I replaced my exhaust with a Flow 40 dual outs and put in a K&N filter. The intake tube was modified with a 3" PVC tube. Re-installed factory because of studying a theory. But any way, at the same time my truck went to the shop for the tranny vibration you hear alot about on this sight and was fixed, and the heat wave moved in. My truck has gone from getting 14-15 mpg to 11-12 mpg, and it's not because of a lead foot. I have adjusted my driving going both ways and I still get 11-12. Is this because of the heat? Anyone else getting worse because of the heat? Or is it from the mods? Or, is it from maybe the tranny not engaging the torque converter properly or what? I would appreciate any ideas.

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Red '97 F-150 SC 4x4 off-road, 16" rims instead of factory 17"'s(borrowed from old '97 reg cab), BFG 265/75 16 all terrain T/A, K&N filter with modified air box, Flowmaster 40 with duals out back, Expedition center console, 3" rear seat lift, after market stereo seen at HTTP://members.sounddomain.com/red97,

 

I have definitely seen a lack of power and mileage due to the heat, but bear in mind the converter will definitely cause poor economy.

I have yet to go back to the stock setup. I did use a 4" tube though.

 

I live in memphis, it is 107 here. We are tying high temps with death valley. Gas mileage SUX. I also have flow 40's and the flows arent your problem. It is runnin the air conditioner that is hurtin.

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'97 F-150 XLT Clearcoat Red
4x2
4x4 wheels
Stepside, K&N, bedliner
32inch tires,flowmaster
tint, matching ford sticker
5spd fully loaded, hidden hitch
Comming soon:
spark plugs/wires,leveling kit,toolbox,
bed rails,push bar, CB with whiplash,
clear corner lenses,brush guard, blackouts,
edlebrock shocks, hypertech, K&N induction system,KC highlighters,
bed xtender, BOSE audio or infinity gold, disc changer,
side steps, dixie horn, white faaced gauges, and those small fender flares some 4x4's have,
matching boddy color of course, and some of those door guards,ventshade visors, power pulleys, that is all
i can think of right now

 

Don't forget that the a/c compressor is working extra hard too.

 

Yeah, what is up with the A/C thing. My fincee has a Ford Focus with a little 2.0 L engine and everyone told her not to run the A/C very much because it would hurt gas mileage. She ended up getting better gas milage. And with her car, when you turn the A/C on it's like driving another car. No pick up from the go. But you turn on the A/C in our trucks with the big V-8, you can't feel any power loss, atleast I can't, but the gas mileage goes down. WHAT GIVES!!!
So it looks like it is probably from the heat and running the A/C combo?

 

The a/c in vehicles eat a lot of power. I've read that our a/c is big enough to cool off a house. Probably an exaggeration, but you get the point.

It's said that at highway speeds, the hit you take in gas mileage is offset somewhat by the more friendly aerodynamics of having the windows closed.

Reason you don't feel the power loss so much in your truck vs. that of your fiancee's Focus has to do with percentages. The a/c in her car uses up a greater percentage of available horsepower than the a/c does in your truck.

Don't most systems these days cut out the a/c compressor when you accelerate? I think it's a vacuum actuated switch. When you accelerate, the vacuum drops and the switch opens. I wonder if the Focus has such a system?

 

Torque is why you feel the hit in the Focus.
High Torque engines (I can't even hardly feel the difference in my 5.4L) don't feel it as much due to the high HP at low RPMs.
You just put your foot in it a little more and whoala HP feels like normal.
Also the Focus kicks on the electric fan causing drag on the alternator.
What is really bad is the A/C runs on all settings except Panel, Floor and Off.
It even runs on Panel/Floor !!

[This message has been edited by 54regcab (edited 09-04-2000).]

 

It is true our A/C is equal to a home A/C unit.

It is also true you will get better mileage with the A/C on and the windows up.

The compressor will kick off when you hit a TP (throttle position sensor) reading near WOT.

 

RED,

Have you reset the computer after the mods you did? Those 2 mods will affect how the computer governs the engine greatly. With increased airflow and less back pressure, not reseting the computer will most definitely hurt mileage.

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Boss™

Ordered June 29th: 2001 F-150 Lariat, Oxford White/Silver 4x4, SC, SB, SS, 99L 5.4L, 44E tran, 7700# payload, Class III Tow, 3.73LS, Skids, Leather Captains, 4W disc ABS, shift-on-fly, keyless, HD everything
Planned Mods:
"Protected by the Owner and his 2 friends, Smith & Wesson" sticker, Westin Chromed Stainless Nerf Bars, ARE LS II bed cover, Bedrug™, Gibson Swept Side Cat Back, K&N filter w/airbox mods, headers, Superchip, 3" body lift with at least 33's, alarm/pager/auto start system, stereo system

 

Yeah, I reset the computer. I've had that A/C problem with every vehicle I've owned. Even my '97 F-150 reg cab 4.2 V6. This is the first vehicle I've had that you can't tell. Although this is my first auto transmission too(which sucks)but what'r'ya'gonna'do. Believe me, her Focus has PLENTY of torque for a little 4-banger, atleast by the seat of your pants feel. You can punch it on the highway in 5th gear and it scoots right out. I'm very impressed. So if any of you wives/girlfriends are looking for a car, they are a great one to look at. And cheep.
It is starting to get cooler hear so maybe things will return back to normal. I'm going to put my cold air intake mod back on.

 

I live in Houston and never noticed a difference from heat,,until I drove it up north in the early winter months. Man, I felt like I had a 5.4 ! It really loved the 40 to
50 deg. temps,especially before and after
it would rain. This has convinced me to
build an isolation box for my fipk. Maybe a
ram air hood,,,hmmmm. ,,,,,,,,,,98

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98 F-150 4.6 Litre XLT2wd Ext. cab
prarie tan/tan int.
K/N gen.II fipk
custom dual exh/gibson rectangle tips
color matched snuglid
B&M Shiftplus
Westin nerfsblk powdercoat
Cobra 75WXST cb w/weather alert
Kenwood cd w/RS speakers,don't laugh it sounds pretty good
On the way/wheels,tires,air dam,
doin the monochromatic boogie
on the front end.etc.etc....etc......

 

It dropped down to the 70s today and all I can say is WOW !!!

 

70's?????

My goodness, It topped 108 today, although the digital thermometer on my truck said 112
and I can tell the difference in mileage.
I'm thinking of switching out Airaid for stock to see if the "heat" thing makes a difference until it cools down a bit.
68 days without rain

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Y2K F150 4x4 XL Med Torredor Red
4.2 5 speed,AIRAID, SuperCHIP,
3.55 LS, Leer camper shell, bedrug,
Ranchhand Rover Brushguard 2X Off road lights
Tint/alarm/ aftermarket keyless entry/locks
2m radio, CB, 3 Scanners
regulator@f150driver.com