Rough cold start and idle

[Maxont]

Im sure this has been posted a million times here but im posting this at work and did not have much time to read through the posts... here goes

I just recently baught a 99 7.3, On cold startups the Engine shakes and knocks pretty bad. After 20-30 seconds the shakes and knocks go away. When i go to drive the truck it is very sluggish and has no power, after about 3 or 4 mins of going down the road the truck "fixes itself" and drives much better. Although you can still notice a power loss and hesitation. Ive noticed you can let the truck sit running as long as you want for it to warm and it still has the sluggish/no power problem. It is only when you get it down the road a bit that the problem gets better.

***Note*** during all this the truck DOES NOT smoke black, white, or anything.

The truck has new batteries, alternator, cps, and the fluids look fine.
Where should i start in trying to fix this problem? thanks

[Maxont]

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[ianstew]

EBPV valve? Or glow plug issue?

[Maxont]

the ebpv should throw a code shouldnt it? im not sure on the symtoms of bad glow plugs... the truck has never really been in temps below 30-40deg and normal starting temp this truck saw was probably 50's... with that being said do you think the glow plugs could really be the problem?... im just not sure on what kind of abuse makes them go bad or even just over time.

[jcs]

How is your fuel filter? how many miles do you have on your oil? I wouldnt think it would be a gp problem in warm temps but you should check the gp relay

[Maxont]

fuel filter looks fine the can was clean too. oil might be getting a little old but is still fine. how do i check the gp relay? i think if the plugs are bad drawing less than 20 amps or something they throw a code?.. just what i've heard from friends

Today when i checked the fuel filter i left the cap off and removed the filter so i could see the fuel inlet. i turned the key on to see what kind of pressure i had, the fuel came through the inlet almost like a garden hose would when turned on. i know the fuel pressure should be at 45-65psi? but i dont exactly know what that looks like nor do i have a pressure tester. any ideas on what the pressure should look like coming into the can?

[Maxont]

GPR is fine, just meter checked it along with the glow plugs which all ohm at .8

[billelf123]

Originally Posted by Maxont

Im sure this has been posted a million times here but im posting this at work and did not have much time to read through the posts... here goes

I just recently baught a 99 7.3, On cold startups the Engine shakes and knocks pretty bad. After 20-30 seconds the shakes and knocks go away. When i go to drive the truck it is very sluggish and has no power, after about 3 or 4 mins of going down the road the truck "fixes itself" and drives much better. Although you can still notice a power loss and hesitation. Ive noticed you can let the truck sit running as long as you want for it to warm and it still has the sluggish/no power problem. It is only when you get it down the road a bit that the problem gets better.

***Note*** during all this the truck DOES NOT smoke black, white, or anything.

The truck has new batteries, alternator, cps, and the fluids look fine.
Where should i start in trying to fix this problem? thanks

Based on my symptom chart for a 2003 7.3L you should be checking your engine oil level, check for oil in coolant, when was it changed last, and is it the right oil for your truck (SAE oil viscosity and API rating). Check for aerated oil. Check MAP Sensor for holes, blockage, or disconnection. Check air intake system: after filter minder. Check intake manifold system for leaks. Check for sufficient clean fuel. Check for intake restriction.

A few more things that you should test are the CMP, ICP, and IPR.

I would also do a visual and follow your fuel supply line back to the tank and look for additional inline filters or mods that may have gone bad.

[Maxont]

i put my buddies superchip programmer/scanner on the truck and changed it to tow safe. now when the truck starts a puff of white smoke comes out. truck doesnt shake as much and also runs better...but still has a hard time starting. any ideas on this?

[billelf123]

Originally Posted by Maxont

i put my buddies superchip programmer/scanner on the truck and changed it to tow safe. now when the truck starts a puff of white smoke comes out. truck doesnt shake as much and also runs better...but still has a hard time starting. any ideas on this?

Without any DTC's to reference its just a process of elimination. There are some really good posts in the Tech section of this forum, I would recommend browsing them and then decide your next move. I think you will find them very helpful.