Sputtering on start up?

20Screw01 · #1 11-01-2009, 10:22 PM

My truck when its cold will sputter almost die and vibrate while spitting blackish smoke out the pipes on startup. Then about 15 seconds later it will run fine? It has new plugs and fuel filter/pump. Fine when its hot....

Any ideas?

Thanks Dave

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jbrew · #2 11-02-2009, 01:23 AM

Most likely the IAC is bad or hanging. Ford states the part isn't serviceable, but you can clean it, successfully. I have. It's better to replace the part of coarse. A bad IAC usually doesn't generate a DTC.

BTW - The IAC is your Cold Start I/A Controller.

20Screw01 · #3 11-02-2009, 01:27 AM

How do you test it to see if its bad? Also would it do it when its cold and then perform normal when its warmed up? Thanks!

jbrew · #4 11-02-2009, 01:41 AM

The giveaway is that your warm start is fine, that's when the O2's are handling everything. I've never tested those actually, I see no point, just cleaned or replaced lol. The circuit can be fine, but if the mechanicals/plunger locks up, a multi meter isn't going to tell you much. I suppose there's a way to test, but 100% of the time, never needed to.

Rock Auto has the best price on one IMO.

20Screw01 · #5 11-02-2009, 02:01 AM

Ok sounds good I will clean it tomorrow. Any tips or just spray it out?

jbrew · #6 11-02-2009, 02:28 AM

Use compressed air/ Seafoams "DeepCreep"/ and work the mechanicals with something blunt, like a small screw driver. Try not to scratch it up inside, just be as careful as you can, but yea, you have to work the mechanicals/plunger while cleaning. Go easy on the air, regulate it down some if you can.

BTW- If you can't move the plunger, you'll need a new one. And, don't use a harsh chemical to clean.

20Screw01 · #7 11-04-2009, 01:31 AM

Ok so I tried another IAC and it didnt fix it. On top of the black smoke (unburned fuel) and vibrating it also feels like its missing also. Could it be a coil? Maybe missfiring and then warming up in 15 sec or so?

AZTriton · #8 11-04-2009, 01:52 AM

Still no CEL coming on? Did you replace with a new IAC? Did you replace the COP's when you replaced the plugs? Although you may have a misfire, doesn't sound like that's the main problem.

You stated it has a new fuel filter and pump; if replacing the pump was due to not changing the fuel filter for too long (can happen and causes the fuel pump to work very hard then fail), you may have fouled an injector. A BG/Motorvac service would be a great idea if you haven't done so in awhile.

20Screw01 · #9 11-04-2009, 02:02 AM

I didnt replace the COP's when I did the plugs and I tried my brothers IAC that I know works off of his truck. I changed the fuel pump due to going to the lightning motor and the fuel filter is about 6 months old and was running fine prior to the swap. Can injectors get stuck at startup and then free up?

Gotts2BMe · #10 11-04-2009, 02:29 AM

try cycling your key a couple times, on, off, on, off, on let it sit for a couple seconds and then crank it over.

jethat · #11 11-04-2009, 11:01 AM

Did you reboot the computer? if you dont restart it, it WILL run like crap after even a new IAC is installed..

glc · #12 11-04-2009, 12:20 PM

Did you use Motorcraft plugs?

20Screw01 · #13 11-04-2009, 12:46 PM

This was not from the plugs due to I had motorcraft in there and it did it with them also. Ngk tr6's went in and I know that there are a lot of lightning owners that are happy with them. So I need to unplug the battery for 10 min to reset the comp? Why would'nt the IAC just adjust?

AZTriton · #14 11-04-2009, 01:55 PM

Why do you need to reset the computer? Because that's how it works! Just like when you install an update to Windows... it has to reboot in order to take effect. Your PCM adjusts to the way your truck runs. Whenever you work on the truck and affects anything electrical, you should always disconnect the negative battery terminal to reset the PCM.

Fuel filters are dependent on miles, not time so if you have 15k or more on that fuel filter, I'd change it.

You stated you dropped a supercharged (lightning) engine in there... was the start of your problems right after you swapped the engine? When did you do this?

20Screw01 · #15 11-04-2009, 02:50 PM

I will try another fuel filter today. This is all with the lightning motor installed 2 months ago. I will also reset the comp today. When I turn the ignition on and off a few times to pump fuel before I start the truck it starts fine so I dont know what the issue is with that? Any idea's?