MPGs run, Aspire SE

[getnpsi]

And by muscle memory i do not mean guessing a timing value, like knowing where every bolt is how far to bend over what extention fits berween water lines just right etc.

[FestYboy]

i hope this helps bring the engine to it's sweet spot.

[TominMO]

Both are supposed to go hand in hand. If you move one it does in fact skew the spark events as well. Just saying if you overdo the cam gear you can fiddle with ignition from inside the cabin to at lesst get a little driveability back until you start over

OK, I see what you're saying. And I just realized a few minutes ago that Arty is right: retarding the cam is also retarding the ignition timing. So tmw I will re-do today's tests, but with my timing gun in hand.

[getnpsi]

Both are supposed to go hand in hand. If you move one it does in fact skew the spark events as well. Just saying if you overdo the cam gear you can fiddle with ignition from inside the cabin to at lesst get a little driveability back until you start over

[TominMO]

I understand he is probably a pro with his muscle memory to hop in and out of the car and adjust timing like we do tire pressure,but would any of those aftermarket MSD box with ignition advance retard knobs work on an aspire or festiva?

You do understand that I am adjusting cam timing, not ignition timing? On the adjustable cam gear there are degree marks for me to use as a reference. No "muscle memory" needed.

[TominMO]

Tom, you have to adjust your ignition timing everytime you adjust the cam timing, remember, the CAM drives the rotor and if the cam moves, so does the rotor relative to the housing. so timing the cam -5, also pulls 5* out of the ignition.

It's a two-piece cam gear, inner and outer rings, bound together by five screws you loosen for adjustment.

When I adjust the cam, the outer part of the cam gear is moving relative to the inner part of the gear; in other words, the cam gear itself (the outer part, with the belt on it) can rotate independently of the cam; the cam, which is bolted to the inner part, stays in one place. So nothing is being advanced or retarded but the cam, relative to the crank sprocket. Ignition timing remains the same.

[jason_]

Gun it! You've gone this far, don't give the housing a twist and call it good....every time I rebuild an engine I throw the gin on the passenger seat and on the break in I'll double check 1/2 through the trip.

Sent from my rooted HTC Supersonic using Tapatalk 2 Pro

[FestYboy]

Tom, you have to adjust your ignition timing everytime you adjust the cam timing, remember, the CAM drives the rotor and if the cam moves, so does the rotor relative to the housing. so timing the cam -5, also pulls 5* out of the ignition.

[getnpsi]

I understand he is probably a pro with his muscle memory to hop in and out of the car and adjust timing like we do tire pressure,but would any of those aftermarket MSD box with ignition advance retard knobs work on an aspire or festiva?

[TominMO]

OK, went out today and ran a bunch of tests, the only variable being cam timing.

Notes:
"-4" = cam 4 degrees retarded; "+4" = 4 degrees advanced.
FP was 37 for all runs, and ignition was not changed from last time; around 13 BTDC.
Tests were a combination of city/hwy, for about 5 miles, just to see how the motor ran.

0......previous test, ran poorly
-4.....noticeable bog off idle, then ran OK
-6.....ran better than -4, but noticed a little pinging
-8.....ran stronger than -6, but pinging more pronounced
+4....seemed to accelerate inconsistently, poor top end
-5.....liked this setting the best; no pinging, decent power

Now I want to go on an extended run to see if the computer likes -5 enough to not throw a code 17 on me. If it turns out OK, I will try to dial in FP to run as lean a possible without a code. I'll probably leave the ignition timing where it is. It didn't seem to be in an excessively lean for any of these cam settings.

[FestYboy]

Scrappy sees 23" Hg at idle (700 rpm). you are correct in stating that the idle vacuum should be as high as possible. since Tom has an adjustable cam gear, he can now use both the ignition timing and cam position to achieve this. unfortunately i wasn't at madness to give you all a hand with things like that.

[zoom zoom]

Man this is getting interesting I want pics! What numbers is the wide and saying at idle and when cruising/ wot? Is the car throwing code 17 at you all the time or just occasionally?

Instead of adjusting the distributor to adjust the idle, why didn't you adjust the throttle screw? Have you hooked up a timing light and a vacuum gauge at the same time? Correct me if I'm wrong arty but I remember you and Charlie saying something about the vacuum gauge should read as high as possible, low 20's at idle (I think Charlie said he was at 23) but none of my cars will go over 18/19 at 800 rpm.

Lovin it man keep at it you'll get this straightened out soon hopefully with 55+mpg numbers.

[TominMO]

@ Arty: I was thinking that this morning, that I will need to up the FP a little. As to whether to advance or retard the cam, I will try both.

I can data-log, but found out when I installed the software on my desktop computer that it made it do some odd things. Shutdown wasn't normal for instance. I even got a warning about installing this software from the computer itself, as I begun the install. I could put it on my netbook, but don't really want to risk screwing that up either.

@ jason: Also agree with what you are saying. I'll just keep trying a few more configurations.

[jason_]

i think youre getting too lean changing mechanical configuration, when the computer is tuned not for a mechanical change, with the static variable of EGR, which is more a more air/less fuel variable.

doubling up your negatives sort to speak....

in my opinion, changing the static mechanical aspect, will upset a pre mapped table. i honestly don'tk now how far you can go, but i think your teasing the limits.

[FestYboy]

well, figure this Tom, at torque peak, you're at your highest VE and lowest BSFC (and concequently the best MPG barring any other factors), so if you're looking to keep things from going lean AND increasing the MPGs, this is what you have to think about. running lean at idle isn't an issue as there's no real load on the engine. honda does this ALOT. you need to find the balance while under load (not WOT) and likely you'll see that this will require an INCREASE in your base fuel pressure especially given the mods done to the engine. so far, all i see (aside from the cam and FPR) is all of your mods leaning tward increasing CFM throughput which will inevitablely lean out an already lean situation in the stock tuning of your aspire.

does your wide band have any data logging capability? if so, i recomend using that function from here on out.