something wrong when trying to hold full boost

[Guest | hype^ |]

i just got a intercooler and upped the boost with a T-piece

im running 12 but i noticed it spikes to about 14 sometimes.

now my prob is when driving fast (racing or whateva) and i try to floor is and hold max boost past 3-4K the car it starts to go crazy..

it feels like its missing or hitting a limiter (fuel??) the car just start jolting really hard ..

its crazy..

whatcha'z recon??

[Merli]

standard ECU's overboost protection.

Solution: Lower boost, or get a PowerFC.

[Guest | hype^ |]

hmmm .. but the mechanic (who does know his shit) set it..

said is was right for the set up..

it was done by mark at hills who dynoed it 6 times till he was happy with it and said it was right... soo... hmm...

[Merli]

Dyno testing won't replicate real world driving loads.

If you don't believe me, turn down the boost and see if it still does it. Then turn it up again, and floor it again. And then turn down the boost and floor it... And then turn up the boost and floor it...

Repeat as many times as it takes until you realise that I'm right

[torana_mad]

welcome to the word of modified cars lol.

man i have had that many probs it aint funny lol. cant you just play with the screw and lower the boost on your Valve.

Ash.

[torana_mad]

oh and turbosmart do a fuel cut defender in a valve and electronic type for around $100-180 and im not sure if it is a good thing/safe to use but you could also put on a air/fuel ratio meter to keep an eye on so that you know if it leans out.

oh and its good to hear your cars back on the road and i cant wait to see that front bar with a nice fat cooler in it

Ash.

[Guest | hype^ |]

lol merli..

thanx for the tips..

u too ash

i just went for a drive with my old man..

it definatly looks to me (who doenst really know much but anyway) like its boost cut..

when it spikes to about 13-14psi the car jolts and the boost drops down to whateva. if u keep accelerating itll go back up to 14 and jolt again.. so on and so forth..

stupid cars!!

[Blitz]

As Merli set you are most likely hitting the boost cut which causes the car to jolt....

v common...

[Zer0]

I have experienced similar. As Merli said its the standard ECU overboost protection, which is not such a bad thing as you don't REALLY want to run a stock R33 turbo at 14-16PSI unless you are looking for a good excuse to buy a new one.

If you want to stop it doing this either turn down the boost, get a boost cut defender or buy a PFC as Merli said.

[Guest Malleus]

I've got the same problem, engine runs smooth until you hit full boost, at which point it goes really shuddery. Got mine tuned by Mark as well, need to take it back and get it adjusted.

Was wondering what it was, if it's just the boost cut i'll be a happy boy.

Matt

[torana_mad]

Hey hype didnt merli have a power fc he wanted to part with

hehe go the full hog mate :uh-huh:

Yeah i hope to be back on road soon but i find out today if i get my new paint or not and if i do car will be stripped down tomorrow and if not the new ignition will be put in and lights sorted.

I also have a truck turbo on its way up from melb :uh-huh: so i got some stupid ideas of what to do with it.

Ash.

[Merli]

I didn't suggest the PowerFC because I'm selling one. I suggested it because it's the easiest and best solution to your problem.

I ran 0.9 bar boost (14psi) on my R33 GTS-t for about 8 months, and it didn't miss a beat.

Anything over 10psi, and the standard ECU starts to retard timing and you get a huge hole in your power curve.

Anythin over 14psi, and the ECU will cut fuel, making your car seem like it just hit a brick wall for a second. That's the overboost protection you're experiencing.

The PowerFC fixes both the retarded timing and overboost protection problems that you are facing.

Here's a dyno chart of my car on standard boost, and then when I tried to dial in 0.9 bar... This wasn't the boost cut, it still pulled smoothly, but you can see where the ECU goes "OH SH1T... too much boost" and retards the timing:

Here's a dyno chart of the car's power after I put the PowerFC in. No other mods since the previous dyno graph I posted above.

[torana_mad]

merli i knew you wanted to sell it so i just gave the hint to hype to help fix his prob and give him more power dont think im telling him to buy cause you said what you said and because you have one for sale it doesnt really worry me who you sell it to but im sure he wouldnt mind one after spending what he did and to have this prob pop up (which cant be helped at that boost) so if he could get a 2nd hand power fc for a good price (and we know your a good guy and look after your stuff) that will make him happy once more

In the end i just wanted to say to hype that you had one for sale merli because it would be worth it for him to get one.

Ash.

[Guest | hype^ |]

lol thanx ash and merli..

unfortunatly new clutch and intercooler = hype with no money!

so ill have find a new fix till i can afford a PFC

[Merli]

Originally posted by torana_mad

merli i knew you wanted to sell it so i just gave the hint to hype to help fix his prob and give him more power dont think im telling him to buy cause you said what you said and because you have one for sale it doesnt really worry me who you sell it to but im sure he wouldnt mind one after spending what he did and to have this prob pop up (which cant be helped at that boost) so if he could get a 2nd hand power fc for a good price (and we know your a good guy and look after your stuff) that will make him happy once more

In the end i just wanted to say to hype that you had one for sale merli because it would be worth it for him to get one.

Ash.

HAHAHAHA... That has to be the world's longest sentence

/me gives Ash a few periods and commas

No worries dude... I was just emphasising that this is honest information, not some ploy to sell my PowerFC.

[torana_mad]

"/me gives Ash a few periods and commas"

none of that stuff is needed on here, i hope lol.

Thats fine mate i just wanted to get my point across and i guess i just didnt stop.

Ash.

[MetBlue_GTST]

Running a completely stock engine, and i do mean completely stock as in standard intercooler, turbo, the lot, the only aftermarket stuff was a blitz BOV and an Apexi F-Manage piggyback ECU running at .85 bar i was able to get 252HP at the wheels... That was at a dyno day, but i did get it dyno'd ages before that and got 245HP at the rears...

If you wanna see a better quality picture just go to my website then look under dyno...

Alan.

[Guest | hype^ |]

well i turned down the boost tonight...

i think what happened is when the boost was being set it was a really hot day.. so when set it was boosting properly to what it was ment to (12psi)...

but when after i let it cool down and took it out in the cool night air it was goin beyond what it was set at .. (to 14psi)

would i be right in assuming this???

so my old man and i went out tonight and set it back to 12psi on the nice cool night air.. not shes running properly.. its hold 12 all the was to redline.. MUCH unlike b4

[Cubes]

Be carefull with your fuel pump.

Providing you fuel pump is not leaning out and already providing good power (its almost dead):

Buy a std generic bleed valve and a check valve which is like a one way valve.

Hook it up to your fuel pressure reg with the check valve obviously between the plenium and the bleeder.

THEN.... slap it on a dyno for approx $140

Tune the Bleeder and the Boost/Timing and get around 170rwkw.

If you fuel pump is crapping its self well you will already be making close to that power level.

Remember some dyno's read different lower/higher.

The figure of 170rwkw is going from two DD dyno's here in SA.

Tilbrooks and RPM In Adelaide.

Both of their Dyno's read very very close.

Some others read higher a lot higher.