Why can't I achive high boost?
 

Hi Guys,
do anyone has a clue why cant i achieve high boost?
Ive less problem when low boost at 1.25bar but when i try high boost at 1.5bar my car will go like boost cut or maybe misfiring when not even reach 1.5bar.

Ive check plug cables and coils, boost and vac leak test.
Commpression test result ok.
Plugs gapped and sometimes it occured at low boost as well.

Will it be the wastegate problem or any other areas that i should check?

Im using Profect B II

Sounds like the tune is limiting you to not hitting the desired boost.

Sounds a lot like fuel cut to me.

Omg...but im on a PFC ecu and how to tell a fuel cut?

Get a wideband o2 check your a/f ratio. I see you drive an Evo 5, which I know nothing about, but if you're hitting fuel cut I would just turn the boost back down to a factory specs and take it to a tuner if you can.

x2

Fuel pump?

Is it a D or L jetro PFC (is the MAF still in place)? Do you have the hand commander installed?

Yes its a L-jetro and ive commander.
Yday when i check on the knock its show 89 which i got a shock and the knock is very inconsistent as sometimes when i trash the car the knock value is just below 35.

What happening??? Will it be the Air flow sensor going cockcoooo???

If it were my car I'd possibly look into the tune, afrs fuel pressure under boost before it starts backfiring and try eliminating knock FIRST. Then go from there to diagnose if possibly ignition system falling off . Good luck :mitsu:

Also guys its a EVO 5 (thin DSM) start with timing system.

It's more than likely your ECU load limit.

Do you have a modded ecu? A lot of my customers with light clutches will call me complaining about misfire when they are resting their foot on the clutch triggering NLTS

If your modded and your plugs are gapped over .021 start there. Re-gap them to .021

James, have you had it tuned since you put your engine together?

Thanks guys for sharing and im running a standalone pfc ecu...

Today ive just added an additional 7psi spring onto my turbosmart ultragate 38mm wastegate.
So,my w/g is currently running on dual springs and hope it will solve the problem,

Will a deteorated cam sensor caused this problem?

Knock of 89 is not good, the least I's start with is getting the map looked at. Is it locked or can you make changes via the hand commander? I would remove 2 to 3 deg of ignition via the hand commander if the knock level is that high (downside is you need to do this each time unless you have datalogit).
What have you gapped the plugs to, and do you have means to monitor AFR's?

All you guys commenting on the 89 knock count.. when have you seen that much knock on your cars?!?!?! I have a 10:1 stroker i've ran at 31psi on 93 @ 12.0:1 and it seems to peg out at 20...

I don't think hes looking at knock sum.. Knock sensors read voltage when the car isnt' knocking.. a great thing called a filter helps it know if its really detonation or not..

if you had a 89 knock count while your car was running it would sound like someone had a coffee can full of rocks and was shaking the holy living piss out of it. If that isn't happening...

I'll help you eliminate the ECU
does it miss any other time other than wide open throttle..

What exactly down to the thousandth are your plugs gapped to. .021 or lower if your on our style ignition and not a DSM style

A CPS that isn't reading at the correct time will cause a **** TON of misfire issues.

How's it start... it start normal?

Hi,
ive discuss with my tuner and tmr we will be doing another round of fine tuning and hopes everything will be just fine...Thanks