Temperature gauge is going crazy

[Ecomike]

Most exhaust system back pressure problems are in the cat or muffler or after the cat.

With the O2 sensor pulled or disconnected it should run rich, ECU/PCM computer open loop mode, but have plenty of power and idle and run perfectly, and run cooler if nothing else is wrong. Open loop mode is gas guzzling mode. Great diagnostic mode!

Lack of a working O2 sensor will damage the Cat over time by overheating it due to to much excess fuel in the exhaust.

The second O2 sensor only confirms Cat operation and is designed to force you replace the Cat when it dies. Tha is all it does. It also confirms the first O2 sensor to some extend, but does not affect engine management.

MAP sensors are pretty much bullet proof, almost never fail, so your Map sensor failures are very non typical! I would suspect the vac line going to it or the wiring going to it! Map sensor is the only one sensitive to air pressure.

Okay, assuming I cut the pipe just in front of the cat, two things:

1) That still leaves open the option that something upstream is clogging the exhaust. Specifically, this exhaust has the "factory error" in it with the pinch just above the flange. What are the chances of something up there clogging the system around the flange?

2) Isn't the lack of the second 02 sensor input really going to foul up the engine computer?? I know it would over time, but would I be able to diagnose an overheating engine with the computer in default? How long would it take for the lack of a second sensor to disrupt the computer to the point of non-performance?

3) What other sensors are prone to fluctuations in air pressure? The MAP sensor I know, but what others?? It could be the engine is running overly rich due to another mis-reading sensor (which also could be destroying the MAP sensor).

Opinions???

 

[Michael Boracci]

Do you know which one? I am having that same problem

 

[Michael Boracci]

I am experiencing a similar problem. Start it temp comes p normally to around 215 ,hangs out there for a while. jumps to 240 for a minute and then returns to 215. The heater is not pumping out heat for at least 20 minutes of running time. So I suspect a bd sensor or the relay. Can you indicate the position of the relay?

New radiator, new t-stat, new water pump , new hoses, flsuhed engine four times in three months, only started doing this after new radiator went in. Wierd

 

[WildernessJeep]

MAP sensors are pretty much bullet proof, almost never fail, so your Map sensor failures are very non typical! I would suspect the vac line going to it or the wiring going to it! Map sensor is the only one sensitive to air pressure.

Yah, I know. Deep water keeps gettin 'em, along with the particular lack of atmospheric pressure. The ones from Chrysler seem to last a little longer, and I put some tin foil over them to keep out the water. That seems to help.