MPGs run, Aspire SE

[eurotiva]

Yup. But why would they sell you three pulls and not let you adjust? You should get basically the same results for all three if adjustment is not allowed. So no one would pay for that service.

BTW what's the latest word from Hollywood? Got an agent yet?

Most shops, around here anyway, charge for time on dyno. If your up there adjusting, it's keeping them from moving the next car onto the dyno. I agree that it's dumb, but that's how that is round here.

No word yet, producer said two to three weeks. I'll definitely keep ya posted.

[TominMO]

Most shops, around here anyway, charge for time on dyno. If your up there adjusting, it's keeping them from moving the next car onto the dyno. I agree that it's dumb, but that's how that is round here.

No word yet, producer said two to three weeks. I'll definitely keep ya posted.

I'll try to get them on a slow day, but regardless, adjusting has to be part of the deal.

[FestYboy]

at idle, you're likely seeing the affects of reversion because there is not enough energy (inertia) in the mass of air that has entered the cylinder to KEEP it in there while the piston trys to push it out with the intake valve still open on the compression stroke (which is what you're exasterbating by retarding the cam). Ideally, you want a full charge to enter the cylinder and have the valve close JUST after BDC, that way you can take advantage of the entire compression stroke before lighting it off for the power stroke. this will net you the most cylinder pressure and therefor better MPG due to the increase in torque.

[getnpsi]

megasquirt owners voice: megasquirt can make you idle 950. No! I wanna see this thing work as factory as possible first. You could bump your idle up when you set your timing again, but the computer probably will drop it back down especially a sequential computer with mass air like in aspire. Festiva brain more archaic.

[TominMO]

at idle, you're likely seeing the affects of reversion because there is not enough energy (inertia) in the mass of air that has entered the cylinder to KEEP it in there while the piston trys to push it out with the intake valve still open on the compression stroke (which is what you're exasterbating by retarding the cam). Ideally, you want a full charge to enter the cylinder and have the valve close JUST after BDC, that way you can take advantage of the entire compression stroke before lighting it off for the power stroke. this will net you the most cylinder pressure and therefor better MPG due to the increase in torque.

So are you saying I should be advancing the cam a little? I remember that Matt said he had designed in a small amount of retard, and also that the cylinder pressure would be lower. I think that had to do with valve overlap tho.

I don't think that retarding the cam is going to give me the results I want. At -4 I got 51.8, at -8 (when I used the original cam gear with this MPG cam, installed one tooth retarded) I got 52.4. It didn't work out too well at 0 either. So I am willing to try +2 or +4, just to experiment.

I think what I am discovering is that while the cam (and timing it) is part of the picture, there is only so far I can go without different fuel mapping via the ECU. So now Megasquirt is looking like a solution. BTW Arty, what was that device you once told me could be inserted between the ECU and its plugs? As I recall it was cheaper but less effective than Megasquirt; but might be good enough for my purposes?

[FestYboy]

Apex-i SAFC-II

[TominMO]

Apex-i SAFC-II

Thanks.

[eurotiva]

Tom, not saying anything bad about an safc 2, or any "piggyback" system, but most just tweak the signal that goes into the ecu, a full standalone will let you have full control of all aspects of your tune.

I'm curious of I can tune mine to get back to 40 mpg. Not sure of it's a even possible with a bp, and non highway geared g series?

My best with my bp was 33 when I had stock ecu, and fmu

[Zanzer]

^ X2

The Apex-i is good mod for boosted cars or people who want a few more buttons to turn and tweak in smaller increments, but for the control you're looking for Megasquirt would be the way to go.

And I'm not knocking the Apex-i either....After seeing it on Dennis' car I'd love to have one to play around with

[TominMO]

Yeah, I went to their site and read up on it, and agree. I also went to the Megasquirt site and read their FAQ page. They are indicating that getting better mileage will be incremental at best, since the vehicle designers are already biasing for fuel mileage anyway. Might pick up some improvement at idle and mid-throttle, but not WOT. So I don't see me buying a Megasquirt for better mileage. I might get just as much by playing with FP, and cam and ignition timing. I suspect I am now in the endgame for experimentation.

