Turbo Boost

[Loc]

I have a turbo boost question. I am just trying to set the appropriate range of expectations for turbo boost pressures for the Series 60. What do you see on the turbo boost gauge when flat land cruising at 65 mph? What is the max boost that you see when you put your foot into it (leaving a stop or pulling a hill)?

Loc

[jack14r]

Loc,Mine has a gauge that goes from 0-30,and on acceleration or up hills it almost hits 30 psi,I would guess about 27 or so.I always tow a P/U truck and it varies from 10-20+ on flat land.On my last trip I was in Florida and watching the temp gauge and the fuel mileage,without the OTR air on,the temp would rise to about 185 and the cooling fan would come on and the fuel mileage would decrease about 1 MPG,at this point the boost would increase also.The temp would cool to about 175 and then the fuel mileage would increase again,when the fan was not pulling a load,I assume it must pull 40-50 horsepower when it is cooling.Jack

[tdelorme]

Loc, I told you man, if you will pull both slides IN when your driving the numbers will be better. And, you can get rid of the WIDE LOAD banner to boot. :):)

[merle&louise]

Loc,

I use the boost gauge to keep from overheating the engine when climbing a grade. As I ascend the grade I reduce the accelerator pressure and watch the boost gauge come down keeping it around 20psi. This helps to keep the engine from overheating. A little caution climbing grades in the summer really pays off in the form of a cooler running engine.

On flat land with c.c. set @ 65mph it reads about 5-10psi.

Hope this helps you. I plan to be in Houston April 4,5, & 6th. If you are free maybe we could schedule a test drive!:D

[Loc]

Jack,

That is about what I experience. I am just making sure that the Deuce is operating within normal/reasonable parameters.

Ted,

Thanks, I was expecting an insightful comment from JDUB, but you obliged. How was the trip to Florida?

Tuga,

The calendar looks good for those dates. Give me a call at 713.831.6496 and we will set something up.

Loc

[Jerry Winchester]

Ted,

He is confusing "Turbo Boost" with "Taco Boost" and I don't think the Millennium came with the optional Bifurcated Auxiliary Digital Generation Augmentation System (BADGAS) unit that differentiates between his stinky taco farts and turbo waste gas.

Tuga, don't come all the way to town just to brown nose with that collie humper. Come hang with the working class folks on the north side of town.

JDUB

[merle&louise]

JDUB,

We are planning a golf trip in Houston April 4-6. We are going to meet up with Robert McDougle and some other guys.
I feel the need to drive an XLII with SLIDES! I want to see them in action. Loc has told me that I can use the bus to go out on the town (you know transport large groups of drunk friends around to all the "gentleman's clubs" (Karen won't be on this trip). I'll call you and we can get together for some BBQ or Tacos or whatever Saturday night:D

[Loc]

Tuga,

You didn't mention that Karen wasn't going to come. I may need to rethink this. Don't yall have to check shower tolerances?

Loc

[rmboies]

Tuga,

You didn't mention that Karen wasn't going to come. I may need to rethink this. Don't yall have to check shower tolerances?
Loc

Not to worry Loc, there is plenty of room in the Millennium showers:D Be sure and take a pic of Tuga and Karen in yours--ha~!

Debi

[truk4u]

Loc Nest,

Make sure Karen is along, Tuga was in Oshkosh last year without her and he really wasn't much fun! In his defense, JDUB and Mango worked him over pretty hard before I got there.:p

[merle&louise]

Loc, Debi, & Truk,

Karen will be on her "girls trip" to Florida on the dates that we will be in Houston. I am really looking forward to driving that Millennium:D I hope that I don't get weak and buy one:eek: The more I think about it, I think that I would prefer a Liberty (it's easier to spell for one thing). Maybe Bob97/00/03/05 can help me find a good deal.

[Joe Cannarozzi]

Tuga you should be proud of your uncommon insight into how to approach a grade.

It is a natural instinct to accelerate harder as the grade increases and the RPM's decrease and pulling a grade a couple of pounds of boost below max. at any given RPM is prudent weather coolant temps. are an issue or not.

