The FSM says that once you replace your TPS, it needs to be calibrated with the EBCTM, but it requires a Tech 1. Is there any way to do this without 1? Or any ideas on where to get a Tech 1?

 

Nah, a multi meter will work just fine.

 

How will a multimeter allow the ebctm to relearn the TPS?

 

Put it this way. You are going to need a scanner if you plan to keep the car. Maybe not today but tomorrow or the day after. Might as well be today.

For a scanner, you can use ALDLDroid or I have an older Auto X-ray and an MT2500 Snap On and TunerPro if I was so inclined.

 

In my later model L98, it assumes whatever voltage (within reason) is presented to it at startup is base. IDK if your year has such features. If you are that worried about the relearn, unplug the battery and start back from square 1 or let it along and it probably will adapt.

I kinda like a scanner to see what the ECM reports the voltage at. You can ground one end of your DVOM and tap into the signal wire but if there is a break in the wire past your inspection point, well....

 

This is the procedure i used on my 94, It sounds complicated , but it is very easy,

IAC (Idle Air Control ) & TPS (Throttle Position Sensor) Calibration

The TPS is on the passenger side of the throttle body just above the IAC. There are three wires on the TPS plug. The top two wires need to be checked for voltage by either the common pin pushed into the metal end method, or stripping a small section of the wire casing away. I stripped away a small section of each wire and soldered two lengths of wire to the two top wires of the connector, kind of like a pigtail so the next time I needed to adjust the TPS I did not have to go through the stripping of the wires again. Set your meter to the low DC voltage scale. After you have attached your meter to the top two wires of the pigtail, turn your meter on and turn the ignition key to the on position, (NOT START). I have read several articles with different opinions as to what the correct voltage should be which vary, the one that worked correctly for me on the 1994 LT-1 motor was .65 volts.
You can check the TPS for proper operation by slowly manually turning the throttle mechanism or have someone slowly step on the gas pedal and watch the meter, If the TPS is correctly working the voltage will slowly increase as the pedal is slowly pushed and decrease as the pedal is slowly released. The TPS is just a potentiometer that reacts to position of the throttle plate.
Now the fun part. To adjust the voltage. The TPS is a fixed part with two #15 torx screws holding it in place. I know there are some cars with adjustable TPS but mine is a fixed position. On an adjustable TPS, if your voltage reading at idle was above or below the .65 volts then it can be easily corrected by loosening the two torx screws and slightly turning the TPS until you get the correct voltage. BUT if yours is a fixed position piece as mine, then what I did was remove the torx screws, remove the TPS and used a small round file to elongate the two holes so that the unit will have a slight movement. I only needed about .050 don’t get carried away, it is easier than you think just use a very small round file and take your time. I had to lower the voltage so I filed in a counter clockwise position on both screw holes. Obviously to raise the voltage you would elongate the two torx holes in the clockwise position. Put the TPS back on and finger tighten the torx screws, watch your meter and slowly adjust the TPS by slightly rotating it until you get the correct voltage (.65) and snug down the screws, not to tight, the TPS is just a plastic body that could crack easily.
Something to remember, if your ever adjust the Idle speed screw, it will probably change the voltage reading on your TPS. So only adjust the idle screw as a last measure, this is why I believe they plug the end so we cannot play with them.
Now for the IAC which is located below the TPS but does not have to be removed. The IAC is basically a small solenoid coil that pulls and pushes a plunger to adjust the air flow at start up and idle. To adjust the IAC take a paper clip and insert it under the dash as if you were getting the code readings from your dashboard. Turn the key to the On position (On NOT START) wait about 60 seconds, this allows enough time for the IAC plunger to travel as needed. After 60 seconds, with the key still in the ON position, unplug the wire harness from the IAC. With the IAC unplugged now turn the key to the off position and plug the harness back in, That’s it..
If you are having start up idle problems then I recommend you do calibrations on both the TPS and the IAC as either one could cause problems.
Both the TPS & IAC have a very long life but do need to be calibrated, so before you go and play with the idle screw, which is the last thing you should do, and if the car has a lot of miles then invest in replacing the TPS and IAC. But if you are in my position which is that both parts were brand new and I had a startup idle of 1300-1500, then follow these calibrating methods and you should be all set.
I hope this helps you out, Best of Luck
Woody

 

It won't. It will set your TPS correctly so your computer will get correct readings.

 

I used scanner for the job. No cutting or splicing. Much neater and no worries. You now see what the ECM sees. Also, why adjust? If it is not adjustable like mine, that is the way the ECM will interpret what the base voltage is.

With a scanner, you can set up the IAC according to the IAC counts which tell me if you have any air leaks. The method you described requires that the tach be accurate and no air leaks are present and everything is in spec.

 

I bought a kit of testing tools for the C4 from I believe Ecklers a long time ago. One of the tools was a "plug in" extension that plugs in between the TPS and the cars harness connection. The tool has two little alligator clips that attach to your multi meter. This allows you to adjust your TPS without punching holes in the wires. If you do make any holes in the wire be sure to tape them up or seal them somehow.

Here is the link to it:
http://www.ecklerscorvette.com/corve...1984-1991.html

This little tool was a worthwhile investment as it really makes the adjustment a simple, painless effort.

When I bought this tool it was one of several tools made to ensure that the components of the fuel injection system were working or adjusted to work their best.

I like tools that make the job as easy as it can be. They mean I spend more time enjoying my Corvette! I hope that you can resolve the TPS adjustment without too many headaches! Good Luck!

 

http://www.ecklerscorvette.com/catal...+tools&x=0&y=0

They are pretty cool till you realize that buying them all, you are halfway or better towards a used scanner and with a half dozen 1 trick ponies that give a quarter of the results.

 

There's a cheaper, multipurpose, no solder product for checking electrical connectors voltage, I already showed these. See https://www.corvetteforum.com/forums/c4-tech-performance/4020924-ecm-reading-5v-tps-signal.html#post1595272255


Basically paper clips made the right way.

 

Kael, that link to Ecklers is for the 85-91, Here is the website for the adapter for the 92-96 Vette. I think it is well worth it, I wish I had found it before I spent the afternoon cutting wires splicing and soldering on a pigtail.. "Live and Learn the hard way"
Woody

 

kael, something to remember, my 94 is an OBD2 connector but the system is an OBD1. as far as I know there is no scanner that will work on this year. I bought a brand new OBD2 and it will not function. If there is some way to change the connector on the car to an OBD1 I would appreciate the info.
Woody

 

What scanner? I have an older Auto X-ray that works on my 91. The new Actron does not work for me. Actron bought Auto X-ray. Tech Support sang the same songs. We do not support that old stuff and Hit the Road Jack.

Maybe a GM Tech 1 would? Or something more professional like a Snap On?