Ok i am not sure where to post this. So i will start here.

When i start my truck (only happens when it is cold), there is a big shudder and it runs like only firing on 3 cyl. I can turn it off and then start it again and everything is fine.

Any ides anyone.

 

Could be bad sparkplugs or plug wires. Just a guess. Could even be bad gas. Might be that IAC thing sticking open or closed. Again, just guessing.

 

Plug's are new. Plug wires are ok (as best i can telli) .

I thought about the gas idea, but has happend through several tanks.

What is the IAC thing.

 

It's probably not just the IAC, but rather the entire engine is plagued by carbon build up.

The IAC is mounted on top of the throttle body. You can remove it and clean it, somewhat. But, I'm thinking this is more EGR related.

You may want to have the engine de-carboned. Not just the fuel system, but the intake manifold and EGR system as well.

Have you done the little things like replace you PCV valve??? The entire EGR system really builds up with nasty mixture of combustion gases and oil. It creates a thick goo. If you pull the PCV tube off the bottom of the throttle body, it will probably pour out; this is what the entire EGR system looks like. It really inhibits air flow.

 

The part that i find strange is that it only happens when it is cold, and then only on the first start atempt.

I can start it, it runs very rough. Then turn it off (after only running for 2 seconds) and it re-start it and everything is fine.

 

Is the coolant in your recovery tank disappearing also?

 

That is a good question.

You had the timing cover gasket replaced. But, did you ever have the lower intake manifold gaskets replaced as well??? If you're losing any coolant, that would explain a lot.

 

mine did this when younger. It was the mass air flow sensor.

 

My 97 F150, having a 2002 4.2L engine, has the exact same problems as yours. Only when cold it will roughly idle for a few seconds and sometimes die. But then when restarted it runs smoothly with no sign of hesitation at all. Also, when the truck has been running for quite awhile, you can slightly hear unrythmic pinging...It seems it pings louder with 87 gas, but still slightly pings when running 93. It doesn't seem to be the injectors, because the beat pattern of the ping does not match that of the engine. I'm hoping that a rod hasn't been slightly bent during the break in cycle. And another thing, when starting the truck after the engine is hot, you hear a quick and loud diesel sounding crank. This is also heard when the engine is hot and you are running at about 600 RPMS.When i took this problem to ford they told me that when the engine is engaging the timing chain is loose and seems to make a cranking noise as it tightens, and also whenever the engine is making low rpms, the chain loosens again and then too makes the cranking noise. They said that was just the nature of the engine. But this still doesn't make sense, because it would make the cranking noise when starting up while cold and it doesn't. I don't think any of these noises are serious, and I am not too worried about them at the moment because of the engines waranty. I would like to diagnose the problem myself, and with your thoughts, so when I take it in to get it fixed, they can't tell me what is and isn't wrong.
Also my coolant level is not dropping, so the gasket failure and timing cover leak is out of the question. The mass air flow sensor looks to be fine, and is clean. Well, I'm not a genius or even anything near that when it comes to our engines, so I would truly appreciate any and all input. Thanks in advance,

isaac

 

the first thing i would do is check compression at these "cold" temps. make sure it isn't a base engine problem. i mean, you can get a cheap compression guage and check that first(just un-hook your coil packs). you cold have low compression in cylinder due to a valve sticking when cold(not all that uncommon) or rings etc. i would check 2 cylinders(when it's cold) at a time to be sure.