Engine/Transmission (1998.5 - 2002) variation in exhaust gas temps at manifold

[dodger22]

Can someone please tell me the cause of differences in exhaust gas temperatures measured at the exhaust ports?



Using an infra-red temperature read-out gauge, I am seeing substantial temperature differences at the exhaust ports. As much as 200* between the highest and lowest reading. (The highest reading was 450* and the lowest - cylinder #5 was 250*). The gauge I am using is just a cheap one so I don't expect it to be accurate in terms of actual temps. but I would expect it to be consistent.



I am guessing that the problem is with the injectors and will be running some cleaner through them to see if that improves the numbers.



The injectors are stock and there is approx 110k on the odometer.



Thanks, Richard

 

[snuff]

i am not a rocket sciencetis or spell check for that matter, but you are measuring metal not the gas itself, the heat has to travel and the metal absorbs heat and reduces the temp, like a heat sink, the metal cools and heats up. i belive yyou will not get as accurate as you would like, also was this on a cold engine or one that was driven for awhile...

 

[TAbbott]

I think you're right about trying to clean up the injectors. I'd suspect that the "hot" ports are not getting fuel that is atomized nearly as well as the other, cooler ports. Instead of the fuel charge all being burned in the cylinder, some of it is still burning as it exits the exhaust valves, creating a hotter port.

 

[dodger22]

The truck had been sitting for a while and the engine was warm but not up to operating temp. The temp pre-turbo at the sensor was about 450* as were some of the ports, but numbers 5 and 6 - closest to the firewall were arouond 250*



I added some conditioner to the fuel and will measure again today.



Richard

 

[dodger22]

Today I took the truck for a drive to bring it up to operating temperature (I had already added conditioner to the fuel). With the engine hot and idling I checked the temps at each exhaust port and the temps were all quite close varying between 215 and 235* so I think I am okay.



Thanks to all who replied.



Richard

 

[NoSeeUm]

I have a EGT T/C installed at the #6-5 cylinder joint and another just downstream from the #1 cylinder. I see as much as 250F at WOT, but typically 150-200F or so with the #1 being low. As the engine cools off, while idling, the temperatures become just about equal. This characteristic has not changed with two different sets of injectors.



Not sure how to explain that either... .



Jim