Fast & Fun

Oddly enough, I had never in my life been to a drag strip. When I was young, there was only one that I knew of in the area, in Scribner. I never did get out there, because once I learned how to drive I had other things to do that seemed more pressing.

I’ve been threatening to take the Mercedes to a drag strip since not long after I got it. After finally getting most of the issues worked out, I decided a couple of Saturdays ago to just do it. I drove down to I-29 Dragway in Pacific Junction, IA. It’s a 1/8 mile track, which I was initially not too happy about, but honestly I think it was a good place to start out. It’s $10 to watch, $25 to race on a “Test & Tune” night, which is most Friday and Saturday nights.

I got there early and checked out some of the other people showing up while waiting for tech inspection. Once the tech shed opened up, I got in line and got my tech inspection card filled out and a number (0773T) on the windshield. I didn’t know what to expect, but the staff there were super friendly and helpful. The track manager offered to make a couple of runs with me to show me what to do, so I took him up on that. Not more than a couple minutes after finishing up with the inspection, I had my very first timeslip in my hand! I ran the eighth mile in 8.6741 seconds, and had a trap speed of 85.28 MPH. I did better, and I did worse, but over the next couple of hours I had a ton of fun and got to meet some super nice people.

I’ve still got a LOT of room for improvement, of course. My reaction time is horrible, usually over half a second. I have found that with the Merc’s big V-12, it doesn’t pay to get on the throttle too early or too much; all it does is spin the rear tires and get the traction control working hard to control wheel spin. Turning traction control off… well, I learned not to do that! Lots of noise, not much “go”. Maybe I’ll learn to better control the torque and be able to turn off some of the babysitter functions, but for now the best recipe seems to be stage, get the RPMs up to about 1200-1500 on the yellow, and when the last yellow comes on release the brake and nail the throttle wide open, and keep it there until you pass the finish line.

I soundly trounced a 5.7 Challenger — no surprise there. Almost kept up with a couple of new-ish, supercharged Camaros, including a ZL1. I don’t know whether they were just running slow or what, but for the most part the Rocket Sled can hold its own despite its enormous heft. Maybe next time I’ll take out a little weight… I didn’t even remove the spare tire, let alone the little cooler in the back seat.

All in all… it was a really fun night, and I can totally understand how it could become a real addiction. And where else will you get to see a Monza with a monster V8 crammed into it?

Misfires — fixed??

I’ve been fighting an intermittent misfire issue on my S600 for quite a while now. It started as a misfire code P0309 (“Misfire damages TWC”) as well as a few assorted other cylinders from time to time. I was also seeing occasional random misfires at idle, mostly on the left bank of cylinders. I changed the spark plugs and insulators, which made no difference. I replaced both coil packs with rebuilt parts from V12ICPack.com, Clark in California. Annoyingly, the errors persisted. I replaced the VT, the 180V/24V DC-DC converter that supplies the coil packs. No difference. By now it was OK, as long as I never floored it — anything over about 5000 RPM would throw a misfire code and shut down one or more cylinders.

I was talking to Clark via email — he doubted it was the coil pack. I disagreed, but was open to other ideas. I looked at the possibility of a bad head gasket, vacuum leak, bad throttle body, anything — but nothing made sense.

Then one night I was on my way home. The car had been running just fine that evening, I even had heat after replacing the valve for the second time. I drove about 12 miles in city traffic, the last 4 or so on the high-speed expressway at 55-65 MPH. No issues. When I got off at the ramp, though, everything went straight to hell. Very rough idle, no power, check engine light on — obviously the engine had shut down multiple cylinders. It took three restarts to get it to come back. The scanner showed misfires on all the left bank cylinders. That happened several more times over the next couple of days, always at idle… but even a very brief push of the throttle would also cause the same sort of multiple cylinder shutdown. It was very obviously badly broken. I am not proud of the words I used during this time.

To shorten a very long and painful story, I pulled the left coil pack and VT, and shipped them both off to Clark. At this point either it got fixed, or the car was going to become a really big gray BBQ grill. While the coil pack was out I got a slightly bent wheel repaired and a tire replaced (thanks, Omaha potholes!). Clark eventually did find an intermittent bad part and fixed it. I got the coil pack back, put it in, and went for a drive… seemed OK. Then the next day I again got a slow start, cloud of white smoke, rough idle, and misfire codes — this time on most of the right side cylinders!! The damn thing was possessed by evil spirits.

As it turns out, it seems that the last round of trouble may have just been a tank of really bad gas. Maybe combined with fuel and spark adaptations being really screwed up, I don’t know. All I know is, the bad idle performance started immediately after I filled the tank with gas from Sam’s Club, and disappeared half a tank later. Since then I’ve driven it for a week in city traffic, on the highway, and we even drove it to KC and back for a raid on Ikea. Zero trouble. Idle, full throttle, long cruises, city driving… I finally, at long last, have my car back.

I think.