Engine/Transmission (1994 - 1998) Changing EGT temps

[McLaughlin]

I installed a Diprcol EGT gauge last fall. Since then it has worked well with typical (pre turbo) temps running between 450 and 600 while crusing around town. Peak EGTs under heavy acceleration were between 1200 and 1300. However, in the last week the I've noticed the EGT temps have dropped by 100 to 200 degrees and now I'm running closer to 300 to 350 degrees and peak temps only reaching about 1000.



Is it normal for EGT temps to change with the season or for the temps to drop after the probe has been installed for a while?



Any suggestions regarding whether there is really a problem or what/how I can do additionally checks would be appreciated.

 

[Matthug]

As ambient temp rises so should the temp on your pyro. You either have a dying probe or else you should check your fuel pressure and make sure everything is working properly. Have you noticed any lack of power?

 

[Howard Durand]

The temperatures you were reading when first installed look pretty normal. The sudden change is not good.

First, make sure your connections are all tight, the output from the probe is in millivolts. Any resistance in the connections will affect the readings.



I would be nervous about a change like that. You don't know for sure which is right but you don't want to take a chance on a gauge indicating 1000 when you are actually at 1300.

 

[McLaughlin]

As ambient temp rises so should the temp on your pyro. You either have a dying probe or else you should check your fuel pressure and make sure everything is working properly. Have you noticed any lack of power?

Haven't noticed a loss of power or boost. I suspect it is the probe. Yesterday, I had no reading on the gauge for the first 15 minutes I ran the truck. After I turned off the engine the EGT temp rose slowly to 200 degrees and then reacted while driving. However, it still seemed be be reading a couple of hundred degrees low.

 

[McLaughlin]

The temperatures you were reading when first installed look pretty normal. The sudden change is not good.

First, make sure your connections are all tight, the output from the probe is in millivolts. Any resistance in the connections will affect the readings.



I would be nervous about a change like that. You don't know for sure which is right but you don't want to take a chance on a gauge indicating 1000 when you are actually at 1300.

You got that right! Fortunately, I don't drive the truck very hard so I rarely get the EGT to 1000 degrees. I'm just keeping my foot out of the accelerator until I get it resolved.



Thanks for the info on the voltages. I didn't have any idea it was that low but it fits with what I'm seeing.

 

[Matthug]

Check your connections before just replaceing the probe. Specifically check the area where you have the wires running through the firewall and make sure they didn't rub through.

 

[McLaughlin]

Check your connections before just replaceing the probe. Specifically check the area where you have the wires running through the firewall and make sure they didn't rub through.

I was afraid you were going to suggest that. I checked the connections between the probe and the wire to the gauge they were tight but I cleaned and recovered them anyway (used dielectric silicone this time). The other place I'm concerned of is the bottom of the A piller the wires seem to be extremely tight as they transition under the A piller. I'll have to take the A piller off to check that and will have to wait until it is a bit warmer since I already broke the A piller bracket once.