Help - I'm frustrated! Ox sensor?

[ITZA72]

My 87 350 and I are not getting along today. After sitting for about 10 days I ran her to the gas station. She didn't start like normal and ran rough (like a stuck choke) but once I got going she ran normal til back to idle. By the time I got her home - she was buckin hard.

Over the last 6 months the check engine light has come on a sporadically but never is consistent so I've ignored it. The wires, cap n rotor and fuel filter are new - I'm wondering if my Ox Sensor may have crapped out? Thoughts?

[KShortell]

Well, if it's the original sensor, it could be getting lazy by now. Try checking for trouble codes. I'm not sure about the R/V series trucks, but I know that lots of the mid-80s GM on-board computers could show the codes by jumping the right terminals with a wire or even a paper clip. I forget which terminals, but I've done it before-- a long time ago...

[old Rusty C10]

you can get a computer decoder cheap and i have a book if yall can get a code out of it i can tell ya what the code is
auto zone will also run codes for free if ya buy their parts

[.38 special]

if it is the o2, I wouldn't use anything but AC Delco. I had a bosch last about 20 minutes.

[ITZA72]

thanks .38 - I'd have gone right out and bought a Bosch cuz of the savings. AC Delco then. I'm taken her to the garage tonite - think it could be the EGR valve. Thanks for the advice

[.38 special]

It sounds like O2 to me but, maybe TPS? But I haven't tuned a whole lot on my truck yet, so I am no expert on the system. Read the code, it should tell you.
Another good o2 is the Denso (I've used them on the Buick, they are nearly indestructable) but I don't know if they are the same, or if they make them for the truck at all, since I haven't replaced mine.
You can get them for like $25 from sparkplugs.com, and they really are better than the delco, at least for the Buick.

[Black872500]

My 87 2500 454 is doing the exact same thing. It is sporadic. It will run fine once, in a while the light will come on then it won't idle and runs like a turd unless your in the throttle. I have replaced the ecm, egr, egr solenoid,ox sencor had the throttle boddy rebushed and supposedly they did a sweep on the tps and it checked ok. After I did the 02 scencor it ran pretty good for a couple days now back to the sme old crap. Shows code 44- lean exaust. I have checked for vacumm leaks, can't find any, the base gasket on the throttle body is new. This thing is really getting undr my skin and getting expensive. It will do this most of the time and then all the sudden run fine for a little while then same old sh*t again.

Greg

[ITZA72]

I remedied mine by replacing the MAF sensor. I wasn't aware the O2 sensor doesn't even monitor the exhaust til it was up to operating temp and thought the EGR was the problem too. As it turned out (I had my mechanic track this down) the EGR was coding but was as a result of the MAF sensor. If you need more info I'll get a part # and send it but I don't think my invoice was that detailed. I can if you need it though. Good luck with that - mines back to running like a dream.

[.38 special]

Are you sure it wasn't the MAP sensor?

[Jason Spears]

Black872500:

There may be several causes to your problems:

Has the distributor ever been moved? Check the timing. Make sure you disconnect the black wire with the tan stripe to keep the ecm from messing with the timing while you are checking it.

To check for the MAP sensor you can check the system voltage vs a known good unit using a scan tool or idle your truck and disconnect the electrical connection, if the idle improves the sensor may be bad.

I've had the vacuum line going to the transmission pop off and cause a very rough idle as well. It was tricky to find because it still looked like it was connected.

did your O2 sensor have a white powdery coating on it?

Code 44 may be caused by the O2 sensor or by low fuel pressure.

Hope this info helps you out.

Jason

[Grim Reaper]

Never had a problem with Bosch O2's. I have ran them in the last 6 vehicles I have owned with no trouble. Also used them on normal maintance for mom's and my sisters cars. Factory equipment for Porsche, Benz and BMW.

My 454 burb is cranky as hell cold. I had it pop off a code 44. I think that I am starting to wonder if it's going closed loop too soon.

Cold it runs horribly rich and idle drops when I would think it's running open loop and running a preset. Bogs bad when it's 2/3's on it's way to normal operating temp. Once I'm up to operating temp she runs fine. I wonder if the temp sensor for the ECM is bad and telling it that it's warm enogh to go closed loop when it isn't.

I'm looking for a lap top now so I can get the Win ADLd software and real time it to see what's going on in it's pea brain.

[ITZA72]

No - you're right - MAP not MAF - my blunder.

Thanks .38