Hi,
I'm inquiring about a friend's truck this time... mine is all good... His is a 2003 4.6 V8 auto (no SAI)
So he has had the engine fully rebuilt and it runs great, except that a few times now, when the engine is cold, it has stalled the first stop after leaving the house.
Once when he let off the gas and came to a stop, and twice it happened as he let off the brake and was just about to go for the gas...
Could this be the idle control valve you think?
I'm trying to help him so we can go wheeling
Thanks for any help!
Cheers
David

 

I'd say CPS but mine only acted up when the motor was hot. I had another similar issue that turned out to be a bad ground.

 

Is it throwing any trouble codes?
You mention IAC. If it hasn't been done before, a good internal cleaning with a heavy dose of carb cleaner and a rag would definitely help. Also make sure it is installed the correct way.
Also... Unplug MAF then run it and see if anything changes.

 

Hi Juke and Frank,
Thanks for the pointers.
CPS was done a couple months ago.
There were a few codes for immobilizer in the past but the immo is disabled. And it had 3 amigos code
I will take a look at cleaning the Idle Air Control valve and see. I don't believe it has been done before at all. Is there any test that can be done to the IAC? Is cleaning simply to spray some cleaner in or is there a trick? (I suppose youtube is my friend here )
Cheers
David

 

Just take it off and hose it out with carb cleaner. I suppose you can try to bench test the stepper motor to make sure it works, but generally that's not necessary.

 

I chased a stalling problem when coming to stop recently. Replaced the cps, then the iac valve. The transmission starting going into limp mode too. Turns out my new cps sensor I installed was no good so keep that in mind. Nothing more frustrating than a bad new part.

any codes? Check for vacuum leaks

 

I guess I will start by taking my Idle Air Control valve and install it on his truck and we will see... during that time we can clean his. I'll report back but in the meantime, if you have other ideas, please let me know!

 

day 5 with my valve on his truck... no stall. I'm back to my truck with his old valve in a couple days. We have cleaned both up with intake cleaner spray and I will install his in my truck. If I start having stalling issues I will know what the problem is...