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A zone of danger.
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Discussion Starter · #1 · (Edited)
I finally got the car to the dyno for the first time, and I have to admit I was very disappointed. The car made an average number at best and performed poorly.

Car settings, best run:
Boost - 1.44 kg/cm^2 (20.5psi)
AFR - ~11.3:1
Plugs - NGK 6097's @ .030"
Fuel - Straight 110 (Torqco)

Car's behavior:
TERRIBLE!
First, that was not my intended AFR, nor boost. I was looking for 22-23psi @ 12-12.2:1 on that fuel, so the numbers are immediately lower than they should be. However, I never got the chance to fix it cuz I couldn't keep the fires lit! As soon as the car hit boost (~4K), it stumbled all the way to redline (all three pulls, all aborted early). It very much resembled spark blowout, but I cant be sure. Pulling timing shouldn't behave like that, and it shouldn't have been pulling with that fuel, AFR, and boost anyway.

THE KICKER:
The car does NOT behave like this on the street, ONLY the dyno! I've run upto 1.60kg/cm^2 (just testing the new spring on the gate) with the same gap/fuel/AFR (or higher) without a hint of misfire.

My thoughts:
I got nuthin, but the graph is below. Little help?


TIA,
Mike
(...and the anti-dyno-queen)
 

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1,262 Posts
That's VERY odd. So you drove it after the dyno session and it pulled fine? AFR's on the graph would be nice. Do you have something to log with?
 

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A zone of danger.
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1,175 Posts
Discussion Starter · #3 ·
I drove it off the ramp and it ran like a rocket, not even so much as a hiccup. I don't have AFR's cuz we only had the outdoor/portable dyno, so no tailpipe sniffer. I did have my on-board WB w/ logger, but didn't save the logs. I only had time to ballpark, hence the 11.3 AFR. I'll save the logs next time, but I can assure you they were 11.2-11.4 accross the open-loop range.
 

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Stock Twins King
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4,545 Posts
I don't "see" any issues except after 6K There is something going there, It isnt wheel spin because that only happens at peak tq around 4600. It definately is breaking up after 6K. It doesnt appear to be coil pack related because that happens a bit earlier at peak HP at 5500K. It can't be turbo related because you can hit 20+ psi. Itis possible that they are getting a little tired and can't handle anything more and just bounce from there.

The only thing Ican think of is your EBC or BC is malfunctioning, or there is a "limiter" set in error and your bouncing off that. It could be coil packs, but they are very evident when the start to break up. Kind of a rapid pa.pa.pa.pa. sound like using a 2-step off the line. It could be a bad ground wire some where. One disconnected ground wire will loose HP.

You didnt mention what BC your using, nor if your a VPC/SAFC user. There could be some issues with the AF past 6K that its starving for fuel. A dirty fuel filter could cause this, or a FPR. Take a look closer to the AF past 6K. Also, what was the ambient temp that day?

Stu
 

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A zone of danger.
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1,175 Posts
Discussion Starter · #5 ·
Thanks for the quick reply, Stu.

I meant to put my sig in the first post but forgot. I'm on the MAF, using a SAFCII and a Blitz DSBC. And just to answer everything you mentioned...

All the runs were aborted around 6K because we couldn't figure out was the problem was, and I got nervous. The breakup started right at 4K, never before, and continued to 6K. The turbos and boost controller should be just fine since on the street they always hit the desired boost level (up to 1.6kg/cm^2). I was watching the AFR real-time on the laptop thru all three runs, and were always right where they were set, so fuel delivery issues should be out.
What you mentioned about the coils, the car sounded exactly like that. But I just dont understand why that would only happen on the dyno. The car is perfectly well behaved on the road and runs like a 500bhp car all day long!
Some other facts:
Temp per the dyno: 82 degrees F
Mileage: Barely over 60K
TRAC fuse pulled permanently.
 

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Stock Twins King
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4,545 Posts
I agree about the dyno vr on-road characteristics. I do find that odd. But non the less, it sure points to deteriorating coil packs. I actually had the same problem at about the same miles as you. If you can afford it, then a new set will be quite noticable in added performance.
 

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A zone of danger.
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1,175 Posts
Discussion Starter · #7 ·
I can get the packs at cost, so I'll try that with new plugs. I'll post the results for reference later...
Thanks again,
Mike
 
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