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Discussion Starter #1 (Edited)
Hey guys it's been a while since I've been on here but I need some help. I recently got a stage 2 tune from BCB and I'm having some issues. At wide open throttle I get a misfire and she doesnt boost properly itll peak around 20 for a split second than drop to 15 and sometimes 10. I put my spare dic on and still same problem, pulled the plugs and they are black and sooty (gapped properly to .9). So shes running rich, rather rich from the smell of the exhuast. I'm assuming this didnt happen over night but I haven't had issues before I put the tune in, is the increased boost exaggerating an issue? What tends to make these cars run rich and or misfire? I only randomly get code for a large evap leak.
Compression test
1-170
2-155
3-155
4-155

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Discussion Starter #3
I would start by monitoring MAF output. Maybe O2S1 too.

Is your PCV system in good shape?
How exactly do I tell If my pcv is in good shape? I haven't noticed anything wrong

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Make sure you have the last update, hoses are intact (secure, not mushy, not obstructed), check valves work properly, and air:eek:il separator isn't plugged or blocked.
 

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Discussion Starter #6
I always suspect an old lazy MAF with these issues.
Is there a way to test the maf? I've been wondering if it is faulty myself as I'm not sure when it was last replaced. I cleaned it but no difference

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Yep, it will throw a code, but if your car runs better you have found the issue, just don't go driving the piss out of it.. If this does nothing, when the car is idling, rap on the fpr with a wrench.
Do you have the old ecu, if so put that back in and see if its a faulty tune?
 

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Discussion Starter #10
Yep, it will throw a code, but if your car runs better you have found the issue, just don't go driving the piss out of it.. If this does nothing, when the car is idling, rap on the fpr with a wrench.
Do you have the old ecu, if so put that back in and see if its a faulty tune?
It only misfires when I drive the piss out of it though. Under normal loads it's fine no issues. I do still have the original Ecu, I am going to switch back if i cant seem to get this issue fixed

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MAF is best observed with a scan tool that can graph live data. You are looking for consistent readings from it under varying conditions. IME, usually MAFs work well at idle but underreport worse and worse as air flow increases.
 

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Discussion Starter #12
Well I ran it with the maf unplugged and no misfires. It didnt boost properly but that at least makes sense.

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How old is maf, if it has 50k then replace it no matter what. It's one of the main causes of burnt pistons in viggens. But yeah, plug in the old ecu see if it changes.
 

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Discussion Starter #14
How old is maf, if it has 50k then replace it no matter what. It's one of the main causes of burnt pistons in viggens. But yeah, plug in the old ecu see if it changes.
I'm honestly not sure, the previous owner didnt keep the best records of service so I can only guess. I took it for a spirited drive with the maf unplugged and it didnt misfire at all, it didnt hit peak boost but that's something i assume should happen. Looks like i need a maf

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