I'm probably just going with the 2.2 myself, they can be had more cheaply with low miles.

That's an interesting thought about the cam timing though, something somebody needs to look into doing. I may at some point when I have that kind of money.

I don't think the megasquirt can control VVT without some modification. Could the stock ECM be modified to control the cams, spark and timing and fuel that way?

quote Originally posted by DustoneGT: I don't think the megasquirt can control VVT without some modification. Could the stock ECM be modified to control the cams, spark and timing and fuel that way?

I think that it depends on how VVT works on the 2.4. If it's on or off, then Megasquirt could probably control it without a lot of work. If the variability is "continuous", then it would probably be more effort than the mpg gain is worth.

The nice thing about using MegaSquirt for that is that the source code is available... Not NEARLY as hard as hijacking an algorithm on a GM computer.

Yes, the VVT is not on and off like "vtec" Megasquirt would have a harder time controlling it, although I see it as a possible future add on for MS. But right now I wouldnt give up my ultimate tuning Megasquirt system for the possibility of a few more mpg, I didnt even build this for mpg, it just happened lol.

I was reading somewhere that somebody burned up a starter because they needed a diode.

Could I get more detail on that? Do I need to do anything special to get the starter hooked up to the Fiero's ignition switch?

that was me .before i got hp tuners i figured out a way to leave the cavalier ignition in the on position and then use the fiero ignition switch to engage the starter .i put relays in the circuit to shut the power to the cavalier wiring off when the car was stopped .the coil power for these relays came off a key on part off the fiero fuse panel .problem was that while cranking the starter ,the voltage drop was high enough to cause the relay coils to drop out and the car would not start .to solve this i ran a wire from the switch to solinoid wire to the coils .this solved the problem but also caused a backfeed that kept the starter engaged and fried it .the diode is in that feed to prevent wrecking another starter .with HP tuners to disable the vats in the BCM you dont have to worry about that .but i will tell you that a starter makes some strange noises at 1500 rpm.

Hmmm. Got me thinking, what would make a superior end result, a stock ECM modified with HP Tuners or the Megasquirt?

Megasquirt Advantages:
Wideband O2 input for constantly corrected A/F ratio
Second MAP sensor capability for atmospheric correction (mountain runs or sudden changes in weather while running)
Software is free, no licenses so if I decide to make an Ecotec conversion kit based on Megasquirt I don't have to shell out big bucks to tune multiple ECMs.
No secrets in the box, so I know that I have optimized my engine to run it's best for my purposes, not the EPA or another government regulator

Stock ECM and HPTuners Advantages:
Uses stock ignition module
Preserves sequential injection, Megasquirt can only batch fire
Less tricky to get running at it's best, the stock setup is a good baseline tune for a stock Ecotec motor
Can use 2.4L with VVT if I find one that fits my budget...MS can't control the VVT

With either setup, I can add a turbo later (or build a lower compression Ecotec and swap in place of N/A Ecotec) and tune accordingly.

That's all I can think of, please let me know if I'm wrong or should add anything to think about when deciding which route to go.

you can also run a wideband o2 sensor with HP tuners as well .the best HPtuners system is the pro version that also includes the scanner .the wideband you add yourself , it does not come with it .i cant knock megasquirt , its just that tuning from scratch is beyond my abilities at this stage anyway .

Can HP Tuners allow closed loop wide band AFR control with a "simple" patch to the stock program, or is their "off-highway" operating system required for that?

on mine there is a screen that seems to allow that .but i have not tried .i think the HP tuners web site has info on what you can do with all the vehicles that are compatible with the latest software .try the frequently asked questions ,lots of info there .

quote Originally posted by DustoneGT: The plan: 2.2L Ecotec, Getrag F23 5 speed Building my own mounts, will probably have to mod the cradle a bit Tsudo 4-2-1 Header, WCF Flowmaster 40 series, similar to stock exhaust tips Megasquirt II mounted in stock ECM location, relay board mounted where battery goes Older GM wasted spark ICM to ignite the A/F mixture Wideband O2 sensor Battery relocated to front (I already have the custom box in hand) WCF Coilovers rear, WCF performance springs front, KYB's all around, GT rear sway bar Kumho Ecsta SPT Tires, 225/45-17 in front, 245/40-17 in back, Konig Incident 17X7 wheels Looking at gathering most of the parts mid to end of January '09.

