The voltage looks good in the log file.

I don't have a FP gauge hooked up but wouldn't I see more issues at higher RPM's with FP issues? Everything seems ok above 2000rpm's. It's only at lower RPM's that I seem to have an issue.

 

Miss read you post. I would not worry if you should be in a lower gear and the car acts that way. Letting the clutch out to much with not enough gas can cause that.

 

I pulled a couple of the easy to reach plugs last night and they look brand new (they have about 20K on them). No oil on them. Gap was set right at .050".

I replaced the coil also. It was looking pretty old and is probably the original one. For $20 why not.

I pulled the MAF. It looked a little dirty so I cleaned it and reinstalled. I did not remove the screen.

Seemed to drive a little better. I need to take of the K&N filter and clean it. It's looking pretty dirty. Maybe it's that simple. PITA to get to though.

 

Was there any soot, indicating a rich A/F mixture?

 

The plugs looked good to me. Here is a pic of one...

 

I checked the air filter and it was fine.

I did some heavy acceleration today shifting from 2nd to 3rd at about 5500rpm's. It's not pulling right at higher revs either.

So there are no codes, no rich indication on the plugs, MAF, Opti, plugs, coil and PCM are all new. It may idle a little ruff but not too bad. No intake or exh leaks. Bad gas mileage. Surging/lurching at low rpms at all throttle positions and poor acceleration at higher rpm's at WOT. Seems to pull ok in the middle.

possible causes:
fuel pump/filter
O2 sensors (not used in WOT operation though)
Plug wires
faulty opti even though new
faulty PCM or incorrect program

At this point should I just take it to the dealer? Might be cheaper then throwing parts at it.

 

I found a crack in the intake elbow right under the hose clamp. Hopefully that is my issue. Ordered an aluminum one from Jegs.

 

If I found the possible issue with my car for that cheap and could get a new cool looking part, I would use one of these.

 

Well, that didn't solve the problem (although it needed to be replaced anyhow). Still stumbles at low and high rpm's and runs ok in the midrange.

Running out of ideas.

 

Looking at the most recent data log, there's something odd going on near the area you point out (record 3650). It's in PE mode, 100% throttle, its in Cell 15 and using the Cell 15 BLM's because its adding fuel with the BLM's (only 2.3%). Given those conditions, and seeing the flag for PE is "1" and the flag for "BLM Enabled" is "0" I would not expect the short terms to bounce around, and I would not expect the O2 sensor voltage to be bouncing around. It's almost like the PCM is still trying to control the A/F ratio. When it first enters PE (record 3640), O2 volts go to 861/848, then drop to 799/781, then to 746/657..... then to 280/209, up to 786/755, then continue jumping back and forth from rich to lean. All this time, the barometer reading is jumping around, when normally it will be stable.

I've never seen a PCM respond to PE mode like that. Maybe someone else has seen this before and can comment.

 

Hi Fred,

Sorry, but what doe PE and BLM stand for?

Well, I took off the air filter and drove it. It wasn't the filter.

I drove it with the MAF unplugged and same symptoms.

Could a restricted exhaust cause issues like this? I have a nasty raspy exhaust rattle if I downshift to slow down. I thought it was a heat shield rattle but maybe it is the cat or the POS flowmaster muffler that is clogged?

At this point if it is not a clogged exhaust I am thinking something is really screwed up with the PCM even though it was dealer replaced not long ago. Maybe it has the wrong program or something.

 

You would notice a plugged exhaust at higher rpm's mostly. If it pulls good at wot, than you are probably not having any issues. It can have it tested pretty easily.

 

See post #36. It doesn't pull good at WOT either. feels like it is missing or stumbling but not as bad as the low throttle stumble.

The car certainly has issues. A healthy normal engine would not drive like this. I'm gonna spend a couple more minutes under and around the engine but if something doesn't pop out at me....

I guess it's off to the dealer to see MR Ben Dover!

I'd love to find someone local with a known good PCM I could try. I dont mind buying one but with it being replaced recently I am very hesitant to blindly drop the $$$.

 

The test on the cat is pretty easy. I would try that and see what you find. Should be pretty cheap also. I ordered a high flow cat on Ebay for pretty cheap and $20 to install. Sometimes its worth replacing old worn out parts and eliminating them. Just as long as you don't just throw parts and money at random.

 

I did a fuel pressure test and it seemed good. 33 psi at idle, 45psi with FPR vac line unhooked. Full throttle driving was steady at 45psi.

I am thinking it is a good idea to replace the Bosch O2 sensors next even though they are fairly new.

I went through all the records for the car and here are all the items that have been replaced before I got it. Some entries have the mileage listed. Car has 198K now:

7/25/2011 ECM (Reman) and program
7/18/2011 Temp Sender
7/10/2011 TPS
7/8/2011 EGR
7/8/2011 MAF (reman)
7/8/2011 Bosch O2 (both)
7/6/2011 water pump and thermostat
7/1/2011 IGN Seal
5/7/2011 water pump
12/4/2010 V-Belt
11/29/2010 Hood Insulator 194001
11/21/2010 K&N FIPK
11/8/2010 Reman Starter
11/5/2010 PCV
12/29/2004 Distributor 190014
12/29/2004 Timing chain/gear 190014
12/29/2004 Spark Plugs/wires 190014
9/18/2002 Inline fuel filter 186618
12/3/2001 reseal oil pan 183458
12/3/2001 Rear Main Seal 183458
12/3/2001 Factory clutch 183458
12/3/2001 Reseal oil filter adapter 183458
12/3/2001 replaced coolant hose 183458
12/3/2001 Replaced U-Joint 183458
5/22/2000 replaced intake manifold gasket 175758
5/22/2000 Replaced seized distributor bearings 175758
5/22/2000 Replaced Water Pump 175758
5/22/2000 Replaced CAT 175758
2/9/2000 Flush cooling system replace thermostat 169550
1/7/1999 Replace Fuel Filter 134335

I replaced the ignition coil last week also.