popping/split loss in power now that i went to 17psi

[j-z]

well i just got done making a DIY MBC. i was boosting 13 psi off the wg and wanted more. mainly i just wanted to get rid of how the wg opens up slightly before you hit full boost. well the MBC works like a fuking charm and only cost me $10 including the $4 tap i had to buy. besides that i just went for a blast down the road. when i first hit it everything was fine. then i hit it again and i heard this split second poping noise intermitently during the higher revs of the 17psi pulls. i could feel it lose slight loss in power right when it made that noise. i have a wideband hooked up on my car right now, and it was dead even at 11.2 the entire time in boost. i also have an ITC hooked up as well. i backed the timing off a few degrees with that since im boosting 4 psi more. my only thought is spark was being blown out... everything on the car from the gauges to the sound of the motor is perfectly normal. btw, i hit %71 airflow with my z32 maf as opposed to %64 at 13 psi . im alot more satisifed with the power now too. i thought it was slow before for 13 psi. for now this is right where i want it. i tried to launch from a dead stop, and....yeah, that didnt work out to well on 255 pzeros. oh yeah, i have bkr7e11's gapped at .34 .

[wild_maxx]

it sounds like spark blowout. Gap them down to .30 and see how it goes. Did you get a step colder plugs? That also helped me out.

[virus77]

yup drop the gap, .26-.30 should be fine.

[j-z]

sweet, so thats what yall think the problem is? im running bkr7e11's which is two steps colder. ill try a .28 gap tomorrow and post how it went.

[KATwo40]

Go with BKR7E's, as opposed to BKR7E-11. The -11 suffix means that they're pre-gapped to .044", which leaves the strap at a funny angle when you squeeze it down to .030". If you'll use the plugs without the -11 suffix, you won't have that funny angle.

Hope that makes sense.

[j-z]

no it makes perfect sense. i know what youre talking about. im still just gonna try it with the ones i have. never knew the 11 stood for pregapped.

[Florida240sx]

Even thouh I'm in Nopi you can still call me.... you be blowing out spark buddy.... need to be at least at 30.....

[Jookmasta]

+5 for lowering the gap...............im also at 17psi and i have em at .26-.28 or so.............

[j-z]

yup it was the gap. i put them at .027 and that did it.

[Florida240sx]

Yo JZ what you doing on Wednesday? I'll come get my wideband maybe, and need to borrow your mafs for a run or 2 to see if mine is bad....

[j-z]

ill be busy till 4 and you dont get off till 5 or so anyways. i moved out here to narcoossee/st.cloud last week (long story). just give me a call and well figure something out. i took your wideband off my car once i hit 17 psi to make sure the AF was still good and it was. call me mang...

[C-Kwik]

There are only two things I am aware of that can help with the wastegate opening before hitting full boost. Use a vacuum source from the manifold rather than the compressor exit or in any of the plumbing before the manifold. This will do two things. The wastegate will see true manifold pressure since you won't be having to compensate for a pressure drop. However, it will subject the boost pressure to a slight spike as it ramps up to peak boost. It won't actually increase the wastegate's response, but since it's further away from the compressor, the compressor will be spooling up more before the wastegate realizes you are at full boost.

The second way and better way if you have the money, is to use an electronic boost controller. Preferably of the dual solenoid kind. These are the quickest responding and generally keeps any spiking to a minimum. Most electronic controllers will spike a small amount, as it blocks the wastegate signal until full boost or very near full boost is reached. Some fuzzy logic controllers try to anticipate, but many have not had good experiences with trying to use these. I've only heard of a few cases where everything works as it should. they generally have more success with these in single turbo applications.

Personally, I would just hook up the signal to the manifold and call it a day. Just don't tune on the bleeding edge of reaching detonation or maxing out the fuel system and you'll probably be fine.

[j-z]

yeah im already running the signal from the manifold. eventually ill get a ebc, but this $10 one works perfect.

[Florida240sx]

I'm off until friday...So whatever time you want to meet up...

[j-z]

ok maybe tomorrow if its not raining. you saw how bald my rears were. would you want to meet up in sanford or something? ill call you in the am tomorrow.

[Florida240sx]

Sounds good