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Infrequent boost and rpms problem
On a trip to Nashville then to Maine.Doing about 400 miles a day.First day
bus ran great for 200 miles then I started to a little holding back from engine speed almost like a brake to slow down then it would speed up.
also noticed when holding back tach would jump then come back.Thought maybe cruise control was not operating right.Started out today ran great for 150 miles started to do same thing for about 150 miles this time a watched the boost gauge and rpms .lt seems that when boost. Was on and high rpms it would both drop out then come back on.last 100miles today bus ran great.
is there something I can look at to see if lose wiring.
is this the turbo
anybody have this problem before
Never happens going down hill
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13 Replies
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How are your Fuel Filters?
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If the boost drops to 0 and then no power, it may be a bad turbo speed sensor.
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no or low boost =black rolling smoke out exhaust.(over fueling) You have a pre egr engine and that is good.
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Hi guys
how many miles to fuel filter change?previous owner was a mechanic said engine was serviced before I brought.put about 5000 miles on it since then.Also how does a turbo speed senser work?
thanks for your help
Jeff and Lindsay
91 Marathon XL -
From the fuel filter standpoint, it is entirely based on how clean your fuel is. There are Manufacturer recommended change intervals,but with bad fuel, starvation occurs rather quick. Since they are relatively easy to change, it’s a good idea to change them to rule out Fuel starving as a possible problem.
2000 Featherlite H3-45
2024 Jeep Grand Cherokee
Leesburg, FL -
Depends on how dirty the fuel is going thru it.
I don’t believe the DDEC I-III engines had a turbo speed sensor
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Easy way to tell if you have a turbo boost sensor is open curb side door for engine, now straight ahead of you is the air intake it runs the length of engine, close to the middle will be a little rectangle box with a couple of wires bolted to air intake that is your turbo boost sensor. It’s black probably 1.5 inches by 3 inches.
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Drove about 350 miles today .ran great for 200 miles had to idle past a accident on highway.soon as I got back to speed it started again for about 50 miles then cleared up and ran great.
crazy I think I will have fuel filters replaced and see what happens I would think that if filters were dirty that it would miss all the time?
going to look for turbo senser
thanks again
ps going to be in Nashville for 5 days so got time to check out
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No, not really on the fuel filter. Filters clog up gradually, and thus restrict the flow. Typically they show up under full load as the filter can’t supply enough fuel for the engine to run smoothly. As you get off of it, the flow requirements lessen and the miss clears up. Good idea to start with the fuel filter(s).
Turbo speed sensor would typically (not always) show up as excessive smoke from the exhaust.
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Hi,
I am sure curious what is causing your problem. We had similar symptoms and many on the forum pointed to fuel filters but it turned out to be our transmission torque converter. We would begin to lose power when accelerating, putting the engine under load, and experience a few hundred RPM drop. It was more like a surge that got progressively worse. We had to get the transmission overhauled as there was some damage. Mileage on the coach just under 200k. Using Synthetic transmission fluid. Hope it’s just your fuel filters. Let us know what you found.
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The likely is a turbo boost sensor because I had them on my coaches. But before I did anything I would see if the coach is showing any codes. It may be necessary to wait to read them when the problem occurs.
Do you get a check engine light?
I bought a used Nexiq reader off ebay for every coach I have owned and in every case what I paid ($500 to $1,000) was cheaper than letting a Detroit Dealer hook his up and begin the rape which was sure to follow. I bought all mine with software for the DDEC version I had.
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Have you checked your air filter? Might be “all filled up”.
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Nashville has an excellent Prevost service center as well as a company called Bus 4 Sale which has excellent Prevost service for a whole lot less. One of these facilites should be able to help you out as well.
2000 Featherlite H3-45
2024 Jeep Grand Cherokee
Leesburg, FL
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