Zetec MPG Advice

[JFrye]

First off, I am looking for better MPG. That is the whole purpose of this thread. I drive about 100 miles a day round trip for work. I currently get about 21-23 mpg. I normally drive about 68-76 mph.

I have an early 2000 model year zx3 with an auto trans with 3.90 gears. Currently I have a 65mm BBK throttle body, FSWerks 4-1 Header, with a sort of custom exhaust system. By this I mean, it is 2.5 inch from header to muffler(muffler is header wrapped on driver side of gas tank) and 3 inch from the muffler to the back bumper. I also have a cheap Ebay CAI(not yet installed, bc I got it used, and I havent bought a filter yet).

I have a few questions about other modifications. I plan on getting Tom's Tune, but am looking for advice if I should try to pick up a few other parts first.

Is a Wideband O2 Sensor required for the tune? If not, is it better to have it anyways?

I am debating on pulling the intake manifold off, and having it ported out. Any real gain by doing this?

Will there be any gains by adding SVT injectors, or SVT MAF sensor? If these are gotten before the tune, will there be any drive ability issues?


Right now, these are the only questions that I have. Keep in mind, that I am looking to increase MPG and not power. Plug, wires, fuel filter, and air filter have all been changed within the last 4000 miles(estimated). I am more than willing to listen to any other suggestions for improving MPG.

Thanks in advance for any input.

[Sponsor]

[sleepyboy]

Porting the intake is mainly to match it to the 65mm TB since the opening is slightly smaller. The wide band is not needed though it is helpful to have. I have one it is was helpful in telling me if I was running lean or rich on some problems that didn't cause a check engine light. With Tom's tune it is not needed to wait for upgrades as he provides free updates so you can add a mod and retune. I know a local member who is on his 6th version of a tune. If you add the SVT MAF you need to add the SVT injectors at the same time as they are both calibrated to each other. Though Tom could tune the MAF to work but it is really not needed at the power level you are at now.

[JFrye]

Will there be any MPG increase with the SVT MAF and injectors though? As I said, my main goal is to increase the MPG from 21-23 to whatever is better than that. I am not trying to set any goal really, bc any increase is better that what Im getting now.

[JFrye]

Also, with the cheap Ebay CAI, it was for a Zetec, so I dont think a SVT MAF will fit? I may be wrong, but I thought the SVT MAF is slightly larger than a Zetec MAF. If this is true, should I try to get a CAI for a SVT, or just get a SVT intake box and snorkel?

With the SVT MAF and injectors, will a SVT fuel pump help with my goals of increasing MPG? Will these items be a simple task? Like just removing my old ZX3 parts and installing SVT Parts, or will there be more modifications needed? Either way is fine, just looking for a heads up before I get into it and get surprised.

[emsvitil]

A simple air fuel mixture meter so you know when you're in closed-loop mode.

See:

http://www.autospeed.com/cms/article...art-One&A=3032

The idea is to learn when you're in open loop mode and then to AVOID open-loop mode............

You also learn how quickly you can accelerate while still in closed-loop, since open loop acceleration is generally a richer mixture than closed loop acceleration.

[thenorm]

svt injectors pump and maf will not help you. you want to decrease fuel economy, not increase your fuel throughput.

the best way to help you would be to continue your tune up.
o2 sensor, pcv valve, check egr. also those big wheels in your avatar wouldnt help either.

spending alot of money on a tune and intake etc, will liekly take forever to pay that back with gas savings (assuming they even save you gas). the only thing that might help is small, light wheels with LRR tires.

[JFrye]

That is not my current car in my avatar. Thats a previous focus I owned. I have new o2 sensors, new pcv valve. Im lowered on Eibach Sportlines, running 14 inch steelies.

[1turbofocus]

With the mods you have I would do a wide band air fuel gauge unless you never plan on going WOT
I would do a tune
180 deg thermostat
SP463 plugs gapped at .060

The tune it self may not do a lot for MPG but what it will do is bring your mods together and that might well gain some MPG , other mods listed will do the same

Tom

[tmittelstaedt]

OK your looking for MPG, let me tell you some facts, here.

1) You will never get the best MPG if your throttle is EVER at WOT. If your highway cruising, your throttle is barely cracked open. That means all the porting and suchlike does NOTHING. Porting makes no difference unless your at WOT. So do most of the go-fast stuff on the car does absolutely nothing.

2) For best MPG you want to have the car at the lowest RPM at all times. Meaning that when shifting you get the car up into the highest gear as quick as possible. And also meaning that you want the tallest gears possible. Your 3.90 axle ratio coupled with 14" wheels is a problem here. What does your RPM run at when your at 70Mph? I'd bet it's pretty high.

3) If your running a catcon, then you have very little choice in fuel mixture because while the engine will be perfectly happy running on a leaner mixture, you will burn up your catcon.

4) remove weight from the car. You said you drive for work - well do you haul passengers around and people? If not, remove your seats and put them in the garage.

5) lowering is good for MPG.

6) reduce speed. Sorry to say this but I'll give you the following challenge. For 1 tank of gas, do not drive faster than 55Mpg on the whole tank. Then check MPG.

7) Does your car have a trunk mounted spoiler bar? If so, remove it - those are MPG sucks. Spoilers work by pulling energy away from going forward and converting it to downward pressure.

8) fuel is wasted every time you apply the brakes. Be forward-looking and pull your foot off the throttle way, way, way in advance of an intersection and coast to the red light.

[DrkKnight614]

Originally Posted by tmittelstaedt

OK your looking for MPG, let me tell you some facts, here.

1) You will never get the best MPG if your throttle is EVER at WOT. If your highway cruising, your throttle is barely cracked open. That means all the porting and suchlike does NOTHING. Porting makes no difference unless your at WOT. So do most of the go-fast stuff on the car does absolutely nothing.

2) For best MPG you want to have the car at the lowest RPM at all times. Meaning that when shifting you get the car up into the highest gear as quick as possible. And also meaning that you want the tallest gears possible. Your 3.90 axle ratio coupled with 14" wheels is a problem here. What does your RPM run at when your at 70Mph? I'd bet it's pretty high.

3) If your running a catcon, then you have very little choice in fuel mixture because while the engine will be perfectly happy running on a leaner mixture, you will burn up your catcon.

4) remove weight from the car. You said you drive for work - well do you haul passengers around and people? If not, remove your seats and put them in the garage.

5) lowering is good for MPG.

6) reduce speed. Sorry to say this but I'll give you the following challenge. For 1 tank of gas, do not drive faster than 55Mpg on the whole tank. Then check MPG.

7) Does your car have a trunk mounted spoiler bar? If so, remove it - those are MPG sucks. Spoilers work by pulling energy away from going forward and converting it to downward pressure.

8) fuel is wasted every time you apply the brakes. Be forward-looking and pull your foot off the throttle way, way, way in advance of an intersection and coast to the red light.

Agreed, I'm getting around the same mpgs with a mixed commute. People don't realize just how much more fuel they suck up when you start going past 55mph. It goes down dramatically, not alittle. The difference in fuel consumption between 55 or 60mph, compared to 70 is as much as 15-20% less mpg. If you fill up your tank and drive 70mph, you'll see the needle drop below the Full mark before you even hit 50 miles driven. But if you keep the speed down 60 or below, the needle will still be at the full mark.

Not sure what kind of roads you are driving on, maybe the speed limit is 65 or 70. If so go the slowest possible without pissing people off or becoming a danger on the road. But if its 55mph and you are just speeding, slow it down. You will see more MPG gains by far then any amount of mods will get you.

Getting the best out of your car is always about how you drive and keeping your car properly maintained.