Very Hard Starting 460 Ford Only When Cold

[Tom Norman]

Our fuel injected 1993 460 is very hard to start, but only when cold. It starts and runs fine when it's warmed up. But it takes numerous "cranks" to get it started when the engine is cold. Once it finally starts I get black smoke/crud out the tailpipe, a very rough idle, and a "Check Engine" light. But after about eight minutes or so (to warm the engine?) the black smoke/crud stops, the idle smooths out, and the "Check Engine" light goes off. Then I have no more problems at all until I again have to start the rig cold.

Ford dealership checked the computer for codes, but got a "111", "System Pass", possibly because they ran the codes after the engine had already warmed up and was running perfectly. There are no stored codes in the computer.

Any theories out there?

[Tom Norman]

Our fuel injected 1993 460 is very hard to start, but only when cold. It starts and runs fine when it's warmed up. But it takes numerous "cranks" to get it started when the engine is cold. Once it finally starts I get black smoke/crud out the tailpipe, a very rough idle, and a "Check Engine" light. But after about eight minutes or so (to warm the engine?) the black smoke/crud stops, the idle smooths out, and the "Check Engine" light goes off. Then I have no more problems at all until I again have to start the rig cold.

Ford dealership checked the computer for codes, but got a "111", "System Pass", possibly because they ran the codes after the engine had already warmed up and was running perfectly. There are no stored codes in the computer.

Any theories out there?

[Retired and Happy]

How many miles on your rig? How do the plugs look when cold? How do they look after the problem clears itself? I assume by cold, you mean outside temperature, not 20 degrees necessarily. I had a smoker once, but it smoked for 1400 miles and we found holes in two pistons. 3 qts of oil every 75 miles or so.

[Tom Norman]

We have 58K miles on our rig. The plugs were changed about 10K miles ago. By "cold" starting, I mean starting up after an overnight stop. Not cold weather here---it's in the 50s or 60s in the morning. The plugs are a bit blackened but a local mechanic said that should not, by itself, cause my symptoms.

[Gary RVRoamer]

Is that a throttle body injected (TBI) engine?

Some engines of that era had a baffle in the air cleaner that was supposed to close to help out on cold starts. Don't know if that applies to yours or not. It may also be misreading the ambient air temp/mass so that the fuel/air mix is off when in open loop mode (before warm-up). After warm up, in closed loop mode, it will automatically compensate for an incorrect reading, but in open loop it cannot.

[Tom Norman]

Hi Gary,

I have multi-port injection, not the single-port TBI. But I do have "baffles" at the end of the two big rubber air tubes that lead from the air cleaner to the engine. I've shot carb spray on them, but that didn't seem to help. Several folks have suggested that the Idle Air Control Valve has gone bad. My next task is to remove that component and clean/check it.

Thanks in advance for any suggestions you might have.

Tom

[Gary RVRoamer]

Unfortunately I am not at all familiar with the engine management system on that engine. My experience is mostly with GM systems and the 96 460 I had for two years ran flawlessly, so never had to dig into it.

Clearly the air/fuel mix is way off when in open loop mode before while warming up. Just what inputs the Ford ECM uses to control things in that mode I cannot say with any certainty. YTou might consider getting a maintenance manual for some diagnostic clues. One of the general Ford ones available in auto parts stores might be sufficient to tell you what components are active in a cold start. They aren't too expensive.

[Tom Norman]

Thanks again Gary,

I'll keep looking. I am determined to fix this thing! LOL

Tom

[Tom Norman]

UPDATE:

The verdict came in today, and it was a bad PCM. After a new PCM was installed it started immediately and ran like a top, just like it used to!

Thank you all for ALL your help on this!!!