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Cummins ISM not reading boost correctly? - Printable Version

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RE: Cummins ISM not reading boost correctly? - Mikesuburban1 - 02-26-2017

(02-26-2017 )Waterloo Wrote:  Replace the Delta P sensor, that moisture you found should not be there, something is wrong. And have you pressure tested your CAC?

Another thing I would do, as I had many weird and wild electrical issues with my ProStar when I first purchased (used) and it was driving me batshit crazy... A mechanic at my local TA pointed out a bad ground when he installed a new alternator, it was all down hill from there...

Start at your battery box... Check your cables for bare wire, exposed bare copper wire, where there should be jacket covering them. Start at the battery box and follow the cabling to their ends, all of the cabling, including the grounds. I found my OEM factory cabling, with exposed copper, in one case there was ten inches of bare copper exposed to the elements! The same with the grounds, I about fell over when I saw what escaped the factory when I really inspected the undercarriage of my ProStar.

I wound up replacing over 100 feet of the stuff, it took me a couple of days and several hundreds of dollars to do this, I have never seen anything like what I found under my truck. After doing this, many of my issues went away, including the funky things my motor would do. It was driving all of my systems crazy, especially at the ECM as the power would spike and drop.

Not saying that is your issue, but it is something I would seriously consider checking out. If my truck came off the line like this, yours could have too, no matter what brand.

Thanks thats a good idea i will check that out tomorrow. Im trying to avoid bringing this truck to the shop i already have one truck down getting a inframe done


RE: Cummins ISM not reading boost correctly? - Waterloo - 02-26-2017

One other thing, check the power wire that runs from the battery box to the ECM. There is an inline fuse, I would replace that, as they do go bad over time, but will not actually blow. There is also on some a resistor or something like that, it escapes me right now... But it will be inline too, those sometimes go bad. This is a simple thing to check along with your cabling.


RE: Cummins ISM not reading boost correctly? - Mikesuburban1 - 02-26-2017

Another thing i noticed the coolent runs 190-200 and the oil 200-215 and this is running empty it never did this before and the coolent in the overflow bottle raises alot to the point it comes out of the cap alittle


RE: Cummins ISM not reading boost correctly? - Waterloo - 02-26-2017

Man, that sounds like a head issue... Been there... I would go get a block test kit from your local NAPA or auto parts store... Many guys poo poo these test kits, but it diagnosed mine in a matter of seconds. Not good, I nursed mine for a year, and then she was building so much pressure it blew out my radiator and my lines running to the Tri-Pac... The Tri-Pac episode was the end... She went in for the in frame a few weeks later. I think you are looking at a big bill here... If you have high miles, sounds like in frame time. If not, you may get away with a head replacement or just a new head gasket. If it is the head, just get a new OEM one, do not get a reman. I think you had a high heat episode, if you have an inline 5 reader and Insite, it will show up. If not, take it somewhere and pull up the ECM recordings to see. Sadly you need to be a mechanical engineer with these new trucks, as these shops are clueless.

You need a Pyro gauge if you do not have one...

I'm sorry to even have to tell you this, it sucks.

Rawze or one of the other guys will chime in with more info and other things to look at... Sad.


RE: Cummins ISM not reading boost correctly? - Mikesuburban1 - 02-26-2017

(02-26-2017 )Waterloo Wrote:  Man, that sounds like a head issue... Been there... I would go get a block test kit from your local NAPA or auto parts store... Many guys poo poo these test kits, but it diagnosed mine in a matter of seconds. Not good, I nursed mine for a year, and then she was building so much pressure it blew out my radiator and my lines running to the Tri-Pac... The Tri-Pac episode was the end... She went in for the in frame a few weeks later. I think you are looking at a big bill here... If you have high miles, sounds like in frame time. If not, you may get away with a head replacement or just a new head gasket. If it is the head, just get a new OEM one, do not get a reman. I think you had a high heat episode, if you have an inline 5 reader and Insite, it will show up. If not, take it somewhere and pull up the ECM recordings to see. Sadly you need to be a mechanical engineer with these new trucks, as these shops are clueless.

You need a Pyro gauge if you do not have one...

I'm sorry to even have to tell you this, it sucks.

Rawze or one of the other guys will chime in with more info and other things to look at... Sad.

The truck only has 200000 on it and the pyro never goes above 950


RE: Cummins ISM not reading boost correctly? - Waterloo - 02-26-2017

That is low miles, the pyro is at the edge, so you may just have a head gasket issue... I would lean towards a bad gasket, OR you have a stretched or lose head bolt. I would pop the top and check the torque of the bolts holding the head to the block. If one has worked its way lose, and this has been an issue on the ISX, you may get lucky. I would go there first, re torque the head bolts. I do not know the torque specs, but that should be easy info to get. I think you dodged a bullet here. ;-)

Side note, the head bolts are one time use, as they stretch. If it is a lose head bolt, I would replace and if me, pull the head, replace the gasket and install new bolts. Not a huge job, if you have a way to pull the head, they are not light.


