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I checked the connector on the ECU, looked very clean and tight. I couldn't really find the earth for the injectors, there are two single wire plugs just behind the RH rocker cover, cleaned them, made no difference.
It is an '89 3.5L flapper.
I pulled the 3 relays in front of the ECU while it was running and it stalled, so I guess they are all fine.
I will check the rest of the loom and the resistor pack tomorrow. I have to pull the plenum off to get to the injectors though, PITA.
Pulled it all apart, there was a heap of fuel in the plenum. All the injector plugs are fine, the earths are fine, the loom is fine.
Put it back together, started it and it ran really good for about 20 seconds, then started doing it again. It was like a switch was flicked.
How hot should the resistor pack be?
I've also just done a check on the pack, it reads 12.7 ohms on 3 of the four pins on one side and 6.5 ohms on all the rest.
On pulling the spark plugs out, 3 of the 4 on the LH bank were black and wet, and the rear one was grey. So I think one out of 4 on that side is actually firing. Would explain the readings on the resistor pack. Does anyone have the correct figures for what it should read?
A reminder the injectors are earthed via the ECU, not anywhere on the engine. Connect a test light between the negative side of the offending injectors and the positive side, see when the light goes bright instead of pulsing. Wriggle the loom while it goes like that. Then test at the ECU pin for that bank if the ECU is doing the shorting. Your ECU may be dead or dying.
I tried checking for an earth fault back to the ECU but wasn't sure if I had it right. I did a continuity test on the yellow/blue wire and it was OK, but I couldn't get a reading on the earth side of the plug.
Testing the voltage on the plug itself while the engine was running, I got 1.5v on the RHS at idle with it creeping up to 2.5v the higher I revved it. On the LHS it was a steady 9.6v on the plug. Would this suggest the resistor pack was faulty?
A volt meter is too slow to see pulses. Try a LED test light, you should be able to purchase one or knock one up out of a cheap LED, a resistor and a clear bic pen, should cost around $1 or so in parts.Quote:
Originally Posted by Not_An_Abba_Fan
I can't see how the resistor will affect the injector function as you say as it is on the positive side and a short would stop the injectors, not keep them on full.
Personally I would try to bludge a spare ECU and try that, might save some time.
I've found another ECU, just have to go get it. 4 hour round trip.
G`day , sounds like your resistor pack from what you`ve posted .
Should be 6 ohms + or - 1 ohm or from 5 ohms to 7 ohms is ok .
The job of the pack is to reduce 12v in to 3v out to the injector .
The ECU controls the entire bank as a unit and can`t give 3 black and 1 grey the pack can .
I'm off tonight to pick up another ECU and resistor pack. I'll try the resistor pack first, then replace the ECU if that doesn't fix it.
Well....not happy.
Did the four hour round trip last night and picked up the ECU and resistor pack. Got home, fitted the resistor pack first just to try it, no difference. Plugged in the new ECU and I was overjoyed, though short lived. It ran fine for about 20 seconds then did the usual and gut wrenching chug chug and started ****ing fuel out of the exhaust again.
I was ready to just shove a match up the exhaust and see what happened.
But I thought to myself that when I was checking for continuity on the harness it was giving intermittant results, so while it was idling (and I use that word loosely because it sounded more like a camel coughing up a lung), I pulled the harness through the firewall from the engine bay and it came good.
So....after all that, it seems like there is a short in the harness somewhere between the firewall and the ECU. Now I just have to pull it all out, strip the insulation and find the bugger.
So thanks PhillpA and bee utey, seems you were both on the money with it being a short in the loom.
An update for those that are interested, I pulled the injector loom out last night and stripped it back and found a nice little burnt out section of one of the injector earths. Right about were the loom goes past the foot rest inside the floor well.
Cut that section out, soldered in a new piece and retaped it and now she's running smoothly again.