Kinda getting frustrated with this board Tried posting in Computer Tech/Lt1/Pacific NW forums without any responses! Anyhow i'll try again... Trying to troubleshoot this low RPM stumble, i have a scanner only for this long weekend. I've done a whole lot of scanning and watching the sensors and think i'm a bit closer to figuring out whats wrong. -HOPEFULLY- someone here can help me out and let me know the likely reason for these readings:

Around 2000 RPM -when applying light gas to accellerate, the car stumbles a bit, if i push the pedal down further it'll catch on and accellerate on just fine. at this same point, when reading the scanner the left and right BLM (long term block learn tables aka RBL and LBL) skyrocket to the max (160) telling the computer that to correct for lean conditions, and my guess is that it's way lean or a sensor is off.

Where do i go from here? Someones gotta be able to help, if you need any other readings i can go out and provide them.. !!

 

Well last day with the scanner.. I think i'm starting to narrow it down even more:

Stumble happens in cells 11, 14 and 15 it seems, which all have the L and R BLM's shoot to 160. Also, during the time's it stumbles under light accel the egr is doing 50% duty, don't know if its related or not.

The other cells all seem to be fine within 10-15 of 128. except for cell 10 which is almost 150 on both sides.

I know this isn't the usual "should i descreen the MAF" or "How much HP will i gain from these mods" but someone out there has gotta have some knowledge of doing something with these scanner readings.

Is my car running lean and not getting enough fuel during these cels? (fuel pump ?)
or
Is my car running rich and the O2's (bosch) are just fouled up? (computer over compensating for a false lean)

 

Any codes? How do your O2's look? Plugs and wires, how are they?

 

Brand new Accell 8mm Heat reflective wires, new plugs. On saturday the car had 2 codes, 022 and 055. 022 is TPS voltage low, and 055 is "Fuel Lean Monitor". In the 2 full days of driving I haven't had any codes come up again in testdrive mode. The O2s seem to jump around a lot fairly erratically, sometimes below 100 sometimes above 900 - all over the place. From what i've read this seems to be kinda normal for O2's to do this.

 

Scanned it again. The O2's must be working fine because i was able to take some snapshots of exactly when the problem was happening and the left and right integrators were basically reading very lean, and the BLM's were maxed at 160.

Would it be logical to concur that i have narrowed it down to either 1 of 2 things:

A) Several Injectors fouled up, if it were just 1 it'd mess up 1 side all the time. Although the left side of the block seems to be runninging significatnly leaner than the right (Left side +10 BLM units high).

B) Fuel pump is dying and there's not a enough pressure. Although this wouldnt explane why the left side is leaner.

I hope one of these are right, after i check the fuel pressure ill go ahead and either replace the injectors of the fuel pump (both of which are expensive, id rather have nice new injectors and clean/sell the older ones).

 

Your O2's sound ok. I had the same exact problem you are having now with the stumble when my TPS went bad and I had the same exact code. If the TPS doesnt see the correct voltage at start up it will throw the code. Try slotting the holes of the TPS and move it towards the front of the car or just get a new TPS.