Continuing Boost Problem

[nabilus13]

I ran a boost leak test this weekend, and found no leaks. I tightened all hose clamps, zip tied all vacuum lines to ensure sealing, and still my car shakes, shudders, pops and gets no added power from the turbo, though the turbo does spool.

I also was told by a couple of friends who watched my go by that when it starts to act up when I try to boost black smoke puffs out of the exhaust. I'm about at the end of my DIY rope and will probably be sending it to the dealership for service in 2 weeks if I can't get it fixed.

Does anyone have any ideas as to what might be wrong and how I can fix it?

[Laserj]

Hmm puff of black smoke usually indicates it being rich. What are the mods on your car? Do you have a datalogger?

[nabilus13]

The engine/turbo is stock, and I removed the MBC in an attempt to fix this. All vacuum lines have been returned to stock. I don't have a datalogger, and only have a narrowband A/F gauge that wasn't wired in when I got it, and still isn't.

[Dizmm]

change your spark plugs. Go get some NGK BPR6es for stock boost, or BPR7es for higher boost.

[nabilus13]

Ran the test this weekend, no leaks. Changed plugs yesterday, and now it boosts. I got Bosch Platinum +2, and they work fine. When I took the plugs out, I found oil on 2 of them, so I need at least new valve seals and maybe new valves. Joy:( ... But, it boosts now. I think I may have damaged a solenoid before I turned down the air compressor, because now my turbo spikes to 16 when I floor it. I'm shopping for an MBC if anyone can recommend a good, inexpensive one.

[Dizmm]

get rid of those Bosch's asap!!! NGK BPR6es or 7es only. ANYTHING else will not work right. You will experience random misfires, and eventually more sputtering.

[nabilus13]

Where can I get NGKs? I'm normally and autozone customer, and they don't have them. I don't want to order plugs online if I don't have to. I'll probably run NGKs when I tear into the valves anyway. These were mainly to find out if it was the plugs causing the problems.

[Dizmm]

autozone should be able to order them and have them next day. Anything other than NGK's will give you troubles. Platinum plugs in a turbo car are just no good.

Also oil on the plugs could be other things besides valves seals/guides. Have you done a leak down test or anything yet. what about just a compression test?

[nabilus13]

How do I do a leak down test?

[Stash]

Napa stocks NGKs, about 2 bucks a piece. You never want to run platinums in a turbo car EVER.

[nabilus13]

Out of curiosity, why are platinums so bad? They've given me enough spark to work up to a little past stock boost so far, and the car doesn't start any harder than it did before.

[Stash]

Why are they bad for a turbo? Platinum is a catalyst for heat... which leads to pre-ignition. They are designed for longevity, in a daily driver NA they work great. Platinum nor Iridium are better or as good of conducters as copper. Additionally, it is always wise to use the manufactuers reccomended plug, nothing will work better. Forget all the +4 superplatinum bullshit. Your not going to gain horsepower with plugs. Use what the engineers designed the engine to work with. It can be acceptable to change the heat range of the plug depending on engine running conditions.

[nabilus13]

Okay, aside from the plug debate (I'll change them later) I have found the cause of overboosting. My wastegate solenoid was shot, so I returned it for a new one, should be in soon.

[cyclone]

Is there a check engine light?

[nabilus13]

Yup.

[nabilus13]

Alright, IT WORKS!!!

Replaced blown wastegate solenoid, and now it boosts (because of new plugs) and no longer tries to go to 18psi. And it's fixed just in time for prom. Yay!