voltage drop 1990 C4
Thread Starter
4th Gear
Joined: Sep 2009
Posts: 4
Likes: 0
voltage drop 1990 C4
My talented mechanic is having difficulty figuring out why the voltage drops when the engine gets hot at the injectors. So far, he has changed the fuel pump, regulator and the pressure went from 20 something to 45 lbs, and filter and the RS catalytic converter that was still the original (LS already changed), the ignition module, and the computer. When the engine gets hot, it bogs down and dies. He said that with the injector unplugged and a noid light in the injector plug, the noid light was barely illuminated. Also it had to run about a half hour before it reacted like a clogged converter. The injectors were recently taken out and soaked and blown by the previous owner.
Just in-
He did an ohm check
1. 11.8
2. 11
3. 6.3
4. 6.3
5. 16.9
6. 3.0
7. 7.6
8. 17.4
Just in-
He did an ohm check
1. 11.8
2. 11
3. 6.3
4. 6.3
5. 16.9
6. 3.0
7. 7.6
8. 17.4
Last edited by UriahJabez; Sep 15, 2009 at 04:55 PM. Reason: new information re:OHMS
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
You have defective injector coils. When hot, one or more injector/s on each or one bank (looks like both according to your ohm readings) is so low resistance, that it loads the ECM drivers which then can't properly pulse the injectors. Your 90 fires each bank of injectors, so they are in parallel and it will only take one defective (yours get defective when hot) injector to hog almost all the ECM pulse current, not allowing the others to get a full electrical pulse. This is shown by the low intensity noid light. Replace all of your injectors.
