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Tuning Megasquirt


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Following the MOT I've been doing some datalogging.

MLV is suggesting some quite weird and wonderful maps. This is after about 30 mins of log...

post-1194-1247037674_thumb.jpg

I do have an RPi High Torque thingy cam (apparently...bottom end is a eBay special), which might explain the rather richer region at about 2500 rpm. I did try this map - idle is appauling, and I get the feeling it is running far too rich (as the 5mpg also suggests...). I also get the impression the engine is down on power - it really doesn't pull much better than a TDi.

So, can anyone suggest why I'm getting such a strange VE table and what I might be able to do to rectify it?

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Yes I prob can but

  • Are you sure (you prob are but to be 100% ) that NB selected and matches settings in MSQ
  • What have you done previously in the way of logging - or was this a "1st"
  • Which version of MLV are you using, and which settings for CLT RPM MIN etc
  • On the anaylse which E N H VH ?
  • spec / size of engine would be good, and where the original MSQ came from and is it Ms1 V3 029V EDIS ?

Nige :)

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When logging sometimes not all the cells get hit in the log and those aren't changed so you end up with weird maps that are a combination of tuned and untuned depending if you hit those cells and when I first tuned I had the standard range rover lambda sensors which totally don't work with megasquirt but the tuning software took a crack anyway.

I also hit a problem of not loading the correct msq into megalog viewer which meant I was getting some old values on ignition and starting fuel levels when I reloaded the map to megasquirt, which meant I was much too lean on tick over.

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Your idle is probably (partly) horrible due to the very large differences between the 4 or so idle figures around 40-50 kPa and 600-1000 rpm, smooth these out to something like:

38 40

35 38

instead of:

30 52

24 30

Play with the figures until you get is smooth, but as Nige says, need a bit more info/check some settings to be specific.

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MLV is rubbish at tuning idle, mainly because you shouldn't really have O2 correction active round the idle point so it has very little to go on. I tend to let it do its thing and then put the bottom corner (4 or 9 cells) back as it was, maybe blend it in a bit round the edges but keep the idle values about the same as whatever you already had (assuming it was idling properly in the 1st place).

As has been said, the longer/bigger the log the better. Half an hour is not a bad start though.

With everything, the computer program is only as good as the data you give it, so it does depend largely on the rest of your settings being sane and things like your O2 sensor being fully functioning (and up to temperature - so try to avoid splashing through puddles while tuning as it will cool the zorst down and throw the readings). Post up your exhaust gas correction settings and we can take a look.

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Yes I prob can but

  • Are you sure (you prob are but to be 100% ) that NB selected and matches settings in MSQ
  • What have you done previously in the way of logging - or was this a "1st"
  • Which version of MLV are you using, and which settings for CLT RPM MIN etc
  • On the anaylse which E N H VH ?
  • spec / size of engine would be good, and where the original MSQ came from and is it Ms1 V3 029V EDIS ?

Nige :)

Yes, NB is selected, but wasn't aware there were different settings for types of NB...I've got a generic one - whatever that might mean :blink: Oddly, sometimes even though I click NB MLV still treats it as a WB and I get a VE table with over 200 in places. Quit and retry it and it works fine. Probably vista being funny...

This was the 2nd Log - the first was 15 mins on the way to the MOT. What MLV turned out looked quite reasonable - although I tweaked the idle on this one to make sure the emissions were ok.

I'm using version 2.954, Min CLT is 71 (but only started logging at about 90), RPM is 500-18500.

E N H VH??? :blink:

Oh, 3.5 with blingy cam thing, and yes, MS1 V3 029V EDIS. MSQ was Fridge's standard starting MSQ for a 3.5 with EDIS.

Post up your exhaust gas correction settings and we can take a look.

I have this turned off currently - is this a bad thing? Mostly because the AFR targets I have in MT are all set to 0.00 and I haven't bothered to look up what they should be yet.

Interesting that MLV is rubbish around idle - that would explain why I've been getting frustrated with it! I'll stick with my own settings for this one I think...

