Not going closed loop
Thread Starter
Le Mans Master
Joined: Jun 2002
Posts: 6,097
Likes: 0
From: High Plains Drifter Fayetteville, AR
Not going closed loop
Got the heated O2 sensor, relay and wiring installed today. Did some datalogging and I'm still not going closed loop. The O2 sensor isn't fluctuating, but I'm getting crosscounts, how can that be?
It started out at 450mv and went up to 623mv very slowly over about 15 minutes at idle.
The relay works, the wiring is hooked up correctly, how can I test for a bad sensor? I don't have the cash on hand right now to just throw a new sensor at it.
This is really pissing me off.
It started out at 450mv and went up to 623mv very slowly over about 15 minutes at idle.
The relay works, the wiring is hooked up correctly, how can I test for a bad sensor? I don't have the cash on hand right now to just throw a new sensor at it.
This is really pissing me off.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Evertime the reading crosses 450 MV you'll get a cross count increase.
As you probably know, the 02 readings should cycle from about .1 to .9 in only a couple of seconds, certainly not minutes.
The 02 needs about 600 F to working and until it does, the ECM ignores it.
Tell us how you wired the new sensor.
Jake
As you probably know, the 02 readings should cycle from about .1 to .9 in only a couple of seconds, certainly not minutes.
The 02 needs about 600 F to working and until it does, the ECM ignores it.
Tell us how you wired the new sensor.
Jake
Thread Starter
Le Mans Master
Joined: Jun 2002
Posts: 6,097
Likes: 0
From: High Plains Drifter Fayetteville, AR
Sensor and harness were sent to me with the headers I boght off another member.
Harness uses a relay for the heating element. The relay has a fused constant 12v input, switched 12v input, and a ground. Grounded the relay and the sensor to the transmission bellhousing near the O2 sensor, there was a convenient bolt there. I'm runing the constant 12v from the terminal behind the battery, and switched from the wiper motor.
Using a test light, I verified that my source at the wiper motor was switched. Then spliced it into the relay. Once that was done, I verified that the relay was working by using the test light. When I turn the key, the realy switches and applies 12v to the sensor.
When I said the O2 readings rose, I never saw it fluctuate from high to low or anything else, would stay steady for a minute or so, then go up a few MV. But I was getting cross counts at the same time? I thought a cross count was when the reading rose above or fell below the 450mv reference signal? I'm about to head back out to the garage and see if I can find what's up.
Harness uses a relay for the heating element. The relay has a fused constant 12v input, switched 12v input, and a ground. Grounded the relay and the sensor to the transmission bellhousing near the O2 sensor, there was a convenient bolt there. I'm runing the constant 12v from the terminal behind the battery, and switched from the wiper motor.
Using a test light, I verified that my source at the wiper motor was switched. Then spliced it into the relay. Once that was done, I verified that the relay was working by using the test light. When I turn the key, the realy switches and applies 12v to the sensor.
When I said the O2 readings rose, I never saw it fluctuate from high to low or anything else, would stay steady for a minute or so, then go up a few MV. But I was getting cross counts at the same time? I thought a cross count was when the reading rose above or fell below the 450mv reference signal? I'm about to head back out to the garage and see if I can find what's up.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
I originally wired my heated 02 to the wiper motor too, but later found out that's not a good source.
Seems that the delay function for the wiper effects the voltage which caused my system to drop out of closed loop. I posted on this before but it's worth repeating.
I suggest you find a different switched 12 volt souce.
Jake
Seems that the delay function for the wiper effects the voltage which caused my system to drop out of closed loop. I posted on this before but it's worth repeating.
I suggest you find a different switched 12 volt souce.
Jake
Instructor
Joined: May 2004
Posts: 163
Likes: 0
From: machesney park il
there are 2 wire harnesses going into the wiper motor,1 in the front and 1 going into the side,both have a 12 volt wire in them.i used the wiper motor source for my heated 02 and found you must tap into the wire from the harness that goes into the wiper motor side.it seems the other wire divides the voltage up if you tap into it so your 02 only gets a few volts.check the voltage on your connection with the 02 tapped into it. you probally tapped into the same one i tried to use at first and are only getting a few volts to your 02...that wire checked at 12 volts until i tapped it,then it showed only about 3 volts. another forum member helped me when i was trying to figure this out. i dont remember exactly why that line divides up the volts ,but when i switched to the other one it worked fine.
Thread Starter
Le Mans Master
Joined: Jun 2002
Posts: 6,097
Likes: 0
From: High Plains Drifter Fayetteville, AR
I used the wiper harness on the side, closest to the booster. I think I have it figured out, had to rewire the relay, but I can't start the car up until tomorrow. Don't want to annoy the neighbors, lol.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
2027 Corvette vs The World: Every Model vs Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer