Where exactly is the EGR temp sensor? Is it the IAT that's in the underside of the plenum? Or is it something else?

 

I think you're right, it's the MAT (misnamed IAT).


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Actually I don't think it's the same thing as the MAT because all the wiring diagrams I can find show a tan wire going to the MAT, but a dark green one going to the EGR diagnostic temp sensor. Is it possible that I don't have one? Maybe it's a MAP vs MAF thing. I've got a 91 TPI, so it's MAP. I'm assuming that if it's there, it's somewhere around the intake, but I've pulled the entire intake off before and I don't remember there being any mystery sensors in there.

 

The EGR temp sensor for my "in-boxes" '87 LB9 goes in the EGR body. It was pointed out to me by the seller, who has a '91 350 TPI clone he built for his factory '90 305 TBI RS. I couldn't tell you what it's called in the diagrams, and he's on vacation right now.

 

The EGR temp sensor is a one wire sensor that screws into the base of the EGR at an angle, below the diagphram. To put blatently, it looks like the EGR valve has a pecker, with a wire coming out the end (thats about the best way to describe it, sorry). It is nothing like the IAT or MAT (depending on what part of the country you are from I guess)

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S/D TPI retrofit including functional PassKey,
22# injectors,
JET AFPR,
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TB Coolant Bypass,
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'97 Bonneville SSE

 

"Base" is a better description than "body". Thank you.

 

Yup, it's attached to the EGR valve. Not all EGR valves have them, I believe TPIs do and TBIs and carbs don't? Not 100% sure. It's used by the computer to tell that the EGR valve is operating correctly. On TBIs, the computer watches the MAP sensor instead for a drop in engine vacuum, so no EGR temp sensor is needed.

The MAT (manifold air temp) or IAT (intake air temp) both refer to the same sensor, I don't know why there are two names for it. But it is used by the computer to tell how hot/cold the incoming air is, I believe TBI and TPI have them and carbs do not (carbs have a choke instead).

 

Right here:



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[This message has been edited by Vader (edited November 23, 2000).]