MPG with late Gen 2 Montero + larger tires?

scrubber3

Not really here
Yeah, I know what e85 is. I know how it's made too... I am curious how it helps clean the injectors. You'd be better off outing isopropyl alcohol in it I think.
 

SoCalMonty

Explorer
E85 would destroy your gas mileage. You need approximately 20-30% more E85 compared to gasoline.

This is why the only "modifications" most cars would need in order to run on straight E85 are fuel delivery modifications (larger injectors). Custom tuning would do you one step better, and in some cases a larger fuel pump. But more often than not, most cars could run on E85 just as they are now. It's a wives tale that the fuel system can't handle it, except in very rare cases on very old cars.

I started running half E85 and half 91 octane in a modified turbo car and ran it that way for a year before going to full E85. At that point, I put in a larger FPR and ran only E85. Eventually, I put in a higher flow fuel pump and larger injectors as it was running a bit lean under high boost and high RPM.

But anyway...E85 will reduce your fuel economy.
 

scrubber3

Not really here
Exactly, which is why it puzzled me when E85 was recommended to "clean" the injectors. Not to mention the residue it leaves behind on equipment that isn't E85 compliant.
 

SoCalMonty

Explorer
In the cars that I've used straight E85 in, there's never been any residue of any sort. Quite the contrary, actually. Pulled out an in-tank fuel pump after 10k miles of going to full E85 on one particular car; the sock filter and pump pickup were spotless as if I just opened them up and hadn't installed them yet (this was in a track car with 298,000 on the chassis, fuel tank, and all fuel lines). Injectors were also perfect.

If you know all about E85, then you know the "gunk" it's said to leave behind is caused by the cleaning action of the ethanol dislodging fuel system deposits which thereby can cause issues.

Yes, iso alcohol would clean your fuel system the same as ethanol - and prevent the buildup of alkenes/olefins. You could use either one; indeed, I've heard of people using all sorts off different alcohols.

Virtually every vehicle built since the 1980's is "E85 compliant" in terms of corrosion resistance, and fuel tanks aren't made from steel anymore. When E85 was just catching on here, I used to post a material compatibility document from DuPont Labs, where they tested E85 with all sorts of rubbers and plastics and metals. Long story short, E85 is not harmful to any modern day materials in fuel systems.

The car I was talking about above was a 1994 Volvo 850, which was driven as a daily for 3 years on full E85, until 25psi wore it out. When I parted it out, all fuel system components were still spotless. I still have the injectors and fuel pump from that car to use in a future project.
 

scrubber3

Not really here
Ummm... No. Nothing you said reinforces your claim. Fuel tanks since the 80s have still been made from steel.. Look at a 2nd gen Monty. Why is it that some cars are Specifically E85 compliant? Why is that since the introduction of 10% ethanol in normal gasoline, small engines have had major issues with gumming up in the carbs? Or even water build up in the bowls?

There still is nothing backing the claim that a small amount of E85 will clean fuel injectors... Most gasoline out today has about 10% ethanol in it anyway. As a derivative of corn, E85 does indeed leave behind a residue and does erode certain gasket materials very quickly.
 
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jeep-N-montero

Expedition Leader
Ummm... No. Nothing you said reinforces your claim. Fuel tanks since the 80s have still been made from steel.. Look at a 2nd gen Monty. Why is it that some cars are Specifically E85 compliant? Why is that since the introduction of 10% ethanol in normal gasoline, small engines have had major issues with gumming up in the carbs? Or even water build up in the bowls?

There still is nothing backing the claim that a small amount of E85 will clean fuel injectors... Most gasoline out today has about 10% ethanol in it anyway. As a derivative or corn, E85 does indeed leave behind a residue and does erode certain gasket materials very quickly.

We are lucky enough to have a local gas station with one pump that still has ethanol free gas, costs about 20 cents more per gallon but worth it for our small engines and storing vehicles for winter. In the last few weeks I fired up our Jeep and the Miata that have been in storage since November, both started right up without a hiccup or rough idle like I would get in the past with the 10% ethanol gas. Downside is that it's only 88 octane if memory serves.
 

mapper

Explorer
We are lucky enough to have a local gas station with one pump that still has ethanol free gas, costs about 20 cents more per gallon but worth it for our small engines and storing vehicles for winter. In the last few weeks I fired up our Jeep and the Miata that have been in storage since November, both started right up without a hiccup or rough idle like I would get in the past with the 10% ethanol gas. Downside is that it's only 88 octane if memory serves.

