causing the stalling, it was my o2 sensors!

story: i figured that the computer goes into limp mode after it stalls, so long as its in limp mode, it DOESNT stall anymore. itll still hard start some though. since this problem was too consistant it couldnt be the optical sensor since if it was truely bad or overheating it would do it more than that one time in regular closed loop. so i ruled out the MAF by unplugging it while in limp mode and it still kicked into speed density. i then pulled the o2 sensors (bosch 1 year old) and the tips were coated in thick black carbon, even inside the slits. these sensors gave me an SES even day 1 from not being hot enough in 6th cruising.

i had the fuel pressure regular diaphram go bad on me right before this stalling problem began and was causing a bad backfire at higher rpm. so i put everything together and came to the conclusion that if i had this backfiring too many times and 2 sets of fouled spark plugs, then the o2's must be fouled. so i left them unhooked so it forced the PCM into limp-dick mode, and low and behold it never stalled. seems like since i have OBD1 and with it not being as sensitive to faults, the PCM never could catch the failing sensors in time before it stalled to give me the o2 code. when i pulled the code 16 from the PCM earlier this month, i was thinking it must still be from 2005 because thats when the previous owner had it changed (oem ac) and with only 10,000 miles on it, nothing leaking onto it but very very light oil from the front main seal, i failed to see how it was bad.

so im going to pick up a set of denso sensors for $38 each since they are pretty stout and have a good reputation so far and since the dealer wants $102 each for AC's

so pretty much im done with these stumped topics hahahaha.

 

you can get delcos for $50 or so from a place like rms autoparts or prolly even sdpc

Matt

 

yea but i dont want to wait because of easter monday for shipping. im picking up a set tomorrow from pepboys.

 

gotcha. well good luck with them

 

well now that i found the problem, now i can finally go back to my appearance plans that ive had for 4 months. starting with FRC's.

 

good to know. I've had an issue on my car for 2yrs now that I still can't figure out. The bad thing is it only happens after the car has sat for hours at a time. Turn the AC on, Press the brake pedal (on occasion) or put car in gear, and it almost stalls (300rpm) but recovers. Has a slight miss @ 1000-1200rpm, range. Sometimes it doesn't do it. I only have a short window to see what the issue is, and havent found a single thing everytime I try. Everything is AC DELCO and pratically new. I've checked wiring 10x up front.

Even Taken the loom off most of it to check wiring. Fuel Pump is fine. About the only thing I haven't checked is the stupid opti.. Nothing in the datalogs show anything besides the obvious dip in idle.

 

how old is the opti?

 

about a year and a half maybe two years. AC DELCO with new vent harness. I dont know what would be going on in the opti for it to do that when it's been sitting then get fine when it warms up (close to closed loop). Perhaps I'll have to pull it this summer and check the inside. I wish I would have read about loctiting the rotor screws before installing.

 

 

well....

drove the car and it was fine for 30 min then it started again.

looks like im gonna have to go LTCC and/or replace the distributor of death.

i just dont get how it would only do it once then when in "safe mode" never again.

 

The cursed opti can do some crazy things sometimes. Just make sure thats what it is before you go buy a new one. Did you check out the harness to the opti? If you got the money convert to a vented or get a MSD cap and rotor. I replaced my stock opti twice within 10k miles but then i got a vented MSD and it has been well over 10K. I absolutely hate the 93-94 optis since they are sealed. I know others have gone 100k on these optis but I was an unlucky one.

 

i just put in a new harness because the low-res wire was bare near the opti end.

im gonna just get another non vented because since ill be running LTCC, no ozone or spark reidue should form.

 

Wow! You must be rich to buy both new!

 

tax return lol

 

you guys think it could be carbon tracking?