Slow acceleration

[ken&ellen]

Most of my trips have involved interstate routes with highway speeds,but this last trip to New York involved stop and go traffic on Rt 13 through Virginia, Maryland, & Delaware. In many cases I would have to stop at another signal prior to reaching 40 MPH. I was towing my Jeep Liberty and did not have any problems maintaining 65+ MPH on the Jersey Turnpike nor the NY State Thruway. To use drag strip terminology it seems slow out of the hole! My '91 Liberty has the 8v92 DD and the Allison 4 speed, which were serviced within the last 3000 miles. All gauges were in the green, air filter is clean, oil level was right on, tire pressure was good, and fuel milage was in the 5 mpg range. Maybe it is too much to expect, but it seem as though I should be accelerating quicker. Your thoughts....ole wise POG members. Ken

[Ben]

Clogged fuel filters could be a cause. All it takes a one tank of bad fuel. That's why some people never fill up when a fuel truck is at the station since filling the station's tanks can kick up all the gunk that is at the bottom of the tanks and allow you to pump some of it into your coach's tank.

[Chris and Debbie Yates]

My 95 Royale also has an 8v92 and I find the turbo comes onstream much slower if I am running the busair, this obviously makes the bus slow off the line but it doesn't seem to make too much difference at highway speeds.
Just my 10 cents worth.

Cheers,

Chris

[Joe Cannarozzi]

Try running the dash blower fan on a higher speed, it will make you think you are going faster! Or get somebody else to drive and enjoy, at the rear. I got a feeling your bus runs fine. As they say, it is what it is.

[Jon Wehrenberg]

K and E,

There are some simple things you can check quickly. Do you get full turbo boost when the engine is running above about 1500 and you floor it? If not, or if it is slow coming up look carefully around the manifolds and the inlets to the turbo for leaks, cracks, bad gaskets, etc. Sooting is the thing to look for.

If that is OK, you are dealing with "density altitude" issues. As the summer air heats up, it is less dense, and is the equivalent of operating the bus at a higher altitude. If the bus is sluggish until about 1500 and then gets responsive your engine is probably OK, it just thinks it is operating at 4000 feet or more.

You should have know that, right? Or don't Mooneys have those issues.

[Ray Davis]

It's interesting you mention that. When I was in Salt Lake City, before the air conditioning meltdown, the bus felt very sluggish when accellerating from a dead stop. I thought at the time perhaps it's altitude, as SLC is up in the 5000 foot area.

[ken&ellen]

Jon, Jon, Jon, Density altitude effects all aircraft. My Mooney had a Ram Air system above 5000 ft, but that did not help with take off issues during the dog daze of summer. I am sure that Jerry will say his Doc Killer does not suffer the effects of density altitude, but to some extent all lose some performance. It is a very good point; however since the trip home was in 90 degree heat with very high humidity. Thanks for your insight. Ken

[Jon Wehrenberg]

You shouldn't have tweaked Winchester. Now he will wake up and want to respond about your accurate description of his flying machine.

Do check for exhaust leaks however, but I suspect it is an air density issue.

[rfoster]

Jon: Glad to see on the board again- The high temps have an adverse impact on the performance - My mpg fell off on my last run to Nashville (600 miles round trip) at 100 degrees from 7.82 to 7.37 mpg. Do you think the temps are the problem, I have looked at everything from tire pressure, wheel bearings, brake drag, air cleaner, fuel filter, etc that I can think of. I did run the OTR air all the way. No good answer other than diesel fuel cost more now and am enjoying it less.

Bling the crap out of em Jon!

[Jon Wehrenberg]

Roger,

Your MPG should improve in the summer and decline in the winter. It is just the way things are because the winter air being more dense will require more fuel. The pilots on this forum can look at the performance charts and see clearly that this is the case.

But do not forget other factors. Are you towing? Are you running in more hilly terrain? Do you have a headwind or tailwind? Is your speed the same? Did you get some biodiesel?

I reset my DD Pro Driver at every oil change so the mileage is spread over a 5000 mile range. That tends to average out minor trip variations. I am now averaging 8.3 on this last 1400 miles (to OSH), but I did not tow, so I expect when I do tow, I will pull it down. If we go to FL via Atlanta and we don't go through the mountains I see about a .5 MPG difference from when we run through the mountains.

I think your range is normal.