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Loosing turbo boost pressure ??????
I am on the road and my turbo boost pressure just stops working. I have pulled the over a couple times and restarted and it works again. Any help on what is causing this would be greatly appreciated.
David
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16 Replies
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What is the code from your information center?
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David like Tom said check your codes. I thought my turbo wasn’t working either and the code sent me to the rheostat on the throttle pedal. Put in a new one and back to normal.
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Check the codes, but I’d bet it’s your turbo pressure sensor wiring harness.
I fought the same issue, replaced the turbo pressure sensor just to find out it was the wiring harness. I used my ohm meter to determine there was a bad wire in the harness, called Detroit in Ocala and went up there to get it.
Took longer to diagnose than to replace once I had the part…
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Sorry for just now replying. We just now got home still with no Turbo. How do you read the codes above that some of you mentioned?? The check engine light comes on but does not stay on after initial start up.
David
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I too had to do a barametric pressure harness on my previous 02 Marathon.
Your codes will be in the information center on your telltale dash. Go to diagnostics. The procedure is in your Prevost manual.
Go here, it starts on section 4.3.
Have you not ever used the information center for trips, miles, fuel consumption, etc?
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I was looking for a code and none that I could find showed up on the dash nor on my Ipad that monitors all of the engine parameters. Do one of you guys have a part # for the harness they may be bad?
David
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Where is this wire harness located??
David
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The turbo speed sensor may be the issue. When they fail they usually start by being intermittent. You need to drive with the computer hooked up and when it goes to 0 do a snapshot. Review the graph and look at the turbo speed, it will probably show 0. When the computer sees no turbo speed it reduces the blade angle to 0, thus 0 boost. It can be changed easily on the coach, just do not spin the turbo while it is out.
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I do not believe that vintage of coach has variable blade pitch. I believe that was on EGR coaches.
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An 02 will be pre EGR as John pointed out.
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Tom,
That is great information you have there on the recall. I will contact Detroit this morning and see if my coach was ever taken care of. Also the part #s are listed if I have to change the parts. Thanks for now, I will post what I find.David
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So I make it to my home town on Monday afternoon. I stop at truck shop and had them look at things to see if something obvious is wrong. The one thing that they found was a fuel filter that really needed to be changed. The filter was changed but still no boost. I made it home and the coach sat until Thursday night. Thursday night I start th coach to head to Little Rock for an early appointment at United Engines. Once stared the check engine light came on. I was more worried about getting out of my neighbor hood with no boost then the light being on. To my amazement, I had boost all the way to Little Rock which is about 80 miles from my home. So that got me thinking, did a dirty fuel filter cause all of my troubles? After explaining what happened to the guys at United Engines, they all said that the filter could have caused my problem but just to make sure they highly recommended that we change the boost pressure switch on the side of the manifold, which they did. Any way after all of this, sure would be embarrassing to find out the dirty filter was the problem. P.S. The barometric pressure switch and harness had already been changed under a recall at some point.
David
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Hope that does it for you David, but as I posted above, mine had also been done previously and failed requiring a 2nd harness.
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A dirty fuel filter is unlikely to have an engine exhibit unpredictable power delivery. When a fuel filter is plugged fuel flow is restricted so under normal driving conditions the engine will operate OK. But when more power is required, such as a hill climb power will dimish, and sometimes the engine will buck and shake. When the road levels out and the flow of required fuel slows down the coach will again act normal.
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I had this same issue last year on my spring drive to the shop. No bucking, just low boost pulling onto the highway and on grades. It was 100% the fuel filter. Just clogged enough to run lean under high demand. Relieved it was an easy fix.
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