I'm having some timing or fueling problems and before I start digging into the big stuff I've noticed that the ambient temp sensor in the front will read negative randomly. It can be 100 outside and it will show below 0. Most of the time it reads correctly though so I would like to know if this is on a similar wiring circuit as other engine sensors and a voltage loss could be causing both problems.
I lost my Alldata access so I can't see the full wiring diagrams.

I do need to double or triple check that I got the distributor in correctly. I picked up a bluetooth obd2 and the torque app. But timing shows about 20* retarded at idle and that does not seem right. If I run the numbers, being 1 tooth advanced on the distributor works out to something like 18* of timing so I might try taking it back a tooth and see what that does.

This is turning into a Catch-all post. I'll try to narrow it down in the next couple hours so it gets back on topic.

 

Ambient temp sensor in the grille has nothing to do with the engine.


Your garage says 1995, but you mentioned OBDII. What year vehicle are we working on? If you have OBD1.5 or OBDII, ignition timing should show ~17 degrees of advance at idle on the scan tool. If the distributor is off one tooth, (27.69 degrees) DTC P1345 will set. No SES light, no code, distributor is installed correctly.

 

Yes I double checked timing and it's on. I suppose it would be obd1.5. Either way it's not very user friendly.
I understand the sensor has nothing to do with engine operation but maybe a similar ground? I'll pull all the grounds and clean up the connection between the ring terminals and the frame or engine block.
I have no idea if the scanner is reading the correct location for the timing value being displayed. Some day I'll make the investment in a good scanner/diagnostic tool.

 

The ground for the ambient temp sensor will have no affect on the
way the engine runs.




Does your distributor cap look like this:







If so, your 1995 has OBD1.5, and the only way to check ignition timing is with a scan tool, and it is not adjustable. Did your scanner show ignition timing as being 20 degrees retarded at idle?

 

Yes last time I connected it was around 20 degrees retarded. I do have the horizontal cap.
I pulled the plugs and 1,3,5 look good white with tan on the combustion side. 2,4,6 were almost the same but they had a flaky look on the combustion side with some signs of a white buildup. So I'll do a compression test from here.

This can be moved since it's not electrical I guess.

Edit: I suppose the buildup/flaky look could be from the vacuum port on the right side. The vacuum line is soaked in oil and I only have to assume it's from the t-case switch(again). Would that be enough to cause a pinging sound around idle? If so,that could be the cause for the timing being retarded.