O2 sensors information

[cook28]

I replaced two O2 sesors following a head gasket change both were pre cat. Are these sensors Bank 1 Sensor 2 and Bank 2 Sensor 2? The reason I'm asking is I have been getting hard starting only in the morning but fine the rest of the day. I have no CEL but the secondary air pump does not initiate. If I'm correct temperature is detected from the O2 to send a signal for air injection to warm sensors, correct. I hooked up my OBD to the laptop and let the car warm up for ten minutes and monitored voltage. The above sensors barely fluctuated from .975-.980vdc. The other two fluctuated from .2 - .7. I believe parameters are up to .8 vdc. Thanks for any help.

[dankad]

Originally Posted by cook28

I replaced two O2 sesors following a head gasket change both were pre cat. Are these sensors Bank 1 Sensor 2 and Bank 2 Sensor 2? The reason I'm asking is I have been getting hard starting only in the morning but fine the rest of the day. I have no CEL but the secondary air pump does not initiate. If I'm correct temperature is detected from the O2 to send a signal for air injection to warm sensors, correct. I hooked up my OBD to the laptop and let the car warm up for ten minutes and monitored voltage. The above sensors barely fluctuated from .975-.980vdc. The other two fluctuated from .2 - .7. I believe parameters are up to .8 vdc. Thanks for any help.

hi, I'm having problems trying to diagnose my "checklight " cause, do you mind telling me what software you are using to measure the oxygen sensor voltages?
Thanks in advance
Dan

[cook28]

Not a problem, here is the web address below. They have a sale right now. I've used it for about four years and think its better than generic readers.

OBDCOM Diagnostic Systems for ALL vehicles

[marti5]

Firstly what springs to mind is unless you have a V8 or V12 you only have one bank??

[cook28]

My E36 M52 has two banks. Two pre cat and two post cat. Did you replace the two pre cat if applicable to your setup? Better yet, what setup do you have?

realoem.com

[cjscopp]

Your secondary air is controlled by a relay activated by the control module with inputs from engine temp and ambient air temp. If your secondary air is inoperative you may want to look at the coolant temp sensors/connectors or the intake air sensor/connectors. This in conjunction with the hard cold start indicates a coolant temp sensor issue in my opinion. You should be able to see the temp sensor readings on your laptop connected to the OBDII ALDL. If the controller is not seeing the correct cold temp sensor readings your cold start strategy wont work and thus hard cold starts.

[cook28]

Interesting, I always knew they were tied in but when monitoring on the program for OBD intake rises and cools as I accelerate and coolant temp sensor starts out about 76-80df and slowly as engine idles goes to about 203 after 10-15 minutes. Does this appear to be normal? I also detected no vacuum from the one of the secondary air solenoid going back to the air pump and valve on exhaust side.I replaced the solenoid and the pump worked for 5 seconds and stopped. I think I cooked the switch. I looked today at the old switch and noticed I was shipped a different number. The Groton catalog said it was for my application but the number were different. I ordered from RME the right one today. I wonder if this switch not in the system would cause the no start

[dankad]

Originally Posted by cook28

Not a problem, here is the web address below. They have a sale right now. I've used it for about four years and think its better than generic readers.

OBDCOM Diagnostic Systems for ALL vehicles

Thanks for the great info man. much appreciated. Problem is, Iam in the UK and we dont seem to have a distributor for these guys. Tried to contact them by Email, they did not bother to respond. I will try to phone them perhaps.

Thanks again.
Dan