For those with EGR or high idle issues

MoGas

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I have been chasing a high start idle for some time now and I was using the o ring trick for a while until I thought more about it. I did all the checks prescribed in the FSM and could find nothing wrong.

I removed the throttle body and it was filthy. I also noticed that a port was completely blocked that goes to the EGR modulator.

The top view of the body.
Sensors006modified.jpg



Port "R" was plugged with garbage at this end.
Sensors007modified.jpg


Port "R" was also blocked in here. I used my welding tip cleaner set and lots of compressed air and TB cleaner to clean these ports. These holes are hard to see as they are ~ 0.030" and inside the body.
Sensors008modified.jpg



This is the EGR modulator that "E" and "R" go to.
Sensors009.jpg



The truck now starts fine and goes to 1200 for about a half second then drops to 800 when cold then ~650 when warm.

I don't know exactly what cured it because I did many things at once:
1. Cleaned throttle body
2 Replaced the PCV valve, grommet and hose
3 Replaced the other PCV hose
4 Replaced the intake hose
5 Replaced all the vacuum hoses to the EGR valve and any vacuum hose on the throttle body.

I haven't run the numbers yet but I'm sure my mileage has improved as I was usually at a half tank ~120 miles and I'm already at 80 miles and the tank is just below 3/4. Power is greatly improved also.


Dave
 
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Good info. I love to see photos of this stuff as it makes more sense to me when I see it rather than talk about it. I have had intermitent EGR issues and my idle starts AT 1500 and settles down to 700 or so after a few moments. Does that sound like high idle problems to you? Thanks for the information.
 

MoGas

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Mine was starting at 1800 when cold and holding there for 2-3 seconds then dropping to 1200 for a few more seconds then to 800 then 650ish after about 2 minutes total.
 

MoGas

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Order a TB gasket and some bulk vacuum hose from Dan. You may also want to get new coolant hoses for the TB too (while you're in there)

Dave
 

supercarrera

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Thanks a lot for the write up. I think I need to do this because mine starts and goes to about 1200 indefinitely until I start driving around.

I notice you don't have the hose clamps on your PCV hoses.

Scott
 

MoGas

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The new hoses are of a different material (thinner wall) and the factory spring clamps were too big. these fit very tightly and I am confident they will stay put for now.

Dan, if you are looking at this, are there different clamps available for the new hoses?


Dave
 

MoGas

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BTW, mine is a 93 with 202k on the truck and 170 on the engine. It was replaced under warranty at 35k for a cracked freeze plug hole.
 

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