Low fuel economy
#1
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I get 17 mpg on long high way cruises (about 75 mph/2800 rpm). Although it is a 24 year old 5 liter engine it seems a bit low for cruising. Or is it normal? Only things I haven't done since I own the car is check the MAF and ECU. Can these cause low fuel economy? What other possible culprits are there: rings, leaking dampers/regulators, carbon build up?
#2
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Seems normal conpared to mine. I've heard of a few guys getting into the 20s but mine doesn't. Of course it seems I can manage to kill the fuel economy of anything I drive.
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I get about 18 (before the Supercharger went on) so you are right in there.
#4
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Has the O2 sensor been replaced?
Knock sensors? Cam angle/hall sensor? Retard will hurt mileage.
Cams at zero?
Autos will get a couple MPG less than manuals.
X-pipe will often drag down MPG - factory cats are best for mileage.
I managed 24.6 mpg (9.6 l/100km) in my '88 5-speed w/X-pipe on a 200+ mile round trip to the beach last month.
Pretty happy with that. Speeds were mostly below 70, though.
Knock sensors? Cam angle/hall sensor? Retard will hurt mileage.
Cams at zero?
Autos will get a couple MPG less than manuals.
X-pipe will often drag down MPG - factory cats are best for mileage.
I managed 24.6 mpg (9.6 l/100km) in my '88 5-speed w/X-pipe on a 200+ mile round trip to the beach last month.
Pretty happy with that. Speeds were mostly below 70, though.
#6
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I get 11-12 mpg. Must be that 2.73 rear end, lots of revs.
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See that makes me wonder. 17 to 18 versus 22 or 24.6 (with x-pipe), that's a huge difference. Can't be all difference auto vs. manual can it?
Ken: O2 sensor has been replaced 5 years/35000 km ago.
Ken: O2 sensor has been replaced 5 years/35000 km ago.
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#8
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Another data point, 87 AT I get 20-22 on the freeway, around 65-70mph. Long gears. Tons of variables to account for your slightly low mpg. Biggest might be your driving style. Subtle changes in throttle application result in big mpg changes. I know cause I drive many miles for work and play around with rental cars mpg indicators and watch how it changes with speed or driving style.
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I still get 19 to 19.5 on the highway if I don't get into the turbo at all for extended times (no fun in that!). I can drop that down to single digits on our fun runs keeping the turbo on full boil....
#11
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My '88 with those loping 2.20 gears rewards me with a consistent 20mpg at 70mph on road trips. I really can't complain too much considering what a joy it is to drive.
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#12
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I get 22 combined city/highway in my 81 ( yes I only have half the valves) but my injectors are 24lb'ers.
I rev it and use the fuel enrichment constantly. Could get way better if I could stay at 70mph... but the loud pedal is just too tempting
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I rev it and use the fuel enrichment constantly. Could get way better if I could stay at 70mph... but the loud pedal is just too tempting
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#13
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Wow!! Some of you guys are getting some seriously bad mileage!!
Granted, I have the 4.7, but I get 24.5 on the freeway, and I don't shy away from the accelerator. '84 5 speed, btw.
Granted, I have the 4.7, but I get 24.5 on the freeway, and I don't shy away from the accelerator. '84 5 speed, btw.
#14
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My 86.5 gets about 19 mpg on highway, I think it's good for the age of the car, it's a automatic, but I do have a 1987 928S4 trans in my 1986.5 and now I get about 21 to 23 mpg at 75 mph, tach around at 2000 rpm.
#15
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I can get 21-22mpg on the highway if I keep it at 65-70.
At 80-85, I get 18-19.
Kept good records of this on my August round trip from NY to San Antone.
The short rearend gearing is stock.
Have a 4.7 Euro S bottom end and heads.
Cams are stock '78 (euroS' left snout broke off)
Induction is stock '78 CIS. ('86 EuroS is in boxes)
At 80-85, I get 18-19.
Kept good records of this on my August round trip from NY to San Antone.
The short rearend gearing is stock.
Have a 4.7 Euro S bottom end and heads.
Cams are stock '78 (euroS' left snout broke off)
Induction is stock '78 CIS. ('86 EuroS is in boxes)