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Chad1 · 04-09-2019, 09:45 PM

I have a 1995 Manoco Crown Royal Signature Series with a M11 Cummins and a 4060 Allison. It has 32,000 miles on it. It has been sitting outside in Florida for 10 years prior to me buying it last week. We put new tires, fluids and filters on it then started the 1500 mile journey home. Had a TCM failure in route but no other issues except I noticed its only producing between 12 and 15 psi of boost. Is this normal for a 1995 M11? Seems like it should be more but I'm not sure and can't find anything online to confirm or deny my suspicion.

jcussen · 04-09-2019, 10:02 PM

Think you should be seeing 28 or 29 psi but only on full throttle at certain rpm's. Might look at turbo or intercooler problems or connections.

Chad1 · 04-09-2019, 10:11 PM

That was what my intuition was telling me as well. I did look over the tubing and clamps and have not found any leaks. I'm thinking it could be a sensor or linkage sticking? Also I noticed the engine temp gauge never registered more than 150 degrees. Actually was always a notch or 2 below the 150 mark. I wonder if the temp is registering too low if the ecu reduces boost?

HJLowell · 04-09-2019, 10:17 PM

Congratulations on your purchas.
Enjoy.
Yes
My boost max is 29.5

I would let a cummins shop or a good trucker mechanic look at it soon and see what they think.

jcussen · 04-09-2019, 10:21 PM

Quote:

Originally Posted by Chad1

That was what my intuition was telling me as well. I did look over the tubing and clamps and have not found any leaks. I'm thinking it could be a sensor or linkage sticking? Also I noticed the engine temp gauge never registered more than 150 degrees. Actually was always a notch or 2 below the 150 mark. I wonder if the temp is registering too low if the ecu reduces boost?

Very possible. If your engine has a wastegate on turbo, good idea to check if is binding, but agree ecu will control fuel injection if all engine inputs are not in range.

tom chelbana · 04-10-2019, 10:06 AM

We had a ISM in a 04 Essex and the ECM said it had 32 psi at it's highest mark but when I added another gauge and had boost levels as high as 47 and 48. As others have stated it sounds like you have a leak in CAC system or waste gate problem.

Jeff753 · 04-10-2019, 06:38 PM

Cracked inter cooler? Is it a side radiator?

Chad1 · 04-10-2019, 10:43 PM

Thanks everyone, my instinct was correct as it appears I should have quite a bit more boost than I had on the trip home. I'm surprised at how well it ran and pulled itself especially up grades with 40 or 50% of the boost not coming to the road party. I will be excited to see how well it runs under full boost. It is getting an extreme RV makeover (not the tv show version unfortunately) in the coming week to 10 days and that issue is on the list. Thank you to those that responded, I truly appreciate it. Exited to be part of the forum.

jcussen · 04-10-2019, 11:03 PM

Quote:

Originally Posted by Chad1

Thanks everyone, my instinct was correct as it appears I should have quite a bit more boost than I had on the trip home. I'm surprised at how well it ran and pulled itself especially up grades with 40 or 50% of the boost not coming to the road party. I will be excited to see how well it runs under full boost. It is getting an extreme RV makeover (not the tv show version unfortunately) in the coming week to 10 days and that issue is on the list. Thank you to those that responded, I truly appreciate it. Exited to be part of the forum.

Bought a series 60 coach a couple of years ago that would only go to about 20 psi, still pretty good performance, but pulled the air intake to the turbo and found damage to the impeller blades. Replace turbo and coach was way quicker at 30 psi. Also found filter not sealed well, so problem was probably sucking dirty air that damaged the blades.