Running cylinder tests

[Lonestar10]

When doing cylinder cut out test today when trying to run on a single cylinder 1,2,3,6 all start out fine for about 5 seconds then it seems every compression stroke it loses about 50 rpm till truck dies. 4, 5 keep right on chugging.

Cylinder performance test shows 1,2,3 bouncing back and forth between fail,pass and 4,5,6 stay on pass.

Injectors were done in March with overhead
Actuators in december and fuel shutoff.
Fuel filters are new, rail pressure 270 at idle, 775 rpm idle

Any ideas? Don't have bubble test kit on hand as I left it at my mechanics for him to use as i thought i wouldn't need it for a while.

[Signature620]

Are you doing this test to diagnose something or just out of interest? No point throwing money away if it's running fine.

[Lonestar10]

Did it because I started truck after sitting 2 days and it was shaking a bit and when I reved it up I wasn't sure if I was feeling some sputtering. Just replaced ECM so paying attention more to little things as the first 2 ecms they tried were junk.

[Rawze]

If you want to be more comprehensive about it then ...

Adjust all the valves and injectors, then do the bubble test, then the cut-out test. - for all you know, the thing might be leaking a bit of fuel into more then one cylinder during the tests.

If it is hard to turn the engine by hand, then it will also not want to run on one cylinder at a time...

-- If there is a lot of friction in the cylinders due to carbon buildup/packing in the rings or when the engine is newly inframed.

[Lonestar10]

10-4 will order a set of feeler gauges and a 1/4 and 3/8 torque wrenches tonight and search for the posts/video for specs. already have a nice extendable 3ft 3/4 wratchet and 6in extension

replaced Balancer/radiator/put air cooler on trans/oil change/new reman ecm all on friday so atleast i already have balancer 1.6 tdc/pin insert/a-b-c paint markered for all the points for adjusting the valves.

i beleive its the angled feeler gauges that work the best right almost at an L?

[Lonestar10]

Would a new ECM need any time to learn like car ecms? Just wondering as only had 20 minutes on my flash from stock to custom and only about 1hr run time total on ecm

[Rawze]

(07-22-2019 )Lonestar10 Wrote:  Would a new ECM need any time to learn like car ecms? Just wondering as only had 20 minutes on my flash from stock to custom and only about 1hr run time total on ecm

It takes about 10 minutes of engine run time after a fresh flash for the ecm to re-build all its ram data. After that, it is stable.

[Hammerhead]

(07-21-2019 )Lonestar10 Wrote:  i beleive its the angled feeler gauges that work the best right almost at an L?

I prefer the 45° feelers myself, but it's a matter of preference.

[Lonestar10]

Those are what I was referring to just brain couldn't get the words to form at the time lol.