[TominMO]

Tom, not saying anything bad about an safc 2, or any "piggyback" system, but most just tweak the signal that goes into the ecu, a full standalone will let you have full control of all aspects of your tune.

I'm curious of I can tune mine to get back to 40 mpg. Not sure of it's a even possible with a bp, and non highway geared g series?

My best with my bp was 33 when I had stock ecu, and fmu

Not too shabby for a 275-HP Festy tho.....

[TominMO]

I'm re-thinking this a bit. Gonna go with +2 on the cam and 13 ignition. That will remove the small amount of retard that Matt built in. Should get rid of my dying-at-idle issue. I will also try dialing back the FP a bit at this cam and ignition setting. Need to pull the cam gear again and reset it to 0, so I can go into + cam timing and have decent ignition timing.

If I don't get satisfactory results with this setup or one close to it, I will pull the cam itself and re-install my stock one (the actual cam that came with this car, since the MPG cam came from my spare JY head). With the stock cam, I will vary cam and ignition timing a little, no more than 4 degrees, and try dropping fuel pressure a little too. I might find that buying an MPG cam is unnecessary; that good results can be obtained with varying either fuel pressure, or ignition timing, or both, with the stock cam.

And if none if this works, I will at least have the stock cam back in there, with more lift and duration, and less overlap, and make better use of Matt's header.

[getnpsi]

Hate to see this happen but i was afraid that the ecu fights mechsnical parameters built into the cams specs. The gains advertised were on a non california carbed model. I think aspire ecu sees more of the picture if you will trying to feed fuel and timing based on incoming air then trimming as needed via o2. Safc tweaks those, efie and voltage out the o2 tweaks the back end but its still not optimum. Your aspire is getting a lot higher mileage than i am getting and i never go over 65. Buy a 88 festiva, swap in b6. Simple haha

[TominMO]

Hate to see this happen but i was afraid that the ecu fights mechanical parameters built into the cams specs. The gains advertised were on a non california carbed model. I think aspire ecu sees more of the picture if you will trying to feed fuel and timing based on incoming air then trimming as needed via o2. Safc tweaks those, efie and voltage out the o2 tweaks the back end but its still not optimum. Your aspire is getting a lot higher mileage than i am getting and i never go over 65. Buy a 88 festiva, swap in b6. Simple haha

Two other issues with trying to get better mileage are (1) engine RPM @ 60 MPH (gearing), and (2) the displacement of the motor, coupled with a programmed "need" for a certain AFR of 14.7 or numerically lower. In other words, if it was a 1.0 liter motor like the Metro 3-cylinder, it would require less fuel to do the same basic job. But in all cases, whatever the gearing or displacement, there is a limit to what can be done, and this design may be close to that limit. And bear in mind that part of the ~52 MPG it's getting is due to the chin spoiler; that seems to be worth 6 MPG by itself.

Edit: Oh duh, just realized I don't need to pull the cam gear, just move it over so it isn't off two teeth. Then adjust to +2.

[TominMO]

Went on another drive today. Cam at +2, ignition at 13. This time I also lowered fuel pressure, for the first time. I went down to 28. After driving for 50 miles or so, I pulled into a rest stop and upped it to 33, because it was running a bit lean and was hesitating noticeably. Also it tended to die when off the gas. Drove back home, and on the way stopped to adjust pressure up a bit more, to ~37, because I was still getting the previous symptoms, but not quite so bad. So basically it likes stock FP. Looking at the gas gauge, it seems about the same as on previous tests. This config was not an improvement. At this point I'm starting to think about just going back to the stock cam, and calling it a day. But I'll do one last test at +2 and 15, with stock FP, because even with FP at 37 it tended to die; so I think it needs a little more ignition timing.