Ok, Rusty and I put on the Ported Plenum and after putting it on and having a short race with each other, my SES light came on. We checked the code and its code 23. TPS Sensor Error OR Low Temprature at Intake Manifold Air Sensor (IAT) Well, after Randy M, and Rusty both searching through the Helms manual have come to the conclusion that the 92 Z28 doesnt have an IAT (unlike the 91 which has it on the air box) and i checked the voltage at the TPS and its fine. I even put it back to the stock position. .58v at idle and 4.00 at WOT. The light seems to come on when the temp in the engine gets to running temp. We are stumped as to what it can be. Any ideas? and if there IS a IAT sensor on my 92 speed density(camaro), WHERE IS IT??? The only sensor that was swapped or even touched durring the swap was the MAP sensor on the bottom of the plenum. HELP! PS. Car runs great, no problems even with the light on.

 

I have a 92 Z/28 so I can tell you this.
The MAP sensor is on the passanger side of the plenum and the MAT sensor is on the bottom and at the back of the plenum.
If the 91 has it in the air box then some one moved it there as it would be in the same spot as the 92 from the factory.

MAT = Manifold air temp.

 

a sphincter says what?

First, Idle air temp (IAT) and Manifold air temp (MAT) do the same job. The helms manual will list the sensor as a MAT sensor. Its in the bottom rear of the plenum.

Second, "I even put it back to the stock position." The TPS on 90-up tpi thirdgens isn't adjustable. The ECM autocalibrates the sensor at zero, so any adjustment isn't going to be seen by the computer.

Third, the MAP sensor is the widget bolted to the side of the plenum with the green plug.

My opinion... You need to go buy a book on TPI and read it cover to cover before you turn another bolt on that car. When you've finished reading the book, let your friends read it. If you don't know where the most basic sensors are in the car, then you don't have an understanding of how the TPI works and you have no business trying to modify it.

 

First off... When code 23 came up we looked in the helms for the code and in BIG LETTERS right under the code it said (IAT) so of course we went looking for the IAT sensor in the index and only TBI and V-6 were comming up. Well, obveously if Helms lists this as MAT instead of IAT we arent going to be able to find it. Second, we DO understand how TPI works and were pretty sure that the sensor on the bottom of the plenum is the MAT, but since we couldnt find a pic or description of in the manual, I decided to come here and make sure before i change it today. Second. The TPS IS adjustable. Just read the tech article on it. Yes, there are ONLY 2 screws bolting it to the TB, but if you loosen it up and make slight movements you will easily see voltages changes of .5 or more. When your car only shows .45v at idle and 3.5volts at WOT, and you adjust it to the min of .58v at idle and over 4.0v at WOT, a huge difference in throttle is felt. I dont see why the computer would throw out what it sees at the TPS sensor when it relies on it to know throttle position. Yes, it may zero out its initial postion to zero and go on the increase from there, but if you dont have at least your 4.0v at WOT, the computer never reacts like WOT should. I DO do my research before I tinker my expensive toys but since this is my car and my TPI, I have all the business in the world doing what I FEEL i WANT to do to it. Thanks for your help, problem SOLVED!

 

Drew,

I think the Guy asked a Valid question, Lay off.

You have good information, but I don't get why You Came off so hard on the guy. We don't all come to this board already knowing everything about our cars, Or else we woudlnt need to be here.

At least he is asking intelligent and specific questions that we can Answer for him with a degree of accuracy.


Save the explosion of criticism for the "How much Horsepower" crowd.

 

I am the Randy Jason is referring to in his post. I can honestly say we all knew the sensor in the bottom of the plenum is the MAT sensor and we all knew the SD or MAP sensor because we had to move it as the new plenum was not a SD plenum. Anyways Drew your criticism is well taken as I agree some research should be done before you tear into any project. That's why as soon as Jason's Z threw a code I went and got my multi-meter, 92 Helms Manual, & my quick and dirty Trouble Codes list from the Thirdgen.org Tech Section. However if you can give so much criticism how much you don't offer us any solutions??? I mean if we are just some guys that have no business wrenching on a TPI system why does Jason know that its either his TPS or IAT/MAT sensor that is throwing a code? If you have some insight please share it along with your wisdom then please do so, I know I would always like to learn more as I believe that I have as of yet to read a book TPI, Camaro, or any other subject for that matter that is complete. I for one would rather get the information from individuals that learned from their experiences working on their own cars

BTW - Jason I do have two TPS sensors and the other MAT on the bottom of my IROC's plenum we could always try to swap them as see if we still get a code