Help with building your Speeduino, installing it, getting it to run etc.
By Billboswaggins
#52298
Hi, I have a 1988 porsche 944 turbo. I'm having trouble starting/running at idle. I am a complete beginner so everything I have done for my config has been adapting settings from other tunes of similar cars since I couldn't find a base tune (I don't think one exists). I've mostly been referencing this thread although it is for a megasquirt. https://rennlist.com/forums/924-931-944 ... eloading=1

The car will catch but backfire randomly, although I haven't run it long, like 2-3 seconds in fear of jumping timing.
I have verified with a timing light the cranking angle is roughly correct at 70. It should be 69 or 68 but I haven't messed with it yet.

What settings would most likely make the engine backfire?

The gamma enrichment goes to 300% to 500% but i'm not sure how much is acceptable while starting.

Any input is greatly appreciated.
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#52303
Yes my bad, the trigger wheel offset angle is at 70*

No I didn't use the speedyloader tune. To be honest I didn't notice it was a generic base tune, I must of overread it or something. Ill start referencing it on things I guesstimated. The tune I uploaded was really for starting and idling, getting it to more under its own power. Things like the injector close angles and IAT retard I didn't want to mess with.
#52308
Best thing you can do is start again.

The base tune set's up things so that they are not just "255" or other weird values which can cause funny things to happen.

So wipe your mega using EEPROM clear in the Arduino IDE. Load the firmware again, then load the Speeduino base tune.

They do your changes by hand and go through every single setting and make sure if it's not something you use to disable it.

All fuel adders (WUE, ASE etc) should be set to 100% regardless of engine condition. You don't want ANYTHING adding or removing fuel at all. All these modifiers rely on the VE table to be correct to work so until then. Keep them off/set to 100%.

Then confirm trigger angle again and try starting.

Once idling and warmed up you can be comfortably knowing that the VE table at idle area is now correct and you can try using WUE next start etc.
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By PSIG
#52336
You could, beyond the default value, but the point is to have as much off as possible that does not interfere with basic running or alter the VE results. One method if cranking is too lean, is to key on/off a few times to get more priming shots for first startup. Tune warmed low-RPM and low-load, then with that base go back to warm-start priming, cranking enrichment, ASE, WUE, etc, founded on a good low-speed tune base.
#52575
Alright I figured out the backfiring issue. My cam sensor was triggering 180* out of phase, even though I put the sensor at cylinder #1 tdc.

On top of that the coils weren't firing properly, sometimes they would all fire at the same time.

I fixed this by making the the spark output trigger from going high to going low. I put it going high since in the megasquirt manual it says the D585 'truck' coil should be put go going high. HOWEVER the tunerstudio notes say this is USUALLY the opposite of megasquirt. Is there a reason for them to differ?

The engine catches but doesn't run. Altering the cranking enrichment makes it better, but even 250% wont start it. This is using the base tune and turning off all the fuel modifiers. Any settings that might have a big impact on starting?

Here is the tune and a log of starting.
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