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98FlameRdDak
Dodge Dakota
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11/01/2002
21:30:32

Subject: Gas milage help??
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Okay here is my story...

After putting up with my truck dying all the time, I decided 2 weeks ago to rip the throttle body off the truck and see what was going on.

I found the throttle body covered in gunk and the idle vavle solenoid half open. The port where the solenoid sits was full of carbon, so I removed the solenoid only to have it come out in three pieces.

After tearing the blades off the TB and removing all the sensors as well, I grabbed an old tooth brush and a can of carb cleaner and started cleaning what hasn't been cleaned since I bought the truck in January 2002.

I found a new idle valve solenoid at Auto Zone and while I was there I decided I didn't like the way the 3923 performed so I bought a set of Denso's to replace the autolites. They weren't that expensive anyway.

After cleaning the TB, I installed the new plugs so that the TB could dry out. Put all the sensors back on the TB and reinstalled the TB with new gasket.

Everything went well until I stared the truck. The truck started but idled real high and then the check engine light came on. I waited for the truck to idle down some before I turned it off to reset the computer. Reset the computer and everything was fine.

During this whole adventure, I decided to remove the K&N filter and put the stock air system back in.

My problem now is some 400 miles later, my gas milage has dropped. I went from 13-14 miles to the gal to 10 miles to the gal. It is costing me almost 35 bucks a week to keep this truck on the road.

I will admit that since I have replaced the spark plugs and cleaned the TB, and replaced the idle valave solenoid, the truck has not died once and the idle is much smoother. Before it would fluctuate from 550-800 at idle.

So my problem is now, what do I need to do to get my milage back up? The cap and rotor look good, the truck seems like it is running good. I can't figure out why my milage has dropped??

I thought it might have been a vacuum leak between the TB and manifold but I hear no hissing sounds and the gasket seems to be okay.

By the way, before I posted this message, I tried 87 octane and 89 octane and see no difference in milage. So where did I go wrong?

Any ideas or suggestions would be greatly appreciated. I dont want to take it to the dealer.

Thanks.

Mark




Smitty1000
Dodge Dakota
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11/03/2002
02:24:41

RE: Gas milage help??
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Try sraying some carb cleaner around the base of the TB. If the Idle changes you've got a vacuum leak. What's the Mileage? And try resetting the PMC. Let me know what happens.



98FlameRdDak
Dodge Dakota
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11/03/2002
09:24:26

RE: Gas milage help??
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98 Dakota 4 by 4 with 57,800 miles. Tried the leak test and nothing appeared to be wrong with the gasket. Have reset the computer 3 or 4 times and still no change. I am leaning towards O2 sensors? But I am not getting any error codes.

Thanks for the help.

Mark




Jake
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11/03/2002
15:07:51

RE: Gas milage help??
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Try putting your K&N back on. That should help out a little. Maybe not 3-4 mpg, but definetly some. Did you gap the plugs correctly?
Jake



dakotamaxx
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11/03/2002
19:17:40

RE: Gas milage help??
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i used too much TB cleaner on my engine and it fried three O2 sensors,,check engine came on and mpg loss!lucky for me they all got replaced by dealer!!!



dmagoo24
Dodge Dakota
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11/03/2002
20:17:01

RE: Gas milage help??
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maybe wrong wire on wrong plugs? maybe...



disturbed202
Dodge Dakota
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11/03/2002
20:27:41

RE: Gas milage help??
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i have a 93 dakota with the 3.9 auto, i was getting 13 at best then changed my o2 sensor and jumped up to 16-17. it never threw any codes either. hope that might help.



rednek
Dodge Dakota
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11/03/2002
21:25:42

RE: Gas milage help??
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try vacuum hoses



Smitty1000
Dodge Dakota
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11/03/2002
23:22:29

RE: Gas milage help??
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If your not getting any trouble codes I dought if it is the O2 sensor(s). At this Point I am leaning toward a bad cat. It seams to be a common thing with these trucks. I dought its the plug wires, usely good for 100k,but it has happened.
the best way to find out is to check the resistance (ohms) with a meter. The resistance should low, 3 or 4 ohm. Rember to watch for the sneeky "K" that sneeks up on the meter meaning Thousand. Let me know



98FlameRdDak
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11/04/2002
19:18:48

RE: Gas milage help??
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No error codes and no vacuum leaks.

