Cummins 2005 ISL low power AGAIN!

[Doug_E_]

What we thought was a sticking exhaust brake on our MH is now a, They don't know. The exhaust brake checked out good and functioning properly.
$515.67 later and Cummins West thinks it could be a faulty turbo.
We can start it up one time and we get full boost (35lbs.), stop for fuel and restart the engine and the boost will only go to (25 lbs.).
I asked if it could be an O2 sensor or an EGR valve, they don't think so.
Would just like it fixed so we can have the reliability back again.

Now they want to put it on the dyno and see if it will give low boost while it's hooked up to the dyno.

[Kidoo]

With all the sophisticated tool they have today, it is amazing how much money you have to throw at to get the troubles solved. I think cummins is a good engine, but their troubleshooting is a farce. With all the engines they have built, they should know all the basic problems and guide the shops a little better than they do. They just want to bank your money.

Shame on you Cummins.

[Doug_E_]

I thought I would up date the final out come on the low boost with black smoke from my ISL Cummins engine.
I was able to get the motorhome in to Diesel Technologies in Fresno CA. yesterday. They called this morning with the news my motorhome was repaired.

Diesel tech found it hard to believe I had taken the MH in to Cummins Pacific (formally Cummins West) 4 times and they hadn't caught the simple repair of the turbo pressure sensor switch.

Anyway the engine is running better than it has in some time and we are very happy campers.

A foot note: The repairs were less than half what I had been paying at Cummins Pacific for a no fix repair.

[Doug_E_]

Trust me when I say, that the ISL is low on horsepower when the problem occurs, Cummins says this particular engine boost should be between 35 - 37 pounds of boost. Cummins also has confirmed there is a problem with this engine, however they have said there is nothing on this engine that will limit the boost because the engine is not up to temperature. The very first time I took the MH to Cummins I had done a little research and asked if it might be the EGR valve, (a known problem), their service tech told me he didn't think it is the EGR valve. The last time I had the MH there, their mechanic stated in his report, the next step would be to check the EGR valve or the turbo. The turbo has been checked twice by them already. I have given up on Cummins Pacific and they have given up on me, and my MH. I have an appointment with a Diesel Tech company in Fresno, just needed to wait until the end of race season to get the MH to them.

[redguard]

Ivylog wrote:
Dang, not only do you double down ... you triple down. Maybe a higher compresson ratio?

ok whats the CR of your 400ISL verses a 2005 ISL or a 2007ISL

[Ivylog]

Dang, not only do you double down ... you triple down. Maybe a higher compresson ratio?

[redguard]

Ivylog wrote:
red guard since you will not believe me you might want to believe Smitty and welcome to the forms.
Also the Aladin system takes digital info from the engine's computer and displays it making it more accurate than any gauge. Comparing a CAPS system to a non ISC is valid as both do not have a variable vain turbo.
Even my 8.3 with a #10 fuel plate will only make 23 psi.

My ISC 350HP 2002 made 31 lbs stock with standard turbo and 39 lbs with a stronger actuater arm system.

The OP says his 2005 ISL 400 makes 35 lbs boost I don't see how you would ever make 400HP with 23 lbs boost? why does it take me 35-37 to get 425HP and you only 23lbs to make 400>?


also to note from my ltd research
It Makes no difference if it is a variable turbo, all the variable turbo does is to get 'on boost' earlier in the rev range and sustain boost at higher engine RPMs

[Ivylog]

red guard since you will not believe me you might want to believe Smitty and welcome to the forms.
Also the Aladin system takes digital info from the engine's computer and displays it making it more accurate than any gauge. Comparing a CAPS system to a non ISC is valid as both do not have a variable vain turbo.
Even my 8.3 with a #10 fuel plate will only make 23 psi.

[Smitty77]

steveownby wrote:

lfeather wrote:

Doug E. wrote:
Ifeather: I appreciate the fact that your 2002 ISL has never produced more than 23 lbs, of boost and that's plenty of power for you.

However when new my 2005 ISL produced 35 lbs. of boost and now it has less, almost no boost when trying to go from a dead stop.

The tech at Cummins West confirmed that it should be producing 35 lbs. of boost with the VGT turbo when working properly.
Thanks for your input though.

Doug

I understand and believe you, No offense intended. I'm just curious about the disparity? Maybe it's year-model?

