Attn: Michael or Scott in the Apex area (or anyone else with a 93-95 525i)...

[billb]

Would either of you guys be "willing" to let me borrow your AFM for a few minutes? I'm trying to find out why my 525 goes through this wonky rich running thing, and I've tested/replaced everything but that. New FPR, new O2 sensor; checked and verified correct operation of ECT, IAT, TPS, CPS; all injectors firing (and clean!), all coils firing. I'm nearing wits' end...

I'm in the phone book, under Bass William, or shoot me an email. It's in my profile. I'm at work this morning (Saturday) until noon, then free from noon -4, and most of the day tomorrow (Sunday).

Thanks guys!

[Bill R.]

engine is warmed up?

Would either of you guys be "willing" to let me borrow your AFM for a few minutes? I'm trying to find out why my 525 goes through this wonky rich running thing, and I've tested/replaced everything but that. New FPR, new O2 sensor; checked and verified correct operation of ECT, IAT, TPS, CPS; all injectors firing (and clean!), all coils firing. I'm nearing wits' end...

I'm in the phone book, under Bass William, or shoot me an email. It's in my profile. I'm at work this morning (Saturday) until noon, then free from noon -4, and most of the day tomorrow (Sunday).

Thanks guys!

[billb]

engine is warmed up?

[billb]

engine is warmed up?

I pulled the cover off the connector and am backprobing the connections. Getting ~1V at idle, and it increases as engine speed goes up. Checking O2 sensor though at the DME, I am only seeing 0.45V...it's not changing, even when the idle is hunting up and down. Isn't 0.45V the midpoint for stoichiometric operation? I can't get it to run long enough for me to crawl under and backprobe the O2 sensor connection, but with the sensor out and using a propane torch, I was able to get it to go back and forth around the 0.45V point, all the way up to 1, down to almost 0. Hmmm, maybe that's where I need to look...if it's not fluctuating, it's not adjusting. Wonder if I've got some wonky wiring going to the DME from the O2 sensor?

[Bill R.]

sensor is up to temperature and working correctly the voltage fluctuations are pretty rapid.. about 3 to five times a second on cars that are adjusting correctly.... What happens if you disconnect the throttle position switch and then run the car? Not the maf just the throttle position switch

I pulled the cover off the connector and am backprobing the connections. Getting ~1V at idle, and it increases as engine speed goes up. Checking O2 sensor though at the DME, I am only seeing 0.45V...it's not changing, even when the idle is hunting up and down. Isn't 0.45V the midpoint for stoichiometric operation? I can't get it to run long enough for me to crawl under and backprobe the O2 sensor connection, but with the sensor out and using a propane torch, I was able to get it to go back and forth around the 0.45V point, all the way up to 1, down to almost 0. Hmmm, maybe that's where I need to look...if it's not fluctuating, it's not adjusting. Wonder if I've got some wonky wiring going to the DME from the O2 sensor?

[billb]

sensor is up to temperature and working correctly the voltage fluctuations are pretty rapid.. about 3 to five times a second on cars that are adjusting correctly.... What happens if you disconnect the throttle position switch and then run the car? Not the maf just the throttle position switch

but let me try it again...

[billb]

but let me try it again...

Pulled a plug..here's what we look like after about 10 minutes total time of running at idle. I'm really suspecting the fuel at this point...it's just too dang coincidental that it's happening right after a fillup (when I was almost empty in the previous tank). Really considering buying several 5-gallon gas cans, siphoning this tank out, and starting fresh.

[632 Regal]

so this happened right after filling up??

[billb]

so this happened right after filling up??

Yep, within about 10-15 miles. Was going to try to drain the tank, but see no drain plug. Going to procure some 5-gallon tanks tomorrow and drain it all out, then put in some known good gas from my 318, and see what we get.

This is so frustrating. All sensors check out good, except I can't test the O2 sensor-it quits before I can get under the car and check the signal at the connector and checking it at the DME, I only get constant 0.45 V, even when it should be closed loop.

[632 Regal]

double check that. I wonder if someone messed up and put some deisel in the tank when filling it up. (not you but at the station)