For an earlier reference, please see:
http://web.camaross.com/forums/showt...hreadid=246869

Okay...I was finally able to log a file in Autotap and ran the car for a while. Finally my SES light came on giving me two codes:

P0174 and P0300

I have looked them up on Shoebox's site and found out what they meant....one is misfiring and the other is fuel system lean bank 2.

I do have some readings from O2's and other sensors also...

The vehicle was operating in closed loop, and this data was taken from the car at idle.

STerm Fuel trim B1......2.3
LTerm Fuel trim B1......15.6
STerm Fuel trim B2......50
LTerm Fuel trim B2......25
MAP............................10.9
MAF............................1.08
O2 sensor B1S1.........ranged from .7 to .785
O2 sensor B1S2.........steady .445 (due to Madwolf)
O2 sensor B2S1.........ranged from .11 to .145 (never any higher)
O2 sensor B2S2.........steady .440 (due to Madwolf)
Inj Pulse Width B1.....3.14
Inj Pulse Width B2.....7.06
Coolant Temp............176

Misfires:

Cylinder 1....................2
Cylinder 2....................88
Cylinder 3....................12
Cylinder 4....................2481 Not a typo!
Cylinder 5....................0
Cylinder 6....................318
Cylinder 7....................0
Cylinder 8....................1471

So, the injector pulse widths are unbalanced. Why? O2 maybe?
Misfires are off the board! And I'm getting no knock retard.

Under a load and moderate acceleration the car spits out bad black smoke and hesitates bad. Any ideas?

 

I would really start witha fuel pressure test considering teh lean system code.

the scan shows that the lean is showing up on bank 2 the most.

consider this. you know the bank 2 02 is reading lean (due to the code) you can induce a rich condition and see if it will switch above 450Mv.

also common things to check are header leaks if aplicable as well as vac leaks.

whats your MAP and BARO KPA?

 

I'm guessing you mean barometric pressure? It read 29.6 before I turned the car off. The MAP reading was 10.9.

 

i'm not familiar with the program your using. but usuly you will see MAP as either a KPA or voltage. and uauly the BARO pressure also as a KPA. i was just wondering cause I can plug them in and see how much vacuum you have. usualy a normal KPA BARO reading is around 100 and a normal KPA MAP reading is around 30 ish and for voltage around 1.5 volts all of this at idle. it does change with RPM and sea level

 

wow - black smoke - given some of those numbers I'm surprized it not raw gasoline.

My laymans opinion is that the misfire is causing a lean condition - (lots of air and no hydrocarbons) - ergo the low o2 reading, the PCM is adjusting by pumping in more fuel - hence the increase in pulse values on one side.


double check that your getting spark on # 4 and 8

you may want to throw the old coil back on

 

don't know how to relate to those numbers of autotap, but to me it seems like a bad pcm.

 

I'm using a program called Autotap. The MAP sensor readings with my program are measured in KPA. My barometric pressure are readings are measured in Hg's (inches of mercury.)

With the research I've found, typically the MAP in KPA sensor readings are close to 1/3 of the barometric pressure readings in Hg.

Those seem normal to me. Its the injector pulse widths and oxgen sensors I'm worried about. I did notice when I was driving it though around 40 mph, the O2 sensor B2S1 never went above .015, while the other one was bouncing all over the place.

 

ok. how many Hg is the BARO? I can convert that to KPA so I can check for a vacuum leak..




EDIT. sorry, I see it now. BARO KPA = 101

map kpa was 10.9?


somethings not right here. are you sure that the MAP is KPA? cause achording to teh formula you are running about
26.5 inchs of vac in teh motor.


could you do me a favor and rechek BARO and MAP and find out exactly how it;s reading? sorry I'm being **** I just wanna make sure I got it right

 

1 atm = 29.92 Inches of Hg
1 atm = 101.325 kPa

 

From the looks of it, it looks like you have a bad O2 sensor on Band 2, Sensor 1...that should be bouncing around from .1xx volts up to .9xxx volts just like your other front O2 sensor is. The easiest way to test it would be to pull it out and put a voltmeter on the two leads (not sure which two leads because two of the four pins in the connector are for the O2 sensor heater) and put a torch on the end of the O2 sensor. The sensor should immediately register voltage on the voltmeter...if not, you've got a bad sensor. I would almost be willing to bet that is your problem right there.

