Testament Posted February 2, 2015 Share Posted February 2, 2015 Well actually, is it a backfire on cranking or key on? If key on then what I said, if cranking check what downtrail said Quote Link to comment Share on other sites More sharing options...
downtrail Posted February 2, 2015 Share Posted February 2, 2015 Depends on your coils if they are smart coils ie inbuilt ignitor driven at logic level and they fire from going low to high they fire the coils as the drives are pulled from 0 to 5v when you turn key on fucked idea I know but you can set your fuel priming pulse to 2s after key on to prevent the booms when you turn key on Lol. How ever if they are normal coils driven through an ignitor then they wont fire. Quote Link to comment Share on other sites More sharing options...
kpr Posted February 2, 2015 Share Posted February 2, 2015 megasquirt 1 Quote Link to comment Share on other sites More sharing options...
0R10N Posted February 2, 2015 Share Posted February 2, 2015 Both of my Link G1s sometimes do this (muffled bang from the intake when you turn the key to ON) - I always assumed it was something to do with fuel in the cylinders still.  The car would run ridiculously rough/rich for the first half minute or so afterwards. Quote Link to comment Share on other sites More sharing options...
peteretep Posted February 2, 2015 Share Posted February 2, 2015 megasquirt  lol wat  it does it on cranking, I havent played with the enrichment stuff yet so thats first option Quote Link to comment Share on other sites More sharing options...
Testament Posted February 2, 2015 Share Posted February 2, 2015 post photo of your setting pages from tunerstudio showing your spark table and general ignition settings, cranking advance etc. Â pete is using LS2 type coils Quote Link to comment Share on other sites More sharing options...
slacker.cam Posted February 2, 2015 Share Posted February 2, 2015 Play with cranking ignition timing first and foremost. I never noticed any loss of sync when we first set it up but it may have developed an issue I guess. MS (as with pretty much all ECUs) fires a priming pulse at power on to make starting easier. You may want to decrease the priming pulse width to see if that has any effect too.  Tom, unsure why you say MS fires the coils at key on but it shouldn't be doing that. Have you seen that happen on your Fiat? Quote Link to comment Share on other sites More sharing options...
peteretep Posted February 2, 2015 Share Posted February 2, 2015 nah I dont get any loss of sync Quote Link to comment Share on other sites More sharing options...
downtrail Posted February 2, 2015 Share Posted February 2, 2015 Depends on coil type see what i posted above they do and its annoying.   Play with cranking ignition timing first and foremost. I never noticed any loss of sync when we first set it up but it may have developed an issue I guess. MS (as with pretty much all ECUs) fires a priming pulse at power on to make starting easier. You may want to decrease the priming pulse width to see if that has any effect too.  Tom, unsure why you say MS fires the coils at key on but it shouldn't be doing that. Have you seen that happen on your Fiat? Quote Link to comment Share on other sites More sharing options...
slacker.cam Posted February 2, 2015 Share Posted February 2, 2015 Depends on coil type see what i posted above they do and its annoying.  Yeah for sure. They are coils with built in ignitors and this can be an issue but in this case the issue happens at the start of cranking, not at key on. I helped Pete to wire the EFI gear and I can't remember if we have the coils always on with the ignition or switched using the FP relay signal. Probably off the FP relay as that's how I normally like to do it. In that case the trigger lines are already at 5V when cranking begins but I wonder if there is an issue where the coils fire unexpectedly when you power them on even if the trigger line is pulled high. It's an easy test which is nice. Just temporarily replace the relay with a wire link and see if that fixes it. Quote Link to comment Share on other sites More sharing options...
downtrail Posted February 2, 2015 Share Posted February 2, 2015 If thats the case then when you turn key on pump will prime. Coils will go live, triggers will go high(if they are triggered this way) . then coil power drops out. then when cranking comences and pump fires up again coils are switched on again. are the coils fired on the rising edge or falling edge of the 5v square wave? Quote Link to comment Share on other sites More sharing options...
peteretep Posted February 2, 2015 Share Posted February 2, 2015 im pretty sure you guys are getting too technical and its just a tuning issue Quote Link to comment Share on other sites More sharing options...
Testament Posted February 3, 2015 Share Posted February 3, 2015 it's a thing though. I had the wrong fuse pulled one time, thought i had pulled the fuel pump and I had pulled the coils when I was trying to diagnose what was eventually a borked ampseal connector - long story short it kept on turning stuff on and off and had a bunch of fuel in the motor. when i figured out i had the wrong fuse and swapped it hit key on and the 2.5" exhaust became a 63mm cannon  luckily no other issues than a fright and a few rattled windows Quote Link to comment Share on other sites More sharing options...
kpr Posted February 3, 2015 Share Posted February 3, 2015  lol wat    just bitter after a ms1 shocked the shit out of me, firing the coils when it should not have been.  sounds like a trigger/ecu issue to me. for it to fire out the intake timing would have to be way out. too much for engine to start.   as for timing at cranking, 10degrees advance will be ballpark 1 Quote Link to comment Share on other sites More sharing options...
