mpg miles per gallon with Triton V-10

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tanksalot
Posts: 64
Joined: Wed Apr 24, 2013 6:23 pm

mpg miles per gallon with Triton V-10

Post by tanksalot »

We've had our 1999 24RB for 5 years. In the beginning we were getting between 10.2-9.5 over about 50,000 miles. After a plug change and a few miles (don't know how many) I replaced all the coils with cheapies. MPG has dropped to 7.5 or so, and eventually we realized we needed a new engine. ($9000 from Ford).

Now we get no OBD errors, it purrs like a kitten, but STILL get 7.5 mpg (just one check, but mostly flat highway in CA). We keep it at 58-62 MPH. This mpg will probably increase somewhat with time, but I'm skeptical of an additional 2.5 mpg. Any ideas?

The motor came with plugs, I had bought new Motorcraft coils in my troubleshooting before getting the new engine. Could the catalytic converter be partially plugged?

What mpg do most people get (without a toad)? We love our '99, but the drop in mileage is concerning.

Thanks in advance!
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whemme
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Joined: Mon Aug 15, 2005 8:05 pm

Re: mpg miles per gallon with Triton V-10

Post by whemme »

I have a 26' RSB on a 2000 E450 V10 chassis now with 114,000 miles on it. It used to average 8.5 mpg pulling a 3400 lb toad but my mileage has slowly decreased to around 7.8 mpg. At 98,000 miles I had the plugs and coils replaced with Ford Motorcraft parts but that never improved the mileage. I also have cleaned the MAF mass airflow sensor which also has not helped. My next step will probably be to replace the Oxygen sensors but my Ford dealer does not think that will help either since I have not been setting any O2 codes. I am puzzled too.

Your 24'RB is lighter than mine and you didn't say if you are pulling a toad. I assume you still have your original O2 sensors?
Bill Hemme - Spencer, Iowa
E-mail: whemme@earthlink.net
2002 Born Free (Ford E-450 V10) 26' RSB
2016 VW Golf GTI - toad
tanksalot
Posts: 64
Joined: Wed Apr 24, 2013 6:23 pm

Re: mpg miles per gallon with Triton V-10

Post by tanksalot »

I honestly don't know about the Oxygen sensor. I can find out from the dealer when he put in the rebuilt engine if the Oxygen sensor was replaced. I believe it's part of the exhaust system, which would mean no. I have a bluetooth OBD reader which has shown no errors. I don't pull a toad, and the vehicle is essentially identical to the configuration 80,000 miles ago.
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whemme
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Re: mpg miles per gallon with Triton V-10

Post by whemme »

Well I would agree that your 24' RB getting only 7.5 mpg not pulling a toad is poor mileage. Actually, your exhaust system I believe has 3 oxygen sensors, one in each exhaust manifold output for both the left and right 5 cylinders and also one in the output of your catalytic converter.

Too bad you didn't first try replacing the O2 sensors and catalytic converter before spending $9,000 on a replacement engine.
Bill Hemme - Spencer, Iowa
E-mail: whemme@earthlink.net
2002 Born Free (Ford E-450 V10) 26' RSB
2016 VW Golf GTI - toad
tanksalot
Posts: 64
Joined: Wed Apr 24, 2013 6:23 pm

Re: mpg miles per gallon with Triton V-10

Post by tanksalot »

The problem with the old engine was repeated misfires and oil-fouled plugs. Changing to new Motorcraft coils didn't resolve it. When cylinder #4 still misfired with the new coil, I tried to change the spark plug but couldn't get the socket on the plug. The mechanic scoped a piece of plastic blocking the plug. After removing the plastic and looking at the plug, it was badly oil-fouled. He ran a pressure test on cylinder #4 and it read 70 psi. Rather than doing just the head, I opted to replace the engine. We live in the vehicle and travel without a toad, so dependability was paramount. I also had him change the exhaust studs on the new engine to stainless steel. (I had one broken exhaust stud, but have read that it was a common issue.

