| Author | Message | ||
| Tom Dessert (Mci5er)
Rating: N/A |
I'm curious about about a few comments from the previous owner of my MCI 5A. Here is the comment "The smog retarder has been removed from this engine by Mike. He says they cause undue wear on the injector rack, since it’s only on one side of the engine. Besides it makes the throttle response much slower. Translation, when it was there, you could stomp on the throttle and the bus would take off nicely from a stop. With it removed, if you stomp too much, too soon, you still take off nicely, and a little bit faster, but the poor guy behind you is in a thick cloud of really black smoke." That said, I have the DD Series Books for the 6v92's and can't find any references to "the smog retarder". Any help would be appreciated. Thanks | ||
| Tim Strommen (Tim_strommen)
Rating: N/A |
This is either a fuel modulator or throttle delay linkage (two different devices, same basic function). These devices reduce the rate of positive change in the amount of fuel that is injected into the engine's cylinders. I'm not sure why the owner would want to remove this device - unless he/she wanted to have more control over the throttle (and was going to take responsibility for the acceleration rate of the engine). If the driver is smashing the gas pedal to the floor to "get off the line" faster leaving a cloud of un-burnt fuel behind, he's overloading the engine, and has a real mental retardation issue with identifying a Sledgehammer Corvette as opposed to a Class 8 Semi (turn him in  ). It takes a good long time more for 20-40 thousands pounds of heavy duty machinery to get to 60MPH than it does a Ferarri... Bottom line is - it's good to hear what a previous owner has done to a rig so that their damage can be undone by you. The wear put on the engine by having a manufacaturer designed component installed should be very little (even if you full-time), and any defects in the design that damage the engine should be pursued as warranty repairs. Cheers! -Tim | ||
| John MC9 Rating: N/A |
Dah Book? "....the "Fuel modulator" and the "Throttle delay mechanism"..... .......Any malfunction in either would result in heavy black smoke on acceleration only......" With oversized injectors, the addition of the delay can allow for a smokeless (almost) acceleration. The downside is, you will have to wait to take off, after stomping on the accelerator. It can be unnerving, I'm told... Aggravating.. to step on the pedal and not much happens, until the engine's ready to let it happen.. I asked about having one installed on my MC9. Two bus garages said to just use a light touch to the pedal; the delay will only get me POd, just as it does for any of their drivers driving any bus that has one. | ||
| Marc Bourget Rating: N/A |
If black smoke on acceleration is, by definition, over-fueling the engine, i.e. drop off in combustion efficiency, I wonder just how much extra acceleration one gets, anyway??? Seems like the modulator/throttle device would allow you to concentrate on where you're going rather than what you're leaving (smoke cloud) | ||
| John MC9 Rating: N/A |
Marc - It's a pollution control device, Marc. Oversized injectors used for a bit of extra power, can cause smoking at inopportune times, like at take-off. The delay eliminates that, but so does a light right foot! Most buses and trucks do not use a delay. If you had one, you'd hate it, I'm very certain. As it had been explained to me, with it, you would step on the pedal, and wait for something to happen. They said it would effect downshifting as well, if used with a standard transmission. Try to imagine having to be a bit aggressive pulling into traffic, and not having the engine respond in the manner you would normally expect from it. That's a ton more distracting, than the worry of a small cloud of black smoke. The bottom line? They told me that it's not standard fare. If you don't have one, don't bother getting one installed. | ||
| Tom Caffrey (Pvcces)
Rating: N/A |
John, if these cause the same delay whether you have some RPM up or not, then when you had plenty of RPM, you might find it just a tad irritating! I think it's the brainless aspect of these improvements that matters. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | ||
| Marc Bourget Rating: N/A |
Something troubles me about sports car expectations from a vehicle that's virtually hauling a house around with it. I recognize, as I type this, that I get extreemly impatient when confronted with traffic that appears involved in a conspiracy to space itself out for the deliberate purpose of blocking me from joining traffic. John, I wouldn't expect it to affect RPM changes, relative to shifting because, with no load on the engine, the RPMs should adjust easily enough with light pedal changes. | ||
| Tim Strommen (Tim_strommen)
Rating: N/A |
Precisely Marc, Unless your Conversion included adding a Pratt & Whitney turbine engine with 20Klbs of thrust, I wouldn't expect a 20Klbs rig to have an exciting "take-off"... That said, I'm sure adding a used engine from a military jet wouldn't be hard to do for a bus (lots of space if you only want to put the engine in ). For merging in traffic, my rule is: if there is someone on the side of my rig, I'll drop back behind them to avoid pushing them over a lane - but the person behind them better move or they'll find out what 30Klbs of bus feels like in their lap. The caveat to this statement is that I >>ALWAYS<< use my turn signals well in advance of any lane maneuvering - and this only applies to forced merges (lane ends, on-ramp, etc.) so the inattention of the driver behind them is their responsibility/fault (and my CHP friends agree...). Although I'll admit it is "fun" reminding aggressive Ford Excursion (SUV) drivers that they don't actually have a monopoly on the highway. I'm also not saying that all rigs should have or need these devices (nor am I defending their reliability), but rather that the purpose of having them there is preventing foolish drivers from over-injecting fuel until the burn isn't being completed. This isn't healthy for a car, bus, truck or the people in the minivan on their way to the asthma ward behind you. Your exhaust is a simple tell-tale of your operator's technique, and maintenance routines - and I have frequently seen people who are obviously driving rigs that are over-loaded, have blown rings, or some other problem driving on the roads out there. Personally I'd get embarrassed if I left a trail behind me that the astronauts in the space shuttle could follow... Cheers! -Tim | ||
