Insane temp problem...FOUND & FIXED! - Page 2

UTKarmann_Ghia · 09:17 AM

Well Warren, I know they checked the mixture at idle, but that's it. And what you say makes sense as the sensor should not make enough of a difference to make a car run sooo lean that it becomes thermonuclear! It's a single-wire o2 sensor, so you really cant miswire this one.

The good news is that I ran it over 250 once and for just a few minutes. Other times it just got to 250 before I finished my drive or just pulled over. I HOPE I did not cause any damage to my engine. I may just get a leakdown test run on it just to make sure. But man, have I missed really running her! She's running just great

speeder · speeder's Garage

Quote:

Originally posted by Steve W
Seems true though - disconnecting the O2 sensor typically makes your car run richer, which as a result, cooler. I know when I disconnect mine, my oil temps are at least 15 degrees cooler.

Steve, I thought that on DME cars, (3.2s), the sensor has to be hooked up to run(?).

Steve W · Steve W's Garage

Hey Denis

- Motronics doesn't need to have an O2 sensor hooked up in order to run, as evidenced by the European spec and ROW versions which don't come equipped with one. However, the U.S. versions with a cat are equipped so to keep the mixtures at stoichiometric or the car can run rich and overwork the cat, also to keep emissions compliant. However I don't have a cat, and in doing some testing on some chips I am working on, I decided to unplug the O2 sensor just to see what the effects were. My car did run cooler by 10-15 degrees, and with the same chip that a lot of the guys here are running and are already reporting a great change in power and throttle response, I got what appeared to be another dramatic level in throttle response and pull than I already had - leaping like a screaming banshee. My fuel mileage has probably went down the toilet doing this though. This is not with my MAF sensor, but with the factory Bosch air flow sensor and a cone filter. I don't know if its my imagination or what, so all you guys running my chips on a non-catted car, unplug your O2 sensor and tell me if you notice anything.

Sonic dB · Sonic dB's Garage

Just replaced the O2 sensor on my 86 and fuel economy went way up.

UTKarmann_Ghia · 10-06-2003, 11:20 AM

Ok, I've run the car for a month (or more) with no overheating problems. Took it for a long drive in the mountains with 80 degree temps and it stayed between 210-220 degrees with the fan disconnected. So it appears that the gremlin is gone

Steve, you mentioned 10-15 degrees cooler for the disconnect, but I was looking at 50-60 degrees temp increase. I do not know what's causing the increase specifically, but disconnecting it fixed my problem. It would have to be either the Bosch generic o2 sensor (I'm assuming that it's generic) or the circuit/computer itself. Either way I'm driving the poop outa her

Kurt B · 10-06-2003, 11:37 AM

This seems reasonable.

I failed smog twice for NOX. High combustion temperatures. I also had a serious detonation problem, even when I poored in Octane booster!

After replacing the O2 sensor and richening up the mixture to 3%, I passed smog (barely, my CO went from below average to the upper limit), but my NOX dropped to acceptable limits.

I also have no detonation, even if I just run straight 91 octane with no booster.

SC-targa · 10-07-2003, 06:15 AM

The CIS mixture test at idle would not identify an O2 sensor problem, since the sensor is disconencted to get a proper mixture reading.

Kurt B, high temps, high NOx and detonation problems are all related to a lean mixture.

NOx forms when there are high combustion temps and excess air. Nitrogen does not burn readily, so in normal combustion, the fuel consumes most of the O2, and the temps are not high enough to generate NOx.