Cold Start Problem
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Senior User
Joined: Dec 2007
Posts: 118
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From: Colorado
Cold Start Problem
Hey guys, my 96 F350, 460 recently developed this not wanting to start after sitting overnite thing. I have crank for nearly a minute before she'll start. She'll sputter a few times then start. This only happens after sitting a day or two. Once she starts she runs fine and will restart easily. I pulled codes (only got 212 in memory, nothing in KOEO. 212 is loss of ignition input to ECM, probably from the MSD 6 ignition dying over the summer). I checked fuel psi cold, 38 and checked resistance of Engine Coolant Temp sensor when cold, got 80k ohms, pretty close to right with a 25* ambient. Not sure what to check next. Any input is appreciated. Thanks.
Tuned
Joined: Oct 2012
Posts: 440
Likes: 8
Possible air idle control problem?
You only need 3 things for an engine to run, fuel, air, and spark.
You have good fuel pressure, but that doesn't mean that the injectors aren't pulsing. But I have never heard of anything temp related causing injectors not to pulse, so we'll say you're good on fuel.
Spark, maybe test for spark after it sits? But just like the injector thing, I don't think it can get so cold your truck just decides to not have spark lol.
So onto air, maybe the air idle control valve is sticking and not being able to properly regulate the air to get a good cold start? That's just my thinking. They are known to get extremely dirty, like carbon build up in them
You only need 3 things for an engine to run, fuel, air, and spark.
You have good fuel pressure, but that doesn't mean that the injectors aren't pulsing. But I have never heard of anything temp related causing injectors not to pulse, so we'll say you're good on fuel.
Spark, maybe test for spark after it sits? But just like the injector thing, I don't think it can get so cold your truck just decides to not have spark lol.
So onto air, maybe the air idle control valve is sticking and not being able to properly regulate the air to get a good cold start? That's just my thinking. They are known to get extremely dirty, like carbon build up in them
Thread Starter
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Senior User
Joined: Dec 2007
Posts: 118
Likes: 1
From: Colorado
Good idea with the ACT, I'll check that. I thought about the IAC but I did step on the gas, figured the engine was getting air. I'll clean it anyways, easy to do. I'm thinking the problem is something to do with the EFI equivalent of a choke. The ACT and ECT sensors have a lot do do with cold starting. Think I'm going to try a shot of starting spray while cold cranking to rule out ignition system.
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Senior User
Joined: Dec 2007
Posts: 118
Likes: 1
From: Colorado
Update. After a bit more troubleshooting I found that my 2 year old MSD ignition coil was only putting out around 10k volts at start up. Once it started, voltage jumped up to 40k. Took awhile to find that. Replaced the coil and she fires right up like she used to.
Fleet Owner
Joined: Oct 2005
Posts: 20,786
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From: Kentucky
Great find! Thanks for reporting back on the root cause and resolution.
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