Ok,

I changed the spark plugs from autolite 3924s to 3923s at .45 gap. No more pinging. The tank of gas i ran right after I installed with the wrong spark plugs got me 10 MPG, a drop in about 1 MPG. Now with the right spark plugs and the fitch I just filled up at 210 miles. I filled 16.8 gallons. Round to 17 gallons. 210/17 = 12.35 MPG. That is city driving, there aren't any highways on the way to work and there is only a mile that I can drive over 45 MPH. 11 stoplights before I get to work in 7 miles. Not a gas friendly commute. Also keep in mind that I am running 24 LB/HR injectors and mopar PCM.I was told that our trucks came with 19 lb/hr injectors. I still have the sticker from when the truck was bought and it says 12 MPG city. Thats with the stock PCM and
stock injectors (and stock tires). So I think 12 MPG in my truck is very good.

My old MPG city used to be less than 11 mpg. So its about a 1.5 MPG increase.That is also with 92 octane, but since I have the Mopar PCM,I must run at least 92 octane.

Performance wise, it hashelped out a lot with throttle response and keeping more consistent power through the low powerband and up hills/overpasses. I amvery happy with it. However, I don't think i would buy one for my wife's Hemi Cherokee. That one costs almost 300 dollars whereas mine was"only" 175. Today I just put my Holley open air element on (like the one indy has) and we will see what I get with that plus the fitch. Today I also did Steve's TPS cleaningDIY and noticed a difference during the test drive. We will see what I get with the open element and TPS cleaning after another week. I think the fitch willhelp those modsto producebetterfuel efficiency results than without it.

Hope this offers insight. But still more to come with my weekly fitch updates.

 

Good to know - I've considered buying one, but never put serious thought into it. Now, it might make me a little more serious.

 

I don't want this to come off wrong so please don't take this the wrong way as I really am interested in how this thing is working.

I don't know how you'll get a good read on this when you're changing stuff. Changing plugs could have given you that lost throttle response back. Also, a non-regulated commute will mess with MPG. You could get stopped at 3, 5, or 11 lights on the way to work and that could really change the MPG.

From a more scientific stand point, is there any way you can take it out on the freeway for some runs to check it with and without the fitch? Heck, resetting the onboard overhead computer's estimated MPG and using the cruise control at the same speed would at least be a start in a controlled test.

Also, did you state earlier that you bought it because of the claim that it could run 87 octane when 92 was called for? Have you tested that out?

I just don't want this to turn into a TB spacer thing where you'd swear it works just because you spent money on it, not because you tested it thoughly and proved it worked with real data.

 

Aim,
I understand what you are saying. I have done spark plug changes before, but i never had anything noticeable by swapping plugs...unless one set made me ping and i changed it then i wasn't pinging. I haven't started to downgrade octanes yet, but i will. I can take it out on the freeway, but i don't know how much that will help because I can't drive 200 miles for fun on the freeway. Don't have the time and i don't want to waste 3/4 tank.

I still have the receipt. And if I am not satifsied with what it says it is supposed to do, then i am going to return it. So far its decent, but if it doesn't work with 89 octane, its going back.

 

If I had some extra money, I would buy one, cut it open, and see what exactly is too it. But one thing that is important to remember is that even mood can have a big effect on fuel economy. So if you just spent $175 on this thing, you will probably expect it to do something, and you may have subconciously changed your driving habits slightly.

Sparkplugs can make a large impact on throttle response and fuel economy as well.

 

210/16.8 = 12.5 mpg. 12.5/11 = 1.136 or 13.6% difference. that is a pretty big jump. keep track of it for 3 or 4 tanks and see if it holds up. As Squirl mentioned however a plug change could help in mileage. I would hold off on any other changes until your convinced the fitch is responsible for the gain. if you can bypass the fitch and go a week or so back & forth to work to get a current mileage to compare against (after the plug swap & tps cleaning) then you'll have a better idea of the improvement.

thanks for the update!

 

After one more week with the fitch, I am gonnareconnect the fuel line in and run a tank. It comes with a quick disconnectto make things easier if you want to run without it. So in 2 weeks you will get the non fitch results after running the fitch for 2 weeks. I decided that because Steve's TPS cleaning tip made a big difference andI am running an open elelent air cleaner.

The reason I bought the fitch was because I noticed something about fuel quality when i was driving from NJ to Oklahoma without the fitch. We stopped on a NJ turnpike gas station (sunoco)and there was a HUGE line. meaning a very busy place so the fuel gets sold as fast as it comes in. I filled up with 93 octane. During that 200 mile leg I only used 16.6 gallons of fuel towing/hauling 2600 lbs added to the tare weight of my truck (HWY miles). I noticed it went up hills better (not as signifigant a drop in MPG upon hitting the hill) because instead of going from 75 MPH to 50 MPH, the lowest it dropped was between 60-65 and it stayed in OD. Then the tank i filled up after that, was at another sunoco but it was not busy at all. My truck sucked 19.5 gallons on 190 miles and dropped back down to 50-55 when hitting a hill. That is a big difference. I figured if the fitch can make every tank perform like fresh gas (like it claims) then it would be worth 175 in my opinion. During a 2300 mile trip I was able to get a real good assessment of fuel and fuel quality. As well as how fuel type and quality affects mileage. I would even buy SPT fuel injector cleaner and octane booster during some fillups, but the gain was minimal.I found out that fresh gas works better thana fillupwith1 bottle of STP and 2 bottles of octane booster, wich was 10 bucks in additives right there.