Thanks Fellas. The exhaust config during the dyno used the inline vibrant resonator and the oval muffler. I feel like it's a pretty damn good sounding combo. Doesn't drone and the volume melts away during cruise speeds.... but when you touch the accelerator it barks and when you go to WOT you get what's in the vids
Oh yeah, that's my Bosch 044 in the background when the car revs down. I found out it gets even louder when the car's running hard.
Carma Performance in Nashville, TN turned out to be a one man operation run by Erin Carpenter. His shop had all kinds of cool cars waiting in line and he was extremely knowledgeable and proved it multiple times during the visit. After talking with me for 30 minutes about the car's build info we loaded it on the rollers. He got started and my car started backfiring like it likes to do. He kept shaking his head and saying "there's no way." He eventually killed the car and we talked some more. He said he was 99% sure the car was misfiring but it wasn't being reported to the PCM. After I let him know the injectors probably weren't the place to look since I've had them cleaned and flow tested we discussed the coils. This was an area I felt had more potential for problems since the coils are low mileage but used and I didn't have a full history on them. Turns out we didn't even get to the coils. With the car on and dyno locked at 30MPH I held the accelerator where the "misfiring" was most active. This caused the engine to really shake around as if 2 cylinders were gone. From there Erin simply unplugged each coil until he came to one coil that hardly made a difference when unplugged. Eureka! However, the problem turned out to be the plug wire.
Even with the insulating boot, the wire was fried. Erin popped on a spare plug and we went back to the dyno with a noticeable improvement. Still, after several more minutes on the dyno he yelled out we probably have another wire in bad shape. Sure enough, he found another one simply by looking at which wire was next closest to a primary.
Threw on another spare wire and finished the MAP and MAF tuning. Took about 2 hours Goodbye backfires
Just a FYI - both fried plugs were located on the passenger side on cylinders 4 and 6. Anyone with a functional heater and AC knows how cramped that side gets. For me it was even worse because I had the bright idea to run my battery lead through the header primaries with 3 layers of fiberglass insulation. The battery cable crowded the wire on cylinder 6 and the dipstick crowded the wire on cylinder 4. Both areas were packed enough that the plug wire insulators made lite contact with the primaries. Even with the insulation and the ceramic coated primaries, the contact was the breaking point. Any contact is going to result in a bad time:
As you can see, the battery lead didn't fare any better; even with 3 layers of fiberglass sleeve made to withstand 1000 degrees. After finding the damage to the spark plug wires Erin told me it was something to look at ASAP. I wasn't really concerned about it shorting out so I made the trip home simply because fiberglass is a very good insulator and I knew it wasn't going to burn up even with direct contact with the primaries. That plus the fact that my battery lead is fused (yes, I'm one of the guys that says you should
still fuse your battery lead despite what other people say) made me comfortable that the car wouldn't short and burn down. Still, I knew it was something that needed attention and this is what I found when I got home. Car is on jackstands now awaiting 15ft of 0/1 AWG for a new run. This time I'll be going the long way around and still doing fiberglass insulation. Even shielded, the new route wont get within 5 inches of the headers.
Finally we got to spark tuning and WOT tuning. Erin dialed both tables in after about 8 partial pulls and 2 full pulls but when we got ready to do the last full pulls and record the pull data we were disappointed to have the Dyno start slipping. Erin fessed up and said the much higher HP car he was dyno'ing last night had similar issues on the dyno and he's afraid his dyno is officially in need of repair. The problems were causing it to slip around ~340HP so that's about all the graph would show before it would dive when it started to slip. He told me in his experience the log data supports just over 400HP to the wheels. Later he confirmed when he extrapolated the duty cycle of the injectors at ~6500RPM
((49 lb/hr * 0.63 duty cycle) / 0.5 BSFC)* 8 cylinders = 494 Flywheel HP * 0.85 drivetrain loss = 420WHP
It's about what I was hoping for although I was a little disappointed I couldn't get a sheet to brag on
Finished up by taking a wild test drive which was hilariously fun while Erin made some final corrections. He then took the wheel and showed off his knowledge of downtown Nashville
Drive home was nice. No backfires, silky smooth acceleration, and
cooold AC. I did kill the engine a couple of times when clutching in to coast to a stop with AC on. I think Erin didn't tune for idle when the AC compressor is on. I let him know and we're going to potentially setup a remote touchup. I did get a little homework though. On the test drive Erin mentioned that he still felt and heard a potential misfire. I couldn't really detect it on the test drive, but think I noticed it on the drive home. I could feel what felt like mini fuel cuts when cruising at very low load and rpm. It just enough to let you know it happened then the power comes right back all within a fraction of a second. The result is a not so smooth cruse as it feels like the car is lightly surging rather than being continuous. So I think I have one more bad wire. I ordered new wires and plugs and hope to finish changing them when my replacement battery lead shows up.
The whole burnt spark plug wire situation make me feel pretty stupid because they burnt with me thinking the insulating boots made them indestructible. I simply got sloppy and let the boots sit on the primaries and those were the ones that burnt. Thing is, I never saw the damage even though I've had the wires off since they originally went on. When I removed them a while back (to check the spark plugs for potential fouls), I didn't bother to remove the insulating boots to check for damage. I just assumed since the boot's weren't burnt the plug wires weren't either...
On the next set I've got to make sure nothing touches the headers. I've got to keep them centered between without contact and they should survive.
Finding the source of the misfires was worth the trip. Such a small thing caused me so much grief and has had me chasing my tail for years now.
All in all it was a wonderful experience. The car made the 10hr trip without any hickups. Granted, the drive home was nicer than the drive up, but it was still a lot of fun and speaks to the car's reliability on a longish trip
Lane
