Well I got the LT1 TB on my 91 L98. The cable reaches, just swapped out the IAC housing since all the ports were the same. The only difference is the coolant passage. (which is bypassed anyway) I found a TPS sensor and harness of a LT1 z28 at the wrecking yard. My harness has black, blue and gray wires. The pigtail from the LT1 has black, gray, green. I looked up some schematic wire charts from here. I have it hooked up black/black gray/gray blue/green. I by passed the cruise vac hose since the cruise doesn't work anyway and ran it to the egr line that hooks to the L98 TB. When I fire it up it runs real rough trys to die. If I give it a little gas it stutters sucks air but I can get it it idle on its own.

Now I was rapping it up to about 2 grand a couple times to see if the throttle response was any better at higher rmps. I heard a small backfire in the intake so I killed it and called it a night. Anyone know what the test process is to find out if the LT1 TPS is good or working correctly?

It should be known: 91 camaro 5.7 SD TPI

 

You need to set the IAC sensor first. You need to ground your ECM first. Use a paper clip or a "key" you can get from a parts store. Plug it into the A and B ports on your diagnostic port under your steering wheel. The top 2 right ports. Turn on the key but do not start. You should hear the sensoe resetting itself. Let it click for about 30 seconds then unplug the connector to the IAC. No you can start the engine and set the "mechanical" idle. Should be a screw on the back drivers side to set the idle. Now kill the car. Unplug you ECM ground and battery too, you may throw a code by setting the IAC. No before you start the car again. Check the voltage on the TPS. With the key on, you'll need a digital voltage meter, check the voltage between the blue and black wires. Check it at idle positien and at wide open. You should be at .54 at idle position and over 4 volts at wide open.

This will fix your crappy idle. double check ALL your vaccum lines too.

 

Yea I use a paper clip to pull codes. How do you ground the ecm? Just checking and making sure you meant to say unplug the connector to the IAC.
I dunno man. I think your post was a late at night post kinda like mine. LOL. Its hard to follow. I'm a mechanic not a tech. I don't deal with testing crap like this so its all new to me.

 

Well we came to the conclusion that the TPS sensor I hacked off a car at the wrecking yard was bad. I picked up one at autozone for $29.99. We hooked it up. Still are not getting the correct readings. But they are at least changing. I think they are changing the wrong direction too. with the volt meter set on 20 we get a reading of 2.93 at idle on the blue and black wires and .83 on at wot.

The pigtail I have is off a 4th gen camaro LT1. The colors are as follows

Car Pigtail from LT1
Black Green
Blue Gray
Gray Black or brown (Hard to tell)

I looked in the chiltons while at AZ getting the TPS. The chiltons shows all years LT1 93-97 to have used the same as my car has blue, black, and gray. WTF gives.

We haven't started it up yet. I don't want to blow the intake off of it or something. After the small backfire we had the other night. Does anyone have a picture of the back of a pigtail to make sure which wires are which considering the colors don't match. We looked up the sensor that I originally had on it (it was aftermarket) Their website had the diagrams and specs on the sensor. So we were wiring it up after the diagram they had there. for which wire performed which function and where it was located on the end of the plug. We do have constant 5 volts running to the plug with key on also.

 

Yes you need to unplug the connector going to the IAC after it resets itself. Grounding the ECM will do this to it. By grounding, I mean using the clip to pull the codes. The IAC maybe still clicking when you unplug it but its ok. Now once you do this, there is no ECM control over the idle. You set the idle mechanically, then kill the car and plug it back up.

Not sure about 4th gen wires though, BUT....You might have timing issues or something to have a backfire in your intake.

 

You do know I'm running the L98 IAC not the LT1 correct? I've never seen anything about this in the chiltons.

The car is running though. Numbers are a tad off. Had to manually adjust idle up to keep it running when cold. I figured it was something to do with the iac but I didn't understand your directions. I've never had such good throttle response with this thing. The other sensor we had on it was screwed. It was dumping fuel. Thats more then likely what the backfire was.

the numbers were
idle is .84 wot is 3.42

 

https://www.thirdgen.org/tpimod2

 

go to the link provided in the previous post by Justin.