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Author Topic: How to Tune for Fuel Economy  (Read 8125 times)

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Offline donnyeagle

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Re: How to Tune for Fuel Economy
« Reply #15 on: January 10, 2013, 10:35:10 PM »
I hear ya on the Festiva. I'm no into owning allot of cars. That's why I want to get this one working. I really like the challenge. I like tweaking. It just seems like I have done allot of the things suggested with no improvement. I do want to try the ECM system and see what happens. Not sure what I have to have hooked up for it to work. I know I have to undo the bypass and hookup the stepper motor. What else do I need to have hooked up?

Offline carnuck

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Re: How to Tune for Fuel Economy
« Reply #16 on: January 13, 2013, 07:27:09 PM »
The first "modification" I do to every AMC I have ever owned is change the ignition coil to match a late '70s Mopar. (NAPA number IC12 or IC12SB the cheaper version) and do away with the horseshoe connector that left me stranded several times. It makes nearly double the spark of the stock coil, which was designed for points systems. You need hotter spark to jump a lean gap on the plugs.
FOR SALE
'87 Comanche 4.0L AW4/NP242 3.73 gears, lifted 5" on near new 33" tires $3500 obo
'82 Eagle Wagon (Brown Betty) 4.2L/727/NP229 and soon 8.25 rear axle and non-vacuum 3.08 front to match. 235/75/15 tires. It's down to minor body work (someone creamed my driver's door but I have another in good shape) almost rust free and interior work (seats are worn and carpet torn). $2000 but about to go up due to more work being done.

Pics of my other for sale stuff http://tinyurl.com/jimsclads

Offline donnyeagle

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Re: How to Tune for Fuel Economy
« Reply #17 on: January 14, 2013, 04:39:57 PM »
Did the Mopar coil help your fuel economy?

Offline eagle87

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Re: How to Tune for Fuel Economy
« Reply #18 on: January 14, 2013, 05:51:56 PM »
for fuel economy i would recommend bosch fusion spark plugs 4508 or platinum +4 4428, as well as replacing the tired fuel pump, and coil (stock coil), what condition is the pcv valve in? and fuel and air filters? and re connecting the ecm would be recommended, what exactly do you have left in your engine compartment for the electronics? does the stepper motor operate when power is applied when the carb was rebuilt?( also are the idle/milture screws set to factory spec), what is the ignition timing set to? also if you reconnect the ecm it must be reset using the correct amc proceedure due to the knock sensor, if you reconnect the ecm i would recommend a new oxygen sensor as well, also using royal purple engine oil i found helped mileage some
2010 Ford Explorer (Red)
2004 Jeep Grand Cherokee Special Edition (Blue)
2002 JeepGrand Cherokee Overland Edition (Silver) Rolled
2001 Cadillac Deville (Silver) Blown Engine :(
1999 Jeep Grand Cherokee Ltd (Graphite) Parts Jeep
1998 GMC Safari (Blue)
1990 Mercury Sable (Red)
1987 Eagle Wagon (Beige)
1987 Eagle wagon (Silver)
1987 Eagle Wagon Limited (Brown)
1986 Eagle sedan (Blue)
1983 Eagle SX/4 Sport (Black)
1982 Concord DL (Maroon)
1968 Rebel Conv (Gold)

Offline greymarooneightytwo

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Re: How to Tune for Fuel Economy
« Reply #19 on: January 14, 2013, 06:38:16 PM »
As someone who just ordered the Motorcraft 2150 and an HEI distributor... I don't like hearing everyone talk about having to reconnect the ECM, I was planning on permanently bypassing it.