It is year model. The first serious EPA requirements went into effect for over the road diesels in '04. In late '02 Cummins begin to introduce up dated engines to meet the standard. Between the end of '02 and Jan '04 Cummins put new fuel systems and VG turbos on most of their engines. Boost went up, temps went up MPG went down. It was the first of many requirements.
Larry

Know this is an old thread that was restarted, but also due to those that use 'search' to research items, I wanted to add some clarification on the cut over from CAPS era to Common Rail with VGT era for the ISL.

We have a 2004 model coach, built Sept of 2003. It has an ISL370 with a build of July 2003. It has the CAPS, with the non VGT turbo.

As stated by others, very seldom see 23PSI boost levels.

So easy to mislead people by accident when doing general statements like the ISC levels are xxx, or the ISL levels are xxx. On any subject, including turbo boost and different smog levels. As Cummins built ISB, ISC (not currently), ISL, ISM, ISX engines over several decades and iterations. Things do vary, so drilling down to the specific engine year and engine level (2003 for example had ISL370 and ISL400 levels, same variations in different years on ISC, ISM, etc.) is the only way to get specific help on an issue for your engine.

And note, not trying to preach or try to ding any posts in this thread. Just trying to point out what is obvious to many of us, but may not be so for newer DP owners.

And in all things Cummins, the best source is a call to Cummins Tech Support with our specific Serial Number, and they can look up specifics for that engine.

Best to all, be safe, have fun,
Smitty

[redguard]

Doug E. wrote:
Just a quick update. The low boost on this ISL Cummins engine is still happening. Cummins Pacific has now told me, they know there is a problem, but they do not know how to fix it, and they do not need my business any longer. I have now made an appointment with a local diesel shop, and they believe the problem is the GSR valve. Funny, this is what I had asked Cummins Pacific a long time ago, and they said they didn't think that the GSR valve was the problem.

what is the "GSR" valve
Thanks

[P_Kennedy]

Did at any point was your mh put on the dyno and run under load for power monitoring?

[redguard]

Ivylog wrote:

redguard wrote:

Ivylog wrote:
I have a 03 ISL and 23-24 is all it 's ever done. Plenty of power and I'm on the heavy side.

I believe you have more boost than you think>??

ISL 425HP has 35-37 lbs boost max

ISC 350HP Has 30-31 lbs Boost max

these are documented facts

My gauge does not go to 30 plus my Aladin which displays electronic data shows 100% power at 23psi. I 'll trust my Aladin system and 10 years of operation over your facts on a later ISL & ISC. I also have a 97 8.3 and 23-24 is all I get out of it too.
PS: fortunately I do not have a variable vain turbo.

If your ISL is a 370 or 400Hp its max boost is 32lb(max) so either your gauge readouts are wrong or your running about 3/4 possible horsepower
comparing an old manual 300HP 8.3 boost to a newer 2003 350HP is not
a fair comparison as those old 300/325 manual 8.3 were not any power house.I had a 1997 325 8.3 and it was suspect at best for power

[Doug_E_]

Just a quick update. The low boost on this ISL Cummins engine is still happening. Cummins Pacific has now told me, they know there is a problem, but they do not know how to fix it, and they do not need my business any longer. I have now made an appointment with a local diesel shop, and they believe the problem is the GSR valve. Funny, this is what I had asked Cummins Pacific a long time ago, and they said they didn't think that the GSR valve was the problem.

[Ivylog]

redguard wrote:

Ivylog wrote:
I have a 03 ISL and 23-24 is all it 's ever done. Plenty of power and I'm on the heavy side.

I believe you have more boost than you think>??

ISL 425HP has 35-37 lbs boost max

ISC 350HP Has 30-31 lbs Boost max

these are documented facts

My gauge does not go to 30 plus my Aladin which displays electronic data shows 100% power at 23psi. I 'll trust my Aladin system and 10 years of operation over your facts on a later ISL & ISC. I also have a 97 8.3 and 23-24 is all I get out of it too.
PS: fortunately I do not have a variable vain turbo.

[redguard]

redguard wrote:

JimM68 wrote:
Odd thread. My understanding has always been that ISC's will normally run 35 psi boost, but ISL's are between 25 and 30, mostly 25....

A ISC from the factory will NOT have 35 lbs boost It has around 29-31 MAX and ISL have as high as 37lbs

these figures are based on a 2002 350HP ISC and a 2008 IS 425HP