[Gary & Peggy Stevens]

Loc,

Hope this helps you. I plan to be in Houston April 4,5, & 6th. If you are free maybe we could schedule a test drive!:D

Wouldn't you know it....... We have a scheduled 2 week vacation starting April 4 with our GD, and ending in Beautiful Seivervill, TN. :(

Tuga, you are going to POG V aren't you, so I can meet you ( and give Karen a Hug ) and show you a real bus? If not, Guess you will have to look at LOC's. :D

[Gary & Peggy Stevens]

. Maybe Bob97/00/03/05 can help me find a good deal.

I know BOB can help you find one, but a GOOD deal for who ?

[merle&louise]

Thanks for the kind words Joe, but I was told how to ascend a grade by a trucker in a Flying J.

Gary, we are going to try to make POG V. Don't be too harsh on Loc, I saw that Millennium at Birdland Coach Services - it is one fine piece of s.s.:D I am looking forward to seeing yours a.s.a.p.

[Petervs]

Now who in their right mind would get advice on climbing a grade from Tuga? For crying out loud, he lives in Louisiana! The biggest grade is his driveway ramp to the sidewalk!

If you want to know how to climb a grade, ask someone from a state with mountains.

I routinely climb grades with the throttle floored. full blast all the way. No problem with overheating, towing, whatever. The Detroit was made to make horsepower and torque, not to be babied all the way to grandmothers house.

I have often climbed a 7-8% grade leaving Lewiston Idaho. One day I had just reset the ProDriver. We drove the first 12 miles or so at full throttle to the top of the hill, and averaged about 45 mph and 2.3 MPG. Makes you appreciate the 7.5 mpg on normal driving all the more.

I suggest from now on we ask Tuga only for advice on partying....ala MArdi Gras.

[garyde]

That's way harsh Brian. But come to think of it, I've only seen Karen driving.

[Gary & Peggy Stevens]

That's way harsh Brian. But come to think of it, I've only seen Karen driving.

And wasn't Karen Looking Good behind the wheel of that "NEWELL" ? :confused: :D

Karen, we all look forward to seeing both of you in Tn.

[Jon Wehrenberg]

Peter has it right in post #16.

What's the sense of carrying around all that power and torque if you don't use it?

I change into performance mode on the transmission so it won't prematurely upshift, and drop a gear as I approach the hill and slam my foot to the floor. If I could get the boost gauge to wrap all around itself nothing would make me happier.

C'mon girls.....boost equals power. The more the better. And the practical side is if you can't run up a long steep grade at max boost without overheating, it doesn't have anything to do with your turbo boost, but everything to do with the fact you have a radiator problem. All the turbo boost gauge is indicating is how much pressure you have in the intake manifiold, which is one indicator of how much power your engine is producing.

[merle&louise]

Hey we've got mountains in Louisiana; haven't you ever heard of Cajun Peak! It's 14.110 feet high and it's famous for auto races to summit.

Hey guys, I was just following the advice of a trucker in a truck stop. I figured he knew what he was talking about (guess he wasn't a POGGER).

Jon, I am going to try using the performance mode on the Allison next time we encounter a steep grade (better yet I'll tell Karen to use P mode!):D

[merle&louise]

Gary + Gary (Gary squared),

We will do our best to make it to Tenn. She does look good behind the wheel of that Newell. You should see the looks she gets when driving in city traffic!:eek:

[Joe Cannarozzi]

Anytime I notice that I cannot get the RPM's to go UP under full throttle I ease out just a bit and let the engine find an RPM that it can hold without my foot on the floor.

Peter and Jon my friends, there are many who practice your technique probably more than not. I work with a bunch of dump truck guys who drive like that.

[Petervs]

Hey Tuga,

Repeat after me:

" I pledge allegiance to the flag Of the Prevost Owners Group of America.

And to the cameraderie for which it stands,

One chassis vendor, over all others except maybe Newell,

With fun and education for all,

and I promise not to listen to truckers at fuel stops any more."


Hey, thanks too for letting me know about Cajun Peak, next time I am down there I will bring my ruler and look for it!

[rmboies]

Gary + Gary (Gary squared),

We will do our best to make it to Tenn. She does look good behind the wheel of that Newell. You should see the looks she gets when driving in city traffic!:eek:

Tuga, Karen is a beautiful lady, inside and out, so of course she gets looks driving that rig:D By the way, you left out Bob's 99 H3 but that's ok, I can't even keep up with the man!

