Title: ME7.5 adjust ignition per gear is it possible? Post by: professor on October 30, 2012, 03:08:42 AM High loads on low gears can exploit more advance for power delivery but higher gears with high ignition can cause struggle on revving up, especially on setups who works over 191.25% loads for half of the rev range and regular gasoline.
Is there a way to adjust ignition per gear on ME7.5? Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: prj on October 30, 2012, 05:09:20 AM Huh???
Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: elRey on October 30, 2012, 05:17:14 AM I think he is talking about spool via timing advance
Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: professor on October 30, 2012, 05:20:36 AM Ignition vs Gear i am asking :)
Yes it can be done closer to what am asking via igntion vs IAT, but there is ignition vs gear on ME7.5? Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: prj on October 30, 2012, 05:58:35 AM I think he is talking about spool via timing advance I think what he is talking about makes no sense at all. professor: Care to elaborate maybe? You are making some really bold statements which IMO have nothing in common with real world scenarios. Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: Gizmo20VT on October 30, 2012, 06:22:15 AM So basically you want timing maps to change when selecting different gears to change the "power band per gear"?
Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: prj on October 30, 2012, 06:41:59 AM Basically on high load the engine is knock limited the entire time, so this entire thing seems completely pointless to me.
Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: professor on October 30, 2012, 06:54:33 AM So basically you want timing maps to change when selecting different gears to change the "power band per gear"? Well sort of. Let me to describe the scenario i faced and based on what i talk about: Conservative ignition request on wot for a car which works at 191.25% load from 3500 till redline. Lets say 18 degrees KFZW and 19.5 KFZW2 (12 tappering to 18 and 13.5 tappering to 19.5 after 4500rpm). On 1st, 2nd and 3rd gear car dont pulls back ignition. On 4th and more on 5th gear ignition retards is reaching 4-6 degrees on each cylinder after 5000rpm. IAT is about +12oC from ext temperature and those results are similar in many continuous logs. So i am wondering how to overcome this issue? We can request a bit aggressive ignition on lower gears and pull back ignition on higher gears? Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: Gizmo20VT on October 30, 2012, 07:06:13 AM This may be a silly answer as Im not really sure where you current power band is or spec turbo.
You could run less timing up top if your out of the efficiency range of the turbo, what octane are you running? Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: Gizmo20VT on October 30, 2012, 07:07:13 AM What about less boost request on Higher RPM?
Sorry for double post. Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: professor on October 30, 2012, 07:17:07 AM Less boost request isnt a option, via bc perhaps, since car runs over 26psi stable boost till redline.
Gasoline is strictly 100RON. Turbo is GT3071 and engine is forged 1.8T20V with stock head. As prj claims perhaps its pointless since ecu takes control and reduces timing accordingly put perhaps lowering requested ignition on high gears and lowering the timing retard can give us better top end power delivery and of course higher safety levels. Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: rajivc666 on October 30, 2012, 07:27:58 AM You can take the code for KfZW and kfzw2 only from http://nefariousmotorsports.com/forum/index.php?topic=1556.90 and use the gear as the counter for switch, it is easy and can be done.
Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: phila_dot on October 30, 2012, 07:34:35 AM There is a reason there isn't a table for this...it is unnecessary.
