ISX 12 spooling at idle
08-03-2021, (Subject: ISX 12 spooling at idle ) 
Post: #1
ISX 12 spooling at idle
Hey guys, new to the Forum.

I have an ISX12 CM2250 that will spool up to 5-10psi at idle for a few seconds and then go away. Happens frequently, about every 10 seconds. I unplugged the EGR valve and then it idles smoothly. I replaced the Delta P sensor and cleaned the ports but no difference. I compared EGR readings to a sister truck and nothing stood out to me. Where should I be looking next?
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08-03-2021, (Subject: ISX 12 spooling at idle ) 
Post: #2
RE: ISX 12 spooling at idle
Do you have Insite? Pull up Data Monitor and watch different params. See what, if anything changes at the same time. Simply unplugging the EGR doesn't really narrow it down, although a full EGR Tune-up would probably be a good place to start. Clean out everything, including the EGR valve. While it's off gently and carefully check the spring loaded butterfly valve. Watch your fingers, but make sure it can open with some pressure and will spring back to closed after. Don't try to force it if it doesn't want to move, mainly because you don't want to get hurt.

The turbo is used for multiple applications on these emissions trucks. From SCR warmup to DPF regens to Jake brake to counter balancing the EGR gas pressure to plain old making power. If you watch the "Aftertreatment Operating Mode" (or something like that) in Data Monitor when these spool ups occur then you'd see if they correspond with an aftertreatment function.

Could also be spikes in sensor readings that the engine is reacting to. How's you IMAP sensor? NOx sensors? SCR temperature reading? and others? Data monitor is good for watching these values for abnormal or erroneous readings or even just patterns that might give clues.

Rawze might have something more precise to point toward.

if you don't have Insite then you should get and Inline 6 Adaptor and a copy of Insite 7.6 as it's your first go-to for diagnosing engine/aftertreatment related issues.


User's Signature: I try to keep it simple, but as is usually the case, my word count rivals that of Dickens.
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 Thanks given by: Running rough , Rawze , Techmech
08-03-2021, (Subject: ISX 12 spooling at idle ) 
Post: #3
RE: ISX 12 spooling at idle
(08-03-2021 )lwilder27 Wrote:  Hey guys, new to the Forum.

I have an ISX12 CM2250 that will spool up to 5-10psi at idle for a few seconds and then go away. Happens frequently, about every 10 seconds. I unplugged the EGR valve and then it idles smoothly. I replaced the Delta P sensor and cleaned the ports but no difference. I compared EGR readings to a sister truck and nothing stood out to me. Where should I be looking next?

Not sure if it is relevant but I had a simular issue on a CM871. It was a real anoyance when reversing on to a dock.

The exhaust pressure sensor tube was blocked.

As mentioned, Insite is your friend.
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 Thanks given by: Rawze , Techmech
08-04-2021, (Subject: ISX 12 spooling at idle ) 
Post: #4
RE: ISX 12 spooling at idle
^^^^^^^^ what he said^^^^^^^^ watch exhaust pressure in insite.


User's Signature: Warranty??? Yeah right, I am the warranty!!!
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08-04-2021, (Subject: ISX 12 spooling at idle ) 
Post: #5
RE: ISX 12 spooling at idle
Yes, I have insite. I was reading some similar threads and ordered the IMAP and exhaust pressure sensors but ill have to check the pressure tube. They really stuff these things into the small freightliner engine bay so i'll have to schedule having the truck for a day to get to it. What is a typical exhaust pressure reading at idle?

I watched sensor readings on insite and didnt see anything that stood out but I did not include NOX sensors and SCR temps ect. I will get it in here and monitor those as well.
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08-23-2021, (Subject: ISX 12 spooling at idle ) 
Post: #6
RE: ISX 12 spooling at idle
I got this truck in and found the exhaust pressure sensing tube on the back of the manifold is plugged. Once I got in there I noticed a manifold leak as well so ill be pulling everything apart and doing an EGR tune up while im in there.

Thanks for the information.
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 Thanks given by: Rawze , JimT
09-09-2021, (Subject: ISX 12 spooling at idle ) 
Post: #7
RE: ISX 12 spooling at idle
I was sent this persons file today. Its a bad delete for sure. Here are the highlights of what is wrong with the program at a glance ...


* No proper engine mode control has been done. This will make the turbo and engine get stuck in SCR warm-up mode perpetually and over-spooling the turbo all the time.

* Instead of shutting things off properly, all they did was add a whole ton of fault codes into the suppression tables... the ECM is screaming about a dozen faults but it cannot display them.

* ALL of the EGr gas request tables are still demanding EGR gas into the intake. None of this has been shut off properly... and this heavily effects the combustion process in negative ways.

* Some complete moron has KILLED the power and torque tables. It is still 1650 ft.lbs and 430HP.. BUT like some kind of complete IDIOT!!>>> they removed the 430HP above 1700 RPM's. I have never seen anyone do this?.. what were they thinking?... the ISX LIKES HIGH RPM POWER>>> NOT LESS POWER!... so unless someone drives this truck at exactly betweeen 1600-1700 RPM range all the time ... this truck will never make its correct power. Someone had to have been smokin' some whacky-weed or somthin' to come up with that s$it-Show of a power/torque curve.

* There was no re-programming of the turbo at all for non-egr and non-emissions operations.. This program will make the turbo eat itself alive wityh over-boosting and over-spooling problems... oh wait.... THEY BLOCKED ALL THE CODES FROM SHOWING UP.. SO THE TRUCK OWNER WILL NOT SEE IT AND JUST WONDER LIKE A FOOL why the turbo goes bad every so often.. WHAT a S$it SHOW!

* ALL of the auxilliary emissions is still active. This means the engine will fight itself nonstop and try to make up for the fact that the DPF is missing.

* Someone has jacked the injection timing out past the safe zones.. and into the realm of it wanting to crack a piston.. Typical of someone who is beyond clueless on how these modern diesel engines work.

-- There are many many more problems with this complete garbage, half-backed, jail-break trash of a program... The only thing saving this engine from destruction is the fact that it is turned down to 430HP and 1650 trq (and far less power levels above and below the 1600-1700 rpm range).

I hope no one paid any money for this crap.. because they got completely ripped OFF!.

Welcome to the bad delete club.

==========

if the program is that half-arssed... then the next concern should be if they bothered to deal with all the hardware correctly or no.. I am thinking NOT.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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 Thanks given by: Techmech
09-11-2021, (Subject: ISX 12 spooling at idle ) 
Post: #8
RE: ISX 12 spooling at idle
(09-09-2021 )Rawze Wrote:  * Someone has jacked the injection timing out past the safe zones.. and into the realm of it wanting to crack a piston.. Typical of someone who is beyond clueless on how these modern diesel engines work.

What degree were the injectors set to fire under full load?
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09-11-2021, (Subject: ISX 12 spooling at idle ) 
Post: #9
RE: ISX 12 spooling at idle
(09-11-2021 )Smiling lemon Wrote:  
(09-09-2021 )Rawze Wrote:  * Someone has jacked the injection timing out past the safe zones.. and into the realm of it wanting to crack a piston.. Typical of someone who is beyond clueless on how these modern diesel engines work.

What degree were the injectors set to fire under full load?

(looked at his file briefly again to verify)...
Only looking at the abnormally created 1600-1700 rpm range (the only place it will make full power because of bad torque maps)...

The Main injection cycle was more than +7 BTDC (enough to cause engine damage after a year or 3) to as much as +14BTDC depending on what engine modes it was jumping in and out of This is even before considering any high altitude modes .. which are advanced even further.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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