Used Laser Temp Gun...One bad injector?

[Justin.Hutch]

So I've had this bad vibration in the truck for awhile around 1250-1750 rpm. I had the tranny rebuilt and the shop told me the vibration could have caused my TQ to start to fail and then caused my pump to fail.

So $3400 later and I got a new tranny but the same vibration. I was thinking it was an injector so I grabbed a laser thermometer and started the truck. I placed it up against each cylinder on the exhaust manifold as it warmed up.

Before it was running everything was around 100*. I started it and after a minute all the cylinders seemed to warm up to around 130-140 while only the #1 cylinder (front right if sitting in the drivers seat) stayed under 105. So I know that cylinder is dead. I'm thinking its an injector, but before I change that is there anything else I can try to eliminate other reasons that cylinder might be dead?

[dray8165]

A very original and unconventional way to check an injector. Traditionally, a scanner would have been used to do a buzz test and a cylinder contribution test. That would be a better way to isolate the injector. You should also check the wiring harness to make sure there are no bare wires or burned pins.

GB Remanufacturing - Tech Bulletin #103

[Justin.Hutch]

Originally Posted by dray8165

A very original and unconventional way to check an injector. Traditionally, a scanner would have been used to do a buzz test and a cylinder contribution test. That would be a better way to isolate the injector. You should also check the wiring harness to make sure there are no bare wires or burned pins.

GB Remanufacturing - Tech Bulletin #103

Well about 500 miles ago I replaced the glow plugs and wiring harness for both sides. Only thing I didn't change was the main plug to the wiring harness so I will check the connection on that main plug for the #1 cylinder. Thanks.

I'm trying not to take this thing back to the shop for this injector after I just spent that much on the tranny

[jbawilliams]

I had exactly the same problem on my 96 PSD I had at the time a few years ago - I checked it with the infrared thermometer - exactly the same way. I swapped the injector to another cylinder and ran it again, and the problem followed to the new hole. It was a pain in the butt to put it all back together again, only to tear it all back down in a few minutes, but by that time I was absolutely certain it was the injector, and a new one solved the problem.

[Justin.Hutch]

Originally Posted by jbawilliams

I had exactly the same problem on my 96 PSD I had at the time a few years ago - I checked it with the infrared thermometer - exactly the same way. I swapped the injector to another cylinder and ran it again, and the problem followed to the new hole. It was a pain in the butt to put it all back together again, only to tear it all back down in a few minutes, but by that time I was absolutely certain it was the injector, and a new one solved the problem.

That's a good suggestion. IIRC the passenger side is a lot easier to take apart too.