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OK, sorry to say this but RTFM :rtfm: - you can't use AFR target maps with a narrowband, you're going to confoose the thing terribly. You also can't really do tuning through MLVV with O2 correction turned off as it does rather rely on that for its operation :rolleyes:

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^^^

:rofl: thats a polite way of saying it :rofl:

OK FWIW

  • Switch o2 correction back on and post up settings
  • Set CLT to 78 seems to help on V8s esp WUE
  • what exactly is your O2 Lamda sensor, when you say "Generic" WTF exactly is that ?
  • You'll therefor need to check the settings vs your lamda
  • Turn fuel over run cut off "OFF" for logging it helps t give a smoother MSQ VE across the range when starting
  • You can Only use ONE log per tune, ie if you log the same MSQ 3 x 30 mins you can ONLY use 1, the other 2 are scrap after 1s use as VE Changed
  • Aim for a log of about 45 mins and try to hit as many cells as you can in this time - drivey allstylee :blink:
  • Forget tickover - MLV and MT won't help, when you have redone MLV and uploaded a new (and improved VE do it
  • The way is to have it good and hot and then manually add in a value to let it tick over smoothly - try around 40
  • and have "40" (or whatever it likes) in any other "Tickover cell" it jumps across down / up / into
  • When you next log you'll loose these, repeat again after the New MLV VE
  • The MLV version you have is fine
  • When you start it up load the XLS 1st, then the MSQ
  • then check it is set for Narrow band
  • Then tick / check "Normal" (for the 1st few good long logs)
  • unless the MSQ is really off then go easy for 2 goes
  • Upload into MLV and run, then save as new MSQ and reload new MSQ
  • Then go and relog agina BEFORE changing any weird cells / tickover cells
  • Repeat, prob at least 3x and at least 40 mins per log
  • Only then tickover and look at odd cells
  • Then relog again, this time say 1-2 hours and when you run MLV run for HARD not normal
  • Only when your finish switch back on Over run fuel cut off :)

HTH

Nige

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:rolleyes: Sorry guys - getting myself confused.

AFR targets were turned off again (knew there was a reason why I wasn't bothered with them...) O2 correction has been turned on with these settings (although I never realised MLV relied on it...):

post-1194-1247069208_thumb.jpg

O2 sensor is one of these: O2 sensor on eBay It's a universal zirconia sensor.

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Here's a clue...

I also get the impression the engine is down on power - it really doesn't pull much better than a TDi.

Here's another:

post-1194-1247091296_thumb.jpg

Notice anything wrong for an EDIS installation?

I've actually now got another interesting problem. With everything set up *ahem* correctly :rolleyes: , the timing is jumping around between EDIS in limp mode and what MS is telling it. Sticking an ancient 'scope on the SAW line, there seem to be a few very ghostly spikes. I've got about half way through re-wiring with shielded cable, but won't finish 'till Friday night...mostly due to the sauvignon blanc I've been sipping all evening....

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Hmmmmm, tried running mine like that once, feck me did it smoke a lot!

Clouds and clouds, black, white, blue.... wow....

Definitely did my bit for global warming that day :)

Well that's the really odd thing - it actually ran really quite well! Went through the MOT with no problems at all. No smoke, but down on power, and a little reluctant to rev under load. However, my crank sensor is slightly out, giving me a limp mode of 8 degrees BTDC.

Quite intrigued to see how it is when it works properly...

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:lol: silly boy :lol:

Well at least you found it, just fixed a fault for someone that was not unrelated to your experience so you're not the only one today :P

I do have to ask why you didn't just download a ready-made MSQ from this forum, give the inputs & outputs a quick check and use that as a known good base?

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I do have to ask why you didn't just download a ready-made MSQ from this forum, give the inputs & outputs a quick check and use that as a known good base?

I did! Not sure how the settings were changed - may have been me when I was fiddling round before the engine was running. Originally I was going to run MS'n'S rather than EDIS. Lucas don't make laptop parts do they?

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  • 3 weeks later...

Sorry to drag this up again, but I'm still not getting a whole lot of sense out of this (although it is a lot better than last time!).

I've done 2 short logs of about 30 mins, and one long of about 50 mins....and MLV is spitting out this:

post-1194-1248598607_thumb.jpg

Comparing it to other VE tables, it seems very flat and un-even. The engine runs quite well with this map, but it isn't so good around idle and I feel it could be smoother.

So, in order, what can I have [expletif]ed up this time?

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Hmmmm

Doesn't look completely wrong.

It will depend on things like Fuel Req engine CC gearing and a whole host of other thing

Go do a 2 hour log, drive it like you have a broken set of toes, find hills, go up flat out,

then in top and make it struggle, go down hills, engine high and braking and at lower RPMs and higher gears,

drive it like you stole it, drive in on flat roads in top foot ghard down from F all rpm to as high as you wnat to go,

do this in differing gears, hold speeds at 30 40 50 60 etc, drive it through heavy traffic, towns, and some ordinary

driving, then re log and piost up results - on MLV use "Nornmal" settings"

Nige

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