Hey Gary, any deal Bob can help Tuga with he will--no doubt he could find him a good one.....we need to get Karen behind the wheel of a Prevost so I say let's go shopping Tuga!!

Debi

[truk4u]

Ah, excuse me boys (Jon & Peter), I think the trucker Tuga talked with is right and he makes a living driving probably 6 - 7 days a week and 120K while us ole farts might break 15K a year.

I for one, downshift on mountains and keep the rpm's high and don't use pedal to the floor. Just like the trucks do, gear it down to keep the rpm's up for cooling because on those real hot days, you could have a real problem.

Why stick the pedal to the floor, lug the engine down to 13 - 14 hundred rpm and watch the temp gauge works it's butt off while the fan cycles every couple minutes since your building serious heat! That fan also costs you HP and fuel as well.

My Pappy would have kicked my ass if I treaded a truck engine like that, give your Mo Jo a break and use the transmission....

This should stir up a S@)& storm....:cool:

[Jon Wehrenberg]

Did we wake you Tom?

What part of my post said I lugged the engine? I downshift before the hill and go into perfomance mode to be able to keep the revs up instead of premature shifting in economy mode.

If I hold my foot on the floor going up Jelico Moutain I can hold 60 all the way up. The engine is singing, I'm making a nice speed, and the temps are nowhere near an issue. I am not going to let off the pedal because if I do I lose speed at which point I get back in line with the slow truckers who also lifted their foot.

[Larry W]

Living in the Colorado mountains we are always going up or down hill. The DD owners manual states that on a long pull to select a gear that will pull the hill and then set the cruise control for the speed that works. This will always peg the boost meter at 30. Have not had heating problems doing this. The cruise not only controls the speed but also the fuel. Think the DD brain is smarter than I am about how much fuel to put to the engine. Seems I read somewhere that this will produce more horsepower than manually fueling the engine.

[MangoMike]

I think I'm only pulling about 25 boost on the H. Should I be concerned?

Thanks

[Petervs]

Jon and Larry said it well. Thank you for defending my position on this. Amazing how often Jon and I see eye to eye, gives me a good feeling , actually. We really must meet in person someday. (Yes, we are working on making it to Spearfish)

The max boost I get does depend on a few things, like RPM, outside air temp, altitude, how long you hold the pedal down, etc. It does take a few seconds to reach max. I usually see 28 inches HG as a max.

MangoMike, if you do not get over 25 inches, you could have a leak in the plumbing. Could be the gauge plumbing or the engine intake plumbing between the turbo and the engine itself. There must also be a wastegate valve, if that is not closing all the way it will provide a constant leak and reduce max boost. Does the gauge read zero with the engine off? You can check that point on it's operating curve easily at least.

And, as to listening to truckers, there is a difference in the value of their opinions in my mind at least, depending on if you are talking to an OWNER operator, or just a hired driver who is running a truck where someone else pays the repair and maintenance bills.

[Jon Wehrenberg]

I should have mentioned that I prefer to ascend a hill with the cruise control on as Larry mentions, but prior to the hill, just as the road is beginning to transition from level to an upslope I go to full throttle to start picking up momentum. Once I have my speed back down to my set point or below in the climb, I can lift from the throttle, because the cruise has taken over.

[Jerry Winchester]

I thought one of the virtues of the Series 60 was the "lugability"?

[Orren Zook]

Just curious, what kind of EGT are you guys maintaining while you're in the race to the top of those mountains?

[Jon Wehrenberg]

Orren, On our 97 the pyro was eliminated.

I miss the pyro gauge so it is only the 8V92 guys that can address that now. On our other coach the max I would see at 2150 RPM and full boost which on my 87 was around 21 or 25 (I can't remember) was around 1100. Depending on how level we were running and if we had headwinds, highway cruise speeds was around 600 to 700.

[Joe Cannarozzi]

Rereading Larrys post he says that the DD manual says "to select a gear that will PULL the hill then choose a speed that works". Pull means being able to accelerate in that gear.
.
A gear that you can get the RPM's to go UP if you try.