Vacuum leaks was the first thing I checked.

Are the catalytic converters covered under some kind of EPA warranty for seven years? If so, how do I go about getting the dealer to cover something like that?

How hard would it be to gut the stupid thing? I live in Indiana and we don't have vehicle inspections so I wouldn't have to worry about that. I guess if the county I live in decided to pass smog inpections, I would worry about it then.

Mark




Smitty1000
Dodge Dakota
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11/05/2002
00:34:55

RE: Gas milage help??
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Cut it out and replace it with pipe



98FlameRdDak
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11/05/2002
19:02:39

RE: Gas milage help??
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if I rip the cat out, what becomes of the O2 sensor after the cat?

Mark




DakotaDan
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11/05/2002
19:49:04

RE: Gas milage help??
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You would probably need the KatBox because you would most likly trip the MIL




Dan

"Can You Hear Me Now"........................................GOOD !!!!!!!!!!!!!!!!!!!!!!!!!

Zaurusman
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11/05/2002
21:46:19

RE: Gas milage help??
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The cat's covered by the 80K emmissions warranty, as is the PCM, etc. O2 sensors aren't. Meanwhile, I'm on cat number four and all of mine rattled when bad. Whatever you do, from what you said of the throttle body, I'd run a good decarbonizer like SeaFoam through that engine and then check the plugs.

HTH

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Zaurusman
'98 RC Red Sport V6 5spd 3.21 15x8's
http://home.earthlink.net/~tiborkun/Dakota/Index.htm

98FlameRdDak
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11/05/2002
22:19:41

RE: Gas milage help??
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Zaurusman:

Never heard of Seafoam. Where would someone get that? Also, If I gut the cat, or remove it, won't I have to replace the cat when I sell the vehicle?

Mark





Zaurusman
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11/05/2002
22:26:08

RE: Gas milage help??
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Dunno 'bout the selling/gutting; never pursued either. But Seafoam can be purchased at O'Reilly's if you have them up there; not sure where else. The liquid is better than the aerosol; produces a much more satisfying plume of smoke. :-)

--
Zaurusman
'98 RC Red Sport V6 5spd 3.21 15x8's
http://home.earthlink.net/~tiborkun/Dakota/Index.htm

-=Ira=-
Dodge Dakota
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11/21/2005
17:39:47

RE: Gas milage help??
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I also need help !!! I done my own exaust work, and when i put my O2 sensors back on, i welded ( yes welded :( ) them back on before the Cat. I know the first O2 sensore is going to be ok. But the one O2 sensor (that is supposed to be behind the Cat) isnt going to be ok. now my truck is running to lean and i got crappy MPG. Is there a way to fool my computer the 2nd O2 is reading good emissions? P.s. O2 sensors cost alot this is why idont buy a new one.



shdow
Dodge Dakota
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11/22/2005
07:03:17

RE: Gas milage help??
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I got seafoam at autozone $5.99 can

I ran my tank down as far as possible and stuck 3/4 can in still running on fumes but carry 5 gals gas for backup I want it to run out
it's 1/8 inch below empty mark right now

I don't know what milage I'm getting but it's better than my ford van I had I guess easy 15 city

I'm going to load it up with a 10 gal even
and track it

stock 3.9 1998 ext cab 4x2
with a k&n type filer right off the air cap might do a pipe to front



Bob Lincoln
Dodge Dakota
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11/22/2005
08:56:08

RE: Gas milage help??
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"Also, If I gut the cat, or remove it, won't I have to replace the cat when I sell the vehicle?"

It is a felony to remove or disable an emissions control device, so if caught you will face a $2,500 fine. If you go to sell it and it is found to be missing or gutted, you will be held re$pon$ible for fixing it at the lea$t, if not charged with the crime.

I don't believe it's a bad cat from these symptoms. And yes, it has a federal warranty of 8 years/80K miles. You may have damaged the TPS or AIS with the cleaner, and won't necessarily get a code.



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