I think if you got a late 80's 4t60 transmission from a caddy deville or something with similar gearing, and swapped out the stall to match yoru engine, you would reach yrou gas mileage goal. granted yoru performance would suffer a bit, but you would be turning incredibly low rpm's on the highway. most deville trannies have a 2.73 final drive. hell, even an eldorado would give you better mileage than that getrag

I think after discussing this a bit here, my original goal of 50 mpg might not be met.

My choice of tires and rear-end gearing probably prevent it.

I've been thinking a little about how you could achieve your goal of 50mpg.

I think you may need to re-think you choice of wheels and tires.

To get the best possible gas mileage you want the lightest possible wheel and tire combination with the lowest possible rolling resistance. This would mean finding the smallest diameter wheel that you can fit on the car that is as light as possible. You would probably want to go with a forged aluminum wheel as they are the lightest, (and strongest), wheels you can get. You would also want to fairly tall, skinny, high mileage, energy efficient tire with the lowest possible rolling resistance,
I don't know how much difference the choice of wheels and tires will actually make on a car's gas mileage, but the laws of physics say that you want to minimize the rotational mass of your wheel/tire combination and to minimize the tire's rolling resistance.
Just a thought, hope it helps.

~Bob

------------------
"Its nice to be important.
Its more important to be nice."

After the topic of wheel/tire choice and transmission final drive kept coming up, I decided to start a new thread on this car build.

https://www.fiero.nl/forum/Forum2/HTML/097165.html

I realize that the 50 MPG goal may be attainable, but I am personally unwilling to make the sacrifices necessary to meet it. I would like to have a 3.8ish final drive and some good, sticky tires. I want good torque and acceleration and I don't feel safe on 185 tires, there are too many idiots out there to dodge on the road.

I'm playing with code59 right now. Its a hacked $58 code originally for the Syclone/Typhoon guys running the 7749 ECM and the 4.3L V6 and dist. I have it running a 3.4L V6 with DIS using the 7730 ECM. The 7749 and 7730 are functionally the same. The advantage of this setup is a 3 bar MAP for boost to 30 psi and wide-band O2 control. It's completely DIY though as the code59 guys are just enthusiasts not making any money from their hack.

This code allows running closed loop AFR's based on input from the WB O2 sensor. You can set the cruise table for any air/fuel ratio. This would be good for stuff like lean cruise at 15.0:1 or leaner. Once you goose it the code drops into open loop and runs the main VE table to get best power. And the best part is a free program called Autotune that helps you dial in your main VE table. You will still have to tweak the timing to your engine manually. And VVT is not supported.

quote Originally posted by DustoneGT: I realize that the 50 MPG goal may be attainable, but I am personally unwilling to make the sacrifices necessary to meet it.

Wellll....there's always the V8 route. I think once you drive my 4.9, the economy thing will get put on the back burner anyway I love the idea of 50 mpg....but I prefer to get it on two wheels instead of 4.

just my suggestion on your 50MPG quest, seems like this thread got WAY WAY off topic somehow though.

id do the 2.2L ecotec, *IF* you can swap in a 6 speed transmission, Otherwise use the 5 speed thats available, see what gear ratios are available, and get the TALLEST gear you can for 5th gear, you probably need to be around 1800-2000 RPM at 70MPH, I highly suggest running 155/85/13's for VERY low rolling resistance.

since the car is a 86, i also suggest running front calipers front/rear so there is no chance of the rear ebrake dragging, otherwise make sure your rear calipers are not dragging at all, use a very light grease in the front wheel bearings, something thats very smooth and wont cause much drag, change the grease every 20-30,000 miles.

if your building the car for economy, you dont need to waste your time with the big rims, body mods, and/or added options.

*IF* you cant live with the 13" rim/tires then i suggest getting a set of 16x6 rims, maybe some 1992 grand am rims or something, im sure there are other's out there, run 205/60/16's on them, *IF* you can find them get 195/65/16's

the biggest thing you can do is to get the lowest rolling resistance you can and keep the RPM's low

matthew

One reason the Iron Duck Fieros do so well in this regard is the 3.35 FD in the Isuzu transmission.

Pardon for not reading the entire thread, but the 1984 Fiero was rated at 50 mpg, why not just buy one?

------------------

quote Originally posted by Firefighter: Pardon for not reading the entire thread, but the 1984 Fiero was rated at 50 mpg, why not just buy one?

where do you buy your drugs?

matthew