Question: Fine tuning

[Bentas1ent]

I just finished installing new injectors and valve cover gaskets as well as moved the mat sensor to the front air box. The job went well and my car does not quit on me when it comes up to running temp anymore. The only slight problem i have is an occasional backfire when i hit the fuel and the idle is at 900 in park but drops to 600 in drive. Are there any fixes for these two items? :W

 

[Hib Halverson]

"Fine tuning"?

If the engine spits back when you open the throttle and the rpm is 900 in neutral, you probably have more than a "fine tuning" problem to solve.

Besides new injectors and moving the IAT sensor, did you do or engine service actions?

Was the check engine light on prior to the injector change when the engine would not idle in closed loop?

 

[Bentas1ent]

reply to Hib

There was no check engine light on prior to the injector swap. Also there were no codes present in the system. I found that if I put my finger under the TPS and lift lightly the idle returns to normal. Should I try to adjust the position of the TPS or should I replace it with a new one???

 

[Hib Halverson]

If you believe there's a TPS issue, I'd adjust the TPS per the Service Manual.

Has the throttle body been changed or have you changed its minimum air adjustment?

Are the injectors OE replacements? If not, describe them.

 

[John Robinson]

If you can change how the car runs by wiggling the wires to the TPS then I would look at the wires and the connector for bad wires. The TPS goes to a ground bundle and corrosion there can cause a bad signal to the ECM from the TPS. I have had the experience of the wires breaking loose in the connector and also being broken. In my case I rewired the TPS all the way back to the ground bundle. In order to replace the wires in the connectors I removed the old wires and went to the junk yard and found a wiring connector with the same type of pin and the I remove the pins from it and put them in the TPS connector. On a side note when at the junk yard I removed a butch of wiring and connectors for future use and it also gave me wires of the correct color to use in my repairs. Another trick is to remove the pins from different connectors and put a male pin on one end of the wire and a female on the other. Now you can plug into any sensor with the jumper and to the wires to the connector with a place to hook up a meter in the wire to diagnose the sensor in real time mode. This is particular handy when setting up the TPS. On the TPS using straight pins to probe the wire to check it for voltage etc will brake the delicate wires. Don't ask how I know.

 

[Bentas1ent]

reply to Hib

If you believe there's a TPS issue, I'd adjust the TPS per the Service Manual.

Has the throttle body been changed or have you changed its minimum air adjustment?

Are the injectors OE replacements? If not, describe them.

The throttle body has not been changed nor has the minimum air adjustment been touched. The injectors are from Jon Banner at Injector Connection. He told me that they are the exact replacement for my car the only difference is that they are stainless steel. To clarify the TPS issue, when I put my finger under the actual TPS lever and lift it up lightly, the idle then goes down, touching the wiring makes no difference. If you believe that the minimum air adjustment and the TPS issue could be the idle problem, I will check them next. Thank You

 

[Hib Halverson]

Start by adjusting the TPS. As John Robinson susggests, if you've got faulty connections at the TPS or the TPS does not work properly, replace it and readjust it per the FSM.

 

[Bentas1ent]

reply to Hib

Start by adjusting the TPS. As John Robinson susggests, if you've got faulty connections at the TPS or the TPS does not work properly, replace it and readjust it per the FSM.

My car finnally sent me two trouble codes which were 22 and 44 so I just replaced the TPS and set it up accordingly. The idle returned to normal and it seems to have stopped spitting back for now. When I drive it now it does not send any codes. I will need to let it sit overnight to completely cool off so that I can see how well it works on a cold engine. One last thing which is an old problem. What should I be looking for when the service low tire pressure warning system light comes on?

 

[John Robinson]

Here is a picture of the test wires I described earlier

 

[Bentas1ent]

Thank You

Here is a picture of the test wires I described earlier[

Thank You!!! That is a great idea for testing.