ISX 2350 485

[zare6]

(02-01-2017 )Rawze Wrote:  

(01-31-2017 )zare6 Wrote:  Hi anybody experiencing declining fuel economy with this engine? I have 200000 miles on it, boost goes to 38 psi runs great dynoed at 440 hp at the wheels, dpf filters are clean, started off at over 7 mpg now I'm down to 5.

A CM2350 has a higher compression ratio than older model engines. That engine can make 700+ HP with only 32-33 lbs of boost. It should be peaking about 32-lbs of boost or so max from factory.

I have test driven many that were factory stock, and it is not normal to have 38. - It is simply too high and it is over-boosting. This alone will make your fuel mileage and engine efficiency suffer/significantly lower. It will also set the engine up for more severe problems like detonation, liner issues, and a cracked head.

Perhaps someone put the wrong (or a bad) program in the ECM? -- OR perhaps you have some sensors reading incorrectly that is causing it.

Start with a thorough EGR tune-up, replace all the EGR sensors, etc. and find out why it is over-boosting.

Also check to ensure your Doser injector is not leaking.

Check that your decomp. tube is not partially clogged. -> http://rawze.com/forums/showthread.php?t...07#pid1807

Also, you should perform an injector leak test...

Hi thanks, the egr has been checked out, cummins had this engine on the dyno after they replaced the liners due to excessive oil consumption and they know what the boost is at, its been like that right from the first day I drove it. Ill look into the doser injector,

[Rawze]

(02-01-2017 )zare6 Wrote:  Hi thanks, the egr has been checked out, cummins had this engine on the dyno after they replaced the liners due to excessive oil consumption and they know what the boost is at, its been like that right from the first day I drove it. Ill look into the doser injector,

you can disagree with me all you want to, but 38-psi on a 2350 is too high boost.

[zare6]

I have never had a check engine light come on for anything, If my rail pressure is lower then normal I assume it would throw a code.

[zare6]

(02-01-2017 )Rawze Wrote:  

(02-01-2017 )zare6 Wrote:  Hi thanks, the egr has been checked out, cummins had this engine on the dyno after they replaced the liners due to excessive oil consumption and they know what the boost is at, its been like that right from the first day I drove it. Ill look into the doser injector,

you can disagree with me all you want to, but 38-psi on a 2350 is too high boost.

I'm not disputing that, my question is what causes it? Generally low boost is an issue , why wouldn't the mechanics at cummins notice that it was out of spec and like I said no codes.

[zare6]

One more thing as far as the ecm is concerned, I ordered this truck new so nobody touched the ecm, and I own 3 others with cats, the trucks work side by side and I monitor the fuel mileage daily, my cats used 40 to 50 litres a day more for the first 100000 miles or so, now the cummins is using 20 to 40 litres ( 5 to 10 gallons)

[zare6]

Id like to hear from others with this engine to see how high their boost is. Thanks

[Nilao]

That check engine light is just like an idiot light in a car. It never lights up till something has already failed. I hate them with a passion. If I buy a car that has no gauges, only lights, I install manual gushes so I can see when something changes. Oil pressure suddenly drops 10 psi? I can see that with a gauge and fix it. The oil pressure light never comes on till the pressure is so low it has already started doing damage. And as an ex-mechanic of light duty cats and trucks I can tell you first hand we never dig into a vehicle unless the customer has made a complaint. We did not get paid to look any farther than what you brought it in for. Now if there was an issue found while repairing the write up we notified the service manager and he decided whether or not to notify the customer. I can tell you first hand 99% of the time the customer was notified of an underlying issue they refused the repair because it wasn't causing their check engine light to turn on. Cummins builds decent engines so long as the builder cares but as you can see on the forum they come right from a certified cummins shop with bad counter bores, piston rings installed wrong, and in my case some of my valves were set to 0. Yes, 0. The valves were riding up against the rockers. These are not the engines of yesterday. The blocks have been made thinner and lighter to meet the demands for lower weight for more freight. They cannot take the abuse the old 3406 cats or n14 could. Rawze had tried to explain why 38 psi boost is too high. If you want to Inframe that sucker at 600k like I did you go right ahead and believe what cummins is spoon feeding you.

[zare6]

(02-01-2017 )Nilao Wrote:  That check engine light is just like an idiot light in a car. It never lights up till something has already failed. I hate them with a passion. If I buy a car that has no gauges, only lights, I install manual gushes so I can see when something changes. Oil pressure suddenly drops 10 psi? I can see that with a gauge and fix it. The oil pressure light never comes on till the pressure is so low it has already started doing damage. And as an ex-mechanic of light duty cats and trucks I can tell you first hand we never dig into a vehicle unless the customer has made a complaint. We did not get paid to look any farther than what you brought it in for. Now if there was an issue found while repairing the write up we notified the service manager and he decided whether or not to notify the customer. I can tell you first hand 99% of the time the customer was notified of an underlying issue they refused the repair because it wasn't causing their check engine light to turn on. Cummins builds decent engines so long as the builder cares but as you can see on the forum they come right from a certified cummins shop with bad counter bores, piston rings installed wrong, and in my case some of my valves were set to 0. Yes, 0. The valves were riding up against the rockers. These are not the engines of yesterday. The blocks have been made thinner and lighter to meet the demands for lower weight for more freight. They cannot take the abuse the old 3406 cats or n14 could. Rawze had tried to explain why 38 psi boost is too high. If you want to Inframe that sucker at 600k like I did you go right ahead and believe what cummins is spoon feeding you.

I get all that thanks, what I don't get is why its so high. Maybe someone can explain this vgt turbo and how it regulates overboost like the waste gate on my Cats.

[Starlight]

(02-01-2017 )zare6 Wrote:  

(02-01-2017 )Rawze Wrote:  

(01-31-2017 )zare6 Wrote:  Hi anybody experiencing declining fuel economy with this engine? I have 200000 miles on it, boost goes to 38 psi runs great dynoed at 440 hp at the wheels, dpf filters are clean, started off at over 7 mpg now I'm down to 5.

A CM2350 has a higher compression ratio than older model engines. That engine can make 700+ HP with only 32-33 lbs of boost. It should be peaking about 32-lbs of boost or so max from factory.

I have test driven many that were factory stock, and it is not normal to have 38. - It is simply too high and it is over-boosting. This alone will make your fuel mileage and engine efficiency suffer/significantly lower. It will also set the engine up for more severe problems like detonation, liner issues, and a cracked head.

Perhaps someone put the wrong (or a bad) program in the ECM? -- OR perhaps you have some sensors reading incorrectly that is causing it.

Start with a thorough EGR tune-up, replace all the EGR sensors, etc. and find out why it is over-boosting.

Also check to ensure your Doser injector is not leaking.

Check that your decomp. tube is not partially clogged. -> http://rawze.com/forums/showthread.php?t...07#pid1807

Also, you should perform an injector leak test...

Hi thanks, the egr has been checked out, cummins had this engine on the dyno after they replaced the liners due to excessive oil consumption and they know what the boost is at, its been like that right from the first day I drove it. Ill look into the doser injector,

Cummins only looks out for themselves.