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bluegrassrv · 01-28-2014, 07:20 AM

Anyone have an idea what would cause this engine to hesitate? From idle, there really isn't any mid throttle. If you want to go, floor it, then wait about three seconds for the power to come on. Once it's rolling, things seem to be fine.

rver98 · 01-28-2014, 04:30 PM

Quote:

Originally Posted by bluegrassrv

Anyone have an idea what would cause this engine to hesitate? From idle, there really isn't any mid throttle. If you want to go, floor it, then wait about three seconds for the power to come on. Once it's rolling, things seem to be fine.

Fuel filters

slemnah · 01-29-2014, 08:59 AM

Fuel filters could certainly be a problem but there are other things to check. what does your boost look like? Is it flat on accel or does it slowly climb as the engine revs up? Are you getting smoke out the tailpipe on accel? How many miles on the coach? Do you know for sure that the transmission is starting out in first gear? These engines aren't known for lightning fast acceleration. Has it worsened over time?
Steve

OLYLEN · 01-29-2014, 09:02 AM

Agree fuel filters is the first and cheapest to check. And the symptoms sound good for the filters, higher power brings fuel flow up and then holds at lower power levels.

LEN

Steve Ownby · 01-29-2014, 09:46 AM

Quote:

Originally Posted by bluegrassrv

Anyone have an idea what would cause this engine to hesitate? From idle, there really isn't any mid throttle. If you want to go, floor it, then wait about three seconds for the power to come on. Once it's rolling, things seem to be fine.

Is this a new to you coach? Is this a change in performance? If new, this may be "turbo lag". The fact that once your rpms come up its fine suggests to me that it's not fuel filters. Even though you have a big engine you also have big weight. Your car probably has more than one hp per 10-20 pounds of vehicle weight. Your coach probably has 90-100 pounds of vehicle weight per one hp.

Diesels don't accelerate so much as they gather momentum. Momentum is a commodity you will learn to manage.

slemnah · 01-29-2014, 12:37 PM

Well said! It takes getting used to since there are only six speeds instead of 10-13 in a truck.

bluegrassrv · 01-30-2014, 09:23 AM

This is a coach I'm considering for purchase. I test drove it last Sunday. I didn't notice any excessive black smoke. I didn't even think to look at the boost gage. My first thought was turbo lag. It literally took at least three seconds, maybe more, to get any movement after flooring the accelerator. Once is started rolling it accelerated just fine. Well, I think just fine. It pulled as well as the Alegro Bus I drove with a 400 Cummins. The Tiffin is about 8,000lbs lighter.

The seller is going to run it through the service center and get back to me. I'm just trying to get some ideas for myself.

Almost forgot to mention, there is absolutely no change in rpm until after that three or more seconds.

slemnah · 01-30-2014, 07:08 PM

I have the 525 hp C13, it has a relatively smooth torque curve as I accelerate. You don't feel a lot of kick in the butt acceleration but if you look down you will see that you are gaining speed and shifting through the gears. I have around 40lbs of boost and it takes a little time to build up to that. These engines don't like rpm. Your maximum torque is around 1200-1300 rpm and max hp is around 1650rpm if I remember correctly. There is a lot of information from CAT that you can find online about power and torque and how to drive a CAT. Totally different than a Cummins engine in my opinion. Don't expect stellar fuel mileage though. Aladdin reading is around 5.5mpg for the life of my engine. I am looking into different ways of increasing the fuel mileage. I weigh around 49k so I am not sure it will ever get much better.
Steve

Steve Ownby · 01-30-2014, 07:30 PM

Quote:

Originally Posted by slemnah

I have the 525 hp C13, it has a relatively smooth torque curve as I accelerate. You don't feel a lot of kick in the butt acceleration but if you look down you will see that you are gaining speed and shifting through the gears. I have around 40lbs of boost and it takes a little time to build up to that. These engines don't like rpm. Your maximum torque is around 1200-1300 rpm and max hp is around 1650rpm if I remember correctly. There is a lot of information from CAT that you can find online about power and torque and how to drive a CAT. Totally different than a Cummins engine in my opinion. Don't expect stellar fuel mileage though. Aladdin reading is around 5.5mpg for the life of my engine. I am looking into different ways of increasing the fuel mileage. I weigh around 49k so I am not sure it will ever get much better. Steve

I wouldn't say the Cat drill is substantially different from Cummins. My Cummins ISM develops max torque at 1200 rpm and is virtually flat up to 1600. Max hp is at 1800 and the engine is governed to 2100. The Cummins uses one VG turbo where the Cat uses two turbos in series. This may cause some minor performances differences but nothing major. It remains true for both that max economy occurs down close to torque max and max climbing/cooling occurs up toward the hp max. All diesels are close to the same just variations due to size.

bluegrassrv · 01-31-2014, 08:49 AM

I just spoke to the dealer and the coach needed fuel and air filters. The fuels were about 50% and the air was plugged up substantially. I was told the road test was great, there's a response at the moment of input.

Thanks folks for your input.