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Hello all! Longtime lurker, but this situation has prompted me to make my first post. I'm sure you all can point me in the right direction.
The car in question is a 1988 Volvo 780, B280F, LH 2.2, EZK115.
I have been chasing a problem where the car will start and drive perfectly well for roughly 7-9 minutes. As the car gets warmer, the car will stumble and buck, and at one point I couldn't give the car gas at all- it just wouldn't move. Some research and experienced friends told me to take a look at the ignition module, as they sometimes have intermittent failures like that, related to heat. I performed the tests outlined in the 7/9 faq on my old ignition module, and it passed when cold, then failed when hot. The ignition coil was a similar story- passed the tests when cold, then failed when hot. At least now I had some direction.
I put both new parts in today. However, when I removed the wiring for the coil, I mixed them up, and I mis wired the new one in. I went to turn the car on, and in KPII, the injectors were all firing. There was one blue wire connected to each of the terminals on the coil, and the red/white wire(tach wire) was connected to the positive terminal. I turned the car off, found the right way to wire it, and now there are the two blue wires on the positive terminal and the red/white wire is on the negative.
Now here's where it gets interesting. If you put the car in KPII, the ignition coil starts clicking rapidly, and when pushed to KPIII, the car will crank but not start. In addition, in KPII the tach registers 1000rpm, even though the car isn't running. Finally, one of the blue wires is getting hot to the touch, and the tach and other blue wire are cool.
I'm confused guys, and getting frustrated. Any ideas? What have I done to my poor car?
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Here's a small update-
Everything is hooked up correctly as best as I can tell. I noticed the fuel pumps weren't turned on when cranking. The first part of the relay will click when I put it in KPII, but it won't close the second contact like it's supposed to.
What needs to happen for that relay to close?
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"The first part of the relay will click when I put it in KPII, but it won't close the second contact like it's supposed to."
• That "second contact" is the Fuel pump relay, which in the 240 LH 2.2 system doesn't close until the ECU grounds its coil during cranking.
"What needs to happen for that relay to close?"
• The simplified answer is in Step 2-b of the sequence that Jerry posted below. The detail is the grounding of the fuel pump relay coil (terminal 86-2) by the ECU, when it receives "timing pulses" from the EZK Ignition CU, during cranking.
What I don't get is this: "If you put the car in KPII, the ignition coil starts clicking rapidly,"
The coil has no moving parts to click. If this is a turbo car, it may have an "Impulse Relay" (near the coil), but I don't have any info on that except that I think it's to "assist" the coil during starting (which would suggest action in KPIII rather than II.)
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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Maybe review lucid's 'Start-run' sequence, which I'm taking the liberty of reposting as it's so valuable.
Bruce, I sincerely hope you don't mind.
Start-Run Sequence LH 2.0/2.2 Version
1) During starter cranking, the distributor Hall sensor sends timing pulses to Ignition Control Unit (ICU)
2-a) The ICU uses these Hall Sensor pulses to trigger the Ignition Coil (– terminal) to initiate timed sparks from the coil.
2-b) At the same time, the ICU also propagates the pulses to the FI ECU, to allow FI operation (no ICU pulses means no Fuel pumping).
3-a) The Fuel Injection (System)* relay (previously energized at Key On) powers the AMM, IAC, ECU, Injectors, and Fuel (pump) relay coil + side.
* The System relay is adjacent to the Fuel relay (same relay type).
3-b) When ICU pulses are received by the FI ECU, it "energizes" the Fuel relay by grounding the relay coil (– side) to run the fuel pumps.
When all these things work, the engine runs until the Ignition is switched off, which in turn shuts down the FI system.
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OK- here's a small update. I realized that I had tried both ignition modules with the wiring to the coil backwards, so if I fried one module, I fried both the old and the new.
I got a brand new bosch module, part 0227100124, and plugged it in. Still the exact same symptoms. The coil still fires constantly when I put the car in KPII. My thought process is this- if it is getting a signal to ground constantly, it would fire. The question is, how do I tell where or what is telling it to ground? Is it the crank position sensor telling the ICU to ground all the time, or is it the ICU itself? More testing will tell, I guess. Any ideas what the CPS voltage or resistance values are supposed to be for an LH 2.2 V6 car?
I'd just try a new ECU and EZK if they weren't the stupidly rare V6 versions...
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Okay, so here's some more information. Using the 760 EZ-115K diagram from k-jet.org, I realized that the colors of the leads that go into and pin-outs for the 1988 780 ignition ECU are completely different.
Even so, I have performed a couple tests and come up with some unusual results. I am getting 0.681 continuity from Pin 5 of the ignition module connector (the grey wire that serves as the means for the ICU to talk to the ignition module) to a number of pins on the EZK connector (Pin 2,10,14,15,18,20,25,32,34,35). In addition, those same pins have perfect continuity to ground.
In my estimation then, Somewhere in there is a nasty short to ground. I'm going to do more testing tonight, but I wanted to post back, just in case someone out there has had the misfortune of mis-wiring their coil and now their car won't start.
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