# Random miss-fire under load - MegaSquirt



## Southcross (Jul 2, 2004)

1.8L 8v, T3 Turbo pushing 7psi (9 peak)
MS2extra 2.0.1, MAPdot
no fueling issues

recently went to BIP-mod for direct coil control (love it), but my random miss-fire hasn't gone away. Only at WOT, it seems that at about 75% throttle I don't have this issue

Using a MK2 electronic ignition coil, NGK BPR7ES spark plugs gaped to .028 (edit: cap,rotor,cables are all new)

could possibly be coil (hoping not, trying to avoid spending money on a new coil if it isn't)? I have gotten conflicting info regarding sparkplug gap, am I going to small a gap (too big?)? suggestions?

old thread re: BIP install http://forums.vwvortex.com/showthread.php?5268028-ABA-coil-on-MS2Extra&p=71644219#post71644219

edit... car goes on the Track at the end of the month for the first time since boosting it... would love to get this solved by then.


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## need_a_VR6 (May 19, 1999)

Try .022, whats the dwell?


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## Southcross (Jul 2, 2004)

need_a_VR6 said:


> Try .022, whats the dwell?


really, go smaller? LOL presently running 3.5ms Dwell, I'm not having any issues with spark breakup over 6500. I just get about 3-6 misses across the range of 4.5k-6.5k under full boost


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## ValveCoverGasket (Mar 20, 2002)

Southcross said:


> really, go smaller?


if its getting blown out (and it kind of sounds like it is...) thatll fix it. ive had good luck with .025, but if you have issues there just bump it down a little more and see if it clears it up at all.

its an easy/quick/cheap troubleshooting step :thumbup:


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## Prof315 (Jan 5, 2009)

This is why I HATE distributors. 20/20T, K03, 15psi, progressive water/meth with an M5 nozzle activating at 95 kpa, LS2 truck coils, NGK BPR6EIX plugs gapped to .045" NO PROBLEM! If your coil(s) won't kill you they aren't hot enough.


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## ValveCoverGasket (Mar 20, 2002)

:laugh: you also arent using a stock coil!


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## Southcross (Jul 2, 2004)

LOL.... I've toyed with the idea of getting a hot aftermarket coil, but I've been bleeding money again this summer, so I've been trying to avoid spending money on one if I don't _need_ it.


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## Angrygilmore (Sep 28, 2008)

in the stand alone I run I can select coil charge time I have an msd blaster 2 coil set at 2.93 millisecond charge time it runs at like 15% duty under load


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## Prof315 (Jan 5, 2009)

ValveCoverGasket said:


> :laugh: you also arent using a stock coil!


Exactly. Why bother with MS as there are so many better options available, and most of them can be found in the junkyard for less than the cost of a new stock piece.


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## Southcross (Jul 2, 2004)

well I was a little off on my gap... was gaped at .025, re-gaped to .022 (smallest my gap tool would go) and made two WOT runs on the highway. Still felt one light miss on each pull, but I was able to pull all the way to my rev limiter (7k) without any concerns or question about how its running. I guess a new hot coil will have to be purchased sooner or later, but I think I can live with what I've got for now. Thanks guys!


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## need_a_VR6 (May 19, 1999)

Yeah if less gap helped you need more coil, even if it is just a good condition stocker.


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## Southcross (Jul 2, 2004)

need_a_VR6 said:


> Yeah if less gap helped you need more coil, even if it is just a good condition stocker.


cool, now to decide on a coil... wish I could find a hot coil that didn't require me to change the end on my primary wire


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## Angrygilmore (Sep 28, 2008)

msd comes with the boot and end for the coil


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## Prof315 (Jan 5, 2009)

Angrygilmore said:


> msd comes with the boot and end for the coil


Good point and a Blaster 2 coil is pretty hot.


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## Angrygilmore (Sep 28, 2008)

I forget im using the blaster 2 or 3


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## Southcross (Jul 2, 2004)

well.. its definitely something else  The next following day, the misfiring came back. Broke down and bought a Blaster2 coil, opened up the plugs a little... great coil, I get way more complete combustion now (Idle is smoother, butt dyno says I have more low end torque, AFRs changed due to more complete combustion), but the misfiring is STILL there LOL 

I'm thinking I'm having some kind of noise issue, I know I've had some noise on my 12v and noise in my coolant temp signal (happens to be right next to my ign distributor)... but doesn't seem to affect my timing. As much as I have been trying to avoid doing so, I might have to try upgrading to the latest firmware, haven't yet as my tune "seemed" to be just fine.


