BUILD THREAD 84 Hurst Olds - TechG8
- Thread starter techg8
- Start date
- Status
I masked off and repainted the lower black section of the body, and the bumpers. Wow it makes a big difference in the look of the car overall. No more dings and chips down there to draw the eye.
Its been running rich of late. Dwell stuck below 30 , not varying at all like it should. I might have a bad O2 sensor or wire.
Its been running rich of late. Dwell stuck below 30 , not varying at all like it should. I might have a bad O2 sensor or wire.
Check your ECM coolant sensor (outboard one nearest the head) wiring to make sure that's not hosed. Check O2 sensor wiring, make sure that didn't get cooked somewhere.
O2 sensor new? Or original? Or ???? TPS plunger operating ok?
84 Cutlass ECM pages 6E1-36 and 37 has a trouble shooting chart for fixed dwell between 10 and 50 degrees.
Start engine, ground test terminal, run engine at 2000 rpm for one minute to heat up O2 sensor. Return to idle, disconnect O2 wiring at O2 sensor plug. Ground O2 wiring going to ECM and leave grounded for rest of test.
If you disconnect and ground the O2 sensor wire on computer side, your dwell should decrease. Book says if it does decrease, to check ECM terminal 14 for an open. If open, repair. If not open--- Leaving it grounded, check O2 wire to ground at the 2 volt or low volt setting on digital volt meter. Should be over 0.8 volts. If not, the O2 sensor is toast. If over 0.8 volts, then O2 sensor connection is bad.
If dwell doesn't decrease when grounding the O2 wire, connect jumper between terminals 9 and 14. O2 sensor wiring goes to ECM terminal #9. ECM grounds the O2 sensor via terminal 14. If dwell decreases, repair open in O2 wiring.
Coolant temp wiring to ECM is terminals 3 (5V reference) and 7 (ground). If dwell still not changing after above check, turn car off, ignition on. Check terminal 3 for voltage to temp sensor. If >4 volts at terminal 3, then it's an open wire to the temp sensor. If <4 volts at terminal 3, it could be a bad connection for O2 sensor and/or bad ECM.
Hope all that crap made sense. If you don't find the issue soon, I'll try and post pics of it later.
O2 sensor new? Or original? Or ???? TPS plunger operating ok?
84 Cutlass ECM pages 6E1-36 and 37 has a trouble shooting chart for fixed dwell between 10 and 50 degrees.
Start engine, ground test terminal, run engine at 2000 rpm for one minute to heat up O2 sensor. Return to idle, disconnect O2 wiring at O2 sensor plug. Ground O2 wiring going to ECM and leave grounded for rest of test.
If you disconnect and ground the O2 sensor wire on computer side, your dwell should decrease. Book says if it does decrease, to check ECM terminal 14 for an open. If open, repair. If not open--- Leaving it grounded, check O2 wire to ground at the 2 volt or low volt setting on digital volt meter. Should be over 0.8 volts. If not, the O2 sensor is toast. If over 0.8 volts, then O2 sensor connection is bad.
If dwell doesn't decrease when grounding the O2 wire, connect jumper between terminals 9 and 14. O2 sensor wiring goes to ECM terminal #9. ECM grounds the O2 sensor via terminal 14. If dwell decreases, repair open in O2 wiring.
Coolant temp wiring to ECM is terminals 3 (5V reference) and 7 (ground). If dwell still not changing after above check, turn car off, ignition on. Check terminal 3 for voltage to temp sensor. If >4 volts at terminal 3, then it's an open wire to the temp sensor. If <4 volts at terminal 3, it could be a bad connection for O2 sensor and/or bad ECM.
Hope all that crap made sense. If you don't find the issue soon, I'll try and post pics of it later.
Just as an oh, by the way, if you DO need to replace the O2 sensor, get AFS-21. ACDelco part. That's the replacement for the discontinued AFS-20 which took over for the original AFS-16P. But if you have any or can get any of these, they'll work.
If you buy another brand, you may have issues. In my experience, I've never had any good luck with anything other than ACDelco O2 sensors. Just my recommendation. GM p/n 25105901
If you buy another brand, you may have issues. In my experience, I've never had any good luck with anything other than ACDelco O2 sensors. Just my recommendation. GM p/n 25105901
Genuine OEM AC Afs21 GM 25105901 Exhaust Oxygen Sensor for sale online | eBay
Find many great new & used options and get the best deals for Genuine OEM AC Afs21 GM 25105901 Exhaust Oxygen Sensor at the best online prices at eBay! Free shipping for many products!
rover.ebay.com
thanks for all that. I have the manual just haven't had time to chase it yet.
Here is some interesting info...BEFORE I pulled the engine it ran on the ECM with no codes. No check engine light.
When I pulled the engine I broke the o2 sensor.
Replaced it with a used/newer one I had in the basement from I believe an 86 olds 307. I believe it was a bosch.
since then Ive had this problem.
at the same time I am fighting the bad gage foil circuit issues that are common......so sometimes I get the engine light other times not. sometimes turn signals work sometimes not. sometimes tach reads high sometimes not.
Here is some interesting info...BEFORE I pulled the engine it ran on the ECM with no codes. No check engine light.
When I pulled the engine I broke the o2 sensor.
Replaced it with a used/newer one I had in the basement from I believe an 86 olds 307. I believe it was a bosch.
since then Ive had this problem.
at the same time I am fighting the bad gage foil circuit issues that are common......so sometimes I get the engine light other times not. sometimes turn signals work sometimes not. sometimes tach reads high sometimes not.
Check your grounds. I could be the printed circuit board as well. The Bosch O2 sensors are known to be garbage. Get the sensor 69hurstolds mentioned above.
- Status
