As headline says K24 went into car, but tuner can't put any bigger boost on it as it runs into huge misfire once the boost kicks in, like a revlimiter style misfire.

First at roughly 3500 rpm, if you back out of the throttle it allows to come back on, then new misfire at 5000-ish, back out a bit again, then it runs clean up top 6000-7000rpm.

AF was deliberately set rich to stay on safe side and it stays rich (there's a 5bar FPR in the car), also when the misfire happens AF goes mega rich due to no combustion.

They tried to smoothen out the boost curve to not come on so hard but still the same issue once boost comes up it misfires.

With a stock X50 tune the car runs ok most of the time driving the car on the street, that's 0.7-0.8 bar max.

Is there a safety function that monitors airflow and creates these cutoffs/misfires when the airflow becomes too big? Or do these cars not have that, and do you think it's hardware related, plugs or such.

The car runs super smooth on light load, part load, up to 70% throttle etc. Just when boost exceeds 0.8bar it starts to sputter.

If you really KNOW this stuff pls chime in!

Thanks!

 

I have had som problems with this, pm me and I can give you my number or skype.
It´s easier to take this in Swedish, at least for Me

 

Spark plugs and/or coils, definitely.

 

Spark plugs for sure. I like the IK22 or IK21 denso. Gap to 27 thousands.

When you force more air/fuel into the cylinder the resistance gets higher making it harder for the electrical energy to jump the plug gap. When the plugs get worn the same thing happens. Closing the gap helps counter the problem as well.

 

simple...
change all sparkplugs and all coils.... PERIOD. Get the ones you know run good at 1.3 bar....
then try again... or before you do do a boost leak test form the turbos... chekc your WGs too... are they opening up at the same rate? what PSI? what boost are you trying to run and on what octane? 91? if so I would keep it under 1.2 bar.... lastly MAF... disconnect the harness to the maf while the car is running... if the car doesnt blip in rpms then your maf is gone too...

good luck
markski

 

subscribed.

 

what he said^

 

Could also be some loose plumbing. But starting with plugs and coils is the next thing.

Who is your tuner? What is he saying? Are you taking it into a shop or just troubleshooting a kit over the phone?

Jim

 

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I have the same thing going on a stock x50 nearing its 30kmi service.

Once I do the service which changes out plugs and coil packs, I'll check back in.

 

Misfires should make a false lean not a rich condition. Like others plugs and coils. Pull the boots off the coils and check them for cracks.

 

this might be a silly question but do you have the psm off?

 

Thx for chiming in guys!

PSM is off.
Plumbing seems fine, no leaks discovered and hoses are tight.
Didn't check the MAF yet but the car runs super smooth in all conditions except when it hits high boost.

NGK BKR7E plugs and 997 coils ordered.
Hopefully can swap these soon.

Car runs ok with 0.7 - 0.8 X50 stock file.

We're shooting for 1.1, maybe 1.2 bar with 98-100 octance gas for sustained road course lapping. With 91 1.0-1.1 or whatever it can take w/o knock.

 

also check the gap on the plugs

 

I don't know what that means.... did you do a pressure test to 23 psi from the turbos? or did someone open the hood pulled the hoses and said "no leaks discovered and hoses are tight".