Diminishing and or low RPM is fine but not with your foot on the floor. I am regularly low in the RPM with my straight-6, there is a great amount of torque in a diesel there, but I do not operate at those ranges hammer down unless it will "pull" out.

As I start a climb and loose speed and the trans downshifts I'll then test that lower gear with full throttle for a bit and if the RPM's are just holding or still going down I again back out a little. At that point it will either drop off and hold somewhere or downshift again at which time I will again test with full throttle. When it gets to a gear that "will PULL the hill" it will be in one that I can accelerate in if I so choose. Then for the 8-V it's 1800 to the top, whatever gear that might be.

[truk4u]

That is exactly my method Joe, you just explained it better. Can't break truckin habits that have served well over all these years.

Your pappy must be proud!;)

[Jon Wehrenberg]

Tom and Joe...I think there are differences that you are not recognizing.

First, manual transmissions are driven differently than automatics. You are the "brains" for the manual, and the automatic has its own "brains", less so on Joe's coach, but more so on later coaches with ATEC.

When you select a hill climbing gear, you can move the pedal up and down until you sense where your speed starts letting off. You do not have to hold your foot to the floor because anything past that point where your speed diminishes is not going to change your speed or acceleration. That is a throwback to mechanical injectors however.

With our DDEC and ATEC controlled engines and transmissions your throttle position is controlled regardless of where you put the pedal. The DDEC will not open the injectors beyond the point necessary to optimize the power. You can call for more power, but you will only get what the engine can deliver whether it is your foot on the pedal, or the cruise control handling the pedal (figuratively speaking).

Prior to the DDEC type engine controls, and what has prompted truckers to claim it is best to keep the pedal at or below the point where the speed dropped off was what would happen if you pushed your foot to the floor climbing a hill on which you could not maintain speed or accelerate. With mechanical injectors, holding your foot into the pedal more than the engine could handle resulted in lots of black smoke. Your pedal was the determining factor in fuel delivery so it made perfect sense for you as a driver to not use so much throttle the engine could not efficiently burn the fuel.

Except for very early coaches, that will not happen any more. Is the old way of doing things valid? It will not hurt, but the way the coaches are set up no matter how much you push the pedal the coach will deliver the maximum performance if that is what you ask of it, and there is not a downside to pedal to the metal.

[Petervs]

Once again Jon has said it very well.

My coach happens to be the first 45 foot Series 60 that Marathon converted, and it came equipped with a pyrometer.

On the flat, cruising at say 65 mph, it reads around 300-400 degrees.

Climbing a big hill, pedal floored, I have never seen more than 900 degrees.

The computer controls it all automatically.

In my airplanes I have pyrometers in all of them and am used to monitoring them closely. They run around 1200 degrees when running rich in climb, and up to 1500 degrees normal lean cruise. But the metallurgy is different and i am not suggesting anyone run a bus at those temps.

[Joe Cannarozzi]

When DD suggests or someone says says a gear that you can pull that hill the definition is clear. It does not mean anything accept you have the ability to accelerate up it.

Why wouldn't the DD manual say: Put your foot on the floor and the computer will automatically do the rest?

When anti-lock brake computers came along all the manufacturers were clear to specify the new technique, to brake people of the old habits of pumping. Seems to me that the computer controlled engines would have included similar instructions.

Jon I remember having this discussion with you the first time we met and at the time I felt I did not know you well enough to pursue the disagreement. I kinda knew this topic would eventually come up. I feel it is a very healthy discussion and now that we know each other a little more will be glad to continue to make it. Looks like some are siding up for it and I have DD in my corner;)

I will agree that under certain circumstances the computer will restrict an excessive amount of fuel to be delivered to the engine under full throttle where the manual fuel pump will not.

Another example:

My straight-6 is a 1950 RPM motor. If I am climbing and in gear-X and can get it all the way up to 1850 and holding at full throttle I will not leave it there. I will back it off to 1750 or 1800 and give it a little breathing room. This technique applies to all engines computer or not.

Tuga what do you think about all this? Gonna change your driving habits or not:eek:

[Jon Wehrenberg]

Joe,

You and I are talking about apples and oranges.

