This is a stock l98, a little history when I bought the car it had a code that was telling me that it was the tps sensor. When I put it on, it idled fine. Now when I use it after cruising arround it doesn't idle good. I idles at about 12-1500 rpm after use. But when you turn it on. It works fine. ALso HOw do I get my voltmeter to measure the tps sensor voltage?

Any comments
:confused:
:banghead:

 

i am having a simular problem with a 94LT1. It started last week and I have not tryed to pull the codes yet. I cleaned the TB the week before and it ran almost perfect till then. I was thinking TPS but I also have an intermittant hesitation issue when i get on it, and I'm thinking opti.

 

on my tpi would the relays trigger the tps code?
thats my nnext move but I'm puzzeld
:leaving:

 

to measure tps voltage you have car in run, engine not running and measure the voltage on the top two wires. The easiest way i found was with to stick a paper clip in the spot the wire runs into the plug. You need two paper clips though, one for each wire. The set point is .54 volts plus or minus .075 volts.

 

For the LT1 guy it may be air leak. I had high idle fixed it about three hours ago. On Passenger side of throttle body it was the second hose down from the top that was about three inches long. Hope yours is that easy.

 

Been there, done that hose. I replaced it when the TB was cleaned. This problem only happens when the engine is hot, if that gives anyone any clues. :crazy:

 

Try resetting TPS, then base idle, and make sure to disconnector Idle Air Control motor when doing so. There is a tech tip on it I think. Hopefully, that might be the problem. Good luck!

:cheers:

 

Under the dash, driver's side near where your right knee would be, insert a paper-clip or wire into the top, right two terminals (A&B) of the ALDL - Assembly Line Diagnostic Link.

Turn the ignition key to "ON" but do not start the engine. The main fan should run.

Wait about 30 seconds, then, without removing the jumper or turning off the key, disconnect the IAC connector from the TB.

Turn the key off, remove the jumper paper-clip or wire and start the engine.

At first it will be a little difficult to keep it running, but that's normal.

Now, after the engine will idle by itself for about 2 minutes or so, use a torx head screwdriver and adjust the minimum idle speed screw on the throttle body to maintain 550 RPM. The service manual may say 450, but GM raised that in a Service Bulletin some time back.

The minimum idle speed adjusting screw on the throttle body may have a factory installed plug that will need to be removed to allow access to the screw.

Now, shut down the engine and reconnect the IAC.

Disconnect the battery cable to clear any stored code from the ECM. Leave it disconnected for about 30 seconds to one minute, then reconnect the battery cable.

Install three jumper wires between the TPS and the TPS connector. Using a digital volt meter, probe the top two jumper wires with probes from the volt meter. Some guys probe right through the factory wiring harness, but I prefer not to punch holes in the factory wiring insulation.

Loosen the two screws that hold the TPS to the throttle body.

Turn the ignition key to "ON" but do not start the engine; view the voltage.

Adjust the TPS by moving it up or down to give you .54 volts plus or minus .075.

Turn the key to "OFF", remove the jumper wires and reconnect the TPS connector.

Drive the car at about 40 MPH so the ECM can learn the new settings.

With the single exception of the IAC connector, I never connect or disconnect any of the sensors with the ignition key "ON" to prevent any voltage spike from possibly damaging the ECM.

You may also need to clean the carbon/varnish from the throttle body butterflies. To do this you need to remove the throttle body from the plenum. If yours is showing a carbon build up, remove the TB clean the butterflies before doing the above adjustments.

If all else is well, you should be good to go.

Jake




[Modified by JAKE, 4:38 PM 5/4/2004]

 

Hey....don't forget to disconnect the timing connector BEFORE making the base idle adjustment. The Tech Tip left out this "lettle" step!
SAM