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visionman

04 Vision Turbo Trouble

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Have two 04 visions with the 460 and are havingturbo issues. The one unit is dropping boost pressure to the engine. We have changed the turbo speed sensor twice and are still loosing boost. One mechanic sugested that the turbo shaft is "floating" and maybe the sensor can't pick up the signal. Is this possible or do we need to be looking at something else?

The second unit has air system problems with the drier blowing off every 20 seconds. This happens on and off, good for half a day then does it for a day etc. We recently changed the compressor, drier and govenor and have had the problem ever since. We have installed a second govenor and changed some lines to it. Don't think there are any leaks to be concerned about. A mechanic is wondering if we are loosing air at the turbo somewhere that is triggering the govenor. No visible air pressure drop is seen on the gauges, yet the compressor still kicks in. Any ideas or info that may help would be great. Would like to make sure we are certain of a few things before we get to changing these expensive turbo's.

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Is the boost pressure drop intermittent or continuous? Has the after cooler and other intake plumbing down stream been checked for leaks? Bosst pressure is not measured by turbo speed, but rater and air pressure sensor.

The air system for the brakes might have the air compressor plumbed into the intake system. Not sure what compressor is used. But the constant purging is not related to intake plumbing. You sure the compressor, dryer and governor were in fact changed out for new units? A bad Dryer purge valve, governor or leak would be responsible for the purges. Does it only happen when running down the road or will it constantly purge when stopped? The truck most likely has air suspension so that might be a first place to look. What dryer does it have?

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On the turbo boost drop problem , check the boost pressure relief valve thats screwed into the intake manifold elbow. Its the valve that has a pipe that comes off of it and goes into the exhaust pipe behind the turbo. We have seen alot of those go bad on the 2004's. the spring wears through the end of the valve. The came out with a new version part#691GC318C

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Have two 04 visions with the 460 and are havingturbo issues. The one unit is dropping boost pressure to the engine. We have changed the turbo speed sensor twice and are still loosing boost. One mechanic sugested that the turbo shaft is "floating" and maybe the sensor can't pick up the signal. Is this possible or do we need to be looking at something else?

The second unit has air system problems with the drier blowing off every 20 seconds. This happens on and off, good for half a day then does it for a day etc. We recently changed the compressor, drier and govenor and have had the problem ever since. We have installed a second govenor and changed some lines to it. Don't think there are any leaks to be concerned about. A mechanic is wondering if we are loosing air at the turbo somewhere that is triggering the govenor. No visible air pressure drop is seen on the gauges, yet the compressor still kicks in. Any ideas or info that may help would be great. Would like to make sure we are certain of a few things before we get to changing these expensive turbo's.

boost pressure drop is intermittent, don't know why intake plumbing would affect pressure side of the turbo. The code that shows up is always the turbo speed sensor.

All components were in fact changed out. We have tried a second govenor, maybe we should try a new purge valve on the AD9 drier. It will blow off steady going down the road or sitting still, then it will work properly for a day. Can't figure out why it doesn't do it all the time.

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The only time we see "turbo wheel speed code" 6-2 is if the wire on the sensor is rubbed and shorting out or the impeller shaft bearings in the turbo are going out and the shaft is moving away from the sensor. Are you sure its 6-2 code and not an 4-5 code(turbo actuator)? If your turbo part# starts with a 631GC5176**** then you have one of the newer style turbos on there. If the part# is a 631GC5171**** then its a wonder it hasn't went out already. If the truck had the old style(5171 series) turbo on it when it was new and someone changed it to the newer style (5176 series) and didnt do the software update in the ECU then that can cause all kinds of strange low power complaints. The boost pressure relief valve I was talking about is on the pressure side of the turbo/intake manifold and if its going bad it will drop turbo boost pressure.

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The wastegate actuator seems to be the culprit on many turbo complaints. As for the air dryer problem check all the air lines for pinhole leaks especially the signal line between the governor and the reservoir(tank).

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On the air dryer the AD-9 has a check valve in the bottom where the air line comes out. If it is not sealing it will let pressure out of the wet tank when the dryer purges causing the compressor to kick back on. This will cause the dryer to purge quite often.

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boost pressure drop is intermittent, don't know why intake plumbing would affect pressure side of the turbo. The code that shows up is always the turbo speed sensor.

All components were in fact changed out. We have tried a second govenor, maybe we should try a new purge valve on the AD9 drier. It will blow off steady going down the road or sitting still, then it will work properly for a day. Can't figure out why it doesn't do it all the time.

May have found problem in bad connection between sensor plug and harness. Not sure but playing at this connection seems to help. Thanks for the info, any ideas on the air system problem on the other unit?

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May have found problem in bad connection between sensor plug and harness. Not sure but playing at this connection seems to help. Thanks for the info, any ideas on the air system problem on the other unit?

I have seen this many times on these units most of them boiled down to the air drier leaking internally! remove the small air line at the air drier install a temporary guage on the end and watch the guage if the gauge stays put once the compressor unloads you have an air drier problem! replace the air drier again.

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