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why now, sudden decrease in mpg???

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Old Aug 12, 2006 | 11:46 PM
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From: hazlet township nj
Default why now, sudden decrease in mpg???

My mpg were always low, but now its really pathetic. It was 13-15 mpg. Now around 8 mpg. No recent changes at all.
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Old Aug 12, 2006 | 11:51 PM
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Maybe your state has switched to ethenol blend fuel..that will do it for sure...even worse if blend is the E85...a few states are at E20....

How is it running? Can you stand on it without any hesitation ?
Rich
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Old Aug 12, 2006 | 11:55 PM
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HOws your air cleaner element ?
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Old Aug 13, 2006 | 12:45 AM
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Spark plugs. AC DELCOs fail fast.
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Old Aug 13, 2006 | 08:09 AM
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From: hazlet township nj
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4 of the plugs are new and the air cleaner is also new. Slight stumble from a stop. Other than that it runs very strong. I use sunocco 93 or Exxon 93 here in Jersey. Not sure about the ethanol content.
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Old Aug 13, 2006 | 09:19 AM
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Originally Posted by 77 zz4
4 of the plugs are new and the air cleaner is also new. Slight stumble from a stop. Other than that it runs very strong. I use sunocco 93 or Exxon 93 here in Jersey. Not sure about the ethanol content.
Slight "stumble" indicates issues with ignition timing or carburator or even a faulty coil...

Why just 4 new plugs ? I'd check plugs...then tune engine..

Rich
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Old Aug 13, 2006 | 09:37 AM
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I had a problem with a Holley. The secondary needle valve was leaking enough to drip gas onto the throttle plates. It ran ok but was a little unsteady at idle.
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Old Aug 13, 2006 | 11:10 AM
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NJ is now at 10% ethanol.

im also curious as to why only 4 plugs? and only thing i can think of
is did you check the replaced plugs for proper gap?
i know a lot of people that think they are gapped from the factory
and just throw them in.
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Old Aug 13, 2006 | 12:31 PM
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Have you loosened the reset the timing lately?? if so, and it was off a decent bit, two things to check, that the harmonica balancer is not slipped on it's rubber damper....and then, IF the timing was seemingly 'retarded' a fair amount when you set it, you may be fighting a slipped timing chain....engine will run kinda rough but still run with reset timing at the dist, which in fact only masks the fact of the cam timing being way in hell off, and it looks 'normal'.....when reset....
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Old Aug 13, 2006 | 02:53 PM
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When checking your air filter did you look to see if your choke was fully open? If it is closed or even partialy closed you will suck a boatload of gas and definetly a hesitation problem.
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Old Aug 13, 2006 | 11:39 PM
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From: hazlet township nj
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I guess my friend only replaced the plugs which were bad. I'll check the choke later and get back to you.
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Old Aug 27, 2006 | 03:25 PM
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Originally Posted by rihwoods
Maybe your state has switched to ethenol blend fuel..that will do it for sure...even worse if blend is the E85...a few states are at E20....
Not true. E10 has been found to provide a slight improvement if any change is statistically significant. If he ran E85 by mistake, the engine would sputter like crazy depending on how much E85 was in the tank. The more the E85 the worse it would be as it would run horribly lean. Of course, if he was running FI the effects would be less. On my C5 I show an approximate 5-9% better MPG than straight gasoline.
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Old Aug 27, 2006 | 04:58 PM
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Originally Posted by TheDarkKnight
Not true. E10 has been found to provide a slight improvement if any change is statistically significant. If he ran E85 by mistake, the engine would sputter like crazy depending on how much E85 was in the tank. The more the E85 the worse it would be as it would run horribly lean. Of course, if he was running FI the effects would be less. On my C5 I show an approximate 5-9% better MPG than straight gasoline.
I think results are much different with pre-1988 cars...
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Old Aug 27, 2006 | 09:17 PM
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Get a full tune up.Check the timing.Check the tire pressure.Replace all the plugs.
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Old Sep 13, 2006 | 06:16 PM
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Originally Posted by rihwoods
I think results are much different with pre-1988 cars...

Not likely. The energy content of E10 is less than 5% difference. The normal variation of base gasoline is greater than that. A drop from 14 to 18 is a lot more than 5%, or even 10%. That's about a 42% drop.

I ran my 74 Hornet on E10/G100 with no noticable difference. Granted my tests back then were not as rigorous as they are now. But no noticable difference is still no noticable difference.

There is no way E10 can be the cause of a 42% drop in fuel economy.
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