There is a small gas station on 13th E and 9th S, near East High, in SLC that has ethanol free premium...if you'd prefer higher octane. I forget the price premium they ask for...but I've found it more than I want to pay. though I suppose for storing vehicles in the off season it may be nice. Lots of good little restaurants nearby that would make the stop worthwhile even if you aren't normally in the area.
 

monkey620

New member
Hey There,

I know this is an older thread but I am having poor MPG problems, worse than the OP, and wondering what some solutions might be. I have a 98' Monty with 33x10.5 and a rebuilt motor with about 1000 miles on it. I have not adjusted the speedo for the bigger tires and am getting 10.5 MPG for mostly in town driving when simply calculating miles on the odometer divided by gallons of gas. Even if I adjust for the bigger tires I am only up to about 12 max. I'm thinking most of the posters here haven't changed their speedo gear and are getting 15-16 even with their bigger tires whereas I am getting 10-11 running regular 87 gas

I've thought about O2 sensors, but don't want to get after those unless it's the most likely culprit as they are expensive and the "check engine" light is not on. If that's what it is, I will gladly spend the cash to save the $$ in gas . . .

Suggestions anyone??
thanks
 

jeep-N-montero

Expedition Leader
Hey There,

I know this is an older thread but I am having poor MPG problems, worse than the OP, and wondering what some solutions might be. I have a 98' Monty with 33x10.5 and a rebuilt motor with about 1000 miles on it. I have not adjusted the speedo for the bigger tires and am getting 10.5 MPG for mostly in town driving when simply calculating miles on the odometer divided by gallons of gas. Even if I adjust for the bigger tires I am only up to about 12 max. I'm thinking most of the posters here haven't changed their speedo gear and are getting 15-16 even with their bigger tires whereas I am getting 10-11 running regular 87 gas

I've thought about O2 sensors, but don't want to get after those unless it's the most likely culprit as they are expensive and the "check engine" light is not on. If that's what it is, I will gladly spend the cash to save the $$ in gas . . .

Suggestions anyone??
thanks

Your biggest issue is that you are putting cheap gas in it, thus reducing engine power, these engines were designed to run best on premium fuel. Secondly, 11-12mpg is not unheard of.
 

mapper

Explorer
Your biggest issue is that you are putting cheap gas in it, thus reducing engine power, these engines were designed to run best on premium fuel. Secondly, 11-12mpg is not unheard of.

Especially for "in town" gas mileage with brand new 33s on.

Also at 1000 miles on a rebuilt motor the computer may still be adapting/fine-tuning parameters to the way your are driving it. Depending on what you mean by "rebuilt" influencing things as well if some parts are still breaking in.
 

monkey620

New member
Thanks a lot for the responses!

I didn't realize that most were running premium fuel and that these engines were really designed for it. So I suppose most who are talking about getting 15-16 MPG are running premium. That would obviously make a difference.

I also kind of assumed that new rings, pistons, bearings, etc. would mean some break in time so thanks for some confirmation. Any on how long it might take to fully break in and advice on break-in . . .i.e. how many oil changes, what to use etc. I've heard a lot of differing theories and so far I have been pretty easy on the motor and changed to oil once and probably going to again this weekend.

On the O2 sensors, I was wondering if they were worth chasing down as they look older, maybe original. And in addition to bad MPG, I have been getting some running rich smell(not terrible) and a little jittery idle at times. Nothing huge on the idle, just popping or moving/hesitating between 600-800 at a stop with no accessories on - not as smooth as I would expect from the rebuild I guess. Yes, I am a little OCD in expecting a perfect running motor from this rebuild, or at least the ability to get it there :) Maybe I shouldn't expect that from a 17 year old vehicle :)

So all that made me wonder if the O2 sensors were partially failing and the culprit of some or all of those symptoms? Possibly? Or is the fuel more likely causing it? Thanks
 

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