Problem When Idle (At Light) - 2001 Job 1

[Samuel Gertner]

Hello All,



I was looking for some assistance with a problem I started having on my 2001 ST Job 1. When stopped at a light I am noticing the engine running a little rough. I feel a vibration which is not continuous but occurs ever so often when stopped at the light. It causes my normal RPM range of 600 to drop down between 400-500. The engine has never stalled from this, and I have not had my CEL light come on.



Note: When accelerating/driving I do not have any problems with the engine and appears to be running normally.



PS.. I have already tried swapping the IAC Valve without any change.



I was wondering if anyone has had this problem and could offer some assistance.

 

[Ben Schepper]

plugs maybe?

 

[Samuel Gertner]

Plugs/Wires were changed approx. 13K ago.

 

[Mat Deegan]

crack elbow?

 

[Samuel Gertner]

It is hard to locate the cracked elbow on a Job 1. From what I know, it cannot be done. Does anyone have any images on where exactly to look?

 

[Chris Taylor]

Check the line that goes in just past the air filter. Just had mine into the dealer for something else, and somehow they disconnected that. Ran rough at idle. Hooked back up, and things are now fine...

 

[Todd Z]

The one hose on a job 1 goes to the valve cover and the other line is the Air intake for the IAC, so you would have seen the hose split or cracked when switching the IAC out.



Fuel filter, Leaky intake manifolds..



ALSO could be the ac compressor kicking on due to the freon being low and the trucks computer is not responding..



Listen to see if you hear the ac kicking..

Todd Z

 

[Samuel Gertner]

It happens even when the A/C is OFF. I just replaced the Fuel Filter thinking that was the problem as well. It did need to be changed, but that did not solve the problem.

 

[Todd Z]

Yes, BUT if the switch is in the off position for the AC and it is low on freon, IT will still click the compressor, Even if the switch is off...



Todd Z

 

[Tom Schindler]

I would be willing to bet it is a leaking intake gasket.





Tom

 

[Ron N]

One thing I would add is to get the Zabteck fuel pressure gauge,it will showif you are having problems with the fuel pressure to the engine. That is why I added it._Ron

 

[Samuel Gertner]

Tom,



Where is the intake gasket located? Do you have any images to help locate it?

 

[Tom Schindler]

The intake gasket is the gasket between the intake manifold and heads, and there is another one between the upper and lower intake manifolds.



I do not have any pictures, per se, but if you are unable to identify the intake manifold, you have no business trying to repair it yourself.



It is not a hard job to do. It really isn't. You are removing your intake gasket and dropping something into the intake can destroy your engine.





Tom