| John MC9 Rating: N/A |
Aww, youse guys are a riot! Marc - "John, I wouldn't expect it to affect RPM changes, relative to shifting because, with no load on the engine, the RPM should adjust easily enough with light pedal changes" Tim - "the purpose of having them there is preventing foolish drivers from over-injecting fuel " Going downhill, attempting to shift into a lower gear, the delay will do just that: Delay the amount of acceleration; delay the rise of RPM. It isn't a "race car" mentality that finds fault with the throttle delay, Marc (and Tim), the died-in-the-wool bus drivers were the ones complaining. I had been told that with the delay installed, you won't get much accelerator reaction (rpm-wise) -as quickly- . It can be disturbing, and distracting. When I bought my MC9, I had been informed that there were oversized injectors installed. One of these days, when I have time, and the idiots at the storage facility move the vehicles that prevent me from opening the side engine doors, I will yank the valve cover off and check the injector size. I don't like the black cloud that emits from my MC9 upon attempted acceleration (from a stop, or at speed), but I have choices: I can change the injectors (and the rack timing), I can add a delay (and change the rack timing), or I can force myself to use as light a touch to the pedal as I can (difficult to do, with an air throttle and an automatic). Attempting to use that light a touch, results in less smoke, but the bus has got to be on level ground, -any- incline at all, and there is absolutely no way the bus will move without producing a cloud of dense, black smoke. (The smoke clears once up to speed, the cloud is within the pollution specs. Although obnoxious looking, it does dissipate in the allotted time; the engine timing is fine) Both bus garages, and a local truck/diesel repair shop, had the same opinions and remedies. I guess you'll have to ask the pros; the ones in the business, (as I have), to get the definitive explanation, and opinion. Oh... and they -all- discouraged the addition of an accelerator delay. I oughta' show up at a rally and let you fellas try to drive my bus without leaving a cloud behind it.... (HAR.... $$$$$ to be made here!) | ||
| Buswarrior (Buswarrior)
Rating: N/A |
Hello smokers. The mechanical 6V92 engines (and some others) have a propensity to leave a "belch of reek" on take-off. This technical term "belch of reek" may be new to you: it describes a nasty cloud of black smoke emitted with a certain amount of force from a tailpipe near you. May be applied to humans too! The earlier MCI 102A, MUI 6V92 turbo, 260 HP, auto tranny, equipped with the equipment intended to control smoke, were particularly scary to try to get out across a 2 lane highway after a line haul stop on the other side of the road. You stood on the pedal with two more cars approaching the gap you aimed at, and hoped nothing changed, and that the car after the gap had his eyes open. And even with the @#@$$# throttle delay, they still left a little belch behind. I am no fan of reek, but I hate the throttle delay more. Confirm that you aren't equipped with injectors bigger than the application should have, and leave the throttle delay in the garbage. my opinion, choose the bits you'd like to have! happy coaching! buswarrior | ||
| John MC9 Rating: N/A |
Thank you buswarrior, sir! | ||
| David Hartley (Drdave)
Rating: N/A |
Maybe you aren't giving it enough air? A poorly flowing air / filter system will cause excessive smoke. I would look to that before doing anything else. My current MUI 6V92TA ex-NJT does not blow rolling black smoke nor did either of my other buses. an RTS and a FLX transit. Although they didn't have oversized injectors either. All setup for 277 hp. stock. | ||
| John MC9 Rating: N/A |
David - "My current MUI 6V92TA ex-NJT does not blow rolling black smoke Although they didn't have oversized injectors either" 'nuff said? | ||
| Tom Dessert (Mci5er)
Rating: N/A |
Thanks all for the insight. I gather from the responses, that I shouldn't worry about it. As far as I know today, the injectors aren't oversized (subject to change when I actually look at them) to the engine specifications. According to the tags on the valve cover the motor is rated at 300 hp and my DD92 series manual says that it is either a "6v92TA (300@1800RPM) w/9G85 injectors 0r (300@2100rpm) w/9G90" Here's an oddity the Book states that the 6v92TA with peek power @1800RPM have a Throttle Delay setting of "DNA". Does that mean Delay NOT Applicable ? All others have specific delays stated. Anyway, thanks all | ||
| Greg Peterson Rating: N/A |
The DDEC has DNA for both fuel modulator and throttle delay because the computer controls the rack. The later model MUI engines all went to a fuel modulator which is superior because it looks at turbo boost pressure. These engine will have a DNA for throttle delay. Finally to all you guys that say a 100 more HP on a 20,000lb vehicle makes no difference you are wrong. I had a 20,000lb RV that I replaced a mech. 5.9L 190hp 480 ft=LB engine with a 5.9L 300hp 660 Ft-LB computer engine. It now moves like a pickup truck instead of a snail big big diff. | ||
| Jarlaxle Rating: N/A |
Seems to me that's probably due to the ~40% torque boost. |