Fixed one problem, now another evolves...

[RuS4ty]

So I finally fixed my misfiring problem the other day by replacing the spark plugs (replaced with NGK platinums) ... and now my boost is acting weird.



So as you can see it spikes (18psi), then drops (9.7 psi), then spikes again (17psi) then goes to the shitter (8psi). The odd thing is that it never request anything over (13psi). I had an issue similar to this a couple weeks ago which was due to a boost leak (torn TBB) which graphed like this:



Not quite the same though.
So could this possibly be due to the wastgates (n75)? I logged those but I'm not sure how to read it. I started to pressure test but didn't have anything to seal off the PCV hole, but noticed slight amount of oil in the accordion hose and a good amount in the TBB.

Any idea??

btw I'm GIAC stage 2+...

[volks88]

get a MBC and bypass the n75

[The_Jerbel]

Log the N75 duty cycle.

[RuS4ty]

Ask and you shall receive...

get a MBC and bypass the n75

As far as a MBC goes, I've really only heard about the vast one being used, are any of the other options any good (i.e. forge from ecs, or the turbosmart one)?

[volks88]

As far as a MBC goes, I've really only heard about the vast one being used, are any of the other options any good (i.e. forge from ecs, or the turbosmart one)?

i used a buddy's turbosmart. i was just eliminating my n75 being bad when i was trouble shooting.

[titleiststud]

I bought a cheapy nxs mbc from ebay and installed it inline with my n75. I need to do some fine tuning, but it will cut out the boost spikes.

[Kruat]

Correct me if i'm wrong, but I thought pltn plugs were no good in our cars?

[RuS4ty]

I'm pretty sure the laser platinums (PFR6Q) are what comes stock with our cars

[lrg8683]

MBC/TCD.. why you STILL haven't done this is beyond me.

[syxxty]

oil in the accordian and tbb is NOT normal. I had some residual oil in one of my black plastic intake pipes from a failed turbo (that has since be replaced). That oil could have messed with you MAF sensor. Unplug it and see if you still get the boost spikes. If not clean your MAF with some throttle body cleaner. Good luck.

[Dr. Jekyll]

Pressure test before you start adding stuff to your car. Looks like a boost leak to me. If you're stage 3- and below stick with Bosch Platin (not platinum) F5dpor plugs. Expensive, but they work the best. As stage 3, I use NGK BKR7E's. They are $2 copper plugs but they work great. But because they are copper you have to replace them every 5-10k miles, vs. the platins that you can run for 20k+.

As for the oil... it all depends. Alot of oil in the TBB probably isn't good. I have seen some ioil n the accordian hose / Y pipe before, because the PVC is right there. So that bit is probably "normal".

[The_Jerbel]

Bosch platins are fine for most stage 3 setups as well.

I need the N75 duty cycle log, not the boost log.

Looks to me like the problem is a bad N75 valve.

[RuS4ty]

The duty cycle is in pink.

It was snowing and 1 degree out, so I wasn't able to do anything today. I did notice a small crack where the y-pipe splits to the PCV which would letting air out... but that shouldn't effect anything major.

[The_Jerbel]

My bad, I didn't notice that the N75DC was on the same graph.

That's very odd. Have you pressure tested the N75 reference and the WG lines? Have you tried swapping in a different N75?

[RuS4ty]

It's cool, I just did that for reference of when it was boosting.

not yet, thats the plan when the weather clears up.