Your practice is to select a gear for hill climbing in which you can actually accelerate up the hill, at least until you max out the rpms in that gear. So basically if I understand your comments it is you preference to just back off of maximum throttle and climb the hill at some speed that is less than your maximum. That's fine and what you are doing is using less than the available HP.

What I am saying is that on mechanical engines you had to do that because it you tried to get more power by using the maximum throttle, all you would do would be to convert fuel into noise and black smoke.

On DDEC and ATEC engines, apart from giving the coach a little premature assistance by dropping down a gear, and going to performance mode, gaining a little speed to help hold the revs up, you can drive with your foot to the floor or let the cruise control hold its foot to the floor. Either way the computers and transmission shifting map are going to take you up the hill at max performance and you will not be experiencing the conditions that used to prevail when there were mechanical injectors.

I can do the same thing you suggest, and that is to climb the hill using less than maximum power. I presume it may impose less stress on the engine, but I view our engines as more than capable of being asked to deliver maximum performance so I choose to attack a hill with all my coach can deliver.

[Petervs]

Joe, you say: '"a gear that you can pull that hill the definition is clear. It does not mean anything accept you have the ability to accelerate up it."

I do not agree with your statement at all. to "pull a hill" is a totally ambiguous group of words. First off, many roads on hills do not have constant grade angles. There are steeper parts and shallower parts. So your speed and horsepower required will vary.

Second, one could easily interpret "pull a hill" to mean continue making forward progress at whatever speed, increasing or decreasing over time. As long as you are not rolling backward, you are "pulling the hill".

Question, do you accelerate from a red light at full throttle, say on a road with a 55 mph speed limit? Do you think if you do you will break some kind of DD part?

Third, if Jon and I drive like we say we do, what do you think is going to happen back there, what is going to break or wear out prematurely? How do you equate driving an empty coach verses a loaded one pulling a 20,000 pound stacker trailer? With one of those I bet your foot would be all the way down much of the time. How about driving into a 40 mph headwind on a flat road, are you unwilling to go flat out then too?

Also, I would really like to see the Detroit Diesel page where this "pull the hill" stuff is printed. I can easily believe a trucker would say it while fueling, but I have a hard time believing a bunch of engineers and marketing types would actually print it for customers.

And Joe, I think you are right about one thing, the POG group is a perfectly OK place to air one's opinions, and I really hope we all buy into the idea that we are here to learn from each other and not be too worried about offending each other. What we all want is the unvarnished technical truth. I hope.

[Joe Cannarozzi]

Peter, it's all good. I have surrendered to the notion that you are as adamant about your driving technique as I.

I never accelerate off of a dead stop with full throttle. The small ratios in the lower gears combined with excessive throttle position creates much unneeded stress on things. I step into it and the heavier I am the slower I step into it. Usually getting close to the floor around the time it is time to shift.

There are few circumstances when I do use full throttle. If I am passing someone so not to linger or if I'm on the downgrade and know of an approaching hill or if I'm rushing but even then only if I can get the RPM's to go up.

To "hold" the hill is when the RPM's remain neutral at full throttle and to "loose" it they are dropping.

Larry eluded to the reference to the DD manual I only referred to it to strengthen my argument.

A headwind is usually not a problem but strong crosswinds often are. Again I would seek a speed that would allow me to operate with less than full throttle.

I will agree with you on DD's poor choice of terms IF for the general public but I would have to assume that they think they are talking to drivers.

[merle&louise]

Hey Tuga,

Repeat after me:

" I pledge allegiance to the flag Of the Prevost Owners Group of America.

And to the cameraderie for which it stands,

One chassis vendor, over all others except maybe Newell,

With fun and education for all,

and I promise not to listen to truckers at fuel stops any more."


Hey, thanks too for letting me know about Cajun Peak, next time I am down there I will bring my ruler and look for it!


I will recite the pledge but somebody needs to show me the secret handshake! We just got back from Indio and 3 guys on Newell row knew the secret POG handshake and I didn't! It was embarassing! When you ask for directions to Cajun Peak remember that there ONLY 3 directions in south Louisana: Up the bayou, Down the bayou, and Across the bayou!:D GOOD LUCK FINDING IT! Are you and Katherine coming to Sevierville?

