M42 high idle after throttle body heater delete

[and_e30]

I decided to change the thermostat, some of the symptoms sounded like it might be stuck open. The car has approximately 150k miles on it and it still has the original thermostat.
Since it is only a $17 part, i figured why not.

I am waiting for the parts to get in this Wednesday.

[dude8383]

Check resistance on that temp sensor. The lower the temperature, the higher the resistance and vice versa.

14 +/- 2F - 7000-11600 ohms
68+/- 2F - 2100-2900 ohms
176+/- 2F - 270 - 400 ohms

Report back with your readings.

[Boris3]

Fluid level and condition now are fine? When you did the flush how bad was the system? Could something be interfering with the temp sensor that goes to the ecu and/or somehow did the flush foul the sensor? The sensor to your temp gauge sounds fine from what you've said but maybe the other temp sensor to the ecu is not sending the proper reading. Ecu thinks the engine is cold and bumps up the idle? Or the wiring from the sensor is cracked/shorting such that the signal is off?

[and_e30]

I had some idle issues that were solved when I removed this filtered extension from the AFM cable. Might be worth a try.

filtered extension? i don't seem to have that. just a direct connection from the harness. no additional extension.

[and_e30]

Did you check your ICV?

Clean it... and try again.

yeah, icv is squeaky clean. i also swapped it out with a known working one and no change in rpms.

[dude8383]

Did you check your ICV?

Clean it... and try again.

[mabeer]

I had some idle issues that were solved when I removed this filtered extension from the AFM cable. Might be worth a try.

[and_e30]

you can test the readout, again don't have the info off the top of my head. Try a search or other folks will weigh in.

Did you have the high idle issue before you did the delete? If not, unlikely that the TPS or the temp sensor would all of a sudden go bad. Leads back to something that happened during the delete and reassembly.

Not sure about this but maybe the ecu needs to "relearn" the new setup. Try disconnecting, waiting and reconnecting the battery. Let it run for a bit to see if the idle comes down as the car warms up.

Carpet isn't stuck under the gas pedal? I'm reaching here...

I actually checked the stuck gas pedal myself, no luck. And no, I did not have an idle issue before the delete. I also disconnected the battery multiple times to clear the ECU. I have doubts that this actually works but I thought i would give it a shot anyway. I heard all the data is stored in the ecu and disconnecting doesn't reset it. Its like turning off your computer, the data is still stored there.

I honestly am thinking it has something to do with the coolant system since I have thoroughly gone through the vacuum lines and connectors when related to the throttle body heater delete and found no issues.

Since I did the coolant flush at the same time, this may be the contributing factor. I heard the m42 coolant flush can be tricky. Again, I have put about 100 miles on the car with no overheating, but the engine temp gauge doesn't fully move to where it used to. However I still get hot heat inside the car.

I opened the bleeder screw on the radiator and no bubbles just constant fluid flow so i don't think there are any air pockets.

[Boris3]

you can test the readout, again don't have the info off the top of my head. Try a search or other folks will weigh in.

Did you have the high idle issue before you did the delete? If not, unlikely that the TPS or the temp sensor would all of a sudden go bad. Leads back to something that happened during the delete and reassembly.

Not sure about this but maybe the ecu needs to "relearn" the new setup. Try disconnecting, waiting and reconnecting the battery. Let it run for a bit to see if the idle comes down as the car warms up.

Carpet isn't stuck under the gas pedal? I'm reaching here...

[and_e30]

no check engine lights. it could be a tps issue. is there any way to test that?

[Boris3]

test the sensor? I forget the proper value but you should be able to search and find it.

TPS issue?

Since you haven't mentioned, I assume your CEL works and you are throwing no CELs?

[and_e30]

or coolant temp sensor (blue one)? Turn the car off and check is plug tight? Maybe unplug and replug, and/or unplug, spray with contact cleaner let dry and replug and see.

Yeah, I did that exact thing this morning. When I disassembled everything I sprayed all the connections with electronic connector cleaner and replugged everything back in. This is getting so frustrating

[Boris3]

or coolant temp sensor (blue one)? Turn the car off and check is plug tight? Maybe unplug and replug, and/or unplug, spray with contact cleaner let dry and replug and see.

[and_e30]

when i start it from cold, it starts out at about 1500rpm and eventually creeps up to 2000 where it maintains.

maybe this could be a thermostat issue?

[and_e30]

I don't think this would make a difference for your symptoms but...see that connector in the top right of your first picture (small connector with the two white/grey wires coming out of your harness near the fire wall), unplug it. It should only be plugged in for 318i/is models without a cat. Notorious for causing idle and warm restart issues. Maybe it's an issue here?

i unplugged it and started it up. didn't seem to change anything.

i plugged it back in while running and no rpm change.