Had car dynoed the power curve is very choppy, car runs fine and isn't down on power. I replaced plugs and coils which made problem better but not fixed. Leak down and compression test are good also scoped cylinders everything mechanically looks good. A/f and boost is also where it should be.
Choppy Dyno Graph??
- Thread starter got_h8rs?
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I would also think belt slip.
whats the smoothness setting on the dyno chart at ?
That's some healthy power ##'s . Most likely it's a combination of belt, tire and clutch slipping.
That would be good boost numbers for an upper pulley. It would rule out belt slip. Since no list of mods, which belt, pulley, tire pressure, etc?????
10% lower pulley, scj tb, jlt intake, full exhaust, revan racing blue belt, clutch is an ace twin disc, tire psi is around 30lbs.
Nice list of mods and good numbers. I would be around 35-40 psi on the tires, for the dyno, but I do not think that is the cause of choppy graph. Maybe some dyno operators will chime in. They see a lot of stuff.
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You sure your A/F is right and you are not seeing knock? I can't read the chart too well but is it showing your A/F above 12?
11.1 a/f ratio
What kind of fuel are you running?
93 octane
I might try some Torco or a tank of higher octane, if I was going back on the rollers.
I want the car tuned on 93 though, I'm going to run the gas out of the car before i go back on the rollers Monday. But it was fresh shell 93 I put in. I'm at a loss for what is causing this.
If you can buy Sunoco and going to run pump gas only, get a tank of that. With or without the sunoco, I would add Torco for the dyno. The tuner knows how much timing to put in for pump gas good or bad. They will not tune up to detonation and stop. That would be too risky. If you have a grill in front of the heat exchanger, I like for the fan to blow straight into the grill, not at an angle. Probably not an issue, but be sure the dyno operator, holds the trac control button down for 8+ seconds to disable all the TC and other nannies. I had to insist with my dyno operator. Let us know how it goes. Did the operator have any comments on the choppy graph?
Ok sounds good, the Dyno operator/tuner is a very reputable guy so he knows what he's doing. My car did it both on his tune and before on Lunds tune from Van. He didn't really know what to say, he thinks it's something possibly timing or fuel related. I tried new plugs and coils with no fix. I'm trying a new fuel stock fuel pump Monday cause the cycle duty and pressure drops off after 5000k
Since you have a full exhaust, next time on a lift, check for any points of contact. These cars are sensitive to spark knock reduction. An exhaust bumping the steering, frame, trans, etc will transfer to the sensors. If they used the stock pipe clamps, make sure the bolts are not bumping the floor pan.
Std numbers read higher.
Ok I've heard that I'll check it out Monday, it would possibly do that to the graph without setting a code correct?
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