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Silver84 · 10-10-2015, 02:58 PM

New manifold and fitted plump were installed.
Loss of power was immediately noted.
On long hills by the time you get 1/2 way up, I am down to 40 miles per hour, and won't accelerate at all.
Dealer said wastegate was stuck 1/2 way, freed it up but the problem is still there.

abarkl · 10-10-2015, 03:00 PM

When is the last time the fuel filters were changed?

Silver84 · 10-10-2015, 04:15 PM

Filters changed 1 week ago. Full service

Steve Ownby · 10-10-2015, 04:19 PM

Quote:

Originally Posted by Silver84

New manifold and fitted plump were installed.

Loss of power was immediately noted.

On long hills by the time you get 1/2 way up, I am down to 40 miles per hour, and won't accelerate at all.

Dealer said wastegate was stuck 1/2 way, freed it up but the problem is still there.

Look at your boost. Check the silicone connectors in the plumbing from the turbo to CAC and CAC to intake.

Steve Ownby
Full time since '07

96 Wideglide · 10-10-2015, 04:23 PM

Are you gearing down to keep your RPM's up close to 2000?

Silver84 · 10-10-2015, 04:54 PM

Steve',,,,, don't have meter to check boost, fittings tight
96 ,,,,,, Changing gearing does not help at all

Silver84 · 10-10-2015, 04:58 PM

How can I observe that vacuum controll is working properly?

luvlabs · 10-11-2015, 07:29 AM

Long hill, speed dropping to 40 mph, sounds completely normal. I don't believe you have anything wrong as your ISL is not going to push your 30,000+ pounds over the hill at 60 mph unless it is a very small grade.

Your exhaust brake is not sticking, you have new fuel filters, you have downshifted and are keeping your RPMS at 2000 +/-, you have no leaks on the intake side of things, your air filter has been changed????? It's about the last thing you can do if you haven't already changed it but if this is a standard 5-6% grade that is common out west, performance seems pretty normal.

stik · 10-11-2015, 08:09 AM

Quote:

Originally Posted by luvlabs

Long hill, speed dropping to 40 mph, sounds completely normal. I don't believe you have anything wrong as your ISL is not going to push your 30,000+ pounds over the hill at 60 mph unless it is a very small grade.

Your exhaust brake is not sticking, you have new fuel filters, you have downshifted and are keeping your RPMS at 2000 +/-, you have no leaks on the intake side of things, your air filter has been changed????? It's about the last thing you can do if you haven't already changed it but if this is a standard 5-6% grade that is common out west, performance seems pretty normal.

Concur with above. The OP is rather vague; what is "loss of power?"

If it is just slowly dropping down to 40 on a 5-6% grade, then yep, it IS normal.

If it is climbing a familiar and often traveled hill that would normally not show any significant loss of speed, then it deserves looking into.

Good luck to the OP, hope he's not chasing is tail!

DDDonkey · 10-11-2015, 08:17 AM

If you feel that your still having problems take it to a shop that has the cummins software (OEM) and a dyno to have it checked. They will check for codes, possibly a cylinder cutout test, and then run it on the dyno to confirm the engines HP and Torque. Depending on the shop they may be able to check the trans for codes and issues also. Good luck!

Gary RVRoamer · 10-11-2015, 09:36 AM

Agree - may well be "normal". Depending on the weight of the coach and steepness of the grade. These coaches have nowhere near the same power/weight ratio as our cars & SUVs. The coach likely has only 1 hp per 100 lbs, whereas nearly all cars are in the range of 1 hp per 20 lbs. Or even 1 per 15 lbs. It ain't gonna race up that hill!

A long, 5-6% grade will get my 37,600 lb rig down to 40 (or less) as well. Can only do so much with 370 hp.

FreedomDream · 10-11-2015, 10:01 AM

Take it to Cummins certified service center who can check turbo boost, read codes and check over all performance. Make sure you tell them about the manifold work you had done and who did the work. They may nee to check to see if correct part was installed. Good luck.

Rich-n-Linda · 10-11-2015, 10:56 AM

I have the 400 hp ISL in a 34,000 pound coach. I routinely run 5 and 6% interstate grades in 5th gear at 65 mph and 2,000 RPM.

40 mph is way too slow. Something IS wrong.

BLK-9 · 10-11-2015, 12:16 PM

Just another thought - wondering if the transmission fluid/filter was checked; otherwise, that 400 should be pushing up a 5-6% grade better than 40 mph. Agree - i think you need to take this into Cummins and hook-up the diagnostics. Something does not appear right here with the OEM settings.