Thank you Debi for the kind words. Karen and I are going to the rally in Sevierville; will you and Bob be there?

[truk4u]

Joe,

You and I can't break the old trucking habits and doubt we ever will. The various driving techniques really don't matter, the engines now days have become idiot proof, so other than an overspeed, the computers will take care of everything.

Like Tony Soprano says, "forget about it."

Hammer down boys, you won't hurt it....

[merle&louise]

Tuga what do you think about all this? Gonna change your driving habits or not:eek:

Well Joe, I respect Jon and Peter's knowledge and education. With that said, I realize that you are both right. It seems to me that we are talking about 2 very different engines: the 8V92 which has no computers in it and the series 60 which is operated extensively with a computer. It sounds like the computerized series 60 "knows when to throttle back" much the same as the old truckers know when to throttle back on the 8V92. So to answer your question, I am going to try using the performance mode on the transmission and see what happens. If the engine overheats I'll let you know:D

[Petervs]

Yeah Tuga,

Jon, I think we have a convert on the very edge of coming over to the Light side.

Sorry to report katherine and I will not make Seiverville, but we are sendding Brian and Beverly as understudies. We are trying for Spearfish later this summer.

As for the Bayou directions, there is one other one, during the hurricane anyway, "Under the bayou."

[garyde]

I'd like to see anyone go full throtle behind Jon, 'the 62 MPH Guy!' Hey Jon , are you a closet full throtler?

[Jon Wehrenberg]

I will let others reveal that. Roger and I have a few thousand miles running together. I'll accept his opinion.

Don't take JDUB's word for it. Going to POG I I was having some fun with him.

[Gary & Peggy Stevens]

Ok guys I have an intermittent issue on my bus.

The Orange Check Engine light comes on the dash, and in the display panel that normally tells the time where you can also modify mileage and check fuel consumption, It sometimes comes up with CHECK ENGINE AT NEXT STOP. When this happens the Turbo Boost Pressure Gauge stops reading.

I don't notice any difference in the power or driving but it concerns me.

I took it to Stewart & Stevenson and they read the DDEC Code which is # 86

The code states in the book, # 86 " External pump or barometer pressure sensor input voltage high". S&S says this engine does not have a barometer pressure sensor?

What should I do or ask them to do? Remember it only comes on once in awhile. I haven't seen the display in the last two days of driving?

Thanks for your advice.

Gary S.

[Joe Cannarozzi]

I think that sensor that reads barometric pressure is also referred to as a map sensor.

[Jon Wehrenberg]

The question is what do they recommend that you do? A check engine light has to be dealt with.

Could it be the turbo boost sensor (located on the passenger side of the engine on the intake manifold) is failing? It determines how much boost you have and it is part of the DDEC calculation that determines fuel flow through the injectors. If it does not sense boost the engine will deliver very little power.

[Gary & Peggy Stevens]

I spoke with both James @ Prevost Car in Dallas, and Dale my service advisor @ S & S.

Dale found out there are some dual purpose Barometric and Turbo Boost Sensors in some of our buss's and that may be the culprit, in causing the intermitant failed readings. He is checking into the actual unit on my bus to see if this is indeed the dual sensing unit, and then will continue diagnostics to determine the next step.

Will get back when I know more, which is something that happens every minute of every day. :D I thought I would say it before everybody else said it. ;)


It's ALL GOOD ! "Loc's favorite saying"
Gary S.

[Loc]

Its all good!

[Gary & Peggy Stevens]

OK, so how many of you know IF YOU have a Barometric Boost Sensor or not attached to your DD60 engine?

Apparently I didn't have one?????? S & S installed a NEW STYLE Barometric Boost Sensor and wired it in line with the Turbo Boost Circuit. I asked the service advisor where they put it, but he didn't have a clue? :(

They also Reprogrammed the ECM to Raise the Software Level and to Sense the New Style Pressure System. :eek:

3 days in the shop, and $ 8 Big Lewbucks later, and I am off again. :cool:

Gary S.

[Jon Wehrenberg]

How many zeros are after the 8 Lewbucks.

