ok. ive noticed on a hard downshift with a normal fuel setup in our cars (normal being larger injectors and a SFMU), you get slight detonation when downshifting right into the powerband. i dont know if its lag from the sfmu to dumping fuel into the cylinders or what, but it always happens. im sure you turbo guys know what im talking about.

i was wondering if the megasquirt can combat or fix this, and how it handles that, just out of curiosity.

______________________________
Matt D.
'06 Evo IX SE
'98 RS-T 13.8 @ 106.1

Aren't the 8 injector guys getting that even? Seems to be a plague. Maybe it's something you can tune out with a slight timing adjustment. If so than I'd say that megasquirt could deal with it.

getty up

-kent-




'98 Talon...gone, but not forgotten

first of all. i dont have those issues with the portfueler.

second.. why would you want to do hard downshifts? do you like beating up your car for no reason?

-"Easy Mac"
05 Mazda RX-8 (RR8 #88)
99 Eclipse RS 398whp & 372lb-ft

LOL, it is called downshifting and people with large size turbos that spool slower use it to aquire some decent boost instead of waiting for ages. How is he beating his car up for doing that?

Maybe the 400hp goal was for a LONG 5th gear pull....no wonder it's not there yet.

JUST KIDDING

______________________________

Ryan
IRyanHester@Hotmail.com

'03 Mazda 6s

Yeah, I do get that slight amount of det too, both audible, and visual from the MSD knockalert. BTW, I use the knock sensor that came with the MSD..I've only really noticed this on a 5th to 4th downshift, when going WOT, and only happens around 15+ psi boost, and ONLY for 1 second. During the 5th to 4th downshift, the RPM band is smack dab in the middle of peak torque, and also, which i think is the main culprit- we are getting just a few too many degrees of spark advance. Combine the spark advance, boost level, and peak torque band during the downshift, detonation happens. I know for a fact it is det, because I can put in some 100 unleaded in the tank, and the rattle is completely gone. Unless your windows are up, and have a keen ear, you may never, ever hear it driving..

This is why I think the MSnS setup will be perfect for. We know have total control of timing under boost. I will be installing this setup hopefully over the winter, and I am going to see how much power the S16G can make on pump 93 octane..I believe once we reach around 15 psi, we are maxing out our stock ignition advance with pump gas and 8.8:1 compression. I'll probably back off the timing 3-4 degrees during peak torque at 15+ psi, then put a few back once out of peak torque up to redline..I'm almost positive that will cure the rattle.

13.5 @108 MPH-2.2 60ft(stupid FWD!)
S16G @ 18 PSI/FMIC/Running on MegaSquirt II (Now with sequential
fuel injection)
My webpage: http://eclipsed4evr.home.comcast.net
-1998 Mitsubishi Eclipse RS-T- "Toy"
-1992 Plymouth Laser Turbo AWD(SOLD)
-2000 Honda CR-V(daily)

No detonation here... no rattle.

Does that answer your question?

When you can control everything... well, you can control everything...

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Megasquirt powered 420A
Custom turbo system

http://www.ms-custom.com

Anyone have logs with this??

It would be nice to be able to log the AF ratio when the shift happens...along with the RPM/TPS logs and knock count

Im going on a limb here but i say this might be because of the fuel pressure needed lets say cruising in 4th (you are auto right?) gear at 3k rpm, then go WOT get a downshift, turbo spools like a mother ..leaving the SFMU having to up the pressure to 5k rpm/wot conditions in a hurry..(correct me if im wrong in the assumption of this..since the pressure differential on a SFMU system is huge between partial throtle at low rpm vs. full throtle in the peak of tq curve)

I beleive any standalone with a 1:1 regulator should keep the pressures in a closer range (therefore also fuel flow), therefore react quicker to provide enough fuel? right wrong?? imput

vote for your choice of body style for Bluie!! http://www.cardomain.com/id/bluemooneclipse

I edited to the wiki!

13.5 @108 MPH-2.2 60ft(stupid FWD!)
S16G @ 18 PSI/FMIC/Running on MegaSquirt II (Now with sequential
fuel injection)
My webpage: http://eclipsed4evr.home.comcast.net
-1998 Mitsubishi Eclipse RS-T- "Toy"
-1992 Plymouth Laser Turbo AWD(SOLD)
-2000 Honda CR-V(daily)

no problems here, downshifting to 3rd at 40mph running 20psi.

Aha there goes that theory

vote for your choice of body style for Bluie!! http://www.cardomain.com/id/bluemooneclipse

______________________________

Ryan
IRyanHester@Hotmail.com

'03 Mazda 6s

it been awhile since i did any kind of pulls. i burn out anything close to 2nd gear. hell. at 80mph ill downshift into 3rd and ill still burn my tires at 20psi

maybe we can meet up since im in illinois till the 14th

Once I drop my new motor in (2 months roughly) I'm wondering how my traction will be at 20psi...

I know they spin like hell...but I'm rolling 19's with BFGoodrich Scorcher tires.....half the tire is basically a slick - it is comletely smooth. At 8psi I even noticed a HUGE traction gain from switch from my old rims and tires.

With my 18" old tires I could go full throttle 8psi thorugh first....shift into second and the tires would break loose slightly then hook up. After switching, I can't even burn these ones out hardly at all and shifting to second they just grab hard....So maybe it won't be THAT bad.

Plus I plan on running some sort of dual stage boost controller to limit 1st gear to 10psi....then up to 20psi after getting into second.

______________________________

Ryan
IRyanHester@Hotmail.com

'03 Mazda 6s

_____________________________________
Scott
90' GSX, 06' Effo SSL

(parting out 95 GS)

yes, i have the quaife lsd. i have 16inch rims with falkin azenis. 20psi 25g turbo, bout 340+- to the wheels will break loose in top of 3rd easy.

So, I'm guessing the MS doesn't use closed loop feedback?

_____________________________________
Scott
90' GSX, 06' Effo SSL

(parting out 95 GS)

vote for your choice of body style for Bluie!! http://www.cardomain.com/id/bluemooneclipse

I remember reading a string over at an EVO board where timign was measured. Apparently, after each shift, the timing would be pulled back a few degrees to apparently prevent this very thing. Of course, that was on a stock EVO computer. I've read about this same issue though on a subbie board, so this issue is quite real.

The MSD knock box may not be the most accurate device in the world, but it's consistency during shifts and high boost runs are unmistakeable. That certainly lends itself to some amount of credibility.

_____________________________________
Jason ESi-T

04' BMW 325Ci
91' Nissan 240SX
98' Eagle Talon ESi (sold)

Hrrrmm, I've never had this problem. Perhaps I did and didn't hear it, I really need to pickup a knock sensor. Regardless I'll be finishing the install of my MS today.

____________________________________________________
four nails four corners four riders and four horses

dirk congrats and good luck on the install. by the way? what turbo setup are u runnin? thanks ben

http://www.imagestation.com/album/pictures.html?id=2134181717&mode=slideshow
t3/t4 setup, je pistone, eagle rods,aem cam gears, crane cams, port and polished head w swirl polished valves, avcr, autometer gauges to be installed, kaminari widebody kit shaved rain seals, door handles, tail lights, relocated gas cap, double humped hood, house of kolors candybrandywine 20in weld evo wheels, air ride, custom fiberglass work (dash interior) more to come just not enough time