Do you know if the multiple misfires could cause serious backpressure from the catalytic converter? I've never gotten an oxygen sensor error on the OBD.
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whemme
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Re: mpg miles per gallon with Triton V-10

Post by whemme »

Well if you #4 cylinder was using enough oil to cause oil fouling of that plug, evidently that cylinder had broken piston ring(s) or other serious problems. Now I understand why you changed engines. I have never gotten an O2 sensor defect code. However I have received conflicting advice on whether I should replace my O2 sensors to see if it would improve my loss of gas mileage. My local Ford dealer says that if my O2 sensors are bad, they will set a code. However, others have told me that as the O2 sensors slowly deteriorate, they may cause loss of fuel mileage before they get bad enough to set a defect code. So I guess I may try new O2 sensors to see what happens.
Bill Hemme - Spencer, Iowa
E-mail: whemme@earthlink.net
2002 Born Free (Ford E-450 V10) 26' RSB
2016 VW Golf GTI - toad
tanksalot
Posts: 64
Joined: Wed Apr 24, 2013 6:23 pm

Re: mpg miles per gallon with Triton V-10

Post by tanksalot »

Thanks, Bill!
My next approach is fuel injector cleaner.
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whemme
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Joined: Mon Aug 15, 2005 8:05 pm

Re: mpg miles per gallon with Triton V-10

Post by whemme »

I would have thought your replacement engine would have come with new injectors - but maybe not?
Bill Hemme - Spencer, Iowa
E-mail: whemme@earthlink.net
2002 Born Free (Ford E-450 V10) 26' RSB
2016 VW Golf GTI - toad
tanksalot
Posts: 64
Joined: Wed Apr 24, 2013 6:23 pm

Re: mpg miles per gallon with Triton V-10

Post by tanksalot »

i'll ask, but don't think so.
Bindshedler
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Joined: Tue Jun 13, 2023 7:20 pm

Re: mpg miles per gallon with Triton V-10

Post by Bindshedler »

We have hade the pleasure of owning a 2000 24 rb, 5 years plus..This spring we did 4000 miles from FL. to upper Mich, to MO then Alabamy to Mobile...Average 9.7 whoke trip .Vehicle had 96000 miles. We drove 33,000 miles averaging
9 plus mpg changed plugs and coil packs at 80 000, used Seafoam engine cleaner, reg maintance..Bought in Nebraska drove home FL in Feb EMPTY, 10 TO ALMOST 13 MPG.Never see that again...Now bought a 2007 26 rsb not sure about milage yet, but 2000 pounds heaver.......
perleys
Posts: 117
Joined: Wed Aug 05, 2015 3:45 pm

Re: mpg miles per gallon with Triton V-10

Post by perleys »

I am following this conversation since I have been frustrated by the low mileage on my 2004 26RSB. I don't tow but am fully loaded as to on-board weight. I don't drive over 65 and more commonly average 60. It I ever get 9 mpg I am ecstatic. I sit more commonly at 8.5 mpg. I had a fuel induction cleaning along with fuel filter change a while back and I couldn't see that it improved anything. Early when I first got it they replaced both front 02 sensors. I remember when I first got the coach people kept saying that the Ford E450 never gets good mileage even if it doesn't have a motorhome on its back! I don't have an OSB reader. Do you suggest that is a good investment?
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cmeadows
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Re: mpg miles per gallon with Triton V-10

Post by cmeadows »

If the engine appears to be running fine and not throwing codes, then it could also be Brake calipers that are not fully releasing and are causing a drag.

Have your mechanic jack up a front wheel. Give it a spin. If it won't continue to spin without assistance, then likely the caliper slides need to be greased and the castings need cleaned. This involves removing the caliper (do not have to remove the flex hose or disconnect the caliper), removing the pins and boots from the front calipers and regreasing. While it is apart, use a file and clean the mating cast iron surfaces of the caliper and the bracket. These surfaces can be coated with anti-seize to slow down corrosion (Permatex 77124 Nickel Anti-Seize). The caliper should slide freely in the bracket. Loose is good, tight is not. Clean and lube the internal slide pins before reassembly (Permatex 24110 Ultra Disc Brake Caliper Lube).

The rear calipers are a bit different. instead of slide pins, there are stainless-steel/rubber/stainless-steel wedges that go between the caliper and the bracket. Remove the caliper, file the mating surfaces to clean corrosion. Clean the stainless wedges (green scotch bright works). Coat the castings where they contact the slides with a good anti-seize or caliper lube (Permatex 24125 Ceramic Extreme Brake Parts Lubricant).

While the calipers are off, wiggle the pads to make sure they are not binding in the brackets. If they are, remove them and file the contact surfaces. This is a good time to replace the pads if needed. Loose is good--tight and binding is not.

There are differences in gasolines. Oxygenated fuels offer lower fuel mileage. The higher the content of ethanol in gasoline, the lower the BTUs which results in lower fuel mileage.

And the easiest fuel mileage problem to solve... tire inflation.
Chuck & Laura Meadows
'99 24RB PSD
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