High idle with ECT plugged in - Normal idle without
01-14-2021, 10:30 AM
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High idle with ECT plugged in - Normal idle without
Alright everyone, I am in need of some insight. I bought my first cummins a few months ago, it is a 2nd gen 98.5 24v 2500. I bought it as the seller was initially selling it as a parts truck, but wanted to sell it whole. It was as used as a sled truck by the owner before him. It had a FASS 165 gph pump, 100-150 injectors "supposedly", and the seller removed his tuner. I have put in a transmission (another used 47re) and have fixed a lot of wiring in the engine bay by locating the stock wire placements, added 2 brand new batteries, and replaced the IAT and ECT sensors. The FASS pump won't pull any fuel from the tank or a bucket (I figured this out after I tried priming with new filters). Consequently, I have put everything back to factory. At the moment the truck is running, but idles at 1300-1400 @ 10-12psi with either the new or old ECT sensor plugged in. As soon as I unplug it, the idle drops to a happy 825ish. I have looked in the forum, as well as others, but I can't seem to find anything that might help me. I know the new ECT sensor is working because I watched the ohm reading drop as the temperature of the coolant rose. I can't test for alternator AC noise because my voltmeter can't read anything that small. However, I did notice that while I had the ECT sensor unplugged and my leads plugged into the ECT harness plug, I saw 1.0-1.1 vac and the vdc climb from 0.62 to 0.8. Any ideas?
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