1995 Volvo N14 Cummins bad injector or dead hole?

Thx for the info pup, but this is a for sure dead miss, not at idle unless hot. Its bad enough under load you can hear the gears in the trans change pitch each time that cylinder misses, but its hard to pin down which one at idle. No check engine light on right now, but i have wanted to know how to get the codes to readout to help me diagnose this.

I have changed the fuel filter, havent run a suction test yet, but i do know the fuel pressure is about 150. I think that since i have the ECM off anyway, i will check that cooling plate valve and make sure theirs no junk in it causing a flow problem. thx again.

 

I sure will! I saw where pablo posted a wiring diagram in another thread for the pin out and wiring of the ecm, and im going to go through and check the injector harness and make sure i don't have a intermittent shorted or open wire or something. There was a lot of corrosion built up behind the ecm where it mounts to the cooling plate, so I'm thinking it wasn't doing a good job of dissipating the heat off the ecm, so that's why i'm having it tested too.

 

WELL... i got the rebuilt ECM back today, and got it installed. NO change...it still had a miss. So now what? I noticed at first when I started the motor, and was letting it warm up, it was idling really smoothly, then after about 10 minutes it started kind of loping like ot does when the miss appears, adn sure enough, it had the miss under load. I stopped on the road and checked the exhaust temps, and number one is still around 230 degree, while the rest were about 400. I have also noticed that if i lug it on takeoff, or sometimes on a gear change, it will seem to miss on several cylinders for a moment. It seems kinda like if you jerk the motor round form torque, then the miss gets worse, which is leading me to think it may be a wiring harness problem. I did a pinout test of the injector harness at the connector to each injector, and all the injector leads measured about 5.5 ohms, no opens or shorts...at least not sitting still. I still need to pull of the rear hold down on the head and check for chafing or intermittanly shorted wires. Also wondering, the two ten amp inline fuses in the harness near the ECM ..do they supply voltage to the injectors?

The other question i have is which way does the fuel flow through the heads? Does it go in at the rear or the front? If it had a fuel flow or volume problem, and fuel is introduced at the rear head first, them that might explain why my front cylinder ex temp is low since that cylinder is not getting enough fuel? I stil need to pull apart that check valve at the outlet of the ECM cooler plate, and make sure its not restricted like was suggested.

PLease help with ideas or tell me what im missing, this thing is driving me crazy!!!

 

Pass through connector on #1 injector has been replaced, it was the first thing i tried along with replacing that injector.

Another couple of things I noticed is it really misses bad about 1300 rpm in neutral, and another symptom it has is to crank about 20 seconds or longer at startup, adn kinda misses on several holes until it starts or i press the throttle down a little.

 

Ok I think I found it, I took off the injector harness, to look it over real close for frayed wires, and when i got it on the bench to test it I found that only 2 injector leads for #1 adn #3 cylinders of the harness connectors had contiunity. I guess when i pulled it of adn started wiggeling it out of there, the intermittant problems i had been chasing eveidently became full on open circuits. NOw ive either got to try and fix that harness or find another one. I thought the wires around where they were bolted to the block looms had maybe frayed and gone open...but after testing a couple of wires, it looks like they came loose inside the main harness plus conncetor coming out of the ECM. IT looks like this had happened on one of the other coneector, because it had been rewired with new different colored leads coming out of the harness connector coming that leads back to the body. Now i know why they did that. I will post an update to make sure this was all the problem, after repairing or replaceing the injector harness.