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92 4x4 EB Misfire

ldearroz

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City, State
Jeddah, KSA
Year, Model & Trim Level
'92 Eddie Bauer
I've got a misfire on one cyl - no fuel - on the farthest right bank cyl, if you are looking over the engine on the front end. I dont know how the cylinders are numbered. It could be no. 5 or 3??? I replaced all spark plugs and HT cables. I disconnected and reconnected the injector connector to confirm it-no change on the rpm. I dont have a wiring diagram, so if anyone' got an EFI wiring diagram which includes terminal pin assignments for the PCM, that would be of great help. Also Ive got this mysterious wiring harness connector that is'nt connected anywhere, I suspect this should fix the problem. I cant find the other connector where it should be connected ? I found it when I was checking the connectors. I just bought this EB 3 months ago-misfire included. It is a white round 4-pin female connector located near the coil packs. It connects with the 3 injectors on the left side (bank - looking front the front end of the vehicle) I have a picture but I cant seem to post it here. My account says I cant post attachements. But- I can send it to anyone by email-off this thread.
Thanks!
 


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wood1

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'93 XLT, Cayman Green RIP
Are you saying that you unplugged the injector while it was running and got no change in RPM? I would check to see if the ECM is sending a pulse to that injector with a noid light, if it is I would suggest you try a different injector.
 




ldearroz

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'92 Eddie Bauer
I dont have a noid light here. But I disconnected the injector connector on the suspect cylinder and found 12 volts on both pins (KOEO). All the injectors seem to be working because I can feel the solenoids ticking when i put my finger on the injectors. Its pretty tight to do all these checks coz the injectors are located right under the intake manifold (on the left bank)and Ive got to do it when the engine is cold. The spark plugs dont have a telltale sign of carbon deposits or being wet with fuel. All plugs seems ok. Which tells me no fuel is being injected. I also brought it to a local shop to have the injectors cleaned with some contraption, a cleaning solution mixed with fuel is used to run the engine. It didnt help. That connector is still a mystery to me :confused: I'm planning to go to the junk shop to get injectors. Also, the cooling system is overheating, when I drive the truck with the AC ON.
 




wood1

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What about checking the compression on that cylinder as well?
 




ldearroz

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I just did check the compression. It's seems OK and even on all cylinders.
 




wood1

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If it's not that injector, I'm not sure what the problem is. You going to swap in another one?
 




Alan_V

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12 volts on both pins (KOEO)

That's not right at all. One pin is power, the other goes back to a transistor in the PCM and is grounded to open and close the injector. It sounds like a wiring problem. The power side may be pinched to the ground side. Start working your way back from the connector and look for wiring damage.
 




wood1

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Hey at least you are thinking... seems to me that KOEO there shouldn't be anything other than a ground coming through both pins anyways. If one was hot then it would hold the injector open...
 








Alan_V

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Hey at least you are thinking... seems to me that KOEO there shouldn't be anything other than a ground coming through both pins anyways. If one was hot then it would hold the injector open...

I'd expect B+ on one pin KOEO. The default state for the ground circuit would be open. When the PCM wants to open it, the transistor grounds the circuit, and the injector opens. As far as the injector, its back yard stuff, but if you wire B+ to one pin on the injector and tap the other to ground, you should be able to make the injector open and close, and you'll likely hear it.
 




wood1

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Thanks for clarifying Alan, that makes sense...
 




ldearroz

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I replaced injector # 6 (I indicated incorrectly this as # 5 previously) with a new injector and the results very good, there is considerable increase in power although, I should have replaced all. But now I have an new problem which is engine overheating. I found a leak in the intake manifold in the front end near the flange where it connects to the upper radiator hose. I tried to use STOP LEAK but it didn't help. I also, replace the radiator cap with a new one. I'm now in prcocess of removing everything on top of the engine to get to the intake manifold. I can't locate the thermostat housing, where is it's exact location??
 




ldearroz

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For everyone's information I found the reason why there is B+ voltage on both pins of the injectors (KOEO - connector disconnected), after someone gave me a wiring diagram. Cyls # 1 2 & 3 are switched on and off with one transistor in the PCM, same with cyls # 4 5 & 6. This is not a sequential EFI system that I found out, rather fuel injections is done by only two power transistors by group - left and right bank.
 




Blacksheep Josh

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I can't locate the thermostat housing, where is it's exact location??

When looking at the engine from the, it is beneath the air intake tube, where the upper radiator hose connects to the engine.
 




ldearroz

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Thanks, for that info. I also found the heater hose already disconnected from the inlet and outlet tubes of the heater located on the firewal. The heater hoses were connected together so the coolant just goes back to the engine block. I traced the hoses and I found that it goes under the right and on the lower side of the engine where the oil filter is located, then goes back out again and goes to the front of the engine to the water pump. I just want to plug these coolant lines since there is no use of a heater here in KSA. Is there going to be a problem if I do this? I suppose I can just leave the inlet and outlet ports on the oil filter.
 




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