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Performance Modifications for the NG900 / Old 9-3 This forum contains PERFORMANCE related Q&A's for the NG900 and 9-3. This may also include suspension.

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Old 12-07-2007, 11:50 PM   #1
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teetering boost

well as the title says i have a problem with my boost teetering, when i open my car up at full throtle in 4th gear or 5th gear the boost will teeter, and i can hear the wg opening and closing ( or what i think is the wg opening and closing) for some odd reason. how would i go about fixing this? is the solution to this my earlier post of adding a helper spring?

also when i floor my car in 3rd and let my boost climb it will stay at full red and then when i shift into 4th the boost only goes up to begining of red, it feels like the wg stays open ? has anyone ever experianced this? any ideas on how to fix it?

i tried using the search tool and i didnt really find much
thanks
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Old 12-08-2007, 05:29 AM   #2
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Quote:
Originally Posted by aero93 View Post
well as the title says i have a problem with my boost teetering, when i open my car up at full throtle in 4th gear or 5th gear the boost will teeter, and i can hear the wg opening and closing ( or what i think is the wg opening and closing) for some odd reason. how would i go about fixing this? is the solution to this my earlier post of adding a helper spring?

also when i floor my car in 3rd and let my boost climb it will stay at full red and then when i shift into 4th the boost only goes up to begining of red, it feels like the wg stays open ? has anyone ever experianced this? any ideas on how to fix it?

i tried using the search tool and i didnt really find much
thanks
BPC valve. I have the same problem and switched out my BPC. Sadly my other BPC isn't up to snuff either so I'm holding off for a bit before I go goldwing.



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Old 12-08-2007, 07:10 AM   #3
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Originally Posted by aero93 View Post
well as the title says i have a problem with my boost teetering, when i open my car up at full throtle in 4th gear or 5th gear the boost will teeter, and i can hear the wg opening and closing ( or what i think is the wg opening and closing) for some odd reason. how would i go about fixing this? is the solution to this my earlier post of adding a helper spring?

also when i floor my car in 3rd and let my boost climb it will stay at full red and then when i shift into 4th the boost only goes up to begining of red, it feels like the wg stays open ? has anyone ever experianced this? any ideas on how to fix it?

i tried using the search tool and i didnt really find much
thanks
Heat soak... The standard viggen ic is only good for about one wot pull. We have all experienced the boost tapering off after one or two gear pulls. With my stage 3 I could get one wot pull in third at good boost, then it would fall off, just like you are describing. The ecu is detecting knock and reducing boost to save you're engine!

With viggen ic, if I went wot in second gear to redline, bam, already heat soaked and my car would dump boost immediatly after peaking when shifting to third gear.

If you were to increase you're base boost to compensate for that, you run the risk of damaging you're motor over time. A little is ok, but you can go too far, for me it was right around 9-10psi on base boost that was too much.

We talk about this all the time in the ic threads. The reason we put monster big ic's on the car is not so much for more power, it gives the car the ability to have that full red boost longer and that means more wot pulls in gears before the ecu will dump boost.

I got 1-2 wot pulls with viggen ic, I got 3 wot pulls with 3" thick mp size ic and I get around 5 wot gear pulls with my larger ets ic before my car will start to reduce boost...

John
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Old 12-08-2007, 07:28 AM   #4
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BPC valve. I have the same problem and switched out my BPC. Sadly my other BPC isn't up to snuff either so I'm holding off for a bit before I go goldwing.
x2

BPC is the problem in the majority of cases. You can try cleaning it out with some electric parts cleaner to see if that'll free it up before you have to buy another one.

Definitely don't buy a brand new one, used is the way to go.
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Old 12-08-2007, 08:47 AM   #5
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I agree the bpc is worth checking, if it boost fine one time and then sticks the next time or gives less boost, clean it out with wd-40 and compressed air from a shop. I have had to clean all of mine many times, I even had one that was sticking right out of the box brand new. I cleaned it with wd-40 and compressed air and it worked 2 days, then stuck again. Cleaned it again, worked a week and stuck again, cleaned it again, worked 3 weeks and stuck again, cleaned it again and it worked for about 6 months.... I have 6 of them in my garage and finally got fed up with the cost and went with a greddy profec b electronic boost controller with its own solenoid valve of much better quality. Holds boost much, much better...

If the boost goes up to its normal place and then falls back, that would be more likely heat soak issues.

Good Luck,

John
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Old 12-08-2007, 11:03 AM   #6
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my tunner has told me after i get a bigger fmic (which i am currently looking for and cant find used )to set my base boost at 9 psi and to add a helper spring, now the bpc, i have 2 and they both seem to do the same thing, when i change my bpc again which problem will that fix the first or 2nd?
are they both symptoms of the bpc being bad?

p.s. i am looking for an mp ic if anyone has one
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Old 12-08-2007, 06:24 PM   #7
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cleaned out the bpc at work today not sure if it worked because i havent had a chance to test it out yet hopefully this solves my problem
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Old 12-09-2007, 10:37 AM   #8
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You have the advice, now you need to test it out! What I saw on the bpc that was sticking is that right after I cleaned it out, it would work fine for a day or so, then stick again. If that happens, you know for sure you're bpc is going bad. Sometimes cleaning them works for a little while and sometimes it does not help at all... I have had the experience of having two bad bpc's. Its not a bad idea to have a brand new on in stock.

I also think you need to put on a nice large ic to eliminate that as the cause of you're tapering boost after one pull... That is a common problem and my car did the same thing until I put a nice bar and plate ic on it.

This is part of the fun of having a tuned car. There are bugs to get out when you start tuning a car and upping the boost. A staged tune with higher boost will bring out the weak-points in you're system. Weak DI, bad bpc, leaking vacuum and boost lines, IC piping boost leaks and the list just keeps on going.

John
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