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 #353856  by adu1982
 
Probably the heater tube is rusted through, or the oring on it ...somewhat common on northern cars....intake and lim have to come of (its under the lim)
 #354307  by nokestev
 
My MPG hasn't gotten back up to the 26 mark, just 24 with the DP Champions.

I fixed the coolant leak, was a leaking o-ring on the tube, just like you said adu. Also the lim gaskets were in bad shape around the coolant passages.
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 #354308  by adu1982
 
Not too shaby....got over 24mpg on the 1500mile trip to snowshoe, up and down between the 2 mountains probably brought down the mpg. But with 4 people, full trunk , 2 pair of skis.....24+ mpg is pretty darn good.
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 #358734  by carlrs
 
Considering what mileage you guys are all getting with good spark plugs, I'm afraid of changing mine now :P

I've got some really weirdly gapped Champions (I think). No idea what exactly they are, they were already there since I got the car in September. I think they could be causing a slight low-rpm vibration, or at least I think so. And I thought that maybe I could get an extra 0.5-1 mpg out of the car with good plugs (even though at that rate, they'll never pay themselves off just from fuel economy changes).

But with those plugs, I'm getting an average of around 31 mpg (mostly highway) and I've hypermiled it to 45 mpg when I was kinda running out of gas. So what do you guys think I should do? Get NGKs for the cost of 2 tanks of gas or just leave the current plugs in there?
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 #358754  by LUNAT1C
 
31 mpg sounds like your engine is running well. Low-rpm vibration I would think is related to something else. I have NGKs in my Special, installed 25,000 miles and 5.5 years ago (two were replaced last summer as a result of other issues, just as a precaution). At 65, my Special gets 25-26 MPG, which is about right for a Special with its lower gearing. Normally I get about 22-23 highway as I tend to set the cruise to 75-80. Speed limit in Michigan is 70 and potentially rising to 75, and everyone typically does 5-10 over, so that whats I have to just deal with.

Generally speaking, spark plugs are fine up to 100,000 miles. If yours don't have that many then they should be fine.
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 #358825  by mnitetrain
 
My old 01 usually gave me around 30 MPG with either Champion or NGK. Have fought with this 04 for better than 23 MPG. Finally see 25-26 fairly consistently, might just be summer blend gasoline IDK.
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 #358934  by mopar39426ml
 
carlrs wrote:
But with those plugs, I'm getting an average of around 31 mpg (mostly highway) and I've hypermiled it to 45 mpg when I was kinda running out of gas.
Holy crap. I've hypermiled to 30... 45 is NUTS!

Teach me your ways! Lmao.

Sent from my SM-N920V using Tapatalk
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 #358935  by InfernoRedM
 
I don't think anyone is getting 45 MPGs in the hills and bends of Western Pennsylvania. I can't drive 1,000 feet without going up a hill or around a bend!
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 #359003  by mopar39426ml
 
InfernoRedM wrote:I don't think anyone is getting 45 MPGs in the hills and bends of Western Pennsylvania. I can't drive 1,000 feet without going up a hill or around a bend!
Oh yeah.

Well, maybe for 500 feet while I'm going downhill...

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 #360027  by carlrs
 
mopar39426ml wrote:
carlrs wrote:
But with those plugs, I'm getting an average of around 31 mpg (mostly highway) and I've hypermiled it to 45 mpg when I was kinda running out of gas.
Holy crap. I've hypermiled to 30... 45 is NUTS!

Teach me your ways! Lmao.

Sent from my SM-N920V using Tapatalk
Oops, I think I converted to imperial gallons, not US gallons :P Actual max mpg I've gotten (downhill doesn't count, I mean average over 40-50 miles) is more like 38.

Anyway, these days might sadly be over for me. I think I'm going to have to sell this car, despite being the world champion in hypermiling it :(

Edit: Disregard the last paragraph; I clicked on NoTime's link in this thread. My car's fine, definitely not selling it yet.
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