Engine/Transmission (1998.5 - 2002) IAT/MAP changed but short lived

[snowman]

I have a 2500 Quad 4X4 stock with Jacobs exhaust brake. I noticed a sudden dropped in MPG (10%), so I changed the MAP and IAT. This resulted in an immediate gain (back to normal) for 1 1/2 tanks. My MPG is dropping again. Boost is normal, at the gauge, as well as fuel pressure. I have checked for air leaks in the intercooler, no problem there either. Any ideas? I am not looking for MPG as much as maybe something worse is causing the problem.



Thanks in advance.

 

[Fishin Guide]

Do you have an e-brake?



Dave

 

[JL penner]

how long has it been since you changed your oil? That could also have something to do with it. Or check the connectors for the IAT and MAP. That could have been your original problem and you temporarily fixed it when you put new sensors on.



JL

 

[snowman]

Yes... Jacobs

 

[snowman]

Oil is changed every 5-6K. Connections seem okay. They appeared fine when changing the sensors.

 

[Fishin Guide]

Yes... Jacobs

There is your answer. The soot is building on the sensor and basically insulating it. A good shot of brake cleaner usually does the trick.



Dave

 

[snowman]

I understand the possibility of the IAT becoming dirty from the exhaust brake, however I have been using one for about 25K miles with no problem. Would you agree that the IAT sensor (brand new, not cleaned) would last longer than 600 miles before needing cleaned?

 

[Gary - K7GLD]

I understand the possibility of the IAT becoming dirty from the exhaust brake, however I have been using one for about 25K miles with no problem. Would you agree that the IAT sensor (brand new, not cleaned) would last longer than 600 miles before needing cleaned?

Only way to be totally certain, is to again pull the new one and check it's condition - if it's still clean, you have some other problem, if it's real sooty again, you'll need to figure out why and what's changed...