Multiple Injector Fail

[Zooks]

Hi All,

I'm after a bit of advice on my 2008 Nissan Primastar van

Its running like crap and has the engine management light on. Its throwing 3 error codes p0201, p0203, p0204 injector circuit A fail.

All this started after a the battery went total flat and when I charged it upthe EM light was on. Took it on a 15 mile drive and it went from slight stuttering on acceleration to dropping to zero revs and almost cutting out.

Is it likely for 3 injectors to go bad so quickly with no previous issues or should I be looking elsewhere?

[NMNeil]

The code description may help
"The PCM is equipped with special transistors called ‘drivers’ to operate the Fuel Injector On and Off in Fuel Injection System. The PCM then expects to see voltage close to battery voltage or “high”. If it doesn’t see the expected voltage, then it determines a problem, setting the Error Code P0201. Also, the PCM oversees the resistance in the circuit during normal operation, and if it sees the resistance is excessively low or high at cylinder 1 injector circuit, or out of its specifications, then it will set the same trouble code."
If the battery went flat all on it's own that would be a good place to start. Make sure the battery and/or alternator is maintaining it's expected voltage.

[GreenV8S]

If multiple injectors are affected at the same time, it's more likely to be a wiring/driver fault than a failed injector. The wiring fault might be on the supply side or the ECU (return) side of the circuit.

[Megaflow]

How flat is totally flat? Modern electronics do all kind of odd things with dodgy batteries even though they have enough power to start the car fine. I'd be very tempted to put a battery on it and reset the codes.

[Zooks]

Megaflow said:

How flat is totally flat? Modern electronics do all kind of odd things with dodgy batteries even though they have enough power to start the car fine. I'd be very tempted to put a battery on it and reset the codes.

Well theres a bit of history to it as was in the garage for a siezed brake caliper. By changing the caliper they somehow created an ABS fault which they rectified (not sure how).

Then lockdown happened and the van sat in their carpark for a few weeks. When I went to pick it up it was totally flat, 0v as in can't even unlock the door, no ignition lights flat. They jumped it with a charge pack but the engine management light was on then.
They assured me it would go out after a few miles, yep gulible me.

I brought it home, stuck it on a trickle charge (its a camper) and again because of lockdown haven't used it for a couple of weeks

I have checked the battery terminals are tight and measured the volts at 14.3 engine running, 12.9 engine off.

I have also had a poke around under the bonnet but theres nothing obvious left unpugged.

Would completely disconnecting the battery and reconnecting be worth a go?

[Matt_E_Mulsion]

The battery is probably shot after it's been discharged to nothing, even though you've managed to charge it back up. The first thing I'd do (and maybe the cheapest) is to replace the battery with a new decent quality item.

[Zooks]

Ok thanks they are about £80 -£90 so not too bad. Even though I can start it and it ticks over it does actually feel like its at least 1 cylinder down when you rev it so theres definately a problem somewhere. Would a duff battery cause this or just cause phantom codes?

[hellorent]

I'd be inclined to disconnect batt - and then touch that to batt + for a couple of seconds then connect batt back up and see what happens re fault.

[Zooks]

Just to update this thread none of the above worked unfortunately.

Managed to get all the codes but P0204 to clear. Measured the injector resistance and no1 - 3 reading 150kohms+ no4 is reading 3ohms. Just got to get the bd out now

Thanks for the help anyway guys

[GreenV8S]

Zooks said:

Measured the injector resistance and no1 - 3 reading 150kohms+ no4 is reading 3ohms. Just got to get the bd out now

Seems odd that three injectors have failed with the identical resistance. Are you measuring directly across the injector with everything else disconnected? I wonder whether you may be accidentally measure the current drain of the driver circuit in the ECU, or something like that, instead of the resistance of the injector itself.

[Zooks]

GreenV8S said:

Seems odd that three injectors have failed with the identical resistance. Are you measuring directly across the injector with everything else disconnected? I wonder whether you may be accidentally measure the current drain of the driver circuit in the ECU, or something like that, instead of the resistance of the injector itself.

I think its no4 that has failed as after clearing the error codes only p0204 code came back. I think healthy readings should be in the kilo ohm range and no1, no2 and no3 all were all between 150 - 170kohm.
I measured resistance across the 2 input pins on each injector in turn but with them in situ and the fuel line still connected, should I have disconnected this?.

I also tried to measure the voltage to the injector as well and was expecting to see 12v to them with the ignition on but could only measure 300mV on all injectors?

I only have a basic multimeter and an even more basic understanding of how to use it so am happy to be corrected

[GreenV8S]

Zooks said:

I think its no4 that has failed as after clearing the error codes only p0204 code came back. I think healthy readings should be in the kilo ohm range and no1, no2 and no3 all were all between 150 - 170kohm.
I measured resistance across the 2 input pins on each injector in turn but with them in situ and the fuel line still connected, should I have disconnected this?.

I also tried to measure the voltage to the injector as well and was expecting to see 12v to them with the ignition on but could only measure 300mV on all injectors?

I only have a basic multimeter and an even more basic understanding of how to use it so am happy to be corrected

I'm not confident you're measuring correctly. The resistance of a healthy injector should be in the region of 10 Ohms for a high resistance injector or 3-4 Ohm for a low resistance (peak and hold) injector. If you can find the electrical specifications for the injectors on your vehicle that would tell you what to expect. You would normally test them by disconnecting the electrical plug from the injector and measuring the resistance between the electrical terminals of the injector. 150 kOhms is definitely not a sensible reading for a healthy injector. Either the meter is faulty or you're using it incorrectly or you aren't making a good connection with the injectors or the injectors are faulty.

If you put your volt meter on the DC voltage scale and measure the voltage between ground and each of the terminals on the plug that connects to the injector, you should find one of them has a constant supply of a little over 12V when the injectors are powered. Note that they may not be powered when the engine is stopped so it would be easy to get a false reading here.

[Zooks]

GreenV8S said:

I'm not confident you're measuring correctly. The resistance of a healthy injector should be in the region of 10 Ohms for a high resistance injector or 3-4 Ohm for a low resistance (peak and hold) injector. If you can find the electrical specifications for the injectors on your vehicle that would tell you what to expect. You would normally test them by disconnecting the electrical plug from the injector and measuring the resistance between the electrical terminals of the injector. 150 kOhms is definitely not a sensible reading for a healthy injector. Either the meter is faulty or you're using it incorrectly or you aren't making a good connection with the injectors or the injectors are faulty.

If you put your volt meter on the DC voltage scale and measure the voltage between ground and each of the terminals on the plug that connects to the injector, you should find one of them has a constant supply of a little over 12V when the injectors are powered. Note that they may not be powered when the engine is stopped so it would be easy to get a false reading here.

Ok thanks for that. I largely followed this guys guide and connected the same way as he did around 00:50

https://www.youtube.com/watch?v=Bf515eBHM1c

I did measure the volts ignition on engine not running because with all the crap you have to remove to get to the injectors it wouldn't run but I will have another go!

[NMNeil]

With a resistance of 150K ohms you only have about 90 microamps to operate the injector solenoid, which is nowhere near enough.