trueburton

My car has always idled a little irregular, but i think it is due to a vaccuum leak in the intake manifold. It would always stay in the 900-1300 range but usually stay around 12-1300. just recently it has started to idle down around 400 and will jump back up to around 1200. Code 22 also came up. The TPS is only about 8 months old and i just recalibrated it about 2 months ago. I don't think it is a bad TPS and the ECM isn't that old either. what else could cause this?

Vader

The first thing to do is repair that problem generating the error code. The ECM will be in Backup Fuel and Spark mode as long as there is an existing error condition. The TPS needs to present a 0.48 - 0.58VDC signal to the ECM when the throttle are closed - period. In order to do that, the TPS requires a 5.0VDC reference voltage across the ‘A' and ‘C' terminals (top and bottom). If the voltage present at these terminals is below 4.8VDC, you have a problem with either the ECM regulated 5VDC power supply, or the wiring to the TPS. If other sensors (such as the CTS) are getting the 5.0VDC supply, the problem is NOT with the ECM. You need to check wiring and grounds. If the 5VDC supply is present at the TPS, check the output voltage between the ‘A' and ‘B' terminals (‘A' being the ECM ground) with the throttle closed and ignition ON. Adjust the TPS position to provide that level of signal at the closed throttle position, then monitor the TPS output voltage across its entire range of motion. The voltage should increase in a linear fashion with increasing throttle opening. Wide open throttle position should provide at least 4.1VDC from the TPS ‘B' terminal.

The next thing you need to do is repair that vacuum leak. No amount of tweaking, no adjustment, nor any quantity of new parts thrown at the control system is going to solve that. The ECM will never be able to operate the engine correctly as long as it is fighting such a variable. Since you are already aware of the leak, half the work is done. All that is left to do is repair it. If you procrastinate, lean out a cylinder, and burn a valve or piston, you'll regret it. At least you'll then get to pull the intake to repair the leaks.

trueburton

thanks for the help i'll check into it next weekend when i'm home