Car Problem

[Dani Boi]

Car is knocking from 70-90 when it's on boost from 5000rpm onwards causing my car to misfire really bad and make my engine light flash as I have the PFC for my R33. The problem has only happened since the car has been tuned (270hp)...The car leaned out on the dyno so they installed a new fuel pump (walboro) to cope with the increase in boost and on the second time dyno'ing everything seemed to run fine, although my dyno graph looks a little strange...doesnt really have a nice powercurve.

The high knocking/misfiring tends to only happen when the car is running on its normal temp of about 80 degrees

Question here is, is my car leaning out in its top end range or is something perhaps on its way out? Still running standard AFM and coils which is what everybody seems to post at first..Not too sure on what exact psi Im running as I have the Profec II. I think the setting are something like this - gain: 10%, Set gain: 0.60 and 1.03 for whatever the other one is lol (I havent touched it since I put it on)

By the way cant ring the tuner as they are on holiday until the 12th May.

Oh and Im also getting that "jolting" in boost range on colder days something about R & R where the cars sucking in too much air so the ecu just dumps a whole heaps of fuel and retards the ignition. Mybe I am running too much boost or my AFM is on its way out???

I was just going to buy the Z32 for my 33 to see if that would fix the problem but I would rather have some feedback on possible causes before I go spending money.

Feedback appreciated

Edited April 28, 2008 by Dani Boi

[paulr33]

hi,

if you have the std turbo, a z32 wont help and is a pointless upgrade

you should read the powerfc faq in my sig and pay attention to the parts talking about knocking

there is lots of information in there on how to correct and fix knocking. you should read all of those parts as you can fix the knocking yourself

[Dani Boi]

Paul, thanks ill give this a go when I get time, although I'm sitll unclear on how this is causing the "jolting" and or the missin problem

[SDEWY5]

jolting sounds like cavitation from your turbo, is this only below say 4000rpm at wide open throttle? and 1.03 bar is boost limiter, on hi boost setting on your profec 2 what percentage is this set at?? u running stock turbo? coz if so thats too high. did they change the tune after u installed the walbro? do u have a adjustable fuel pressure regulator?

Edited April 27, 2008 by SDEWY5

[bumble_bee]

how much boost can the stock turbo take?

i believe 14.7psi..but thats on the stock ecu...

but what about if u had a power fc..???

lik in "Dani boi" case...

well, i still got stock turbo..a few mods..and running a apexi neo to adjust my a/f ratios..

and i cant put in that much higher of a % off fuel into the car on the rev range...

example.. +10% etc.. would easly push max air-flow...

becoz my a/f max'es out!!

so yeah... a z32 afm would help...

and the stock afm is restricted to an amount of power...

and he believes he has 270hp..

and i too have around 250hp.. and on stock ecu...

so a new afm wouldnt hurt..

cold be a fault fuel pump...or something along those lines aswel..

[paulr33]

hi,

the stock turbo effiency is about 12psi, anythign else just adds more heat and risks the life of the turbocharger

this is regardless of ecu you are using, be it stock, powerfc, motec etc

the stock afm is fine for upto 250rwkw, upgrading it at 200rwkw gives you no benefit as the stock afm and z32 are the same physical size

[Dani Boi]

jolting sounds like cavitation from your turbo, is this only below say 4000rpm at wide open throttle? and 1.03 bar is boost limiter, on hi boost setting on your profec 2 what percentage is this set at?? u running stock turbo? coz if so thats too high. did they change the tune after u installed the walbro? do u have a adjustable fuel pressure regulator?

Yeah below 4000rpm is generally when it happens so for example when Im cruising on the highway at 100 and I put my foot down in fifth thats when it jolts keeping in mind the 33's rev at about 3000rpm at 100km/h. Whats "cavitation", I've never heard of that term before? This is what my tuner has set my profec at:

Hi - Gain: 10%, Set Gain: 0.60, Warn: 1.10

Lo - Gain: 10%, Set Gain: 0.40, Warn:1.00

lo/hi peak: 1.03

(I always drive on Hi)

I do not have an aftermarket fuel regulator and am running the standard turbo still for series II R33

And yeah as I said I dont know if they put my car back on the dyno or they just tuned it with the standard fuel pump at 7psi because the 270hp i made is only @ the flywheel so that be lucky to be making 200rwhp which seems incredibly low considering the mods i have on the car.

Edited April 27, 2008 by Dani Boi