Weird O2 readings.....

[Royal-T-Ltd]

Okay..... [bkgrd info] i have been fighting an odd drivability problem for the last couple of weeks... the car started randomly shutting down when warm. Block Learn is pegged at 160... i have since checked ALL vacuum lines, replaced an old PCV valve and sprayed Throttle Body cleaner on all lines and Intake. I have reset the IAC, verified all other numbers are within spec, reseated all connections to the ECM/PROM. I have managed to get idle down within spec but randomly when driving i can watch the 02s on the scanmaster and for long periods of time they will read 000.000 and then the BLM is 160 and wideband drops way fat, it drops to 10.0 which is the minimum, so its probably even richer..... i have also replaced the O2 as insurance that it is working properly. CrossCounts are good. Until i saw the O2 numbers were wacky i was gonna throw on another MAF just to see if it made a difference - now i am all confused after seeing the 000s.

My car is a chip car with a Gen2 translator and a 3.5" Aluminum LS1 MAF..... what am i missing.... Until now my T-type has been trouble free and i wouldn't hesitate to drive cross country.... now i can't drive to work.... i am getting depressed and missing all the good cool weather....


so in conclusion, Help a Brother Out


aaron

 

[87geeinn]

Injector hanging open?

 

[Royal-T-Ltd]

Injector hanging open?

good thought but IMO if the injector was hanging open the Block Learn would be maxed out the other way, showing a rich condition and pulling feel..... at least that's what i would think - i could be wrong

 

[aminga]

I think you have to address why the O2 is dropping to zero. Then see where the BLM's go. I'd check the grounds.

 

[Royal-T-Ltd]

I think you have to address why the O2 is dropping to zero. Then see where the BLM's go. I'd check the grounds.

You are correct i think the dropping signal might be causing the high BLMs.... my question is why... nothing has changed and everything seems tight.... will double check grounds but kinda doubt......you never know though

 

[aminga]

You are correct i think the dropping signal might be causing the high BLMs.... my question is why... nothing has changed and everything seems tight.... will double check grounds but kinda doubt......you never know though

The O2 has it's own ground on the ECM. At the ECM harness D6 and D7 are the signal and ground (don't remember which is which)

 

[Royal-T-Ltd]

The O2 has it's own ground on the ECM. At the ECM harness D6 and D7 are the signal and ground (don't remember which is which)

thks! I will check it out after workAaron

 

[87geeinn]

Hmmm, interesting. I just re-read your post and it's difficult to say. For one, your BLMs and 02 numbers suggest an extremely lean condition, whereas your wideband is showing completely opposite (i.e., a very rich condition). Do you have a fuel pressure gauge you can hook up and monitor while driving? Could be fuel component related or electrical related. Kinda hard to say at this point. You say it shuts down? As in stalls? When warm only? Does it start back up immediately? In my experience, grounding issues will not usually cause the car to shut off once running. Yes, it may act real funny and all sorts of gremlins show up, but I've never had one shut completely down as in your case.

Done any recent mods to the car?

 

[Royal-T-Ltd]

Hmmm, interesting. I just re-read your post and it's difficult to say. For one, your BLMs and 02 numbers suggest an extremely lean condition, whereas your wideband is showing completely opposite (i.e., a very rich condition). Do you have a fuel pressure gauge you can hook up and monitor while driving? Could be fuel component related or electrical related. Kinda hard to say at this point. You say it shuts down? As in stalls? When warm only? Does it start back up immediately? In my experience, grounding issues will not usually cause the car to shut off once running. Yes, it may act real funny and all sorts of gremlins show up, but I've never had one shut completely down as in your case.

Done any recent mods to the car?

No... you must understand the ECM... when the computer reads Rich it pulls fuel and leans the car out.... as my BLM shows an EXTREMELY Lean condition the ECM is just dumping in Fuel to [in this case] OVER compensate.... this is normal correction.... i just got in from messing around with the car... i will test drive later and see if anything helped

aaron

 

[Royal-T-Ltd]

Do you have a fuel pressure gauge you can hook up and monitor while driving? Could be fuel component related or electrical related. Kinda hard to say at this point. You say it shuts down? As in stalls? When warm only? Does it start back up immediately? In my experience, grounding issues will not usually cause the car to shut off once running. Yes, it may act real funny and all sorts of gremlins show up, but I've never had one shut completely down as in your case.

