Engine/Transmission (1998.5 - 2002) can you drive with the IAT unpluged

[grass hopper]

can you drive with the IAT unpluged or will it hurt the truck? i am still trying to find out whats wrong with my truck and if it won't hurt the EMC or the truck i will try it. i just need it to get to normal driving temp then i can shut it down & restart it to see if thats it.

 

[timbo]

Prob. wouldn't it, but it will instantly bring on the CEL light! The IAT always needs to send a resistence back to the ECM. Do you currently have a CEL light ON? What is your problem?

 

[grass hopper]

Prob. wouldn't it, but it will instantly bring on the CEL light! The IAT always needs to send a resistence back to the ECM. Do you currently have a CEL light ON? What is your problem?

no i don't have any CEL light on.

so are you saying it won't hurt to drive it just enuff to warm the coolent?

here is the link to my post with whats going on with the truck.

https://www.turbodieselregister.com...e-one-please-help-i-m-have-major-problem.html

 

[mhenon]

It won't hurt anything. You'll just have to get the codes cleared and CEL turned off as mentioned.

Mike

 

[timbo]

Sorry I did not realize you were the guy will the other thread going on. I Feel for you dude! My suggestion would be, go to radio shack and buy a 5K - 10K resistor and plug it into the IAT plug and see if it repeats. Costs around 1 dollar to try. GOOD LUCK ON FIXING IT !!

 

[timbo]

I have another thought here. Does it do this crazy crap if you warm it to about 140-150 shut if , then restart it?

 

[AFoulk]

I don't mean to butt in, but where is the IAT located? I've been told its in the intake right behind the MAP sensor, but I wasn't able to find it. Did I just not look hard enough? its kinda hard to tell with those plugs and wires in that area. I'd like to pull it and the map sensor and clean them. Also, what does everyone use to clean them.

 

[bnbrown]

the IAT is located on the drivers side, near the firewall (closer to the firewall than the MAP sensor). The MAP I do not think can be cleaned, I just replaced the MAP if I had doubts of it. I have cleaned the IAT with carb cleaner, used a spark plug socket with universal joint to get it out.
Grass Hopper, have been reading your other thread, hope you get that figured out, you've tried all the things I would have.

 

[grass hopper]

I have another thought here. Does it do this crazy crap if you warm it to about 140-150 shut if , then restart it?

yes it will start around that temp but not all the time a few times it's done it at a higher temp.



I will try that 5k-10k resistor. i will heading to RS tomorrow.



thanks for all the help guys. wish me luck

 

[mhenon]

I'll be down in Round Rock in a few weeks. If there's anything I can do to help you out let me know.

Mike

 

[Tinman]

Correct me if I'm wrong, but the ECM uses the temp imput from the IAT to fuel. I. E. cooler (denser) air, more fuel. This is why in winter fuel mileage goes down, the ECM is lightly "over fueling". I've alway noticed the truck runs a lot better in warmer ambient temps. So I've been wondering if one was to put a constant resistance resistor in the circuit for a warm intake temp, winter mileage would improve (and the truck may run better). Just curious. I assume if you unplug the IAT it would default to the lowest fueling.

 

[mhenon]

"... I assume if you unplug the IAT it would default to the lowest fueling. "



That's what I think will happen. I've left my MAP sensor off by accident and the truck ran but was a dog. Felt like about 100hp. The IAT would probably do something similar and default to the safest setting.

Mike

 

[grass hopper]

Correct me if I'm wrong, but the ECM uses the temp imput from the IAT to fuel. I. E. cooler (denser) air, more fuel. This is why in winter fuel mileage goes down, the ECM is lightly "over fueling". I've alway noticed the truck runs a lot better in warmer ambient temps. So I've been wondering if one was to put a constant resistance resistor in the circuit for a warm intake temp, winter mileage would improve (and the truck may run better). Just curious. I assume if you unplug the IAT it would default to the lowest fueling.

so your thinking that by unpluging the IAT the ECM will think its still cold and over fuel the motor? if so that kind of whats happening when it gets warm its like the ECM is over fueling but the only thing is you just touch the pedal and it will rev.

 

[timbo]

The IAT mostly changes timing, i'm currently fooling the IAT so the ECM thinks its hot to actually retard timing! To understand this concept a little better go to this thread i started last winter. https://www.turbodieselregister.com...-1998-5-2002/174551-miss-only-edge-fixed.html Also take a look at my sig. then note the hp/tq, I don't think there was much defueling going on! As far as your prob. I would pull the vital connections apart and clean them and get some dielectric grease then reconnect. If that doesn't cure it, get a hairdryer and warm indiv. componets(on a cold motor) trying to isolate the culprip. If you have a laser thermometer it would be a good idea to check temps on indiv. components when you have the problem and then wait for cool down. Then heat each one back up to temp you noted earlier while it was running. This way you can get each component exactly back to the problematic temp. I would heat the VP with the hairdryer as a starting point. Hope this helps!