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Another 8V-92 Boost concern
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Still a bit confused. Asked a friend (retired Detroit machanic) about the boost guage. His reply was the series 60 from that vintage is controlled by on board computer. He felt that if all feels to be running good it would probably not be of great advantage. He did note to keep an eye on my exhuast digital readout as it will also indicate boost problems if readings come close to the 950 degree alarm and do not back down.
There is room in the dash for the bost guage, question is was the bus wired for optional guages? If so install would be a bunch simplier.
All this info is great!
Happy motoring
Richard -
Yes the engine DDEC control reads its own values for boost, but there is no harm in you having that gauge.
I do question the comment about the exhaust temperature or EGT. Nobody as yet has been able to show me a shred of information about what that value should be or its limit.
That also is good information to have available, not because as a driver I intend to operate my coach based on the EGT reading, but because I would have another reference point to help anticipate a problem.
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What is the performance module your taling about for this engine. Does it involve reprograming the DDEC?
thanks. Bill Guy
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Jon, every DD dealer has a Field Service Data Book thats has the EGT for all DD engines that little book is kept out of reach for the public but it is out there,tell me what engine you need the EGT reading for and I will be more than happy to send you a copy in black and white from the service data book that is the best I can do for you
good luck
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Clifford,
Do you need engine serial numbers? I’d like see those max EGT numbers for the 500 HP 12.7, The 575 HP 14 liter from around 2000 and the 2006 14 liter EGR motor. Are those temps before or after the turbo?
Thanks,
Ken
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Clifford,
We would love to have those numbers and I will put them on site as an article or link. We get a lot of these questions as you see.
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Whiskey Bill,
Sorry I have not been on here in a few days.
If you are asking me about the performance module I have,,,, it is an inline, plug and play module. Weather sealed quick disconnects, male and female, and plugs into the harness and boost sensor (located on the passenger side of the engine between the Turbo and valve cover).
It plugs inline with the Boost Sensor and gives the ECM an inhanced signal so the injectors feed slightly more fuel to get the RPM’s rolling from a dead stop. Very similar to how the performance programmers work on other Diesel trucks.
Before installing the module I could set the parking brake and floor the accelerator and the bus would not move for maybe 45 seconds, and then barely move.
Now I can set the brake, floor it and it will immediately start moving. No longer anemic performance, and much more fun to drive.
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Is this a test to set brakes then gun it. Inquring minds want to know! I hope my brakes would hold, probably twist the drive shaft into.
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Info: We have an H3-40 with an 8V92TA. The bus was built in Aug 1990. It has a +/- 15 boost gauge which I presume is factory original. Obvioulsy it has never seen a negative reading. When we got the coach in 2009 the boost was rarely above 12 even on grades. Turned out to be an exhaust manifold gasket. When W. W. Williams went to replace it the exhaust manifold came off in three pieces. They found a good used one and put it on. Boost was then routinely off the end of the scale (15+) until recently. Last few weeks traveled from MI to AZ and was getting +14 on grades. Turned out the manifold pressure hose from the turbo to the boost sensor had failed. It was so brittle it crumbled. Replaced it (on the road) and it runs like a new engine.
So here’s my question: Can I buy a boost gauge (of the right physical size for the dash) that goes from 0 to +30 and simply replace the gauge that is there? Or is there more to it than that? Like other posts here, I am a former (private) pilot and I am used to having gauges that give me accurate information.
Thanks. ~Bruce
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Bruce, You have identified the 2 biggest issues relating to boost on the 8V92. The short section of hose to the turbo boost sensor is important because the sensor is providing information to the DDEC and that affects how much fuel the engine gets when you step on the pedal.
The common problem with the 8V92 regarding lost boost has been experienced by a great number of owners of that engine. Your boost gauge is communicating to you when there is an issue. If the manifold does not crack (usually at the ears under the fasteners) it is a failed exhaust manifold gasket, usually blowing from beneath the manifold. Try to keep the areas around the manifold very clean because that is going to help you a lot in detecting the problem which will show up as black soot on the silver paint.
I think over the years Prevost had manifold pressure gauges with different upper limits. It might be worth a call to their parts guys to see what pressure ranges are available. I know I had one that measured boost in the twenties on my second coach. If you want to go all out you can buy (on ebay) a Nexiq reader with DDEC II software that you can leave hooked up to read every piece of data relating to your engine to the fraction of a degree or PSI. Or you can spend serious money and get a Silverleaf that will display that information on a laptop.
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Thanks Jon. I will try the parts folks in Elgin. I’ve had good luck with them.
I have the interface box for the Silverleaf VMSpc but have never hooked it up. I also have a ProLink set up with the correct module and connector for the DDEC II and have used it a few times. The problem with both is that the diagnostic connector is in the bay under the driver’s seat, not under the dashboard. I have never taken the time to figure out how to route the cabe from the connector into the cockpit.
The other problem with the VMSpc is that it requires a Windows based computer. I have an older laptop (WinXP) set aside just for this purpose but have not yet figured out where/how to mount it. I will probably have to mount it remotely and get a small (8″) flat panel monitor to mount someplace where I can see it. We attended a seminar at the FMCA convention in Madison, WI in 2012 but on by the President of Silverleaf. It was very informative and I would really like to get this thing operational. The seminar was not a blantant sales pitch; he talked in detail about how to drive a big diesel-powered vehicle using the information available from systems like the Silverleaf.
~Bruce
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I have used my Nexiq reader just to get baseline data. I know what my boost, normal coolant temp, normal oil pressure and a variety of other measurements are and if I sense something has changed on my coach it is easy to plug in and see if something varies from normal.. Mine is an under dash hookup and I just have my wife read the data while I drive. My reader has plenty of cord so it works from the connector behind the seat as in my previous coach or under the dash as in the current one.
But I don’t bother with trying to read all the data available under normal conditions. It can drive you nuts if you become fixated on something.
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Bruce, you can see how I made my tablet mount below. If you want to use
the Silverleaf I recommend using an 11 inch tablet. It only requires an
entry level Windows based tablet. Mine is a Samsung ATIV T500. If you
have DDEC II and If I remember correctly the Silverleaf may not work
correctly with DDEC II. Be sure you ask the folks at Silverleaf. I
replaced my original boost gauge that read a max 15 lbs with one that
reads up to 50 lbs. Yours should be a mechanical gauge also. Just pull
your dash back and have a look at the rear of the gauge. If has a small
nylon tube connected then it’s mechanical. It’ll be easy to find a good
quality replacement for it.prevostcommunity.com/forum/threaddetails.asp?Category=General%20Discussions&ThreadID=2951
Ken
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Bruce
Our coach Is a 1992 XL with an 8V-92 as well. We use an iPad App , which is free at the Apple Store for a Glass Dash. Several years ago, a fellow bus owner , translated the ECM language for DDEC II, III, and I believe DDEC IV. A Cambox which plugs into the diagnostic port and wirelessly transmits to the iPad, or for that matter, an iPhone and theApp creates a glass dash with all the guages in several configurations to choose. Our ECM shows info to some of the gauges the App has, but some like transmission keypad position doesn’t show. But other info like speed, rpm, boost, coolant temps register. We lOve it. Need more info, PM me. The Cambox cost us about $8000 plus the cable from it to the diagnostic port
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Do you have a suppliers name for the Cambox.
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