92integragreen

This problem has been bugging me for a year already, and it is getting worse.
92, integra, 5-spd, 229,000 miles. I never get a Check Engine Light.
The car runs fine until it warms up to normal operating temperature. Then it has a rapid jerky misfire until about 3000 RPM, in any gear, then it pulls fine until I shift. Lifting during acceration will make it stop misfiring, and accelerating very slowly will keep it from misfiring.
The idle is very rough and I had to raise it to keep the car from stalling.
The dealership had it for a couple days and could not find anything. They checked the fuel pump and fuel pressure. They also tried replacing the distributor assembly with no change. In the end it was a very expensive car wash.
I replaced the fuel filter, plugs, wires, cap, rotor, and a PCV valve that tested bad, with no change to the problem.
The IAC valve and Oxygen Sensor test ok. When I pull the connector off of any of the sensors they give me the CEL light as expected. The problem does not change with or without the sensors connected.
I tried resetting the ECU by pulling the Back Up (7.5 amp) fuse with no change.
Any Ideas?

FooD2000

You make sure that it has a light bulb for the cel behind the gauge cluster?

92integragreen

Thanks for your reply.

I did consider that the bulb might be bad. So, as I mentioned in my ramblings above, I removed some of the sensors to create a problem, and the CEL always verified the problem by coming on.

I should also mention that the car is completely stock.

Still open for ideas

MTEng

The CEL should come on when you start the car.... when you put the key in the "ON" position.

fjm1

Sounds like you threw alot of parts at the problem! Maybe clogged air filter/intake problem. Disconnect the air intake at the throttle body and take a short drive.

Also, might be an injector issue. Not sure how to test for this, others might be helpful.

92integragreen

Just to clarify the CEL light does come on as normal when you start the car. Then it goes out as normal when the car is running. I never see the CEL come on after that.

Rgarding the parts installed so far. The plugs, cap and rotor were due anyway, and with the plug wires I found one that had high resistance so I replaced the set. It seemed like the problem went away for a while with the new wires, but it could be that the problem was less severe at the time. They all test fine now.

I checked the intake from the air cleaner and it is clear, and I went for a ride without the air cleaner installed, no change. I suppose I could try taking it off at the throttle body but it all seems clear.

As far as the injectors, I wonder about them also. The problem seems like it is fuel related but when I pull the hot lead off of one injector at a time there is a clear difference, so I know they are working at least somewhat. Short of replacing them I don't know how to make sure they are ok.