Code 31 - Camshaft Sensor - ZR-1 Net Registry Forums

Patton · 09-02-2005

First and foremost Happy Labor Day weekend to all and even though most of us will be having fun, please keep your hearts and prayers with our fellow country men effected by Katrina.

Thanks to all who helped and are helping me with my secondary vacuum system problem Iâ€™m sure I will have my own project results to share with you all soon and just might help somebody in the same situation. I have one other problem I must address however, and I cannot find a copy of the shop manual for my '94 anywhere. I am still pulling a code seemingly unrelated to the others, 31 - Camshaft Sensor,... Where the hell is this thing and its related circuit? Maybe a part number or two? Any help would be great!! Thanks!!

Patton · 10-01-2005

Hmmm,... not a good sign.

crjspo23 · 08-04-2012

Just had a similar problem. Backed my 90 ZR-1 out of the garage and it started idling rough, smoking, and Service Engine Soon light came on. Checked the code and found code 31, Camshaft sensor. Any words of wisdom to troubleshoot and correct?

Mystic ZR-1 · 08-04-2012

Cut to the chase, Injectors...

tomtom72 · 08-05-2012

Could be, or check the MAP hose at the rear of the plenum. As for the DTC 31 Cam position sensor, it's a hall effect sensor in the left cylinder head. I used to get that DTC quite a bit till I cleaned the harness connector.

In any event, if 31 does "set" the ECM puts the ignition and injectors into batch fire and locks out secondary port throttle activation. It assumes that with no cam position sensor, the car can't use our DIS box to control spark. It then chooses to use what I think is a limp home method of ignition control.

Are the injectors OEM? What color smoke? Kind of greyish to dirty white? You didn't happen to get a wiff of the smoke? Did it make your eyes water? That usually is a lean condition which supports bad injectors. It would be better to hook up a scanner to see what the ECM is seeing. Or pull a few plugs from both banks to see what combustion looks like.

Tom

crjspo23 · 08-05-2012

Thanks Tom. When you got the 31 code did you just clean the harness connector up near the brake master cylinder with dielectric spray or something similar?

I don't think it's injectors as it ran fine until the SES light kicked on and it started running rough and got blueish smoke, like it was running rich and loading up.

I've seen a couple comments about the MAP hose. Where is it and what do you look for?

09-02-2005	#1
Patton Join Date: Dec 2003 Location: Sacramento, CA Posts: 220	Code 31 - Camshaft Sensor First and foremost Happy Labor Day weekend to all and even though most of us will be having fun, please keep your hearts and prayers with our fellow country men effected by Katrina. Thanks to all who helped and are helping me with my secondary vacuum system problem Iâ€™m sure I will have my own project results to share with you all soon and just might help somebody in the same situation. I have one other problem I must address however, and I cannot find a copy of the shop manual for my '94 anywhere. I am still pulling a code seemingly unrelated to the others, 31 - Camshaft Sensor,... Where the hell is this thing and its related circuit? Maybe a part number or two? Any help would be great!! Thanks!!

10-01-2005	#2
Patton Join Date: Dec 2003 Location: Sacramento, CA Posts: 220	Re: Code 31 - Camshaft Sensor Hmmm,... not a good sign.

08-04-2012	#3
crjspo23 Join Date: Jun 2012 Location: North Carolina Posts: 22	Re: Code 31 - Camshaft Sensor Just had a similar problem. Backed my 90 ZR-1 out of the garage and it started idling rough, smoking, and Service Engine Soon light came on. Checked the code and found code 31, Camshaft sensor. Any words of wisdom to troubleshoot and correct?

08-04-2012	#4
Mystic ZR-1 Join Date: Jan 2010 Location: Mystic CT Posts: 2,631	Re: Code 31 - Camshaft Sensor Cut to the chase, Injectors...

08-05-2012	#5
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,609	Re: Code 31 - Camshaft Sensor Could be, or check the MAP hose at the rear of the plenum. As for the DTC 31 Cam position sensor, it's a hall effect sensor in the left cylinder head. I used to get that DTC quite a bit till I cleaned the harness connector. In any event, if 31 does "set" the ECM puts the ignition and injectors into batch fire and locks out secondary port throttle activation. It assumes that with no cam position sensor, the car can't use our DIS box to control spark. It then chooses to use what I think is a limp home method of ignition control. Are the injectors OEM? What color smoke? Kind of greyish to dirty white? You didn't happen to get a wiff of the smoke? Did it make your eyes water? That usually is a lean condition which supports bad injectors. It would be better to hook up a scanner to see what the ECM is seeing. Or pull a few plugs from both banks to see what combustion looks like. Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

08-05-2012	#6
crjspo23 Join Date: Jun 2012 Location: North Carolina Posts: 22	Re: Code 31 - Camshaft Sensor Thanks Tom. When you got the 31 code did you just clean the harness connector up near the brake master cylinder with dielectric spray or something similar? I don't think it's injectors as it ran fine until the SES light kicked on and it started running rough and got blueish smoke, like it was running rich and loading up. I've seen a couple comments about the MAP hose. Where is it and what do you look for?