TBI INJECTOR / ECU HEAD ACHE !

[krmiller07]

I recently had both injectors replaced, along with trying 2 different ECU's. One which was remanufactured, and one from a running Pathy in the salvage yard.

 

The problem is that the 'primary' #1 injector cycles and sprays normally, and then when the 'secondary' or #2 injector is suppose to cycle or 'spray' it wont do anything past 2800 RPM's. The ECU goes into 'fail safe' mode. Confirmed power to both injectors, and have eliminated any possible problems from within the wiring harness, from splicing into the wiring harness and bypassing the main harness, to get power directly from the battery and running a 'hard wire' to eliminate the rest of the harness coming from the plug out of the ECU.

 

The ECU is showing a 'code 51', which is suppose to be the fuel injector circuit. However, the truck will only run on one injector and then starts to cut out or miss fire when revved past 2800 RPM's?

 

I have now tried 2 different pair of injectors and the same #2 injector fails, and 2 different ECU's thinking the driver was fried on the original ECU. Both ECU's have the same and correct part # as the original the truck was built with.

 

Has anyone else on here had this problem, or an idea what might be causing this? I've had the truck at a tech's shop for over a month and he's as stumped as I am.

 

Would a faulty throttle position sensor (TPS) cause this.

 

Any help, Idea's and comments would be greatly appreciated! : )))

 

Thanks

 

krmiller07

Edited November 10, 2014 by krmiller07

[Hellfirez31]

you have a short somewere in the TBI harness going to the ecu only thing that could cause that is electrical to my knowledge ..

[daczone]

I would plug your plugs one at a time to identify the bad injector. Should be able to find it.

 

I thought I'd read somewhere that the VG30 fires from group mode and switches to batch mode past a certain RPM. I think there was a TSB on it where Nissan was reflashing cars. Seems odd yours is a certain RPM. Perhaps when it switches modes. I suspect you have a shorted injector that is bring the whole system down when it switches to batch mode. (Just a thought)

[Slartibartfast]

The '89 is TBI, so it's just got the two injectors.

 

All I can think of is a wiring fault between the ECU and the #2 injector. You could probably figure out which wire it is on the ECU plug and test from there to the injector plug.

[Mauitrailguy]

Try switching the wires on the injectors and see if the other fails also, that will tell you if its the harness.

[ezlife]

I could maybe see a TPS in Short cuasing this. Your on the right track. The computer is reporting the failure, not the problem. I would check all inputs. Maf to o2 sensor.

Edited December 5, 2014 by ezlife

[Kingman]

So, have you by chance ohmed the old and new injectors to make sure the impedance is the same?

[azdonald]

Did you ever resolve the issue I believe I'm having the same problem code 51 checked voltage as it states in the fsm and am only getting voltage from 2/5 of the wires that connect to the ecu

[Cowcreektx]

Please tell me someone has the answer to this dilemma

[Backpacker]

Please tell me someone has the answer to this dilemma

I bought the truck off the guy that posted above you. It was throwing codes for Cylinder Head Temp Sensor, Crank Angle Sensor, and Fuel Injection Circuit in limp mode.

I replaced the Water temp sensor behind the timing cover which removed that code, then tested and replaced one of the fuel injectors and now its running flawlessly with zero fault codes.

 

The 2 injector TBI system uses one injector at idle, and uses both under load. I'm not sure what else puts it in limp mode but I know the injector does for sure so I would start there.

I would start with checking the injector resistance because its the easiest test:

unplug the injector harness connector and test the resistance between the two top left pins, then the two top right pins, should be about 1.5 ohms each. if its not, replace it or rebuild the bad one. ~$60 to rebuild and ~$300 new a piece

Edited November 9, 2016 by Backpacker