924Board.org

[-nick]

Hey guys,
Getting the ignition setting correct has finally let me move on to getting some other things straightened out.

Here's a link to my post over on the MS forum. Basically, I have a 50/50 chance at startup of having the engine run with good AFR's, matching what I expect, or having it run very lean AFR's which are undrivable. I'm speculating that injector staging is to blame, but I really have no idea what's up.

http://www.msefi.com/viewtopic.php?p=179960#179960
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1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

[Lizard]

what firmware are you running? if you havent done so already, export your tables and load the latest and try again.
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3 928s,

[Min]

Are you using a second barometric pressure sensor, or are you using barometric check on startup?

Log of the nasty behavior?

Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

[Min]

if you turn the key on to accessory and leave it for 2 seconds, then try to start the car, does it start fine everytime?

Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

[-nick]

D@mn! Min, if you're ever in town, drink are on me.

MS was set to for "initial barometer correction" and for some reason it would occasionally peg at 120kpa (the upper limit). Of course, that was the fuel map that I had been fine tuning When the correction read 100kpa on startup, like it should, it was running very lean.

I've changed it so there's no correction ever now. And have started working up a new fuel map. I don't know it would grab 120kpa as a reading, but until I plan a trip to the Rocky's, I'm not worried.

Fixed my misfires at high revs and inconsistent startups in the same week. I'm a happy camper! Now it's just plain old tuning. I'll crank it up to 10psi tomorrow and play around...
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1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

[Min]

no worries man, I'm always here to help you have my msn too if you need me.

I kinda live in the rockies, so I've got constant barometric correction installed (second map sensor) and well, I like it so far, to leave this area I gotta go up alot, or down alot, so, its a nice feature.

Did you end up loading the new MS2 Extra code?

Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

[-nick]

Yep, I'm running the 9/2007 Beta code. Everything is working fine for me, but I also have any and all acceleration enrichments turned off. Other than off-idle response and very short lean spikes on tip-in, I don't miss it. I'll get it up and running eventually though.

This is with 4 squirts alternating. However, I can't get my low rpm and high vacuum AFR's any leaner than 11.5:1 unless I cut the fuel completely. I'm running into my opening times and with two squirts of fuel per cycle and 440cc injectors, it just won't get any leaner - unless I got to one squirt per cycle.
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1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

[Min]

May need to turn down your fuel pressure. Then using a rising rate regulator to bring in the fuel higherup when needed. At least thats one way to do it. Do you notice any improvements in how the car runs from the MS2 regular code?

Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

[-nick]

I didn't notice very much of a difference - except the injector opening time and battery correction accuracy made a big difference. I can turn every item in the car "on" and AFR stays perfectly steady. That definitely wasn't the case with the regular code.

I thought about a rising rate regulator. I'll have to look into it more. I definitely need the fuel up top. Hitting ~70% duty cycle already with just 10psi.
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1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

[endwrench]

Interesting as I thought one of the main advantages of MSII was the much greater resolution for better control of big injectors at idle. Sounds to me you need to play a little with your opening time again. I know you had your injectors tested for opening time but this may not transfer directly to MS. Could be some latency or something in the software. You should be able to easily control your idle mixture with these injectors. There are some with injectors twice that size doing it. I have to run 1 squirt with MS1 and essentially the same size injectors. My car actually idles better with 2 squirts but it starts hard. I do idle on the rich side though. Still haven't finished my WB build yet !

Todd
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'79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!....

[Min]

[-nick]

Idle AFR's are just dandy. In fact, I'm inching toward stoic at idle as I get the map more refined. The trouble is that my 20kpa bins are all "1" VE and as I approach 20kpa and <2000rpm the AFR drops down into the 11's.

My 170kpa bins are already at 170VE and the 200kpa bins will probably be touching on 200VE once I get to the point of tuning them MS tops out at 255VE, so I could lower the req fuel to get more resolution at the bottom, but I don't think that I'll ever hit an optimal 15:1+ AFR at those low kpa bins.

I think the options are going to be to check into a rising rate regulator and/or drop down to 2 squirts alternating. Then again, I don't know how much of an impact leaving those bins rich will have on fuel consumption?
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1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

[endwrench]

Min, when MS2 first hit the market a lot of guys with monster injectors switched because they couldn't get there engines to idle. I remember reading several reports of success with this but then they started biching because of no bells and whistles like the Extra code. Not a problem now. I've even read of several people who switched to the High Res Code for MS1 Extra and solved there idle problems allowing them to run more squirts.

Nick, I guess I misunderstood your post. I thought you had idle problems. You do seem to have a problem with your required fuel though as Min said. My top Kpa is 170 and I'm only seeing 122 VE at 6000 rpm. I idle around 40 VE and 40kpa. I run a 20kpa line too but just run it about 15kpa below my 40 line just because the only time my engine hits it is under decel. Works fine for me but to each there own.

Todd
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'79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!....

[Min]

[Una]

It's definitely a Req fuel problem if your VE is going down to 1.. How high does your VE get? I believe you have up to 255, so if you are only going up to say, 120, change your Req fuel and scale the whole table up, so your highest is up near 200. That'll push your lowest VE up as well.
Do you have multiply map turned on, or off? With a VE that low, it sounds like you have it off. You may need to turn it on, which will also raise all of your required VE numbers (and require a complete retune).
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Brian near Seattle, WA
'82 Porsche 924