - ie: header, larger exhaust piping, intake?

The car gets it's A/F mix from the ECU when cold. When warm, the 02 sensor starts calling the shots on the A/F mix.

If you have no header and exhaust mods, I would say that you may have an issue with your 02 sensor on it's way out.

If you have header and exhaust mods, then there is a possibility that your ECU needs to be reprogrammed to take into account the changes that you have made.

Reset your ECU by removing the battery cable for a short time. If it clears up somewhat, then you're on the right track.

You should seriously look at getting a code scanner, you can pick them up off ebay for $20-25 bucks. The tool is indispensible when you are faced with an issue you are experiencing now...

 

[egnorant]

Thought

I had this problem in reverse though. Would act up while cold and run fine hot! It was a defective temp sender. Computer read the signal as already warm all the time. Maybe yours is reading as always cold!!
Bruce

 

[Racingboy532]

Thanks....these are some great ideas. The car has zero mods outside of shocks, wheels, synthetic trans fluid and no interior. The cat has been replaced according to the previous owner and it appears to be a stock replacement.

The future of this car contains BIG plans....not your average fare however.

I am basing a cage design on this (thanks Ted) and turning the hatch into a rally car someday....(see attachment).

 

[rd]

Run the self diagostic with the check engine light and see what you have. I would do this before replacing any parts.

If I had to guess, I would go with a bad plug wire, a dying coil, or the TFI module or dist pickup assembly.

I would find a way to get codes if at all possible. The CEL method is annoying to me because I have a scanner, but it works just as well once you get the hang of it. Did this back in Nov to our 2.3, after I fried my scanner. Found a dead Map sensor quickly.

 

[Racingboy532]

It looks as though I owe everyone an apology....I was mistaken about my parts replacement. I thought I had replaced wires but....I didn't. It is amazing the things you forget in the course of a year!

Anyway, I recently replaced plug wires and solved my misfire problems. The car is much more enjoyable to drive now! It does still seem a little down on power when it gets fully warmed up. I have yet to buy an OBD scanner but I intend to do so.