Community Forums

Montrealer · 03-29-2010, 02:21 PM

I'd like to leverage your collective knowledge:

1) My coach doesn't have a turbo / boost gauge and I'm wondering if adding one would be a worthwhile undertaking. I know the gauge tells what amount of pressure the turbo is generating, but what story does that information really tell? Those of you who have this gauge, how do you use it to manage your engine / driving?

2) I'm considering buying a Trip Tek computer that would, amongst other things, provide a boost pressure reading. However, this reading is contingent on my engine computer providing this data in the first place. My engine model is the 03 ISL 400 and the chassis is the 2005 Freightliner XC. How can I tell if my engine's computer transmits this data?

CC38EL · 03-29-2010, 04:37 PM

Your ISL does in fact provide a tremendous amount of information. Much more than just turbo boost. Boost pressure is important to know in order to understand how well your engine is performing under load or at idle. However, if you just tap into the appropriate connector with the right piece of equipment and you'll have all the information you need.

Cummins makes a device called the Road Relay 4. It's a simple led readout that uses a small screen and many menus. Cost is about $1000 with adapters. It connects to the Cummins J1939 or 1708 connector.

There is also the SilverLeaf. Cost is about $450 with adapters. It connects in the same fashion, but requires a PC for display.

I don't know anything about the Trip Tek. What I've read is that the Trip Tek won't provide as much information about the engine and transmission as the RR4 or SilverLeaf; but I'll leave that to the Trip Tek experts.

I use the RR4 (got a great deal) and wouldn't drive a diesel MH without having the ability to display the engine/transmission information. Has saved me many a trip to a Cummins dealer for a costly analysis.

Gary RVRoamer · 03-30-2010, 08:10 AM

Whether boost tells you anything depends on how much of a gearhead you are.

1. More boost means more power and less fuel economy. You could use the boost gauge as a feedback mechanism if you are trying to maximize fuel economy.

2. The amount of boost vs the max gives you an idea of how much of its power the engine is putting out. If your engine is not achieving its max rated boost (the max depends on engine model and year) at the peak horsepower RPM, then something is not working properly.

Frankly, most people aren't going to find it all that enlightening. I have the TripTek on my 2004 ISL 370 and check boost once in awhile, along with other stuff on the coach data page. I find engine and tranny temperature and gear in use to be at least as valuable and probably moreso. I don't need a low boost reading to tell me when the engine is sluggish - I can feel that if it happens. And I know the fuel economy goes down as I push my foot down on the accelerator. Besides, the TripTek's continuous mpg readout keeps me well aware of that.

emiddleb · 03-30-2010, 10:04 AM

Short answers - 1) yes. 2) yes

Ok, a longer real-time example. My Vectra is currently at the Cummins center. On my first drive this season I had a big lack-of-power when driving. A quick glance at my gauges showed me I was only getting 2-3 lbs of turbo pressure. My Trip-Tek confirmed it.

Don't know if it is the root-cause or a symptom, but gave me a starting point to discuss with the service guys. Any data is better than none.

Like the other posters said, it's not something I check regularly, but if you don't have some sort of monitor I would certainly recommend getting one. If nothing else you might catch a small problem before it becomes a big one.

two-niner · 03-30-2010, 11:26 AM

I totally disagree with telling the mechanic what is wrong, in most cases.
You could be sending them on a wild goose chase. Cummins has the best diagnostic tools available. Why not let them use it? What's so hard about saying "no power".
Their time is your money.

Respectfully, Kerry

EngineerMike · 03-30-2010, 12:10 PM

Boost tells most folks very little, until it comes to a severe lack of boost. Then you can point to the at least part of the problem. Any decent tech who plugs in their software & test drives will have that info within seconds. So the info is more about what do you do with it. IIRC Road Relay gives you exhaust gas temp if your rig reports same; this is way more useful than boost for most folks (again if you use it) because you can allow your turbo to cool down before engine shut down if you had it screaming hot just when you hit the offramp. I didn't get EGT off my 06ISL with Silverleaf 400. Don't know if I have it on the 08 Silverleaf (haven't installed it yet).

Oddly, the wife missed Silverleaf on the 08 coach more than I and I probably wouldn't have bought it otherwise. I have gear-max and gear-selected on the Allison shift panel, and Cruise noted on the Actia LED screen under the speedo (your gauges are probably different). Silverleaf will allow road speed, boost gauge, tranny temp, engine temp, torque, and one or two other electronic gauges, as well as substitutes for the rear camera screen (leaves a thumbnail of rear view on the screen if so configured). I think RR does these same outputs maybe minus road speed, tho in less elegant fashion. Don't know about Trip Tek. Wife liked Silverleaf's great big speedo number as it was easy to read while paying attention to driving, and the alarm it gave when we overheated once (which I liked also).

CC38EL · 03-30-2010, 12:13 PM

I understand what you're saying, but I would never tell a mechanic what was wrong unless it was something so obvious (such as 'the engine is laying on the ground') that it couldn't be misinformation.

But, without an engine monitor of some kind, especially with diesels, you're left to your own devices and a Cummins analysis service if your engine dies for no apparent reason.

I don't see anything wrong with telling a Cummins tech that 'I got fault code xxx'. Any good tech is going to ask you SOME type of question about your issue.

For example, on our recent trip to Florida, my coach died in the middle of I-95 in downtown Jacksonville, FL. We were stopped in traffic and temps and guages were ok when it just quit.

Without my RR4, I would have not been informed that the fault was related to the engine control module (ECM). Not knowing that, I would have turned it off and waited for a tow. But thinking (or rather hoping) that the ECM might have a few automatic resets, I waited 5 minutes and restarted and got out of traffic. A call to the local Cummins guy, with the fault code in hand, turned out that I had 1 of 3 possible problems. 2 were fuel related, and the other was the catastrophic 'fuel pump is failing'. But, since the code had reset, he stated that he could not troubleshoot the problem (because the fault was now inactive) without pulling parts and seeing what was broken. Fuel pumps are several thousand dollars.

We got through the bad fuel and the problem did not return. At a minimum, I saved myself 2 hours of labor and potential tow damage.

That's the type of info that RR4, SilverLeaf, and probably the Trip Tek can provide the user. Information that would benefit the wallet and the Cummins tech.

emiddleb · 03-30-2010, 12:20 PM

Well, as an update...

Mechanic said 'no trouble found' since no ECCs anywhere recorded. Wasn't until I pointed out boost and low power that they said 'hmmmm...'

I do agree with what you said about not telling mechanic what's wrong. Please note I did NOT say 'fix turbo'... I said 'low power' and one thing I noticed was low boost pressure.

Same way I'd tell a doctor 'chest pain' but not 'heart attack.' One's a symptom, the other is a diagnosis.