phosphoricum

Hey everyone,
While in the process of trying to get my gross poluter (CA) 1990 accord dx with 140,000 miles to pass smog I tested the oxygen sensor and it was not functioning well so I replaced it with a new one. now before I replaced it but after I tested it this weird stalling thing started happening where if i blip the throttle once it is released the engine bogs way down and almost stalls-sometimes it does, and then the idle fluctuates for a few seconds until a stable idle is re-esablished. I figured that the oxygen sensore must of just quite so I replaced it. The problem is still there and is unchanged. The new sensor is reading correctly, the sensor heater is getting battery voltage and shows the proper resistance. I have checked the wires and connectors for the sensor and wiring harness figuring that it must have been a bad connection, but they are all working well with the exeption of the signal wire in the wiring harness-I can't figure out how to trouble shoot it. Now I have recently cleaned out the egr ports, replaced the catalytic converter and run a bottle of injector cleaner through the car. the timing is set to factory and the IAC valve and fast idle thermo valve both checked out ok. I checked that the throttle position sensor is getting the right voltage but could not figure out how to get at the contacts on the switch itself to test it's resistance. Also the engine isn't throwing any codes at the moment. I just can't figure out where to look next. I really think that me futzing with the o2 sensor started this but everything relating to it seems fine. Sorry for the long post but I could really use some help here. Thanks in advance

phosphoricum

Forgot to mention,
the engine only stalls once it is warm, when it is cold it runs fine.

phosphoricum

Anyone know what could cause this only when the engine is warm? what changes when the engine warms up?

phosphoricum

Anyone?

StimpyBoy

You said you checked the IAC valve, are you sure it was clean? I'd possibly run a bit of compressed air or some sort of cleaner through it to be sure.

The car being okay when it's cold would possibly suggest the FIV is doing it's work, and then when it's warm the IAC isn't. Of course it could be tons of things besides that, but it's cheap and easy to recheck.

phosphoricum

Thanks for the reply,
I will do that. I was also wondering if possibly the bosch o2 sensor just isn't working right and maybe I need to replace it with a denso. It seems like it should be either the IAC the o2 sensor or the egr isn't holding vaccum. Anyone else have a problem with bosch o2 sensors?

BOOST_92

Have you checked all your vaccum lines. My 1992 accord used to do that when it was warm but I found out that it was going into vaper lock. One of the vaccum lines was old and weak and would collapse and sort of suffocate the engine just as you have explained. Good luck.