stalls occasionally on start

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May 6, 2008 | 01:30 PM

adipose

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stalls occasionally on start

my 1993 4.9 I6 stalls about once out of every 8 start-up attempts when cold. It will however start the 2nd subsequent attempt everytime.

My recently replaced PCV valve has improved engine performance and mpg's but has not solved this challenge.

Any ideas out there on what's causing this?

Adipose

May 7, 2008 | 07:43 AM

385seriesHemi

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Joined: Jan 2006

Posts: 1,101

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From: Malvern, Ohio

Maybe its got Chebby syndrome

every chebby I have had took 2 key turns, except it was everytime pretty much starting it but not every 8 like in your predicament.

I am assuming this happens every 2-3 days? The thing that comes to mind for me is maybe an emissions system problem or loose/faulty connection some odd place. See if any codes are tripped.

May 12, 2008 | 11:07 AM

adipose

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UPDATE:
After driving the truck for a week after replacing the PCV, truck has yet to stall on start-up.
If your Inline 6 is experiencing poor gas mileage, replace that PCV pronto! It will help.
Adipose

May 20, 2008 | 04:54 PM

demarpaint

Mountain Pass

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I would also have a look at the EGR valve, check for vacuum leaks. Mine drove me nuts with start and stall problems that sounded similar to yours.

HTH,
Frank D

Jun 18, 2008 | 06:05 PM

adipose

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PCV valve seemed to be a short term fix. Stalling upon start challenges cropped back up about 3 weeks after PCV valve replacement.

What do you think the leading cause of stalling on a cold start could be ?

thanks,
Adipose

Jun 18, 2008 | 07:24 PM

Harte3

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Joined: Dec 2006

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From: Spokane, WA

It's a Ford syndrome

Sounds nearly normal for a carbed engine but not so much for an EFI.

Jun 18, 2008 | 07:48 PM

Heavy_Metal

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IAC valve is a known problematic piece of the EFI system on ford vehicles, it looks similar to a little electric motor attached near the throttle body with 2 small bolts and one connector. Pull it off, clean the unit itself with some carb cleaner or something. Also clean the orifice in the intake real good that the valve bolts into. The orifice can become very resrticted with carbon and oil deposits causing a rough or no idle situation. In most cases this is the problem. You can also replace the gasket between the TB and intake. The factory one is real weak and breaks apart internally causing a vacuum leak. Basically if your gasket isn't sticking out between the TB and intake, it has been partially sucked into the area between the TB and intake.

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Jun 25, 2008 | 05:08 PM

adipose

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UPDATE:
Found the green wire from EGR valve disconnected. Broken 90 degree angle vacuum hose fitting. Must have been broken by past mechanic or previous owner. Anyhow the truck is running allot nicer now. It accelerates allot smoother and runs better in general.

Since connecting it, the truck has not yet stalled on the first cold start up of the day, but has come very close to stalling, catches and continues warm up sequence (hi RPM to lower RPM etc...)
Wondering if that IAC valve still needs a cleaning that Heavy_Metal brought up.

All in all pretty happy about that EGR fix so far.
Hope MPG's increase from the 14.5 mpg's (town and freeway) work commute.

Adipose