Question Why ?? is my truck running poor?

[twt]

I have a intermittent miss that is worse with a heavy dew. I have put in new injectors $$, new torque converter $$. This problem is at low rpm & little throttle about 2 to 5 psi boost. I think there is a module under the left fender that converts 12 volts to 140 volts dc could it be at fault? Has anyone had a problem like ths or am I the lucky one? One shop wants to do a compression test then take the motor out to check the camshaft$$$. Any thoughts & suggestions will be appreciated.

 

[Zookie400]

you are thinking of the injector driver module, or IDM. i have seen a bunch of water intrusion caused failures with the IDM. your problem seems to be tempurature related, although you describe it as dew? or is it really only when the hood is wet?

do not take the engine out to check the cam. you can check the cam by taking off the valve covers and watching all the rockers. a compression test should not cost much, but i dont think your problem is compression related. low compression would cause bluish smoke, or a misfire at unboosted conditions. once boost picks up even 1 psi low compression misfires usually will disappear.

when was the CPS changed last? mine did some funny things in cold weather when it was on its way out.

you could take a look at the UVCH's and valve cover gaskets for burnt, loose, or corroded connections. corroded connections quite often are affected by temp. and humidity.

also, are we talking about a dead miss, that shakes your coffee out of the cup? or is it more of a weak cylinder that is better heard than felt?

 

[twt]

I have already changed the drivers side wireing & the gasket,nothing changed . I`m thinking it could be the module under the fender because it is a small miss & comes & goes with temp & humidity.This feels like the timing is off & or like you have bad spark plug wires. As soon as you get 10 lbs of boost the problem is masked. I`m thinking about asking the shop that did all the $$$ work for me if he will loan me a module.

 

[BJS]

IDM or MAP sensor

A compression test is not a bad idea but I don't see a reason to pull the camshaft, unless they think that they need to do that to check the pushrods. I have seen several trucks who described the very same thing you are when they bent a pushrod just slightly. They are easy to check if you do the work yourself but will be expensive to pay a shop to check.

 

[JLDickmon]

IDM or MAP sensor

x2
plus the UVC harness on the side that didn't get changed..
not saying it's bad, just saying it should be checked.

water damage to the IDM would be pretty easy to spot.. the aluminum case corrodes and the paint peels off in a big sheet..

when you pull the wiring harness off it, you may have water drain from the unit (mine did)

 

[twt]

I think I am going to take the inner fender out to see if the module has any damage, then I will replace the RH wireing & gasket. I kind of think it is the module because it is a random miss & it can
miss two or three times in a row & it is getting worse.

 

[Zookie400]

when you pull the wiring harness off it, you may have water drain from the unit (mine did)

isnt it amazing how a little dribble of water can ruin a grown man's day?

tw- be careful where you choose to check your idm. sometimes if its full of water, after you go and disturb things, it decides to give up the ghost....the only good news then is that your skip is fixed. step two....make it run . keep us posted

 

[twt]

I got the IDM out of the case - spotless . Sealed it back up & put it back in.I would like to know where the sensors are that tell the IDM to fire??