better mpgs?

[WalterMitty]

Central Sequential Fuel Injection to Multiport Flexible Injection actually.

So is this an improvement over a normally operating SFI or only an improvement if you already have a problem?

That doesn't look very clear re-reading it.

I can get close to 14 on the highway with 285's and the cruise set in the 70's. I'm not willing to switch to 245's and cruising speeds of ~55 to achieve 18-20 though; my time is worth more to me, especially on long distances.

So is this more of an upgrade when a repair is needed as opposed to a self justifying refit?

 

[ibchrisp]

CSFI to MFI

Great question, I hope this answers it.

I had the injector/poppet valve (on cyl #4) become restricted and it was causing a misfire. I actually bought one of the CSFI injectors (for $60) and replaced it, the miss did go away and my Tahoe ran as good as it ever had since I bought it (with 100K miles on it). But about a week later I drove a friends Tahoe (w/275K miles on it) that he upgraded, it ran so good I pulled my Tahoe apart and did the upgrade.
FYI, I have 275/75R16 Goodyear Wranglers and whether towing or not my MPG does not seem to vary until I exceed 75-80 MPH.
I did encouter one problem (that I caused) and that was after installation of the MFI I encountered a misfire on cyl #2. But upon inspection I discovered that during reassembly I accidentaly bent one of the pin terminals on the electrical connector for that cylinders injector, so I straightened it and the problem was solved, so be careful. With gas approaching $5 a gallon here in So. Cal. the retrofit is well worth it!! Good Luck

 

[sparg93]

Good info IBC.

Just to supplement - I also completed the upgrade on the spider (order the Delphi unit - OEM manufacturer - from Amazon for $230) b/c I had minor leaks on both banks that BlackBear picked up on. It wasn't enough to throw a code, but it was getting close.

Prior to the upgrade I was running 285's with 2" lift and averaged ~15mpg. Now I'm running a 4.5" lift and about 500lbs more in weight and I've retained my 15mpg (whew) after the upgrade.

My truck always ran really smooth and had power on tap so the only improvement I saw was simply not loosing mpg's when I should have. I guess the upgrade netted me about 0.5 - 1.5mpg improvement.

2hrs for the job is moving really quick...it's a piece of cake, but if you haven't done the work before, assume it's going to take the better part of the day. Also, you must have a torque wrench on tap...don't put the plenum bolts back on by feel.

 

[robhenry2990]

http://www.amazon.com/Delphi-FJ10566-Fuel-Injector/dp/B000TYLIFS/ref=pd_bxgy_auto_img_b
i got like a +3mpg off of this and it runs like a rapped ape good upgrade well worth it. i would also seafoam everything to help clean it out along with a QUALITY PARTS tuneup and i think you would see some noticeable gains

 

[Dalton916]

I converted my stock Tahoe (265/75/16 AT's) a few weeks back from Central SFI to the MPFI (Also bought from Amazon). I had planned on doing it, but it degraded to the point I HAD to do it. Fuel mileage had crashed to around 12.5.....

First tank after the upgrade was 13.3, second tank was 15.5, 3rd tank after was 16.9 and the 4th was also 16.9 mpg. None of these miles were interstate and no trip was over 25 miles long. Up and down hills and curvy ass roads and a decent amount of time in 4wd and/or pulling a boat. The dang thing runs like a dream!

 

[Ceejkay]

i see you said you just bought the truck, but what about a full fluid change and tune up?

 

[LittlePearl13]

Haha well, now that I know what it stands for.... I still don't know what it really means. I get that it has to do with the Fuel Injection, but I don't understand how it works, what it is, or how you would go about an install like that.

 

[WalterMitty]

Haha well, now that I know what it stands for.... I still don't know what it really means. I get that it has to do with the Fuel Injection, but I don't understand how it works, what it is, or how you would go about an install like that.

If you're driving a 95 don't you have TBI? If you do I don't think this would be an option.

 

[SunlitComet]

There are performance upgrades related to TBI as well but usually start at $500+

 

[tlamot01]

Unfortunately, we will all be forever plagued with poor gas mileage in our large SUVs. This is without a a doubt due to the addition of 10% ethanol (which is proven to lower MPG - just Google it). Those of us who remember the pre-ethanol days, can convincingly say our trucks got the advertised 13 city/ 18 highway with absolutely no mods. After ethanol, we were luck to get 11 city / 16 highway. Ethanol is by far the worst government mandate of the last 30 years. It has destroyed MPG, is strip mining our land and costing us more in tax dollars to produce than we will ever see in benefit.
Sorry, but as long as you're dumping crap-anol in your tank, there isn't much you can do to improve MPG.

PS. Our beloved elected officials have considered (been bribed/paid off to) boosting the minimum blend to 20% next year. So get ready to see your MPG go down by that same margin - again.

98 Yukon SLT (Elec Fans, K&N FIPKII Intake, Complete AC Delco tune-up, MPFI conversion, Underdrive pulleys, Headers, remote start)