Checking for Missfires in a m1009

[Jmeggz89]

I am trying to check for a misfire in my 86 m1009 I have heard of doing a cylinder balance test but I want to avoid that if possible. I also have heard of using a temperature reader and read the heat on the headers for each cylinder but don't know what kind of temp variance to look for. Any suggestions on the temp variance or another way to check for misfires?

 

[Barrman]

The clean and easy way is to use a infrared non contact thermometer. You will find most of the cylinders are pretty darn close to the same temp. Of course, the ones closest to the cooling fan will be a bit cooler than the ones near the firewall.


The messy way that will leave no doubt in your mind about if a cylinder is working or not is this. Fire it up, let it warm up and then use a 3/4 open end wrench to loosen the fuel line on an injector. Fuel should spray out, stop when that happens. The idle should also drop when the fuel comes out. Tighten it back up and do another injector.

 

[Jmeggz89]

Yeah that's the power balance test I was talking about lol. How mutch temp diffrence is ok 20 degrease ten? Also the only reason I ask is bc at idle every now and again I feel a little extra rumble you knw like a car that has a miss every now and again at idle. It happens when the truck is at idle. Its an extra vibration real quick and then regular for a few second then another vibration.

 

[Jmeggz89]

Also can I use reg 6.2l injectors in that and if so are they the coarse thread ones or the other ones?

 

[IdahoPlowboy]

You should have fine thread injectors.

 

[Barrman]

Listen at your exhaust too. My M1009 had an idle that felt and sounded like a gas engine with timing advanced waaay to much. The exhaust note was never constant from either side. I did the injector line check, all good. I did the temp check and all were within a few degrees of each other. I even swapped all the injectors out. No change.

I ended up swapping the IP. It was leaking from the throttle shaft too. Now, each exhaust pipe has a super steady beat. You are probably going down the same road.

I don't want to give exact numbers for the exhaust temp. It depends so much on things only you can know about. Outside temp, how long the engine has been running, where you are taking the temp and even how far away your gun is. My suggestion is to start checking each cylinder and writing down what you get. Drive it, check it, drive it some more, check it. You will find a pattern. There are conditions where 50 degrees is all the difference between a working cylinder and a dead one. Other conditions and it will be 200 degrees.

That make sense?