I have a 1996 Pontiac Trans am...I have a 230 236 Comp Cam with the 1.6 RR, pushrods, springs...yada yada yada...well I just rebuilt the motor a few weeks ago and everything was running fine...then the other day I was driving and the car started to stumble in low RPM's...(I have a scanmaster)and it threw a code for the right 02 sensor...so I changed it and the car was running fine...then yesterday the stumbling started agian...no codes but it seamed from the scanmaster that in low RPM's the left side was bottoming out on fuel delivery...In knowing that I changed the left O2...whats funny is that it doesn't stumble all the time...sometimes, and when it does stumble it dies at lights and runs really rough...But agian no codes..so I dont know what to do...could my (new) left o2 be bad...or is it something else??? Please help me soon...I need my baby back.

thanks
matt

 

Could you describe this scenario a bit further?

 

optispark?

 

according to the scanmaster it was bottoming out on the fuel delivery....saying the the right side was correct at approx 128-130 and the right side was droping to around 108-110...so I dont know my friend said that that ment that the left side was bottoming out...BUT WHY??? does that make sense???

thanks
matt

 

Check all your fuel lines, check your fuel filter and if none of that is messed up, check your injectors and fuel pump.

 

switch the o2 sensors around, if the problem switches sides, then its your 02s, if it doesnt, its probably injectors or something else

 

If you have BLMs under 128, the PCM is pulling fuel, because that bank is getting way too much fuel. 108 is the minimum I think.
Switching the O2s is a good idea. When I had the split BLM issue it turned out my right bank injectors were leaking as hell.
Fuel pump, fuel filter, regulator is outta question right now, as you have a problem with only one side of the engine.
Oh, btw, in what cell does this occour?

 

I have a similar problem. My BLMs are higher on one side. I've replaced both O2s, fuel injector, spark plugs, wires, header gaskets and I still have a stumble. I've given up.

 

I'm sorry to hear that dude.. Are you suffering from that infamous "1000-2000" stumble that was discussed big times, or another problem? Are you saying you have one bank leaner than the other?
Just trying to help you...

 

I pretty much have the same problem as everyone else(stumble under load around 2000). I also get a little miss around 5500. The BLMs on the left side will be 128 at idle and 118 on the right. Would that be a possible cause of my stumble? The only thing I can think of that would cause BLMs like that I've replaced.

injectors
O2s
exhaust and intake gaskets

 

I have the same problem only that when my car is cold it runs o.k once it warms up it starts stumbling and idling rough. it sounds like a harley-davidson. i guess because the timing is all messed up.