Community Forums

max49 · 03-17-2012, 04:38 PM

On my exhaust pipes on both sides, about 3 ' back from the exhaust manifolds I have what must be some kind of sensors in the pipes. I would imagine they must be temperature sensors. This seems like it would be a good idea to see what these temperatures are. If one side runs hotter than the other it would be nice to know. It might let us know why we burn spark plug wires or if we have a lean condition on one side.
Is there a Scan Gauge code where we could monitor this? If we can't is this just sending information to the ECM or ; what does it do?

Coma · 03-17-2012, 04:51 PM

I would guess these are Oxygen sensors. They provide feed back to the ECM in order to control emissions.

DriVer · 03-17-2012, 07:43 PM

Max49, Coma previously responded that those are indeed O2 sensors. What they do is monitor the Oxygen in the exhaust stream and make adjustments to the fuel air mixture via the Powertrain Control Module (PCM) that you have on your P Series. When these devices start to go bad in my experience they could call for the PCM to demand more fuel killing your economy since the extra fuel is not really needed.

When they work, they provide input to the PCM and help provide acceptable MPG values as part of an overall emission control strategy.

If there is a problem with the O2 sensors, you should get a DTC code on the ScanGauge.

max49 · 03-17-2012, 11:12 PM

Thanks Coma and Driver. I guess I can't monitor the exhaust temps after all; but at least I know where the O2 sensors are in case I suspect a problem with them.
I wonder how my 180* thermostat affects the O2 sensor and how it changes it's report to the PCM.
I believe DieselClacker has had his 180* for a long time and said he did'nt notice any side effects except that his heater did'nt get as warm as it did.
I have noticed that when my engine is actually at 180*, according to the SG, the IP temp gauge reads about 1/8" below right dead center.

Arch Hoagland · 03-17-2012, 11:57 PM

It's very easy to monitor that temp. Get an IR gun and shoot it.
That is how I learned of IR guns many years ago. I was in a muffler shop and the guy in the work bay was underneath a car up on a rack with the engine running. He was shooting the temps of the exhaust from the engine to the tail pipe.
He said that's how they found blockages in the exhaust system that would create problems with power, etc.
I use one all the time on my rig. Mostly for tires, brakes and pumpkin temp.