Done any recent mods to the car?

Yes i have a FP gauge and it reads completely normal.... when it shuts down... mostly after driving, it stalls at the stop light, but then i can start it back up and keep it running within a few turn overs... i'll keep you posted.

aaron

 

[87geeinn]

No... you must understand the ECM... when the computer reads Rich it pulls fuel and leans the car out.... as my BLM shows an EXTREMELY Lean condition the ECM is just dumping in Fuel to [in this case] OVER compensate.... this is normal correction.... i just got in from messing around with the car... i will test drive later and see if anything helped

aaron

Yes, that was what I was saying, just in different terms. In other words, the BLM correction is pegged at the farthest end of the correction table (beyond it's ability to control fueling), thus suggesting that the ECM "thinks" that things are still lean, when in fact the ECM seems to be piling in waaaay too much fuel as evidenced by your wideband readings. Sorry for the confusion.

 

[Royal-T-Ltd]

Okay.... more updates, I reseated both ECM bulkheads, i reseated both Chip and Calpack, i reflashed software on Gen2 to current version 1.21 [i had 1.03] and reprogrammed Gen2 [just in case i had a funky setting], i made sure all pins were straight and no corrosion, especially on pin D6/D7 of bulkhead [purple and light tan wires], i triple checked connection at 02 sensor for tightness.... ALL TO NO PREVAIL

...now comes the fun part.... i guess i have to trace the purple [and Light Tan Wire] and make sure there are no breaks or rubbing anywhere... oh and i will borrow a computer from my brother just to verify my ECM actually works

.....Anybody else ever have this problem where the 02 signal justs "drops out"

Aaron

 

[TurboDave]

I don't know if it was ever posted, but what exact NB O2 are you running?

 

[Royal-T-Ltd]

i just switched to a new AC/Delco.... i believe [off the top of my head] an AF22?? i also have a NEW NTK i could try but i was trying to avoid throwing parts at it.... LMK what you think Dave.

thks

aaron

 

[TurboDave]

You may have missed my posts about the problems associated specifically with the AFS-22's. They are a nightmare. We tested several here, and they all displayed the same troublesome issue:

Any, and I mean any acceleration caused the O2's to drop to 000 and stay there untill lifting or idling or light throttle cruise.

Get rid of that AFS22 immediately!

 

[Royal-T-Ltd]

You may have missed my posts about the problems associated specifically with the AFS-22's. They are a nightmare. We tested several here, and they all displayed the same troublesome issue:Any, and I mean any acceleration caused the O2's to drop to 000 and stay there untill lifting or idling or light throttle cruise.Get rid of that AFS22 immediately!

Dave that is exactly what mine is doing.......u are the greatest..... I pray that is what it is

 

[Royal-T-Ltd]

>>>UPDATE

Dave - You ARE Da'Man!!!!

i am back in the game!!!! Who would have thought out of all the years i have owned the car and all the parts i have installed a Brand New AC/Delco part was my downfall :-\ .... that P.O.S. O2 sensor has been driving me nuts for 2+ weeks.... if only i would have known to search for the part #.... who would have known... i am just elated that you found my thread.... damn i'm happy.... it sux that i missed the last two weeks of cool nice weather - but whatever - i am just happy to drive my car again... thanks a million, i owe you a frosty cold beverage of your choice!

aaron

 

[TurboDave]

Glad I could help. Catch me at the tb.com nats.

 

[GNBUICK87]

Glad I could help. Catch me at the tb.com nats.

Dave What O2 sensor should i get instead of installing the A/C Delco one is there a part number Or a vender that sells the correct one i need.

 

[TurboDave]

Lot's of guys seem to like the Denso brand. Me personally, I prefer the AC AFS-20