This is handled by load. Rescale the axis if you have to. Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: prj on October 30, 2012, 08:17:15 AM Well sort of. Let me to describe the scenario i faced and based on what i talk about: Conservative ignition request on wot for a car which works at 191.25% load from 3500 till redline. Lets say 18 degrees KFZW and 19.5 KFZW2 (12 tappering to 18 and 13.5 tappering to 19.5 after 4500rpm). On 1st, 2nd and 3rd gear car dont pulls back ignition. On 4th and more on 5th gear ignition retards is reaching 4-6 degrees on each cylinder after 5000rpm. IAT is about +12oC from ext temperature and those results are similar in many continuous logs. So i am wondering how to overcome this issue? We can request a bit aggressive ignition on lower gears and pull back ignition on higher gears? Let me start by saying that what you want to do is a very bad idea, and this is because you will melt the engine doing what you are doing. The reasons you are seeing more ignition retard are as follows: 1. The cylinder charge is probably higher due to higher boost in higher gears. 2. The EGT's go up, making the combustion chamber hotter and more prone to detonation. Now, what you are doing by retarding timing in higher gears is going to spike the EGT's even more. You need to control your EGT's properly and enrich the mixture. As phila_dot said, the reason this is not done is because this is inventing a solution to a problem which does not exist. If you are capping out the load axis in the map, then underscale your load up top, and you can specify the ignition angle for every load as needed. I also don't see how reducing advance is EVER going to make anything better under load. Reduced timing - lower efficiency, more waste heat, higher EGT's, less torque, less power and so on. This has nothing to do with Motronic per se, it seems that you have a few core principles of the internal combustion engine wrong. Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: professor on October 30, 2012, 10:50:51 AM Load is adjusted to meet engine load with different boost levels, but load on peak boost level is same for 3rd 4th and 5th gear, so on wot it follows same ignition map line.
Its same cause via bc its works 5% more wg dc on 3rd, 0% on 4th and -4% on 5th gear. Also it works with max 800-810oC at 5th gear redline (on down pipe) with rock stable lambda 11.6:1. But retards are higher especially on 5th gear as result of combustion higher temps and engine stress. So would be best to lower the boost more on 4th and 5th gear and adjust the ignition if needed closer to 2-3 retard. Thanks for the answers. Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: prj on October 30, 2012, 12:50:30 PM Then you are running too rich in low gears and too lean in top gears.
These 5V engines tend to make peak power at around 0.8-0.82 lambda, you are running richer than that through the range it seems. Richer lambda is needed in most cases only for EGT control. Do you have any EGT control? Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: professor on October 30, 2012, 01:35:10 PM Yes i set fueling based on MKRL after 140% load, lamfa is set to 0.82 until 600oC where BTS with 0.79 target used for high loads/rpms too.
After 850oC FBSTABGM is taking control, without needed more than one/twice so far. Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: prj on October 30, 2012, 01:36:53 PM 600C does not really need that much enrichment, I'd trigger it higher.
Do you have an actual EGT sensor on the car? Or when you are talking about 800-850C it is simulated EGT's? Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: professor on October 30, 2012, 03:06:35 PM Yes talking simulated egts for FBSTABGM.
Egt gauge/probe beeps after 800oC so foot is lifted of the pedal and has happend one/two times. Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: prj on October 30, 2012, 03:51:20 PM Simulated EGT is usually very wrong, especially if underscaling load and running lots of boost.
Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: professor on October 31, 2012, 12:37:03 AM Correct thats why an ext egt gauge/probe is necessary.
Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: prj on October 31, 2012, 01:39:33 AM Regardless, if your load does not peg, then your ignition angle depends on IAT and EGT.
Gear has little to do with it. So use those functions to tune. Use LAMBTS to enrich more on higher ignition retard and all will be well. Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: ibizacupra on October 31, 2012, 03:38:49 AM Simulated EGT is usually very wrong, especially if underscaling load and running lots of boost. Is the egt simulated or does it use lambda heater temps? between 1.8t files I have looked at the trigger threshold for going into bts seems to vary on similar turbo'd engines, but which have different b1s1 lambda locations... Those which have lambda's further down the downpipe seem to have lower trigger temps.. Seemed to suggest to me the lambda temps were relevant on no egt sensor equipped cars what do you think? Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: phila_dot on October 31, 2012, 05:23:30 AM Is the egt simulated or does it use lambda heater temps? between 1.8t files I have looked at the trigger threshold for going into bts seems to vary on similar turbo'd engines, but which have different b1s1 lambda locations... Those which have lambda's further down the downpipe seem to have lower trigger temps.. Seemed to suggest to me the lambda temps were relevant on no egt sensor equipped cars what do you think? No, this is completely modeled. Title: Re: ME7.5 adjust ignition per gear is it possible? Post by: ibizacupra on October 31, 2012, 10:08:11 AM No, this is completely modeled. hmmm ok. weird coincidence when I have logged it and see it swap to bts tho.. accurate model (as std) thankyou |