Offline eagle87

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Re: How to Tune for Fuel Economy
« Reply #20 on: January 14, 2013, 07:02:10 PM »
i have 5 eagles and a concord with the ecm connected, once tuned exactly (there very sensitive) it is possible to get upwards of 25 + mpg hwy
2010 Ford Explorer (Red)
2004 Jeep Grand Cherokee Special Edition (Blue)
2002 JeepGrand Cherokee Overland Edition (Silver) Rolled
2001 Cadillac Deville (Silver) Blown Engine :(
1999 Jeep Grand Cherokee Ltd (Graphite) Parts Jeep
1998 GMC Safari (Blue)
1990 Mercury Sable (Red)
1987 Eagle Wagon (Beige)
1987 Eagle wagon (Silver)
1987 Eagle Wagon Limited (Brown)
1986 Eagle sedan (Blue)
1983 Eagle SX/4 Sport (Black)
1982 Concord DL (Maroon)
1968 Rebel Conv (Gold)

Offline carnuck

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Re: How to Tune for Fuel Economy
« Reply #21 on: January 14, 2013, 07:31:17 PM »
As someone who just ordered the Motorcraft 2150 and an HEI distributor... I don't like hearing everyone talk about having to reconnect the ECM, I was planning on permanently bypassing it.


The ECM isn't on my list of things to have. Mind you my end game plan is EFI from a Cherokee
FOR SALE
'87 Comanche 4.0L AW4/NP242 3.73 gears, lifted 5" on near new 33" tires $3500 obo
'82 Eagle Wagon (Brown Betty) 4.2L/727/NP229 and soon 8.25 rear axle and non-vacuum 3.08 front to match. 235/75/15 tires. It's down to minor body work (someone creamed my driver's door but I have another in good shape) almost rust free and interior work (seats are worn and carpet torn). $2000 but about to go up due to more work being done.

Pics of my other for sale stuff http://tinyurl.com/jimsclads

Offline eagle87

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Re: How to Tune for Fuel Economy
« Reply #22 on: January 14, 2013, 07:37:13 PM »
carnuk, did you know there is, or atleast was a direct retrofit kit from chrysler for the 4.2 L jeep engine (ie amc engine)?
2010 Ford Explorer (Red)
2004 Jeep Grand Cherokee Special Edition (Blue)
2002 JeepGrand Cherokee Overland Edition (Silver) Rolled
2001 Cadillac Deville (Silver) Blown Engine :(
1999 Jeep Grand Cherokee Ltd (Graphite) Parts Jeep
1998 GMC Safari (Blue)
1990 Mercury Sable (Red)
1987 Eagle Wagon (Beige)
1987 Eagle wagon (Silver)
1987 Eagle Wagon Limited (Brown)
1986 Eagle sedan (Blue)
1983 Eagle SX/4 Sport (Black)
1982 Concord DL (Maroon)
1968 Rebel Conv (Gold)

Offline carnuck

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Re: How to Tune for Fuel Economy
« Reply #23 on: January 14, 2013, 07:45:32 PM »
The Chrysler HO EFI conversion kit? No longer available, but a '91 to '95 XJ setup is pretty easy to convert into the Eagle, especially if you are doing the head swap anyways. I have a J10 with 4.0L/AW4 and we converted my Spirit of the Eagle to 4.2L/AW4/NP242. He plans to switch to EFI later, but the 4.2L gets 20 mpg already with the non-feedback BBD I modified on it.

The best part about that kit was the MPFI intake designed for the 4.2L head that clears the brake booster. I plan on an Astrovan Hydroboost to cure that issue.
« Last Edit: January 14, 2013, 07:51:43 PM by carnuck »
FOR SALE
'87 Comanche 4.0L AW4/NP242 3.73 gears, lifted 5" on near new 33" tires $3500 obo
'82 Eagle Wagon (Brown Betty) 4.2L/727/NP229 and soon 8.25 rear axle and non-vacuum 3.08 front to match. 235/75/15 tires. It's down to minor body work (someone creamed my driver's door but I have another in good shape) almost rust free and interior work (seats are worn and carpet torn). $2000 but about to go up due to more work being done.

