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Coldheader 10-15-2015 06:36 PM

Diesel Issue?
I have a 2007 fleetwood with the CAT C9 400hp diesel. I just picked it up from a private owner and I am not sure if i have an issue or not. It has 22,000 miles on it. I start it up and warm it only for a minute or so, it idles great but occasionally when i take off it feels like it is "missing", it was very bad my last time out but other times hardly noticed it. It usually powers through it and after the motor warms up past 150 degrees, it runs very smooth. Is this an injector issue or do most of these larger diesels do this? My last diesel pusher was just a small and older 5.9 cummins but it never did this. I would think an injector issue would happen all the time, even when warm?

Dutchstar08 10-15-2015 06:41 PM

I don't know about the C-9 but when I had my C-7 it ran like a top. Smooth never a hickup. Same for my now 8.9 cummins.
What you might want to check if the fuel filters and air filter.
If they have not been changed in a long time that's the first thing I'd do.

sam60 10-15-2015 06:50 PM

Welcome to iRV2!

I'm not sure that I have an answer but a good start would be to check the clamps in & out of the turbo and intercooler. It would be peace of mind at a minimum. :flowers:

Mac99 10-15-2015 06:51 PM

You are supposed to let it idle until it warms up completely
before driving it. At least 5 minutes for my ISC, until the
temp gauge moves out of the blue range. Depending on
your gauge, I'd suspect 1/4 to 1/3 of the gauge range,
maybe more in cold weather.

slickest1 10-15-2015 08:06 PM

Like said above warm it up for five or ten minutes. Use your cruise control to idle it up.
If it still does this I would change fuel filters, and if in fact you don't know when they were changed last I would just change them.

1bigmess 10-15-2015 08:14 PM

You don't have to warm up a modern diesel engine. Many fuel injection systems have a little quirk in them. I have a motorcycle that runs smooth as an electric motor above 1K RPM, but under that and it might stumble a little if you make a little throttle change in a lower gear.

Start it up, confirm oil and air pressure (if air brakes), drive it gently until it warms up or at least the first few minutes, then drive it like you stole it if you want to.

Mr. Hipster 10-15-2015 09:46 PM

Poor advice^^^. A good warm up is cheap insurance, or at least be easy on the throttle until temp is up to normal. Diesels rattle and bang due to serious forces within.

1bigmess 10-15-2015 09:58 PM

A good long warm up dilutes oil with unburned fuel. Getting that thing up to temp a little quicker by driving it easy for the first few minutes helps get cylinder temps up to good operating range. cylinder temps not in good range and you get unburned fuel, and some of that has to get down to your oil by washing down the cylinder walls.

Hey, it's your engine. I don't pay a thin dime for any of your maintenance and repairs. Do watcha like. Don't trust me, be skeptical, it's healthy. Verify this with the folks that fix the things, go to CE conferences and meetings to learn about the newest engines in their product lines, and are supposed to know more about their product than you should.

sam60 10-15-2015 10:09 PM

My old C8.3 runs great after the air bags are full and I hear the relief valve dump. About 2~3 minutes.

My 05 Cummins pickup leaves the driveway after about 10 seconds of warm-up. 302K miles on it now.

The OP needs to look at filters etc. as already mentioned. Eliminate the easy things first. JMHO

FunGus 10-15-2015 10:18 PM

If my C9 is not past about the 140-150 range it will also stumble a bit like it's missing. I have since started letting it warm up an extra couple minutes and it doesn't happen.

FIRE UP 10-15-2015 11:23 PM

Here we go again with the "Warm up" thing. Diesel engines are still DIESEL ENGINES! But, the operational characteristics, the smog compliance requirements, soot output, and more, have all changed drastically in the last few years. And, If you read authoritive excerpts from competent tech mags and articles on diesel engines of today, you'll see that there's no need to warm them up. The old, OLD school of warming up over the road rigs has been gone for decades. Although most of those boys still do it some. There's just no need or, requirement in todays technical diesels.

It always cracks me up when some YAHOO pulls in to get fuel for his 8' OFF THE GROUND DIESEL FORD pickup and, leaves it running. Airhead!

In thirty years of driving fire trucks, and all the changes that were in those engines etc. over that time, we NEVER had any engines go south due to lack of warm up for FULL THROTTLE operations to get to an emergency.

Yes, there were some issues every once in a while with injectors leaking, turbos gone south, CACs with major leaks (mostly because of severe tweaking of frames etc. for rough driving characteristics and, LOUSY SAN DIEGO ROADS, etc.

But, warming up most of todays diesel coaches is not needed and, a waste of fuel and also, AN ANNOYANCE! In our coach, an '04 Itasca Horizon 36GD with the C-7 330HP, I fire it up, make sure all systems are a "Go" for Houston and, we're off. That engine has 62K on the clock and runs like a noisy sewing machine.

As for the OPs issue, he stated it's worse at times, not so bad at others. Pretty sure warming that engine up has no effect on what his issue is. I hate intermittent problems. If somethings going to break, THEN BREAK! That way I can fix it. But, maybe if I were the OP, I'd take a good look at the fuel filter(s) as a simple, fast and for the most part, CHEAP attempt at remedying this issue.

If that don't do it, then you go into it deeper.

Gormleys 10-16-2015 07:39 AM

First off, Coldheader, welcome to the Forum!

Your first question sure hit a home run. Hopefully, you learned a couple of things without being turned off by the spirited dialogue.

Keep asking 'em!

Mac99 10-16-2015 07:56 AM

A fire truck parked indoors in a climate controlled environment
is San Diego, Ca is not representative of motor home usage.
Cummins clearly states that a warm up is required for my ISC,
and that is what I do. It only takes a few minutes for a cold engine
to come up to operational temperatures.

Mr. Hipster 10-16-2015 09:09 AM

Anti warm up guys, panties in a bunch today? Easy operation after air builds up is normally adequate. Keep the throttle mashing under control until thermostat opens, that's all.
Regarding the 'new tech' engines with urine in a tank and regen cycles and such, I'll stay with my vintage/repairable/affordable fleet, and plug them in @ night.

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