+- Rawze.com: Rawze's ISX Technical Discussion and more (http://rawze.com/forums)
+-- Forum: Big Truck Technical Discussion... (/forumdisplay.php?fid=1)
+--- Forum: ISX Related Help (/forumdisplay.php?fid=68)
+--- Thread: Popping Under acceleration (/showthread.php?tid=10718)
Popping Under acceleration - Phoenix6189 - 08-18-2026
Have a 2250 that blew a head gasket, after replacing the head their is a popping under acceleration now. Seems to be coming out the intake side. Worse of course with turbo pipes installed. Thought head may have had some bad valves so installed new cummins head. Same issue. Doing a cylinder cut off doesn't seem to change anything. Is demandated by member. Bought an injector to move around. No change. Checked Base timing and lash twice. Acts like it out of timing. Thinking Cam, but dont see anything obvious, but it ran fine before it went down. Cam has over 800,000 miles on it. 1.3 million on motor, cylinder height is .013. Motor and Injectors inframed 300,000 miles ago. Acts like Fuel or timing. Exhaust looks black and white, unburnt fuel.
RE: Popping Under acceleration - Rawze - 08-18-2026
To ensure it is not program related ...
Copy program from ecm and e-mail to to me for a review of what is in the ECU. For all anyone knows, it could be in need of software update, etc.
- Also, after backing up the ecu programming as is, re-flash it to latest factory software and run it around the block with the factory programming in it ans see if the issue clears up.
--------------------------------------
Mechanically, as far as the popping goes...
== If the overhead cam is not damaged / flaky and worn really REALLY badly then its not likely the cause.
== What wedge was used on the valve cam?. - You sure it was wedged right? and was not out 180-degrees?.
== It is all OEM turbo, manifolds, overhaul kit, head etc?.
== OEM injectors?.
== It it all matching components according to the engine ser#?
== What are the intake/exhaust valve clearances measuring at this point, now that is has a few miles of running on it?.
== Will it pass an injector leak test exactly as it shows in this video?..
info: https://rawze.com/forums/showthread.php?tid=8728&pid=75483#pid75483
== What is boost getting to in a hard pull // hard acceleration when its happening?.
... and .. what are you calling a popping?...
... a 'Chihht' ... 'Chihht' ... 'Chihht' ... sound?...
or a distinct, sharp ... "Pop" .. ... "Pop" .. ... "Pop" .. sound,?..
??? or something else?.
is it subtle?... or very loud?... etc?.
and is it every revolution of engine?.. every few revolutions on the r3egular/... or simply random?..
RE: Popping Under acceleration - Rawze - 08-18-2026
(08-18-2026 )Phoenix6189 Wrote: Have a 2250 that blew a head gasket, after replacing the head their is a popping under acceleration now.
...cylinder height is .013. Motor and Injectors inframed 300,000 miles ago....
If all you replaced is the head and head gasket... I Gurantee that you just completely wasted all your moneys on it just now!.
there is no way in h#ell that it was only the head gasket alone,.. and not a liner dancing in the block if it ran 300k miles before letting go.!.
here is your future... read it carefully ...
info: https://rawze.com/forums/showthread.php?tid=4797&pid=41315#pid41315
RE: Popping Under acceleration - Phoenix6189 - 08-18-2026
(08-18-2026 )Rawze Wrote: To ensure it is not program related ...I'll look up how to backup ECM tonight.
Copy program from ecm and e-mail to to me for a review of what is in the ECU. For all anyone knows, it could be in need of software update, etc.
- Also, after backing up the ecu programming as is, re-flash it to latest factory software and run it around the block with the factory programming in it ans see if the issue clears up.
--------------------------------------
Mechanically, as far as the popping goes...
== If the overhead cam is not damaged / flaky and worn really REALLY badly then its not likely the cause.
== What wedge was used on the valve cam?. - You sure it was wedged right? and was not out 180-degrees?.
== It is all OEM turbo, manifolds, overhaul kit, head etc?.
== OEM injectors?.
== It it all matching components according to the engine ser#?
== What are the intake/exhaust valve clearances measuring at this point, now that is has a few miles of running on it?.