A turbo boost sensor costs less than $100 and involves a screw and a short piece of tubing, or if mounted directly to the intake manifold a gasket.

Ten minutes. No programming, no magic.

[Ray Davis]

Something doesn't quite add up. If you never had one of those sensors previously, why did you all of a sudden start getting the warnings?

Am I missing something obvious here?

Ray

[Orren Zook]

It was probably a warning that you might have too many lewbuck$ on the bus and they wanted to help by lightening your load......

[Gary & Peggy Stevens]

Jon, it was two "0's" after the 8. And yes the sensor they added only cost $85.00, but there was the 6 hours of labor to test, install, upgrade the software, and misc. shop stuff, (rags / hand soap etc.. ) you know...... All the things they needed to do to get the price jacked up ? :confused:

Anyway I better not have that intermittent warning light come on the dash anymore? They said the Code 86 had come on 36 times, according to the reader, and I remember it coming on maybe 6 times since I have driven it, so I guess it was driven like that for quite awhile before I got it. I could have let it go, but didn't feel right, so I fixed it.

The service advisor @ S & S initially said, my year of bus doesn't have a B. sensor, so go figure. :confused:


Ray, I don't think when you take these bus' in for service, anything is OBVIOUS ? Sure wish I lived closer to Tn.. Loc is just no help with this stuff?


Gary S.

[Jon Wehrenberg]

Gary,

This is instructional in that S&S reached into your wallet and did an extraction.

If I have to have someone service my coach I follow the Ken Z school of though in that I stay right there. Then I ask dumb hard questions like if you are going to charge me more than the 15 minutes to replace the sensor explain carefully what I will be getting for the money you are charging.

Can I defer the process or the repair? What would have happened if the sensor did not fail and you did not spend six hours (that's bullshit I think) upgrading my DDEC? You see where I am going with this.

BTW, I had a funky sensor once. The codes gave me information about turbo boost, but since I was flashing the code I did not have any detail beyond that. When I talked to the DD dealer they thought it was the sensor which the codes would indicate, because I had already verified the turbo was working. But then they told me thay needed my coach to go through the entire thing because it could be a bad ground, a bad connection, etc. etc. I thanked them for their concern, ordered a sensor, put it on and never had any more issues. You can make almost anything a bigger deal than it really is.

[Ray Davis]

I guess I will just remain a bit confused.

If they indicated that they had removed the old sensor, replaced it, AND did all the other upgrades (to jack the price), then it would make sense to me.

But, I don't understand how a coach that evidently didn't have a sensor and worked just fine for some long period of time, started generating codes that didn't before, and adding a new sensor solved the problem.

Mark me as confused ... :confused:

Ray

[Jon Wehrenberg]

Our coaches have a turbo boost sensor. It measures the amount of boost pressure which it communicates with the DDEC.

The DDEC processes that information and meters the correct amount of fuel to the engine. If fuel flow was a constant, you would have lots of black smoke until the turbo boost pressure increased sufficiently to provide the correct amount of air for the fuel being injected.

As emissions standards increased, the turbo boost sensing got much more sophisticated. CA for example has a snap throttle test that must be passed. At idle the throttle goes from idle to full throttle almost instantaneously. Since the turbo has not spun up at that point the DDEC will not feed enough fuel to make black smoke. As the turbo boost increases, and is sensed the fuel flow to the injectors increases proportionate to the amount of oxygen available for combustion.

My guess is that Gary has an updated sensor, more sophisticated than a simple sensor which just measures air pressure in th eintake manifold, and software required to read the data, so his coach likely runs cleaner than others of his vintage.

[Loc]

Gary,

Give me some credit. I was more help than you know. I called Dale at S&S and had him put the rest of my outstanding bill on your tab. He told me that JDUB had made the same call a couple of weeks ago, but added to my bill - so in a way you got the double team. Thanks!

Loc

[Gary & Peggy Stevens]

My guess is that Gary has an updated sensor, more sophisticated than a simple sensor which just measures air pressure in th eintake manifold, and software required to read the data, so his coach likely runs cleaner than others of his vintage.

I'll stick with that answer.... It works for me. Thanks Jon

Hey Loc, BITE ME !

Gary S.