3800Pro Forums banner
1 - 17 of 17 Posts

·
Registered
Joined
·
22 Posts
Discussion Starter · #1 ·
I have an erratic O2 sensor. :mad: I replaced it with a brand new Bosch sensor after my connector melted when it conacted the rear header. It bounces around wildly, from less than 100 to over 800 within a few scans of my LS1M scanner. I did put some low lead fuel in at the track, but hardly ran it at all before I took the first scan.

Any ideas? Ed thinks I ruined it with the lead, so I plan to get another one and try it out, but I think it was erratic even before the 4 gallons of LL fuel I put in.

I also disconnected my ICCU to see if that was the problem- it isn't.

I have a stock computer and am planning to swap with my DHP to see what it does.

Any other help will be greatly appreciated!
 

·
Registered
Joined
·
1,577 Posts
The O2 sensor only reads at WOT. Any other time it is going to "bounce" up and down the values. If it is not giving a fairly steady reading at WOT then it may be a bad or burnt sensor.
 

·
Premium Member
Joined
·
2,450 Posts
dayday said:
The O2 sensor only reads at WOT. Any other time it is going to "bounce" up and down the values. If it is not giving a fairly steady reading at WOT then it may be a bad or burnt sensor.
What??? The sensor reads all the time except when the PCM is in "open loop". I haven't heard anything good about Bosch sensors.
 

·
Administrator
Joined
·
3,246 Posts
Agreed, bosch sensors have a bad history in our motors. Your 02 values should bounce low then high at idle or cruise. At WOT they should stay constant and typically you would like them 910-940 depending on your motor and mods.
 

·
Registered
Joined
·
1,224 Posts
Running leaded fuel is a bad thing to do. It will coat the O2 sensor and that will give inaccurate readings. Also Bosch is junk. Only get AC Delco, more expensive but they work.
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #8 ·
Thanks guys- I plan to get another from Ed. I only ran a few gallons of Low Lead aviation fuel thru. I have heard that heated O2 sensors (ours are heated) are less suceptable to lead fouling. But I'll trust you guys that Bosch is junk, and try a Delco.
 

·
Registered
Joined
·
22 Posts
Discussion Starter · #9 ·
Swapped with a stock O2- same problem! I am swapping the DHP with my stock computer tomorrow.
 

·
Registered
Joined
·
49 Posts
Maybe you could try an o2 simulator. My o2 sensor is junk too and I'll have simulator installed this Saturday. I'll let you know how it works out.
 

·
Registered
Joined
·
9 Posts
Ok.. this is probably a stupid thing to say, but, when I had this problem in an old GA... I replaced the sensor and the "Check Engine" light was still coming on and repeating the same old errors and the car was running like junk.

I disconnected the battery. Waited a couple of minutes. Hooked it back up and the computer picked up the new sensor and that was the end of my problems.

Like I said, probably stupid and a different car, but, if you haven't done this, might be worth a shot.

John
 

·
Registered
Joined
·
49 Posts
kurt said:
This is the FRONT O2 sensor- you can't simulate it, you need it to tune your fuel.

Kurt
Ah ok. I didn't realize it was your front one. Good luck!
 

·
Registered
Joined
·
14 Posts
I'm having the exact same problems, i was getting a heater circuit malfunction with the old sensor, and i bought a bosch one (oops) and now i have numbers jumping all over hell at WOT. Guess were in the same situation, i dont know what to do.... let me know if you find a solution
 

·
Registered
Joined
·
81 Posts
I'm currently having the same problem but my o2 is a GM sensor and is like 9 months old.
I'm throwing no codes but the o2's at WOT aren't locking.

Here's a copy of a post I made on HPtuners forum

I just scanned my car for the first time with new motor aswell as it being the first time using the HPtuners scanner.

This is on a 98 gtp full rebuilt motor with heads, Intense S3 cam, balance shaft removed etc...

The car hasn't had a case learn done yet if that makes any difference.

I initially had a miniAFC on to lean out my idle a little bit because of the fumes are pretty bad (temp solution until I learned how to do it with hptuners) When I did WOT runs, the 02's weren't locking whatsoever as if it wasn't going into open loop.
I parked the car and was thinking that the miniAFC was causing issues so I removed it.
I did 2 other runs at WOT and the 02's locked. I was thinking that the miniAFC was shot.
Then on the third run and every run afterwards, same problem again, 02's won't lock.

What could be causing 02's not being locked at WOT?
The car felt strong when they locked but felt real weak when they didn't.
 
1 - 17 of 17 Posts
Top