== Will it pass an injector leak test exactly as it shows in this video?..
info: https://rawze.com/forums/showthread.php?tid=8728&pid=75483#pid75483
== What is boost getting to in a hard pull // hard acceleration when its happening?.
... and .. what are you calling a popping?...
... a 'Chihht' ... 'Chihht' ... 'Chihht' ... sound?...
or a distinct, sharp ... "Pop" .. ... "Pop" .. ... "Pop" .. sound,?..
??? or something else?.
is it subtle?... or very loud?... etc?.
and is it every revolution of engine?.. every few revolutions on the r3egular/... or simply random?..
Cam looks fine. #6 Wedge, Wedged CAM and set insert pin on balancer. and Pin went in correctly.
Dumb question, is there 2 places on the cam the wedge will go in?
ALL Cummins parts in IN-FRAME, Turbo, injectors. Don't know for sure what they set the cylinder height to.
This time Cummins told me they only had a reman head available.
All parts came from Cummins for the Ser # everytime. Stopped going to the dealership after all i kept doing was go to Cummins anyways.
No miles on it. It started the popping under acceleration after I started it and let it get to temp.
Re checked Base Engine timing, and valve lash and they are spot on.
Did a fuel pressure leak down and it leaked around 900 psi. I'll rewatch the video and do it again tomorrow to make sure.
It's a pop-pop-pop, but its not consistent. Turbo pipe off not too loud, with pipe on its loud.
And it doesen't happen every revolution.
Lot of exhaust plum. Runs great at idle. I'll be taking a video of it tomorrow and see if I can get a more definitive answer.
And Crap Rawze, I had to check my Pants after your second comment.
RE: Popping Under acceleration - Rawze - 08-19-2026
(08-18-2026 )Phoenix6189 Wrote: ...
Cam looks fine. #6 Wedge, Wedged CAM and set insert pin on balancer. and Pin went in correctly.
Dumb question, is there 2 places on the cam the wedge will go in?
...
There kind-of is...
There is only one slot cut into the balancer that the pin fits into, but just by feel alone, I have seen where the pin seemingly drops in and somewhat locks in place, that is several degrees before that point.
- However, it will be in too far .. or not far enough, depending on where it lands... and I can easily see where this can fool someone into thinking its in the right place.
The giveaway is that the 'PIN' position on the crank shaft damper will not be aligned to the mark of the gear cover ... but the issue is also that the gear cover and/or crank shaft damper is sometimes not installed when someone is settings the overhead cam.
- After engine is all back together, and engine is fully at room temp again ... all someone has to do is rotate engine around by hand and insert the overhead cam wedge until its fully seated + rocking the crank gently, and then see if the crank is aligned with the 'PIN' position (every other rotation only) .. and that any play in the crank movement is even to the left,. end then the right of that center-pint mark while only the overhead cam is pinned.
... I have done this more than a few times over the years to find slipped cams, improper assembly, etc. of the front gear train, etc. - Have you done this test?>,, and how close was it from one side to the other?.. and how close, once pinned as well, because it only take a couple of degrees of error and things will be screwed up.
Here is more info on cam wedges and tricks for installing them where they will NOT slip, etc. Many mechanics get this wrong due to lack of proper training ... especially at the stealers$its...
https://rawze.com/forums/showthread.php?tid=6824&pid=60202#pid60202
RE: Popping Under acceleration - Rawze - 08-19-2026
== check to see if it does this with factory programming it it once you figure out how to make backup oif ecu...
backing up ecu info: https://rawze.com/forums/showthread.php?tid=8425&pid=72945#pid72945
== email me a copy of the program in there to get reviewed, for good measure, and to see if it needs updates, etc. applied to it.
== Also are the cam and crank position sensors new?.
== Will the engine run on only one cylinder at a time?>. exactly like mentioned here?.
info: https://rawze.com/forums/showthread.php?tid=7747&pid=67948#pid67948
== and has anyone done a proper inspection of the tone ring on the crank?> ... This, to ensure it is not damaged, and that it has ZERO play or wiggle to it?.. It is rare, but I have seen them come loose and/or get damaged slightly during other repair work, that can cause the type of issues that your describing.
related info: https://rawze.com/forums/showthread.php?tid=7754&pid=67992#pid67992