After installing the M62 Supercharger I keep having issue with idle and my truck dieing.

Normally this happens when in the drive-thru, atm, or like backing into the garage.

I give it just a little bit of gas to get the truck rolling and then let off and the truck powers itself, as it starts to slow down it dies.

Now I didnt have this issue before, but when I installed the supercharger my IAC was extremely dirty, so I cleaned it with brake cleaner like I have done in the past.

I dont think the IAC does anything while in D or R, only in P and N? Is this correct? I cant remember.

I might just bump my idle up, it idles at about 700 which seems kinda low to me.


maybe something else I should check?

 

I'm pretty sure the IAC does work in D and R. Mine is going bad and sometimes when I come to a stop it doesn't open fast enough and the trucks idle drops down really low and it shakes like its going to stall, but it opens before it actually stalls. IMO I don't think raising the idle will fix it, it's not like you've got a set of aggressive cams in the truck. I would buy a new IAC.

 

there was a problem on this with stock 4.0L needing to be reflashed do to a problem code in the ECU your new program MIGHT have that problem in it.. that would be worse case

first i would start with the IAC

 

First thing I'd want to know is if the blower by-pass is set right. It needs to be open at no boost. Most likely that's not your issue.. but it needs to be checked so you don't run in circles chasing your tail.

On my eaton 112 it's vacuum operated and is on the drivers rear.

Rich

 

The IAC is active all the time, in all gears, even when the engine is running well above idle. The supercharger is a load on the engine at all times but the PCM should be able to learn the new IAC duty cycle for the additional idle load. Still, if the IAC is sticking, it may not be able to recover fast enough after blipping the throttle.

Do you have a way to monitor A/F ratio? Do you have a blowoff or bypass valve? The supercharger may be causing mixture excursions when the throttle snaps shut.

 

you should clean that kind of stuff with TB cleaner, not break cleaner it too harsh and may melt some plastic elctronics.

 

Interesting never heard of that before.

How do I go about checking this? Mine is vacuum operated on the drivers side, I questioned whether or not it was working, in the manual it specifies to be extremely careful with this while installing the charger, being mine is used I have no idea what its condition is.

So it could still be IAC, but if you are leaning towards these other items first I need to check that. I have no way to monitor A/F ratio or even boost right now. I still dont know what gauges I want or should need. I dont want to waste money on some gauge that really doesnt help.

I plan to order an A/F ratio gauge, boost, and fuel pressure. I will order these soon as I didnt think about this causing the issue.

thanks for the ideas guys. I will report what I find once I get some gauges in to help.

 

I'm not familiar with your blower. But it should have a by-pass system that internally bleeds boost back to the intake side of the blower.
At nearly any measure of vacuum this is taking place. As you approach near zero vacuum that valve closes and you start to build boost.

On my eaton I raise the dashpot until the valve lever is not touched. I then lower it until the dashpot is pushed in by 1.5 - 2.0mm (0.060" - 0.080")

From there I raise or lower it to tune how quickly the boost vs throttle position comes on.

Rich

 

Just to make sure we are talking about the same thing...

Is it this?

 

Yep.

The dashpot operates a shaft that goes to a plate/bore that allows the boost to "bleed" back to the inlet side in non-boost times.


Rich

 

3 of my moms 4.0L SOHC explorers did it.. its like an sudden erratic idle then die..

like i said its prob not this but just throwing it out there..

 

ok, I think i understand, I will take a look at it tonight.

thanks!