Engine/Transmission (1998.5 - 2002) Ready to ditch the box.

[NoSeeUm]

yep, I never changed it to a potentiometer for fine tuning.

Do your grid heaters still work OK?



I have been thinking of trying this bomb.



Jim

 

[GOT-Torque]

What grid heaters? :-laf



They used to work just like normal when the switch was off. If the switch was on, the ECM sees an intake temp of 200 degrees and therefore the grid heaters don't cycle at all.



Now they just take up space on a shelf in the garage...

 

[NoSeeUm]

What grid heaters? :-laf

OOPS!



I intend to leave my grid heaters in place, but I would like to move the IAT out of the intake manifold to prevent it from getting crapped up. Not sure if I want mount it in the intake horn or just somewhere behind the intercooler (outside of the radiator).



Currently, I am now going the down that " IAT - Timing - Fueling Road " that you went down not so long ago. I must have read 50 IAT threads lately. Allot of words with very little substantial information as to exactly how it all works. :-{}



I know about what the IAT temperature offset is compared to OAT under most conditions for my truck. I can tune my fooled IAT temperature pretty well I think.



I was also thinking of rigging up a switchable IAT imput that I could mess around with the engine tuning. Just to see the effects of fueling / timing for IAT's that equal too about 30-40F and and another for about 100F. The low temperature to add timing for fuel economy and the high temperature to quiet the timing rattle. Might be nice to be able to switch the mode I want to be in.



The IAT and grid heaters deal has me confused anyways. On cold nights with the grid heaters plugged in the IAT will rarely be below 100F when I start the truck. I have no "Wait to Start", but the the grid heaters still come on and cycle after the truck starts. I am thinking maybe OAT has a role. The coolant temperature is also around 100F for those starts.



There seems two be to modes for the grid heater logic. First one is pre engine start up and the "Wait to Start" light. Second one is engine running warm up until 20 mph or so when they go off for good. Confusing.....



Jim

 

[GOT-Torque]

IAT will dictate whether the grid heaters run for 1 sec, 7 sec, or 15 sec during the wait to start light (#'s could be wrong but I do remember three different timeframes based on IAT). Then once started they will cycle on and off for a set amount of time, or until you hit XX mph, or until coolant temp hits XXX degrees (I think).



The only thing I know for a fact is that they don't ever turn on if you remove them...



I do remember reading of people that moved the IAT to the intake horn or intake plumbing and then reported that the grids fired longer or cycled more. Just remember that the engine block retains alot of heat for a long time.