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-   -   1999 Cummins ISM turbo boost psi??? (https://www.irv2.com/forums/f115/1999-cummins-ism-turbo-boost-psi-524568.html)

00zx6r 02-10-2021 09:56 PM

1999 Cummins ISM turbo boost psi???
 
Does anyone know the normal turbo boost range? I purchased 1999 H/R Navigator 70k miles Cummins ISM no EGR. I put in few thousand miles since purchased and have never seen the turbo boost passed 15 PSI. No codes, new air filter, new fuel filters, new coolant and trans coolant. The local shop checked found no leak in the CAC and proposed to replaced the turbo. Brand new turbo installed and the turbo boost still not passed 15psi.
I am towing 7k lbs trailer no problem on the flat but 35-40 mph up 6% hill, is this normal? This is my first diesel pusher, I used to own class C E450 for 15 years with same trailer weight and can do 6% hill in 45 mph. Also the diesel pusher has 4:30 in gear ratio.
Thanks!

okcnewbie 02-11-2021 07:09 AM

Not the same but I have a 400 ISL and I've only seen 23 boost.
I know with mine I have to manually down shift to get the rpm around 1900 or so for going up inclines. It's funny but my "cruise" is better at driving this thing than I am so far.
I have figured out that I can't just push the pedal. There's more to it or so it would seem.
I don't think I've really gone up a mountain yet though.

wolfe10 02-11-2021 07:11 AM

Call Cummins with your engine serial number to find out what boost PSI should be. If more than a few PSI lower, start looking for a leak in hoses or CAC.


Cummins 800-286-6467

bigjon42 02-11-2021 12:04 PM

I have a 99 monaco exec, ISM 450, and consistently get 30lbs boost pulling grades. Your boost is too low, could be fuel filter issue. I have seen this problem from others with pluged fuel filters. Good luck !

Outbound 02-11-2021 12:57 PM

My 500 ISM gets about 25 lbs max, thats 6% grade pulling car trailer.

Kurt Averill 02-11-2021 06:40 PM

My M11 450 gets to 28-30 depending on temp / altitude etc. after rebuilding the turbo and having the CAC re-cored. before the re-core got about 24 max. pulling a little over 10k in enclosed trailer....
Using a Silverleaf VMSPC - but the boost gauge agrees - the boost gauge is a manual gauge so you want to be sure the tubing is good no kinks or holes etc.

DieselDisco 02-11-2021 07:22 PM

It could be that POS gauge on the dash that I wouldnt trust at all (along with the temp gauge and oil pressure). My 01 ism500 showed 38psi when I first bought it but when I put an autometer gauge on it the real boost was 28-29psi which was also verified by the obd2 monitor that I have.

jcussen 02-11-2021 07:33 PM

Had a 99 ISM 450 and also saw about 28-30 pounds of boost.

TFarmer 02-13-2021 10:57 AM

Work the waste gate back and forth and see if it moves freely. It could be staying open a little causing the boost to excape out of the exhaust passage on the housing. I just went through all that. Mine was stuck shut and the pressure from the turbo not being directed out of the exhaust when letting off the throttle was being stopped in the CAC. (dead head pressure) It can only take so many hits and mine blew the top seam out of the CAC. This is bad! but after removing it from the R/V it got worse. The Hot air coming from blown seam on the CAC had made a hot spot on the radiator and it looked like it was gonna leak soon. So this little cast-iron valve can be VERY costly. I purchased mine from a deadbeat seller that knew this was a problem and wouldn't help with the repairs. But its mine and I had to find the problem and fix it correctly. I was getting $15k to 20k quotes. Make this part of your regular maintenance and work the valve several times and keep it oiled.

00zx6r 02-28-2021 12:59 PM

Update,
Contacted Cummins, provide the ESN but tech was not able to give the average turbo boost psi.
Dropped off the motorhome to friend of friend to get more help on the CAC could be leaking, after looked into it he found no leaking, bottom line is the turbo boost still low (less than 15 psi) and I am still feeling lost the power.
Next step, I will try to replace the turbo boost sensor.

twinboat 02-28-2021 04:25 PM

Have you checked the fuel line for a inline filter hidden along the chassis rail ?

Its more like a strainer but over time it does get plugged up.

No fuel, no boost.

Fu227 02-28-2021 06:23 PM

Quote:

Originally Posted by bigjon42 (Post 5631967)
I have a 99 monaco exec, ISM 450, and consistently get 30lbs boost pulling grades. Your boost is too low, could be fuel filter issue. I have seen this problem from others with pluged fuel filters. Good luck !

Same with mine...highest I've seen was 32 psi on the gauge and the road tec

twinboat 02-28-2021 07:00 PM

1 Attachment(s)
I just stole this picture from another post .

It shows the strainer I mentioned connected to the copper lines.

You may not have one but its worth a look.Attachment 319671

00zx6r 03-01-2021 09:02 AM

Quote:

Originally Posted by twinboat (Post 5654525)
I just stole this picture from another post .

It shows the strainer I mentioned connected to the copper lines.

You may not have one but its worth a look.Attachment 319671

Thanks twinboat - I will check it on my motorhome.


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