Hey people

I went off happily to get my car tuned yesterday, firstly put in new spark plugs, cleaned air filter, replaced gearbox and diff oils, anyway,

we got it on the dyno (not sure what brand) and away we went, it was going ok, then we noticed that once the secondary turbo came online the boost would surge, hard to explain but the boost curve looked like a mountain range lol up down up down etc......... the guys couldnt figure it out,

i had the standard ecu with me so i plugged that in and did a trial run it was running rich as so we did a power run, everything was fine just a little rich, no boost surge at all, which makes me think that it is something to do with the settings on the pfc..........., I did read somehwere that the pfc had a boost cut if it over boosted, but cant remember where lol and cant find it again, could this surge be caused by boost cut and then boosting again and then boost cut etc... boost is controlled by the commander and is set to .80 bar

i dont know what other info to add so if any questions please ask i searched but all of the surging probs i found were at either idle or light throttle, this is under WOT

any ideas would be much appreciated,

Thanks Mark

 

.8 Bar is about 12psi for the PFC. What boost were you trying for?

You need to reread the PFC manual about how boost is controlled, pages 27 & 28.
Especially the bottom of page 28 , just above the CAUTION!

Duty Cycle controls boost, Boost controls fuel cut which you were most likely having.

And why are you using the crappy PFC boost controller for a half bridge port engine?

 

i've been having the same issue. but mine is just mild port.

it's a 2nd turbo i have there... this one doesn't have and crack on the manifold ends.... the shaft play is excellent.. no free play...

tried flicking with the duty cycle... it's still the same.. i was set on boost to 0.8 Bar... and i turn down the duty cycle to 60... and i'm boosting 0.7 bar...

still flicks... then i set it back to 70.. boosting at higher... guess i'll live with the fluctuation

oh yeah... heard someone say before the wastegate control solenoid might be giving the issue if it's not working well. my friend replaced that and no issue with the boost anymore.

i'll try flicking to push up the boost value and see if it helps....

 

hey thanks for the reply firstly i wasnt tuning the car, there were 2 guys doing it, so i figured they would know what to do........ we were aiming for the 12psi, i am familiar with pressures bar or psi, have been working with them for years, so got that bit right lol

I have now read the manual my self and understand the duty cycle, as far as i can gather i would need to lower the duty cycle to try and stop the over boosting, and in turn fuel cut.

The best idea would be a manual boost controler, and not use the pfc, I did have one but it grew legs lol so i will have to get another one,

If i up the boost level in the pfc and lower the duty cycle to try and stop the fuel cut to see if that is whats happening, would i need to be re tuned for that just for a trial or would it be ok to test with out tuning? I can actually feel the car surging on the road as i drive so would be able to tell if it had stopped. (hope that makes sense)

I am using the pfc only because when i rebuilt the engine, the insurance company declined the mechanical claim to rebuild the motor, and i ended up falling short of cash, i wanted to do intercooler and radiator and clutch and other bits aswell, im getting there slowly lol

Thanks again Mark

 

hey yeah it sounds the same as mine..... I replaced 2 of my solenoids just recently and tested the rest, they all seemed to work perfectly, but maybe i need to check again. I was gonna try raising the boost level on the pfc to see if that helped, but just not sure if that will hurt my motor??,

 

Raising the BOOST VALUE in the PFC will raise the fuel cut level. Lowering DUTY CYCLE will lower boost. Always set Boost higher than you plan to run to prevent fuel cut.

I use the BLITZ DSBC EBC but the PFC will still control fuel cut. My PFC BOOST is set at 2.00 but I only run 1.07BAR boost.

How well are your tuning dudes familair with the PFC and DL?

 

Chuck, all this time I thought if you set the PFC boost control function to off it wouldn't effect fuel cut. Interesting I need to check mine.

 

Sweet thanks you, i will try it tonight to see what happens and let you know,

I dont know how familiar they are.... not very by the sounds of it, i got recommended them by the shop that rebuilt my motor, but might do some research and find another place,

Thanks again Mark

 

hey mate which shop is it?? in AKL??

 

hey dude, it was on the dyno at i think it was called high velocity ?? his name was gavin but he didnt tune it, someone else did, do you know anyone up there that specialises in pfc tuning? Thanks

 

Ok so i have been having a play with the boost settings and duty cycle % the boost is now set at 1.15bar and the % is set as low as it can at 20% that is for primary and secondary,

Im 99% sure the surging has stopped, but now i am over boosting to .94 bar instead of .80 bar,

So thanks heaps for the help in sorting this, i will have to get a manual boost controller and port my waste gate to get the boost spike fixed now

haha its awesome to fix these probs thanks again