Notice also that most of your misfires are on the passenger side of the engine...that first sensor on bank two is the main contributing factor in how the PCM decides to control the pulse width of the injectors on that particular side of the engine...with your injectors pulsing at 7.06, it is basically flooding the cylinders and fouling the plugs out....might also look at a new set of spark plugs after you get your problem figured out...

E-mail me if you need any more info.

 

I'm willing to bet that BOTH MAP and BAR are in "inches of mercury"..... it would be normal to see 29 to 30"Hg for barometric pressure at sea level, and with a stock cam, normal MAP at idle woud be 9.5-10"Hg..... so that looks normal. It would not be normal for the MAP in kPa to be 1/3 of the BAR in "Hg.

You also seem to have different units for the MAF than many people are used to seeing.... that appears to be measured in "pounds per minute".... that would convert to about 8.5 grams per second (gps) so that looks normal. Confirm MAF is in pounds per minute.

The right bank of your engine is totally screwed up, and its pouring in fuel it doesn't need. It is very unlikely that it is a problem with fuel pressure.... that would be affecting BOTH sides of the engine.

You also have a problem with both O2 sensors if they are reading a relatively steady .700-.785V on the drivers side, and relatively steady .110-.145V on the passenger side. At least the drivers side should be fluctuating over a broad range of .1XX - .9XX Volts. If it was in closed loop, it should have been jumping over a much wider range.

Just a wild guess... but I'd say you have cross-firing between #4 and #8 plug wires, which was correctly picked up by "BPS" as the possible cause of unused oxygen pouring out of the misfiring cylinders and into the exhaust, forcing the passenger side O2 sensor to read too low, causing the PCM to pour in fuel the engine doesn't need... and causing #2 and #6 to misfire ocassionally because they are wayyyy too rich.

Swap the pre-cat sensors from side to side, and see if the problem stays on the passenger side. That would rule out a faulty O2 sensor, and point you in the direction of faulty wiring, or the previously mentioned misfire/cross-fire problem.

I think you also might want to read my scanner writeup.... it mentions the differences in units of measurements, and what might be considerd "normal" for these engines..... and there are several people who responded that might also benefit from a quick review of the basics.....

http://members.aol.com/InjuneerZZ/ScanMast.htm

 

The MAF readings that I'm getting are pounds per minute. I'm at work this morning and I don't have my laptop that I was using with me to look, but I'm pretty sure that's what it was.

Okay, oddly enough that does make sense. However, what the heck does "crossfiring" mean? That's the first time I've heard that term in reference to misfiring cylinders.

Injuneer:
I use that scanner page all the time. Its become a great resource for me in diagnosing problems with my car. Thank you for posting that information for people to see. And your knowledge about these cars is amazing. I do know more than the average joe about LT1's, but I still have more to learn.

I think I'll replace the O2 sensor, clear my DTC's, and see how it goes from there with another scan.

Thanks guys!!

 

This is another thing I've never really understood either. How is it that the PCM adjusts all those fuel calculations when its seeing readings from the O2 sensors bouncing all over the place?? I did think when I was out driving it that the one O2 sensor seemed to be acting really weird by showing low readings. Not to mention there doesn't really seem to be a FULL-PROOF way to test your O2 sensors and see whether or not they're bad.

 

don't forget to address the crossfiring issue - you likley have the plug wires reversed from the opti to # 4 and 8 clyinders.

Also double check the wires going to the injectors - the connectes should be numbered to match the cylinder.

reread Injuneer's writeup on Left Integrator/Right Integrator and Left Block Learn/Right Block Learn[

QUOTE]Not to mention there doesn't really seem to be a FULL-PROOF way to test your O2 sensors and see whether or not they're bad.[/QUOTE]

generally if they are not bouncing between 0-1000mv something is wrong - they are definately broken or disconnected if they read ~constant all the time.

 

Hmm, when I replaced my opti with a new unit from Jason Cromer, I double checked the wires to be sure, but I could look again. Wouldn't it run a lot worse if I had a plug wire crossed? It starts with no problem, idles somewhat smooth....its just during acceleration and maintaining speeds that it starts to hesistate and blow out black smoke. I could check my injector wires though. Its possible I mght've gotten one swapped. I doubt it though. The length on those injector wires are pretty set to fit. And I was pretty careful about that when I did my intake leak fix.