Roman Posted February 3, 2015 Share Posted February 3, 2015 Interesting article. Â http://www.usrallyteam.com/content/tech/injector_staging_article.pdf Quote Link to comment Share on other sites More sharing options...
Roman Posted February 6, 2015 Share Posted February 6, 2015 Hmmmm so I've got MAP and MAF sensors wired into my car, I still think MAF looks to be more accurate / easier to interpret changes. As per VVTI changes.  I like to know that at WOT I'm getting XYZ grams/sec of air rather than just 100kpa across the board or whatever.  At the moment though I've just got the MAF logging as a 0-5 volts because I havent calibrated it, I need to know grams/second vs voltage.  I've got two sets of data I can mash together to make it work I guess, going off some of the datalogging from factory ECU previously.  But just thinking about how the two compare to tune with.  With MAF, at low rpms you never hit the peak airflow readings, at WOT through the rev range you work diagonally through the map:   But so that means the whole bottom row goes to waste except for 1 cell value, because you only reach 180 grams/sec at peak power rpm. Then as your revs go down you lose resolution in your table because at peak power you've got say 10 rows to work with, but at 2000rpm you've only got 3 or 4 rows that you ever reach.  Soooooo does the extra accuracy of the sensor offset the lack of table resolution? It probably still does, since most factory cars use MAF these days. I guess it comes down to how well your ECU can interpolate between rows and how sensitive it is to voltage changes.  Onnnn the other hand. With MAP, your WOT is pretty much just working with the 100kpa row and you've got full resolution at each rpm down to peak vaccum.So you end up using the full table as WOT is the bottom row:   But the sensor itself seems less senstive to change / less accurate.  So the toss up is to whether I would prefer to have high senstivity in the sensor but low resolution to tune with. Or vice versa.  Since it doesnt cost me anything but time, I think I'll calibrate the MAF sensor and then put a full tune on both.  I suspect that the MAF tune will 'hold' better with changing conditions compared to the MAP sensor which I guess is a lot more reliant on the IAT sensor being super accurate and other constants being... constant.For example if you've got a ram air type thing going on, if you're going faster and there's more air stuffed in then the MAF reads it fine. But MAP doesnt necessarily know how to account for the VE change unless you have barometric compensation setup, from the area where your inlet is.I think I'm going to get one of the stick style MAF sensors, and bung it in a 3" or bigger pipe and roll with that / datalog both / maps for both / decide later / more scope for rambling / coupe lifeEDIT: Just thinking about it, I could setup a second fuel/ignition map that it switches to below say 25% or 50% throttle. Then use this as a high resolution map for the low airflow area of the MAF sensor at lower rpm.  Get dat good economy, hnnnnggg Quote Link to comment Share on other sites More sharing options...
kpr Posted February 6, 2015 Share Posted February 6, 2015 i would say both are far more accurate, than the geezer on pc link jaming the numbers in to get the afr right anyway. not likely going to change the afr enough to gain or loose anything 2 Quote Link to comment Share on other sites More sharing options...
Roman Posted February 7, 2015 Share Posted February 7, 2015 Hmmmm so I setup the MAF with a calibration table and tuned fuel only on it today.  So first thing I notice... Rather than random peaks and troughs in my fuel map, it's much smoother. Although there are pressure spikes or troughs because of resonance or whatever, the airflow is reasonably constant by comparison.On my MAP map I had to increase resolution around the 45000rpm mark to tune around a big dip.  Also it ran like a sack of crap at first, and I was thinking about throwing the towel in and going back to MAP.But with some persistence it's running really nice.  Still I was still using the MAP sensor for ignition I datalogged it all and then manually translated that into a MAF ignition table.  Either way the car is driving really awesome now, feels and cruises along like a factory car which is awesome.  Another problem I had with the MAP sensor is that it was reading 100kpa while cranking because it doesnt generate vaccum yet, so it was dumping in heaps of fuel and I had to turn off all of the enrichments etc to get it to start.Where as the MAF just shows 3.5g/s which is accurate right from the start.  I just need to finish an audio output / knock sensor setup then I'll start having a play with the ignition timing while cruising and lean it out a bit. Quote Link to comment Share on other sites More sharing options...
kpr Posted February 7, 2015 Share Posted February 7, 2015 no drama to change the cell it sees cranking.  since it will only ever see that cell when cranking.  also, likely a dip at 45000rpm because the rods are no longer in the block at this point 8 Quote Link to comment Share on other sites More sharing options...
eke_zetec_RWD Posted February 7, 2015 Share Posted February 7, 2015 Yea once I reved my pinto to 45000 rpm and it also had a dip. I have found Map, when tuned correctly, works perfectly fine under all conditions. ( except with huge cams and quad throttles ) 1 Quote Link to comment Share on other sites More sharing options...
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