Cylinder 2 Misfire, Injector Failing?

[Rock2025]

Hey all,

2001 QX4 built 06/01 with 148000mi. Early spring I had a misfire on cylinder 2 and after some investigation I found that mice had chewed the wiring to cyl2 injector in half. I repaired the wiring and everything was back to normal and running great. Around this time plugs were changed with Bosch Iridium. Two weeks ago while driving, P0302 and P1320 popped up causing a flashing CEL, poor acceleration and vibration at idle all typical of a dead cylinder. It starts right up no problem but its immediately obvious that I am down a cylinder. Since then
-6 new NGK coil packs
-6 new NGK plugs
-New fuel filter
Cylinder 2 coil pack spark is confirmed, compression test showed 60PSI which I know is low and believe the seals on my tester are leaking. The connector that plugs in to the injector has 14v to ground on one terminal and 3-6v fluctuating on the other to positive. I really don't want to replace injectors but I feel that's what it is coming down to. Cylinder 2 spark plug is dry after running for a few minutes leading me to believe the injector is shot. I just find it odd that it is the same cylinder which I had issues with this spring. I know O2 sensors come into play, but it runs rough as soon as starts regardless of clearing codes or disconnecting the battery. Any last ditch suggestions before the intake gets removed and injectors replaced?

This spring I also had a P1441 PCV Bypass code, P0300 and randomly a EVAP leak would pop up. I believe the EVAP code is from the fuel filler neck leak.
Thanks!

[VStar650CL]

The 14V on the supply and fluctuating voltage on the output is 100% normal. Check the ECM output wire on another injector that's working correctly. If you see approximately the same voltage then the problem with the injector is mechanical and the injector is shot. If it's very different then the problem is electrical and you should check the wire between the ECM and the injector to make sure it isn't high-resistance. If it ohms out good then the injector coil is shot.

[Rock2025]

So I spent a lot of time over the summer going through what I could, replacing vacuum hoses, checking connections etc. There is more that I can dig through but that'll wait till warmer weather. I did end up replacing all injectors with remanufactured one as I didn't want to spend more money throwing new ones in after not confirming that was the issue. The misfire is still occurring.

The car sat for most of the fall till I decided to drop it off at a shop down the road. They spent some time trying to scan the ODB with a diagnostic scanner but really weren't able to collect any usable data. Given what parts I threw at it already, they are lost of words as to what could be the issue.

I currently have a cylinder 2 misfire code and one for the swirl control valve (probably because I was messing with it a while back). I did another compression test and had about 120psi on both cylinders 2 and 4. Occasionally the ABS and 4WD drive lights come on and the 4WD diagram on the dash goes dark. Once final gear is shifted, the whole car will shake uncomfortably but if overdrive is switched off then things will smooth out and it drives okay. Is it possible timing has slipped, wouldn't there be additional issues? Is my ECM fried? It is a great little car (I'm 6'4" so the car is little) and in great shape so I would hate to send it to the scrap yard. For what I paid for it and the current worth, it doesn't make sense to keep dumping money into it. Any additional ideas are greatly appreciated.

[D-Rock81]

Get a long screwdriver put it on the injector and the handle end up to your ear. Listen too see if you hear the clicking of the injector turning on and off

[D-Rock81]

Sorry. I missed that you put all new injectors in

[Rock2025]

I tried that with a mechanics stethoscope before I decided to swap injectors but was not really able to pin point a repeatable ticking sound other than the internals of the engine. I think it's coming off the road next week and will have to sit until warmer weather to mess with it unfortunately. I'm at a loss with whats going on, unless its the ECU or damaged wiring, possibly grounding I don't know. I appreciate any other ideas.

[Rock2025]

An update to anyone who may come across this.....I FINALLY figured out the issue. The car sat in my yard last summer un-drivable and in the fall I decided it's time to fix it or scrap it. I did something that I should have started with and that was checking the wiring. Doing so led me to checking resistance at the ECU for the injectors. All of the injector circuits measured the same except for cylinder 2. I purchased an ECU, key and key cylinder from ElectronicBay, installed the equipment, turned the key and voila I no longer had a misfire on cylinder 2. No idea what had caused the ECU to fry the injector circuit, but I've put many miles on it since the swap with no issues. Now I need to do the brakes and sort out the ABS/4WD light gremlin but I'm happy to have it back on the road.

[VStar650CL]

The injector drivers are unprotected MOSFET's which die in a hurry if they get shorted or overloaded, so I'd check the #2 wiring for a short to power before calling it good. With the ECM and #2 injector both disconnected, you should see at least megohms of resistance between the two injector wires. If it's less than a meg then the insulation is leaking someplace inside the harness, usually from the injector wire-pair chafing on one another at a bend. That needs to be fixed or the problem may recur. If the insulation checks out, then you may have just had a FET which died of old age.

[Rock2025]

I didn’t think about meggering the wire out, just hoped that the problem would go away. I will definitely do that to ensure no future issues, thanks for the insight!

[VStar650CL]