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Unread 07-22-2015, 08:56 AM   #1
Sxynerd
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Drop in MPG? Was 17, now..

My 3.7 WK has always gotten a steady 17mpg with mixed driving. In the last two weeks it's dropped dramatically down to the 11's and in this tank it is sitting at a 1/2 tank for 50 miles.

There is no smell or visible fuel leak that we've noticed and it drives normal. My first thought was that someone was syphoning gas but we've never had those kinds of troubles before.

The tires are properly inflated.

Are there any known mechanical issues that could be causing this? I have not found any searching so far.

06 WK 3.7 70k miles - stock

No CEL

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Unread 07-22-2015, 09:03 AM   #2
JKM
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When was the last time you changes the plugs? Air Filter, PCV, etc.
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Unread 07-22-2015, 09:15 AM   #3
Sxynerd
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January for all of them. I have also not found any vacuum leaks.
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Unread 07-22-2015, 01:11 PM   #4
luckyse7ens
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calculate manually
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Unread 07-22-2015, 02:33 PM   #5
johngreen1234
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Calculate manually.

Also, look under the car and see if you've added a lift or knobby tires recently.
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Unread 07-22-2015, 03:40 PM   #6
Sxynerd
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I do calculate it manually. Every single tank for every vehicle for the last 30 years. lol

It sure would be cool if some gnomes snuck under it and put a lift and mud tires on it when I wasn't looking but I don't think that's how that works in real life.


I'm going to go through it all again tonight but I'm not sure what it could be that would still retain prefect driveability. That's a drastic drop, almost too drastic for anything except something devious or catastrophic. My F150 on 35's is getting better mpg than the grocery getter, lol.
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Unread 07-25-2015, 11:36 PM   #7
KillaJeep4569
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Quote:
Originally Posted by Sxynerd View Post
I do calculate it manually. Every single tank for every vehicle for the last 30 years. lol

It sure would be cool if some gnomes snuck under it and put a lift and mud tires on it when I wasn't looking but I don't think that's how that works in real life.


I'm going to go through it all again tonight but I'm not sure what it could be that would still retain prefect driveability. That's a drastic drop, almost too drastic for anything except something devious or catastrophic. My F150 on 35's is getting better mpg than the grocery getter, lol.
Hey man I am in your boat. I was getting 16 to 18 MPG. I got Cat Code so I replaced o2 sensors. Still got code, Then replaced Cats. Still Got code, so I had to do some modifying of downstream o2 sensors.

But Now I am getting 11.7 to 12.4 MPG and Im not sure why or wtf happened.
i just replaced, and upgraded parts to make better. So why would this happen?
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Unread 07-27-2015, 08:39 AM   #8
Sxynerd
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I replaced the Air filter and PCV again just to be safe. This time though I use a Chrysler pcv instead of the autoparts store brand. Both seemed fine but PCV's can be picky. Since we don't have any codes I am starting to lean towards the tires. I won't have any results for a few more days till we burn through this tank of gas.
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Unread 07-27-2015, 08:41 AM   #9
paroxysym
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throw some seafoam in the tank and a can in the brake booster- clean 'er out.
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Unread 07-27-2015, 11:05 AM   #10
Sxynerd
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Seafoam, lol. Never in a million years. I don't subscribe to that Bull****.
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Unread 07-27-2015, 11:55 AM   #11
paroxysym
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Quote:
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Seafoam, lol. Never in a million years. I don't subscribe to that Bull****.
just saying... my v8s getting and has continued to get better mileage than your 6banger kid
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Unread 07-27-2015, 03:20 PM   #12
Sxynerd
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just saying... my v8s getting and has continued to get better mileage than your 6banger kid
Go troll someplace else, Kid.
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Unread 07-27-2015, 03:25 PM   #13
paroxysym
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lol good luck man
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Unread Yesterday, 04:42 PM   #14
luckyse7ens
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Quote:
Originally Posted by paroxysym View Post
just saying... my v8s getting and has continued to get better mileage than your 6banger kid
cmon...

While plenty of people do, and thats fine, I don't buy in to magical fixall's like seafoam either.
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Unread Yesterday, 05:21 PM   #15
Chirpz
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Quote:
Originally Posted by Sxynerd View Post
Seafoam, lol. Never in a million years. I don't subscribe to that Bull****.
Here is some anecdotal "Seafoam Bull" for ya. I too was not a believer, but....

This spring, my Honda scooter quit running... it would start, putt along at 3-5 miles per hours, stall out... repeat, repeat. I was dreading doing repairs on it since it is difficult to work on and I'm lazy. Put in a new plug, no help. So in desperation, I put 3 ounces of Seafoam in the 2.5 gallong tank. I cranked it up on the stand and let it run at 3000 rpm's for about 15 minutes then drove it around the block. Problem gone.

My Snapper lawn mower did the same sort of thing this spring on my first mowing of the season. Start, run 45 seconds, quit, restart...repeat repeat repeat. I put 2 ounces of Seafoam in the tank. After two more cycles of the bad behavior, my power was restored and the problem has not returned.

I have not continued to use Seafoam in either machine, but will again if the problems return. Why not? If it doesn't work, you can always take the repair approach.

My neighbor's lawnmower had the same problem... same cure cleared it up too.

Granted, this does not prove anything... just my experience. Maybe worth a try.
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