How long does it take for an O2 sensor to heat up? I get a trouble light on cold start, but not on restart after 20 seconds. Is this sensor the culprit?

 

The o2 has to reach 5-600f to become active.
the engine would be about 160-200f for this to happen unless you have a heated o2.

 

Thank you.

do have a heated 02 sensor, but also a three-row radiator which doesn't reach 160F until I've driven four or five miles.

 

In a lot of gm ecm calibrations the engine won’t enter into closed loop until 160f or higher.
Any trouble codes with your mil ?

 

If you've ever driven/ridden in a car with old Christmas tree twinkle light style AFR gauge hooked up to a narrowband O2, you may have noticed on a cold start the twinkly lights kind of stick, or flicker between one-to-three segments of the bar of LEDs. It'll sit with that couple bars lit and won't move much until the engine has been running awhile. After it warms up, the resistance starts to cycle and the gauge starts wiggin out from the rich to lean side, that's about the only easy way I can tell when the O2 comes up to temp. As you can imagine, a cold start on a winter morning or night, it takes a lot longer to come up to temp, compared to a warm start in August. There's no right/wrong time limit.

That said it shouldn't matter. The ECM doesn't care if its a heated o2 or not, one just heats up faster, the signal to the ECM is identical it's just the heated O2 starts cycling faster.

Don't go with guess work. Pull the code. Get the code definition and troubleshooting pages from the manual for your setup, and follow the diagnostic steps/flow chart. Doubt it is the cause of the problem, the hot/cold start difference is just a symptom of whatever problem you have. The code, and charts for isolating it's causes will lead you to the problem by taking you down a path marked with breadcrumbs, eliminating possibilities in a logical manner, until the issue is resolved.... Usually.

 

Rather than fast heating when cold, isn't the main benefit of a heated O2 to keep the sensor at operating temp even during a prolonged idle? So you aren't cycling back and forth between open and closed loop?

 

Thanks, Drew. I pulled the codes. Took awhile to track down year and body model for replacement engine, upgraded to 350 cc.

I'm getting these codes & what my Innova 3140b reader says they mean:

CODES
14 - Coolant sensor or circuit faulty -signal voltage low or shorted. (Car has replacement 3-row radiator with dual electric fans)
36 -Direct ignition system (DIS) fault - loss of 24X signal or extra or missing pulses in electric spark.
43 - Electronic spark control (ESC) circuit problems; Electronic spark timing (EST) circuit--low voltage.
45 - Rich exhaust indicated --left side on dual oxygen models. [My car doesn't have a rear oxygen censor; no cat converter.)
46 - Power steering pressure switch failure or VATS failure. [Switch turns on,, but cruise surges & won't hold a speed]
51 - Computer problem, bad PROM or EXM/PCM [ECM has been recently replaced[
52 - Calibration package chip or oil temperature sensor fault.

Hardware P4 ECM model, 1227165 prom; software $6Ebin from 1989 Camaro; engine 89-350 bored out to 354, called "Wonder." #V1004CKH/17R426073..
54 - Fuel pump circuit fault or Mix Control M/C solenoid fault or ECM fault

I'm having these problems by eyeball:
(1) Oil pressure gauge hits pin &on cold start & stays there; drops as oil heats.
(2) Cruise control doesn't work; it surges.
(3) RPM and slow idle extra high on some starts & at highway speeds, but sometimes okay..
(4) Bad mileage 11.5 mpg instead of 14 mpg from EPA; running rich & oil getting dirty rapidly after oil change.
(5) On cold start, check engine light comes on. If I turn off the engine for 20 seconds, turn ignition key on for 20 seconds, then start, check engine light goes off & stays off.

Oil Pressure problem seems clear; fuel mix, too. Maybe a vacuum switch problem?

Thanks for helping this old English major.

 

Your code 36 maf description is incorrect.

http://www.chevythunder.com/Flow%20chart%20index.htm

though the ecm has been replaced it could be bad especially throwing a code 51. The memcal very rarely fails.

 

Thank you.

 

If you provide the code off your memcal (4 letters). I can see if I have that file.
If you wanted to mail me your memcal and pay return shipping I can check it out if I have the file to see if it’s corrupt.
The silver sticker on the memcal should start with the letter A

 

Thank you. Will look.

 

Yup. It was the ECM. But this is the fifth time I've replaced it in the last two years. What gives?

 

Are you getting the ecm from the same manufacturer? Cardone?

 

Yes, and I keep sending them back.

 

It's the memcal.

 

New ecm throwing a code 51 ?

 

Yes, Code 51& 52, ECM on my 1991 camaro RS needs repair or replacement. The original ECM number is 1257155. The original PROM # is 25173303; prom; software $6Ebin from 1989 Camaro; engine 89-350 bored out to 354, (called "Wonder.") has engine no. V1004CKH/17R426073. Delco will repair my bad ECM, which cuts in & out when tapped and there seems to be a burn mark on the edge of the PROM/ Can you help me out here? AC Delco will repair (replacement no. 88991940) but will take six weeks.

 

Are you sure about the ecm number ?
This is tbi ?
should be a 1228746 if it’s tbi
what are the letters on the top of the prom ?

 

This is TPI. ECU # is correct, but it's a replacement.

 

I have a 165 ecm . Ecm for 86-89 tpi.
Confused about your service numbers and that’s it’s a rs.
I will sell you. As for the memcal let me know the letters off of it and I can get one together as well. Or if you want to mail me yours I’m sure I can refurbish it.

 

software $6Ebin from 1989 Camaro; Is this what you need?

 

Is that what the prom says ?

 

That's what I was given, when that engine was installed. Programming is above my pay grade.

 

The four letters identify the programming you have.
without knowing this I have no idea what’s needed.