Overboosting and some other issues
06-01-2005, 02:38 PM
#1
Former Vendor
Thread Starter
Overboosting and some other issues
Reading thread about Guru chip's max boost raised some questions...I thought I'll start a new thread although my questions are also there.Please give me some VERY simple answers...
But before the questions some background.
Current set-up:
-Guru V7 (or V8) chipset
-Guru MAP-kit, ie. AFMLink
-KKK 27/6 hybrid with 60mm turbine wheel
-Siemens 72lbs/hr injectors
-stock snorkel and airbox
-3" exhaust all the way from turbo
Problems started after changing the turbo and injectors,with stock turbo and injectors a/f adjustment at dyno was easy ( 278hp/5500rpm @flywheel /1,2bar-12,5 to 13,5 a/fr).
At last dyno after changes run mixture stayed at 14,75 no matter what done.Produced only 330hp/6000rpm @flywheel /1,0 bar.We didn't dare to try higher boost.FQS at DME was set to match injectors and almost all fuel delivery problems are counted out.
During our trip to Germany I encountered problems with WOT acceleration at 4th/5th gear...all OK until 5000 rpm,boost as set ( 1,0 bar ) and narrowband not below stoichiometric ( best it could do... ),but after 5000 boost started to rise with rpm and at 6000 there was 1,3bar.At first good pull I didn't notice this boost rise ( there was some traffic to observe with speed above 200km/h ) and the ignition cut-out scared the hell out of me,it felt like something grabbed and held the car.Well,I thought that mixture went lean,it started to knock and KLR did what it's meant to do.Then I started to observe gauges and noticed this boost rise.After reading that another thread it seems that this overboost protection caused ignition cut-out.
BTW, partial-throttle acceleration goes well,I managed to get 280 km/h to the tach at 6400rpm and 0,6 bar boost. It's just long duration WOT,dyno pulls didn't last that long either.
I just checked my AFMLink settings and loggings with SerialLink.Max gain is set to 5,00V.What puzzles me is that at loggings Vecu shows 52 at idle,and 255 at WOT when boost exceeds 0,9 bar ( 0,9 - 1,1 bar ) ,independent of rpm ( eg. 4700-5700 rpm ).
To questions:
1) Should this Vecu be multiplied with something ( like 0,02 ) to get actual voltage that is inputted to the DME ? ...and DMELink gets 1,04V at idle, 5,00V at max.
2) Or is there something wrong with my AFMLink and maximum voltage DME gets is 2,55?
3) Do I gain something from playing with this max clamp voltage,even if I'm not going to use more boost than 1,2 bar.
4) Has this lean mixture at dyno something to do with voltage AFMLink sends to the DME.
5) Should I try with different FQS settings? After first start with new gadgets my car run with overly lean mixture,I had to add about 30% more to get it running smoothly,even though FQS was set to larger injectors,this with idle...
6)Overboosting (unwanted boost rise)....bad wastegate or something else?
I already got good answers from Duke for questions 1-5,but second opinions are always nice to get!
But before the questions some background.
Current set-up:
-Guru V7 (or V8) chipset
-Guru MAP-kit, ie. AFMLink
-KKK 27/6 hybrid with 60mm turbine wheel
-Siemens 72lbs/hr injectors
-stock snorkel and airbox
-3" exhaust all the way from turbo
Problems started after changing the turbo and injectors,with stock turbo and injectors a/f adjustment at dyno was easy ( 278hp/5500rpm @flywheel /1,2bar-12,5 to 13,5 a/fr).
At last dyno after changes run mixture stayed at 14,75 no matter what done.Produced only 330hp/6000rpm @flywheel /1,0 bar.We didn't dare to try higher boost.FQS at DME was set to match injectors and almost all fuel delivery problems are counted out.
During our trip to Germany I encountered problems with WOT acceleration at 4th/5th gear...all OK until 5000 rpm,boost as set ( 1,0 bar ) and narrowband not below stoichiometric ( best it could do... ),but after 5000 boost started to rise with rpm and at 6000 there was 1,3bar.At first good pull I didn't notice this boost rise ( there was some traffic to observe with speed above 200km/h ) and the ignition cut-out scared the hell out of me,it felt like something grabbed and held the car.Well,I thought that mixture went lean,it started to knock and KLR did what it's meant to do.Then I started to observe gauges and noticed this boost rise.After reading that another thread it seems that this overboost protection caused ignition cut-out.
BTW, partial-throttle acceleration goes well,I managed to get 280 km/h to the tach at 6400rpm and 0,6 bar boost. It's just long duration WOT,dyno pulls didn't last that long either.
I just checked my AFMLink settings and loggings with SerialLink.Max gain is set to 5,00V.What puzzles me is that at loggings Vecu shows 52 at idle,and 255 at WOT when boost exceeds 0,9 bar ( 0,9 - 1,1 bar ) ,independent of rpm ( eg. 4700-5700 rpm ).
To questions:
1) Should this Vecu be multiplied with something ( like 0,02 ) to get actual voltage that is inputted to the DME ? ...and DMELink gets 1,04V at idle, 5,00V at max.
2) Or is there something wrong with my AFMLink and maximum voltage DME gets is 2,55?
3) Do I gain something from playing with this max clamp voltage,even if I'm not going to use more boost than 1,2 bar.
4) Has this lean mixture at dyno something to do with voltage AFMLink sends to the DME.
5) Should I try with different FQS settings? After first start with new gadgets my car run with overly lean mixture,I had to add about 30% more to get it running smoothly,even though FQS was set to larger injectors,this with idle...
6)Overboosting (unwanted boost rise)....bad wastegate or something else?
I already got good answers from Duke for questions 1-5,but second opinions are always nice to get!
Last edited by pete95zhn; 06-02-2005 at 09:39 AM.
06-01-2005, 02:54 PM
#2
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Were the chips remapped after the Turbo and injectors were changed ? That would surely cause some weird problems. I think generally Danno reburns for $100, but don't quote me on that.
06-01-2005, 11:42 PM
#3
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Dude save your self some time and hassle and try and call John at vitesse and see if you can work something out - his chips are just out of this world - smooth idling, and awesome power across the power band