Threaded Mode | Linear Mode

1096 · 04-21-2021, **(Subject: ISM MISFIRE @ 1500 RPM )**

I'm having problems figuring this out. Misfire on #1 at 1500 RPM. Cummins ISM #35248744 320,000 miles. International 8600 (Thirteen Letter S___ Spreader)
I did a cut out test. Replaced #1 injector. Adjusted the valves. Rebuilt the Davco filter. new fuel lines. This is my other truck, not the one you programmed.
STILL MISSING ON #1 AT 1500 RPM. NO CODES before or after.
Next up: Fuel Pressure at pump. Clear hose at pump to check for bubbles. Inspect pickup tube in tank. Inspect Cooling plate. Ohm Injector harness. Swap ECMs with the other S___ Spreader, same ECM different program.

Got any suggestions? Or should I just keep on Parts Changing?

Injector did fix it, initially, lasted less than a day. before it started misfiring again. got injector new from Cummins.
WTF (what's the Foundation)

tree98 · 04-21-2021, **(Subject: ISM MISFIRE @ 1500 RPM )**

That's got a high pressure rail right? Im pretty sure it does so did you do a leak down test?

1096 · 04-21-2021, **(Subject: ISM MISFIRE @ 1500 RPM )**

No high pressure rail fuel from pump goes into head. Can't do a leak down like on an ISX

tree98 · 04-21-2021, **(Subject: ISM MISFIRE @ 1500 RPM )**

Maybe your new injector is a dud?? Did you try moving that injector to another hole and running cut out test again to see if you can move the problem? Maybe pressure test the head to rule out a valve/head problem.

Rawze · 04-21-2021, **(Subject: ISM MISFIRE @ 1500 RPM )**

(04-21-2021 )tree98 Wrote: ... Maybe pressure test the head to rule out a valve/head problem.

Maybe back off all the rockers/valves so that the valves are all closed and pressurize the intake manifold to about 20 psi? .... check for compression leaks at the valves?.. and then do the exhaust manifold side?

I have found many mysterious combustion and fuel mileage problems by simply doing this, finding out that the valve seats are worn out/leaky in older engines or engines with used head on them.

1096 · 04-21-2021, **(Subject: ISM MISFIRE @ 1500 RPM )**

(04-21-2021 )tree98 Wrote: Maybe your new injector is a dud?? Did you try moving that injector to another hole and running cut out test again to see if you can move the problem? Maybe pressure test the head to rule out a valve/head problem.

This is now on the list!

1096 · 04-21-2021, **(Subject: ISM MISFIRE @ 1500 RPM )**

(04-21-2021 )Rawze Wrote:
(04-21-2021 )tree98 Wrote: ... Maybe pressure test the head to rule out a valve/head problem.

Maybe back off all the rockers/valves so that the valves are all closed and pressurize the intake manifold to about 20 psi? .... check for compression leaks at the valves?.. and then do the exhaust manifold side?

I have found many mysterious combustion and fuel mileage problems by simply doing this, finding out that the valve seats are worn out/leaky in older engines or engines with used head on them.

GFI (Good Frontal Intelligence) This is going on the list! Thanks