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## Prof315 (Jan 5, 2009)

Have you checked for timing drift? How about basics like cap and rotor condition? A worn or cheapo rotor can ground under heavy load and cause a miss.


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## Southcross (Jul 2, 2004)

Prof315 said:


> Have you checked for timing drift? How about basics like cap and rotor condition? A worn or cheapo rotor can ground under heavy load and cause a miss.


all brand new (well.. under 3k miles new) Bosch cap & rotor, NGK plugs


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## Prof315 (Jan 5, 2009)

Southcross said:


> all brand new (well.. under 3k miles new) Bosch cap & rotor, NGK plugs


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## Southcross (Jul 2, 2004)

Prof315 said:


> :banghead:


directed at my answer? or agreeing with how I feel, "bangin' my head against the wall"? LOL


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## Southcross (Jul 2, 2004)

I'm wondering, I have never tried the ignition noise filtering that MS2extra has, not even sure how to set it up...


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## Prof315 (Jan 5, 2009)

Southcross said:


> directed at my answer? or agreeing with how I feel, "bangin' my head against the wall"? LOL


Agreeing with how you feel. As far as the noise filtering goes, _I think_ the MS/Extra manuals have some info on it. I have never needed it so......


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## Southcross (Jul 2, 2004)

Prof315 said:


> Agreeing with how you feel. As far as the noise filtering goes, _I think_ the MS/Extra manuals have some info on it. I have never needed it so......


yeah, sadly the track record of the MSExtra manuals being up-to-date and accurate.. yeah, you get what I'm saying LOL


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## ValveCoverGasket (Mar 20, 2002)

just for kicks, try moving to the 2.1.0 (or maybe even newer!) code...
or have a look through their release notes and see whats going on... ive found some of these mysterious issues (that cant be blamed on hardware) clear themselves up with a newer code version sometimes despite being undocumented in the release notes..


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## Southcross (Jul 2, 2004)

ValveCoverGasket said:


> just for kicks, try moving to the 2.1.0 (or maybe even newer!) code...
> or have a look through their release notes and see whats going on... ive found some of these mysterious issues (that cant be blamed on hardware) clear themselves up with a newer code version sometimes despite being undocumented in the release notes..


yeah, been seeing posts to that same affect on the MSExtra boards... oh and I typo'd I'm running 2.1.0d, 3.1.1 is probably my next bet... I have only been avoiding going to it because I would need to rebuild a new tune (engine constants, misc tables, etc) as they changed variables in the MSQ. not end of the world, but I find remembering what all I set to what a PITA


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## ValveCoverGasket (Mar 20, 2002)

just take screen shots of all the important windows, and export the fuel and spark into vex files.

then save whats currently in the car. go inside on the couch and grab a beer, and work offline to build the new file. walk back to car, download data, and youre done.

not so bad :thumbup:


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## Southcross (Jul 2, 2004)

ValveCoverGasket said:


> just take screen shots of all the important windows, and export the fuel and spark into vex files.
> 
> then save whats currently in the car. go inside on the couch and grab a beer, and work offline to build the new file. walk back to car, download data, and youre done.
> 
> not so bad :thumbup:


yeah, I know... but a beer typically turns into 12, and I forget all about the car LOL


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## Southcross (Jul 2, 2004)

first impression of 3.1.1... runs like TOTAL ass, horribly miss-firing right off of idle (timing is correct), AFRs seem waaay off. I wound up adding a huge amount of fuel to keep it from jumping to 22:1 AFR, but still won't Rev at WOT... I'm going to 2.1 after 1 more try (raining right now)


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## Southcross (Jul 2, 2004)

Southcross said:


> first impression of 3.1.1... runs like TOTAL ass, horribly miss-firing right off of idle (timing is correct), AFRs seem waaay off. I wound up adding a huge amount of fuel to keep it from jumping to 22:1 AFR, but still won't Rev at WOT... I'm going to 2.1 after 1 more try (raining right now)


damn it, after the rain passed, went to re-flash the ECU and got an error (I didn't notice before??) :banghead:

took the ECU inside and flashed it on my MegaStim, no error... loaded my MSQ, swapped it back in the car, and seemed to run just as good as it did before... GAHHHHHH

no time this evening to see if it fixed my mis, that and I need gas :laugh:


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## Prof315 (Jan 5, 2009)

Southcross said:


> yeah, sadly the track record of the MSExtra manuals being up-to-date and accurate.. yeah, you get what I'm saying LOL


Yeah but the developers have been working HARD on them. They are getting much more unified and complete.


