I've got a car that was professionally built with a Comp Cam, AFR 165 Heads, Vortech V2 supercharger with aftercooler, Methanol injection, MSD boost retarder, 30lb injectors, Diablo chipStock bottom end.
During the tune/dyno the car starts missing at around 4000rpm/load. It appears to be an ignition problem. This was not a problem before it was strapped to the dyno. If we back-off the timing, we no longer have the 4000rpm problem, instead it spark nocs continuously. It does have a stock distributor with MSD cap.
Where are you trying to go with the tune? If it doesn't miss unless you have it on the dyno, presumably you are trying to add timing or adjust the mixture when you experience the problem...
What did you do to get more fuel pressure when you added the supercharger? It seems like you might be running out of fuel.
__________________
tripleblack
"You can never be free until you let yourself go."
After the first problem on the dyno, it now anytime under load. It does not miss when in Nuetral, revving to 4000.
The car has an aftermarket inline fuel pump and gauge. We're getting 40lbs on the gauge.
I'd try bumping up the fuel pressure. That stock short block IS NOT going to like detonation under boost.
What MAF are you using?
__________________
1992 Deep Emerald Green Mustang GT Hatch, 5 speed, 2.73s, Mac fenderwell cold air intake, '93 Cobra MAF, Mac 70mm throttle body & spacer, Explorer intakes, Mac unequal headers & offroad pipe, Magnaflow catback, Walbro 110lph fuel pump, Jet adjustable FPR, MSD Blaster coil, Accel 8mm wires, FRPP aluminum quadrant, UPR firewall adjuster, stock cable, Granatelli upper control arms.
Waiting to go on: Granatelli lower control arms, and GT40 Iron heads!
New cold plugs, stock distributor with new MSD cap. 32lb fuel injectors with Methanol injection under boost. The car was detonating under boost before the new problems. It has a 24lb C&L MAF, with adjustment for the 32lb injectors being made at the SCT chip.
It's blowing unburnt fuel out of the tain pipes when ignition misses at 4000.
Also... while on the dyno the fuel mixture read 11.5:1 during the 4000rpm mark...
That's richer than Bill Gates! I wonder if the boost is blowing out the spark? You might try some of those Den$o Irridiums, they're supposed to be the best thing for boosted apps. I don't know if it's because they resist spark blow-out better, or what, I've just read that they're the way to go.
__________________
1992 Deep Emerald Green Mustang GT Hatch, 5 speed, 2.73s, Mac fenderwell cold air intake, '93 Cobra MAF, Mac 70mm throttle body & spacer, Explorer intakes, Mac unequal headers & offroad pipe, Magnaflow catback, Walbro 110lph fuel pump, Jet adjustable FPR, MSD Blaster coil, Accel 8mm wires, FRPP aluminum quadrant, UPR firewall adjuster, stock cable, Granatelli upper control arms.
Waiting to go on: Granatelli lower control arms, and GT40 Iron heads!
try removing boost retarder for testing.if spark was blowing out you whould have a lean reading.o/2 sensor only reads 0/2 if the cylinder dont fire it dont burn the 0/2 so the sensor reads it lean not rich.just a little fyi.
__________________
because a engineer said so!! 93lx street car 8.81@153 and 93lx 10.5 car[ 7.21@182 new record for me]
start from the beginning do a comp test if it passes do cylinder leak down test.if it passes both test you well know it's not internal.you can rule out rings,head gasket,burnt valve,piston land. rule out mech failure so you don't chasse the tail.!!! than look for elec failure
__________________
because a engineer said so!! 93lx street car 8.81@153 and 93lx 10.5 car[ 7.21@182 new record for me]
speedytang your ball drive will run circle around a gear drive.ball drive?? asuming your 535rwhp you have between 580-640 at the flywheel with about 15-20% lose in the drive train.that's not all that to talking smack.wifes 05 3v with wipple charger has 571rwhp.90&92lx had no problems intel the dyno runs.the problem is most dont have any idea how a car reacts on it.i have rebuilt more engines that some one burnt up on a chasse dyno.use a real engine dyno tells you better info.and you can repeat the numbers over an over again.never well chasse dyno do this.to diff makes of chasse dynos can be 25-30%differents.engine dynos can very 2-3% differents.i'm not trying to be dick but every ones throwing rwhp numbers out their.rwhp are JUNK!!!!!!!!! their is no way wife's 571rwhp that's like 680-700 flywheel hp.NEVER HAPPENING.
__________________
because a engineer said so!! 93lx street car 8.81@153 and 93lx 10.5 car[ 7.21@182 new record for me]
1990 Mustang 5.0 Ignition Problem under boost 
Where are you going? 
