1992 3.9 V8 hot start issue related to - wire from coil to ECU
#1
09-17-2017, 07:50 PM
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1992 3.9 V8 hot start issue related to - wire from coil to ECU
Hey,
Just finished putting a fresher 3.9 with new cam, lifters, seals, and gaskets in. Got it running, pumping oil, pushing coolant around, etc. It will not restart when hot. My friend (Rover tech) and I have triple checked the timing. We've tested fuel delivery, injector pulse with noid lights, spark, each wire, etc.
We have found that it's over fueling on a hot restart and flooding. When we pull the tach input to the ECU wire off of the "-" terminal on the coil it will sputter then crank. If I touch that wire on and off of that negative terminal while cranking it will start then I can put the wire on the coil and leave it running. It'll be really rich then settle right into idle.
We have tested the ICV, idle is set right, timing is at 10degrees (here in Colorado that's a good setting).
I put a new MSD Blaster 2 coil in it today and that didn't make any difference. I'm using Rover wires and NGK copper plugs. I've also swapped O2 sensors, coolant temp sensor, fuel temp sensor, TPS switch (from engine that was pulled out of my rover that ran pretty well inspite of low compression).
Any thoughts as to how leaving that "-" from the coil to the ECU. This is the White wire that joins the MAF wires in the loom back to the ECU. Labled as going to 162 in the Rave Workshop manual schematic. It's labled as "Coil Negative(engine RPM input to ECU). I think it's flooding and by pulling this wire it's cranking and sparking without additional fuel so it clears out and sputters then by putting the wire on and off quickly as it cranks I'm giving it enough fuel to start but not too much to flood. Once running I can connect and it runs fine.
Thanks in advance. I've been searching all over for a solution to this issue.
Just finished putting a fresher 3.9 with new cam, lifters, seals, and gaskets in. Got it running, pumping oil, pushing coolant around, etc. It will not restart when hot. My friend (Rover tech) and I have triple checked the timing. We've tested fuel delivery, injector pulse with noid lights, spark, each wire, etc.
We have found that it's over fueling on a hot restart and flooding. When we pull the tach input to the ECU wire off of the "-" terminal on the coil it will sputter then crank. If I touch that wire on and off of that negative terminal while cranking it will start then I can put the wire on the coil and leave it running. It'll be really rich then settle right into idle.
We have tested the ICV, idle is set right, timing is at 10degrees (here in Colorado that's a good setting).
I put a new MSD Blaster 2 coil in it today and that didn't make any difference. I'm using Rover wires and NGK copper plugs. I've also swapped O2 sensors, coolant temp sensor, fuel temp sensor, TPS switch (from engine that was pulled out of my rover that ran pretty well inspite of low compression).
Any thoughts as to how leaving that "-" from the coil to the ECU. This is the White wire that joins the MAF wires in the loom back to the ECU. Labled as going to 162 in the Rave Workshop manual schematic. It's labled as "Coil Negative(engine RPM input to ECU). I think it's flooding and by pulling this wire it's cranking and sparking without additional fuel so it clears out and sputters then by putting the wire on and off quickly as it cranks I'm giving it enough fuel to start but not too much to flood. Once running I can connect and it runs fine.
Thanks in advance. I've been searching all over for a solution to this issue.
#3
09-20-2017, 09:15 PM
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Problem solved. 
So if during reassembly you plug your #1 injector connection into your coolant sensor and plug your coolant sensor plug into the #1 injector it really messes up the way your Rover runs. LOL I just had it running, restarted multiple times, and test drove it. I'm so happy right now. WOOHOO
So if during reassembly you plug your #1 injector connection into your coolant sensor and plug your coolant sensor plug into the #1 injector it really messes up the way your Rover runs. LOL I just had it running, restarted multiple times, and test drove it. I'm so happy right now. WOOHOO
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