RE: Cummins ISM not reading boost correctly? - Mikesuburban1 - 02-26-2017

(02-26-2017 )Waterloo Wrote:  That is low miles, the pyro is at the edge, so you may just have a head gasket issue... I would lean towards a bad gasket, OR you have a stretched or lose head bolt. I would pop the top and check the torque of the bolts holding the head to the block. If one has worked its way lose, and this has been an issue on the ISX, you may get lucky. I would go there first, re torque the head bolts. I do not know the torque specs, but that should be easy info to get. I think you dodged a bullet here. ;-)

Side note, the head bolts are one time use, as they stretch. If it is a lose head bolt, I would replace and if me, pull the head, replace the gasket and install new bolts. Not a huge job, if you have a way to pull the head, they are not light.

Wouldnt i be loosing coolent if it was a head gasket and how would that relate to my boost problem with it spiking?


RE: Cummins ISM not reading boost correctly? - Waterloo - 02-26-2017

(02-26-2017 )Mikesuburban1 Wrote:  
(02-26-2017 )Waterloo Wrote:  That is low miles, the pyro is at the edge, so you may just have a head gasket issue... I would lean towards a bad gasket, OR you have a stretched or lose head bolt. I would pop the top and check the torque of the bolts holding the head to the block. If one has worked its way lose, and this has been an issue on the ISX, you may get lucky. I would go there first, re torque the head bolts. I do not know the torque specs, but that should be easy info to get. I think you dodged a bullet here. ;-)

Side note, the head bolts are one time use, as they stretch. If it is a lose head bolt, I would replace and if me, pull the head, replace the gasket and install new bolts. Not a huge job, if you have a way to pull the head, they are not light.

Wouldnt i be loosing coolent if it was a head gasket and how would that relate to my boost problem with it spiking?

You would not necessarily lose coolant with a bad head gasket, but when you said the coolant jug was building pressure, that is usually a sign of a bad head or gasket. That is why I suggested a block test kit to see if you have exhaust gas in your coolant system. When my head failed, I had no coolant loss, other than what was passed through my hose clamps, and eventually my coolant jug. I routinely pull oil samples and had it tested. I never had coolant in my oil, but boy did I have exhaust gas in my coolant system. It built so much pressure that it actually blew my radiator apart sitting at the dock at the GM plant here in Lansing where they build the Camaro... This was a year ago, and the guys on the dock still chide me on that.

Another place to check is your air compressor, sometimes those will leak into your coolant system, at least on an ISX.

Your other issues are not related.


RE: Cummins ISM not reading boost correctly? - Mikesuburban1 - 02-26-2017

(02-26-2017 )Waterloo Wrote:  
(02-26-2017 )Mikesuburban1 Wrote:  
(02-26-2017 )Waterloo Wrote:  That is low miles, the pyro is at the edge, so you may just have a head gasket issue... I would lean towards a bad gasket, OR you have a stretched or lose head bolt. I would pop the top and check the torque of the bolts holding the head to the block. If one has worked its way lose, and this has been an issue on the ISX, you may get lucky. I would go there first, re torque the head bolts. I do not know the torque specs, but that should be easy info to get. I think you dodged a bullet here. ;-)

Side note, the head bolts are one time use, as they stretch. If it is a lose head bolt, I would replace and if me, pull the head, replace the gasket and install new bolts. Not a huge job, if you have a way to pull the head, they are not light.

Wouldnt i be loosing coolent if it was a head gasket and how would that relate to my boost problem with it spiking?

You would not necessarily lose coolant with a bad head gasket, but when you said the coolant jug was building pressure, that is usually a sign of a bad head or gasket. That is why I suggested a block test kit to see if you have exhaust gas in your coolant system. When my head failed, I had no coolant loss, other than what was passed through my hose clamps, and eventually my coolant jug. I routinely pull oil samples and had it tested. I never had coolant in my oil, but boy did I have exhaust gas in my coolant system. It built so much pressure that it actually blew my radiator apart sitting at the dock at the GM plant here in Lansing where they build the Camaro... This was a year ago, and the guys on the dock still chide me on that.

Another place to check is your air compressor, sometimes those will leak into your coolant system, at least on an ISX.

Your other issues are not related.

Im going to test it tomorrow i hope its not a head gasket that would suck.