I am running spark, using the timing map similar to ner's and under high loads on the engine and over 10psi, I get a backfire type studdering at about 5k and up -could this be the timing map or is it more likely plugs/wires or coil pack. I am running stock wires and coil pack and have my plugs gapped to .025. I have my afr right at 11.5

What sounds should i be listening for beside detonation when i am tuning the map and what adjustments need to made when those souds are present.

I am trying to eliminate whether it is software or hardware.

Originally posted by rs-pssst
I am running spark, using the timing map similar to ner's and under high loads on the engine and over 10psi, I get a backfire type studdering at about 5k and up -could this be the timing map or is it more likely plugs/wires or coil pack. I am running stock wires and coil pack and have my plugs gapped to .025. I have my afr right at 11.5 What sounds should i be listening for beside detonation when i am tuning the map and what adjustments need to made when those souds are present. I am trying to eliminate whether it is software or hardware.

That's the exact same issue i had over 10 psi boost. Its a spark intensity issue, related to dwell time. Wasted spark dwell in the code was not right for almost all code versions, which means the coilpack is not getting charged fully. James had released code version 025i6, which he and others say has much better dwell. Try that code out and see what happens..I went the easy way out, but unfortunately was an expensive solution, by hooking up a Crane ignition box. I use the mitsu ignitor to fire the crane box, and it works beautifully. Ignition boxes dont rely on dwell, because of the box's ability to fully charge the coilpack almost instantly.

I also can't run the dwell control for some reason... I have to run minimal for hei.

If i try dwel control 7.0/3.7/0.5 I can't even get down road because it is studdering so much. Whats up wit that?

Originally posted by rs-pssst
I also can't run the dwell control for some reason... I have to run minimal for hei. If i try dwel control 7.0/3.7/0.5 I can't even get down road because it is studdering so much. Whats up wit that?

Try a running dwell of around 4.3 ms. You sure its not lean misfiring? That can cause bucking esp at high vac low load. My car will even do that at an A/F of 15.2:1 or higher..these engines like fuel..

Don't use the "Minimal..." setting, it will yield charge times which are too long at lower RPM's which heats really heats up the module and too short at high RPM's which will result in a misfire. My current dwell settings are 25/5.5/0.1, the cranking dwell is very high because I measured the stock cranking dwell and that was around 36ms! A shitload of dwell indeed, so I tried to match it in megatune but it won't let me go above 25ms. Although if your current cranking dwell numbers work just fine, stick with those.

Dwell control works a lot better with the new code releases. Anything after 025i6 is game.

I've been messing with my spark table a bit recently, I have replaced the original file with this new one so all of my old posts with my spark table should automatically update themselves, but I'll post it here too.

if it is a lean misfire, then why would my fuel map be perfect for stock ignition and minimal for hei, but not dwel control?

I guess I'll try try the different firmware today

Fixed the problem -it was a setting in the codebase section. I had some spark outputs on the wrong setting -haha. I fucking love this -I pulled a hard pull to 16psi and lit up second with no backfiring.

Fucking awesome -now to finally use megasquirt for what its all about.

Nice work. Those outputs caught me the first time too, I was so confused as to why it wasn't working.

What code version did you end up using?

the s19 and so far tested up to 19psi with no backfires or spark problems. ngk 7e's gapped to 0.035, w/stock wires and a s16g