Can't get engine to idle

boosted84

Member
Hey guys been chasing my tail here. Car has been sitting since 2004 just did a rebuild on it. It starts up idles and dies .... It will do this until warm then stay idling at 400-550 rough...no vacuum leaks. then shoot up to 1500 rpm ... Precision te60 . 60# injectors 212-206 cam. Scanmaster shows codes for intake temp coolant intake reads 71 and coolant at -37 which I believe is default .... These are both brand new sensors. Iac reads 175 .. if you rev it it runs fine but won't settle into an idle. Any ideas ?
 

Macsteve829

New Member
Coolant sensor should read the coolant temp at startup. If it thinks it's -37, it is going to richen up the injector pulse greatly. Ohm the coolant temp sensor, even though it's new, just to be sure. You likely have an open wire either supplying the reference to the ct sensor or the return wire to the ECM is broken somewhere.
 

Chuck Leeper

Toxic old bastard
Staff member
for intake temp coolant intake reads 71 and coolant at -37 which I believe is default .
^^^Treed! 😁
Coolant at -37* will force a cold start afr, even when warmed up.
AIT at 71*. What does it read when engine is dead cold, KOEO?
Fresh fuel system?
What are the rest of the SM readings?
 

salvageV6

Daily Driver
At approx. 70 degrees you should read 2,000-4,000 ohms across the sensor terminals disconnected from the wiring in the car.
There's a ground splice for the 5V return line up in the harness on the pass. fender near the relays and MAP sensor, itcould be a bit corroded.
Or the pins at the ECM, Pin C10 is the coolant sensor yellow wire, D12 is the 5 Volt return black wire, if the TPS and MAT sensors work it's probably not the return line at the ECM, more likely at the splice area.
If you jump the yellow wire at the sensor to a good ground with sensor removed it should read over 200 degrees.
 

salvageV6

Daily Driver
Have to check both those sensors wiring back to the ECM with an ohmmeter sensors unplugged ECM connectors unplugged, or if you have a spare ECM that would also be a good first test and a chance to clean the connections and inspect them on both conectors and the chip socket, especially with a car that's sat so long.
 

boosted84

Member
Ok coolant temp sensor is fixed ... Have to get a new pigtail for intake temp sensor .... Still in same boat now that coolant temp sensor is working no more light for that though
 

scgnx2

Active Member
Are those numbers from after you fixed the coolant sensor?
If so, IAC is way high should be 20-40 or so. The O2 is also reading rich.
Do a search on this board for resetting the IAC/TPS sensor.
 

boosted84

Member
Are those numbers from after you fixed the coolant sensor?
If so, IAC is way high should be 20-40 or so. The O2 is also reading rich.
Do a search on this board for resetting the IAC/TPS sensor.
Ok I will do that process as soon as I can and post new scanmaster numbers
 
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