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Jackie Dempsey
Jackie Dempsey,
Category: Medium and Heavy Trucks
Satisfied Customers: 22
Experience:  Diesel Technician at Cummins Pacific
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I have a isl g cog and have multiple miss fires

Customer Question

I have a isl g cog and have multiple miss fires
Submitted: 9 months ago.
Category: Medium and Heavy Trucks
Expert:  Jackie Dempsey replied 9 months ago.
Hello! Thank you for choosing Just Answer, my name is ***** ***** I will be glad to assist you with this issue. A couple question to begin: Are there any fault codes present? Have you checked each coil to ensure there is not a shorted one? In my experience with the ISLG engines they are very touchy, if you do not torque each spark plug to its specific torque (20ftlbs) that is a possibility for a misfire. I know that sounds silly but I have seen it happen.
Expert:  Jackie Dempsey replied 9 months ago.
In my experience, 9 out of 10 times with these engines the misfire is caused by fouled plugs or a bad coil. There is of course possibility for harness damage however not likely. You can switch around the coils to see if the cylinder misfiring changes with the coil. If you find that it does, then theres your culprit ;)I am also curious if there is any smoke accompanied with the misfire? These engines are known for the number 1 cylinder to crack. A cracked piston would of course cause alot more of an issue than a misfire however if there is white smoke that could be a factor. Just a thought! I have rebuilt and dealt with these guys since they were released. I work for a Cummins distributor so I see the front lines of what these engines come in for the most.
Customer: replied 9 months ago.
It has a #2 cylinder mis I need to check compression on that cylinder and I have replaced the oil on #2 cylinder but I show all cylinders mis firing some codes are 2594,2534,2536,2533,
Expert:  Jackie Dempsey replied 9 months ago.
Thank you for that information, have you verified that the ECM calibration is up to date?
Customer: replied 9 months ago.
No I haven't why would that be an issue ,just a question.. Do you work at cummins in Rialto with Leroy and them?
Expert:  Jackie Dempsey replied 9 months ago.
I am trying to think outside the box pertaining to the issue, I have seen instances where there was an out of date revision per the calibration and once updated the misfires went away. It is not common for the calibration to be the fix but I have seen it. I am also not recommending to just re calibrate it to fix it, however checking the ecm calibration couldn't hurt. I can walk you thru it if needed. I do not work at Cummins Rialto. Is there any smoke present? Or any other symptoms accompanied to the misfire?
Customer: replied 9 months ago.
No smoke .it says #1,2,3,4,5,6 mis fire and I am was wondering y I have error on the status mis fire so I did swap out the icm but it was still there.
Customer: replied 9 months ago.
Will one mis fire cause all of them to mis fire?
Expert:  Jackie Dempsey replied 9 months ago.
If the harness is shorted out in the right spot yes, but one faulty coil will not. Did it begin only with cylinder 2 or did it spring up with all of them at once? Why are you partial to #2? Just curious
Customer: replied 9 months ago.
Because #2 is missing for sure ...I swapped a new coil out but didn't have a plug to put in . I need to check compression in that cylinder. But with cummins insite it shows stop engine and all cylinders are mis firing on mis fires.
Expert:  Jackie Dempsey replied 9 months ago.
All plugs were done 5,000 ago? Cummins plugs correct? Nothing aftermarket? Make sure also that all of the connectors for the coils are alright. If one is missing a pin or dirty etc that could be a factor as well. Compression should be checked I agree, my best advice would be to: ***** ***** plugs are good and even swap em all out if possible see if that clears it up, make sure they are all torqued to spec and use only Cummins plugsEnsure that all coils are functional by swapping them around with the new one, I highly doubt that all coils failed at once but hey engines do strange things sometimes! Verify there is no misfire or ignition related revision for the calibration Cylinder 2 wont cause them all to misfire but if theres an electrical issue starting with 2 then it is possible. But lack of compression there wont cause it across the board
Expert:  Jackie Dempsey replied 9 months ago.
I hope that I have been able to assist you with your request, if you have any further questions please don't hesitate to ask! When you are ready please take a moment to rate my service on this matter. Have a great day!
Customer: replied 9 months ago.
What should compression be on the cng engine
Expert:  Jackie Dempsey replied 9 months ago.
I apologize for the delayed response I had not checked my email for a bit. I am not sure on the exact reading however I can guide you through how to find it in Cummins Quickserve online if you would like
Expert:  Jackie Dempsey replied 9 months ago.
Hello! Just wanted to check in and see if the issue has been resolved? If you require additional assistance please let me know, I am happy to help! If everything has been resolved please take a moment to rate my services for this question. Have a great weekend!

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