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## Prof315 (Jan 5, 2009)

And just as a note. You really WANT to run the most current stable release firmware for MS ALWAYS.

For MS2/E that means either 2.10d ( check that, I think there is a 2.10e) or 3.1.1. James, Ken and Jean, ( the MS2/E developers) are constantly adding improvements to the code. I'm really suprised 3.1.1 ran like a$$. When I switched the race cars over to it they got happier.

AHHH I just remembered. Check the MAP sampling angles in your 3.1.1 msq. There are certain angles that motors (especially 4 or fewer cylindeers) don't like at all. But get it to the correct angle and things will be wonderfull. We saw fully 10 kpa lower on the ITB'd race car with a 318* cam, the thing actually idles at 1100 rpm and 60 kpa!


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## Southcross (Jul 2, 2004)

Prof315 said:


> And just as a note. You really WANT to run the most current stable release firmware for MS ALWAYS.
> 
> For MS2/E that means either 2.10d ( check that, I think there is a 2.10e) or 3.1.1. James, Ken and Jean, ( the MS2/E developers) are constantly adding improvements to the code. I'm really suprised 3.1.1 ran like a$$. When I switched the race cars over to it they got happier.
> 
> AHHH I just remembered. Check the MAP sampling angles in your 3.1.1 msq. There are certain angles that motors (especially 4 or fewer cylindeers) don't like at all. But get it to the correct angle and things will be wonderfull. We saw fully 10 kpa lower on the ITB'd race car with a 318* cam, the thing actually idles at 1100 rpm and 60 kpa!


 the change to "e" revision was only a fix to the (IIRC) the 60-2-2 wheel, didn't apply to me... my inquiries into upgrading to 3.1 or 3.1.1 was always suggested to me if the car is running right (which I thought it was LOL) "don't fix it if it aint broken". _my definition of what is running right has now changed LOL!_

I was also told that several (many?) of the variables had changed and I would need to rebuild my tune... not really true, the "few" variables that did change were for options, and were options for options that I didn't even have turned on... so I was worried/annoyed for nothing

I noticed the "degree" for MAP sampling... it was defaulted to 90* my guess is for peak vacuum to sample at approx 75% of stroke, 135*?? suggestions for tinkering? Under boost, I'm sure it wouldn't matter too much LOL

I drove it this morning to work, and it drove AWESOME. Idle is way smoother and so is free rev (pulling out from a stop)... things I always attributed to having a big cam and big injectors. Car cruises a lot quieter too. Best though was 2nd gear pull to 6500 and no noticeable miss, won't know for sure until I get more seat time.


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## ValveCoverGasket (Mar 20, 2002)

so are you on 2.1 or 3.1 now? im confused haha


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## Southcross (Jul 2, 2004)

ValveCoverGasket said:


> so are you on 2.1 or 3.1 now? im confused haha


LOL, I _was_ on 2.1.0d, just upgraded to 3.1.1


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## Prof315 (Jan 5, 2009)

Southcross said:


> I noticed the "degree" for MAP sampling... it was defaulted to 90* my guess is for peak vacuum to sample at approx 75% of stroke, 135*?? suggestions for tinkering? Under boost, I'm sure it wouldn't matter too much LOL
> 
> I drove it this morning to work, and it drove AWESOME. Idle is way smoother and so is free rev (pulling out from a stop)... things I always attributed to having a big cam and big injectors. Car cruises a lot quieter too. Best though was 2nd gear pull to 6500 and no noticeable miss, won't know for sure until I get more seat time.


135* is a good place to start.

That sounds like the experiences I have had upgrading to 3.1.1. 

:thumbup:


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## Southcross (Jul 2, 2004)

wound up going as high as 160* for the MAP sampling... may not be perfectly ideal, but it seemed to give the most stable "lowest" kpa reading and smoother idle, throttle response seemed good as well. I'm sure more tweaking is in order, but I can live with my current options.

took it for a test drive at lunch, and baring needing more tuning from upgrading my FPR to 4-bar, it pulls nice and hard with no miss-firing. :thumbup:


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## Prof315 (Jan 5, 2009)

EXCELLENT! :beer:


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## ValveCoverGasket (Mar 20, 2002)

good stuff :thumbup:


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