I installed a new fuel pump on Sunday night. No change in the stumbling problem, though now my car hasn't seemed to 'cut out' periodically like it was doing repeatedly during the week.

So anyway... last night I installed a toggle switch between the two O2 sensors and my Autometer a/f gauge. It's next to my shifter if you must know (man, it's painful drilling holes in your interior). The results...? Even though the a/f ratio for the #1 and #2 cylinders is reading full rich under part throttle, the a/f ratio for the #3 and #4 cylinders is reading FULL LEAN. The stumbling problem appears to be leaning out to the point of detonation on half the engine.

I'm thinking this might be a problem with the fuel injectors...? Any thoughts anyone?

 

its the open/closed loop problem i think

 

Have you tried removing both o2 sensors completely? You'll get a check engine light but it might eliminate the 'stumbling' problem.

 

Here we go...

The car was lukewarm when I unplugged both O2 sensors. I reset the ECU and fired it up. It did its characteristic stumbling idle, but I got no CEL. I drove it around until it was fully warmed up, then did some 8000 rpm blasts, still no CEL. I also did the part-throttle test for any signs of stumbling and/or leaning out, and it was perfectly behaved. I just... don't... understand...

 

does your engine just stumble at idle or in motion?

 

raeneshadow, if you're talking about a 'stumbling idle' I'm quite sure 1st gen B16as are known to do that. Mine does it until the engine is fully warmed up. It just flutters from 900rpm close to 0.... sounds like it's going to die at times... but i'm not worried about it. 3 other guys I know with 1st gen B16as, they do it as well.

Anyway hope you get those gremlins eliminated from your engine

 

after having mine tuned up, and the idle loosened a fuel pressue turned up mine does it too, it revs quicker tho. Sometimes it worries me, but othertimes it just reminds me of a car with some fat *** cams...

 

It only stumbles at idle. If you're on the throttle it runs perfectly. I've tried putting it into open loop operation so it ignores all the sensors, but the problem remains... .

I'd really like to fix this problem rather than just live with it... If I try driving the car when it's cold it'll just stall .

 

ouch mine never stalls, must be a bigger problem... have u tried adjusting your idle control, and your spark plug gaps?, sometime too much pressue from the spark plug depth can make the crank stall out..


[Modified by TheShad0w, 7:02 PM 7/17/2001]

 

There's a big-*** description of what I've done and what I'm going to check in the topic 'changing igniter...'. I've just replaced the plugs and gapped them so that's probably not it .