Pics of my other for sale stuff http://tinyurl.com/jimsclads

Offline eagle87

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Re: How to Tune for Fuel Economy
« Reply #24 on: January 14, 2013, 08:05:47 PM »
would the kit we are talking about be the 1st one listed here from summit racing?

http://www.summitracing.com/search/department/air-fuel-delivery/part-type/fuel-injection-systems/make/jeep
2010 Ford Explorer (Red)
2004 Jeep Grand Cherokee Special Edition (Blue)
2002 JeepGrand Cherokee Overland Edition (Silver) Rolled
2001 Cadillac Deville (Silver) Blown Engine :(
1999 Jeep Grand Cherokee Ltd (Graphite) Parts Jeep
1998 GMC Safari (Blue)
1990 Mercury Sable (Red)
1987 Eagle Wagon (Beige)
1987 Eagle wagon (Silver)
1987 Eagle Wagon Limited (Brown)
1986 Eagle sedan (Blue)
1983 Eagle SX/4 Sport (Black)
1982 Concord DL (Maroon)
1968 Rebel Conv (Gold)

Offline donnyeagle

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Re: How to Tune for Fuel Economy
« Reply #25 on: January 14, 2013, 08:17:02 PM »
I just had a strange thing happen. I filled up and topped off after a 110 mile mostly 55 mph run, about 20% hilly. I got 25 mpg, Sweet. I'll keep you posted. I think it may be as a result of an adjustment to the metering rod piston position. I loosened the small flat head screw on the pump counter shaft, light pushed down on the metering rod assembly while lightly pressing down on the tab near the flat head screw and then I tightened the flat head screw. It seems to be running better now. Time will tell.

It amazes me that so much un-burned gas is being wasted on so many of these engines. How can an engine run so rich and still run decent? Strange.

Also on the PCV valve. I have been experimenting. I tried hooking up 2 PCV valves (some say it works better on and older 258). So far this has lead to increased oil usage, difficult tuning and an erratic idle. I think it is bleeding to much air with two. I switched back to the correct setup with 1 PCV valve from the front opening on the valve cover with the evaporator tank teed in and an open connection from the rear opening on the valve cover to the air cleaner. It seems to run best this way. This engine doesn't seem to have a big blowby problem.

Thanks for all of the posts!!!!!! Hopefully it will help allot of our fellow nesters.

Offline carnuck

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Re: How to Tune for Fuel Economy
« Reply #26 on: January 14, 2013, 08:51:55 PM »
It's available again? Cool, but $till too expen$ive though. EPA put it on hold in '05 I was told.
FOR SALE
'87 Comanche 4.0L AW4/NP242 3.73 gears, lifted 5" on near new 33" tires $3500 obo
'82 Eagle Wagon (Brown Betty) 4.2L/727/NP229 and soon 8.25 rear axle and non-vacuum 3.08 front to match. 235/75/15 tires. It's down to minor body work (someone creamed my driver's door but I have another in good shape) almost rust free and interior work (seats are worn and carpet torn). $2000 but about to go up due to more work being done.

Pics of my other for sale stuff http://tinyurl.com/jimsclads

Offline donnyeagle

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Re: How to Tune for Fuel Economy
« Reply #27 on: January 16, 2013, 08:50:56 AM »
Here's an interesting idea. According to info I have been reading if the coolant temp switch is unplugged the ECM does not operate. Would that be EASIER than the bypass. Also a dashboard switch could be connected to the coolant temp switch connector and then you could turn the computer off or on when ever you want to. Hmmmm, might be fun.

Offline greymarooneightytwo

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Re: How to Tune for Fuel Economy
« Reply #28 on: January 16, 2013, 01:22:23 PM »
That sounds brilliant...

Offline ammachine390

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Re: How to Tune for Fuel Economy
« Reply #29 on: January 16, 2013, 03:40:00 PM »
Here's an interesting idea. According to info I have been reading if the coolant temp switch is unplugged the ECM does not operate. Would that be EASIER than the bypass. Also a dashboard switch could be connected to the coolant temp switch connector and then you could turn the computer off or on when ever you want to. Hmmmm, might be fun.

Don't think it would work right. Computer may not go into closed loop until the coolant is warmed up, but I believe that it always controls the ignition timing. And if the coolant is reading cold all the time, timing will be retarded giving poor economy.
Dan
1981 AMC Concord DL 258 Auto

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