I have a head scratcher of an issue!!

My 1988 4Runner is only running on two cylinders. I have been working this for a while and will start with the troubleshooting I have found applicable.

Using the noid light, I have discovered cylinders 2+4 are not getting signal to fire the injectors. I have ohmed out the wires to the ECU and found them good. I Ohmed out the wires to the resistor, good. Ohmed out the resistor, 3.0 Ohms, good. All readings were taken on all 4 injector plugs. THis tells me (presumably) that all my wiring is good and my resistor is good.

I swapped my ECU for other 89661-35110 ECU's I have on hand. NO CHANGE!! WTF AM I MISSING??? Sill only getting noid light on 1+3.

Cross posting this to other groups to see if anyone can point me in the right direction.

 

these trucks have a history of injector wiring splices that corrode and break, to the point where they can't carry enough current to fire the injector: https://forum.ih8mud.com/threads/a-2...-i-had.311436/

there might be a couple of wires still connected so it passes a low-current ohmmeter resistance test, but can't actually fire the injector... my '86 had it, what a nightmare to troubleshoot, not sure if toyota was still splicing with the '88 and up.

it's a last-ditch effort because you have to cut the harness open to find it :-/ if you can locate a used engine harness for your '88 it might be worth trying that first, then fix the old one if that's the problem.

 

There is that resistor mounted on the right inner fender wall that controls the fuel injectors, and I believe in pairs. It'll have a part number printed on it thats something like 28515-xxxxx. It has two different connectors coming off it.

 

Yes, the 3 Ohm resistor, I have checked mine as well as replaced it with a spare I have. No change.

 

i would attempt to swap the injector connectors with each other, ie, 1 for 2, and 3 for 4. if the problem migrates to cylinders 1 and 3, you'll have narrowed it down significantly. the injectors all fire at the same time, and i have swapped connectors to different injectors to verify problems either with an injector or with wiring/connectors.

unlikely that 2 injectors just quit, so it is more likely a wiring issue, but that test will confirm it.