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-   -   File this under: "You're a dumb A**" (http://www.318ti.org/forum/showthread.php?t=44299)

joe1602 06-12-2018 07:23 PM

File this under: "You're a dumb A**"
OK, So my son (teen ti) & I did our first National Auto X this past weekend with the ti. Of course we were a bit outclassed by some more modern, up to date vehicles but that was not the real story. We have been building this car over the past 4 years to be respectable in the STX category on the regional level. To date we have: Ground control coilovers, Koni yellow adjustable struts/shocks, Turner Camber shims (around 4 degrees negative camber and 1 degree toe out), X-Brace, 28mm Eibach front adjustable sway bar with powerflex bushings, adjustable sway bar links, new HD control Arms, HD tie rod ends, HD race control arm bushings, poly transmission mounts, Poly subframe & trailing arm bushings in rear, rear shock tower brace, fogged airbox. StopTech performance brake pads with stock rotors & calipers, LSD, Kosei K1 wheels 17x8.5, 245/40x17 Bridgestone re71r's, 10mm wheel spacers up front, 3mm rear spacers, stock plug wires, new fluids & spark plugs each year, plus a flash to the DME from Barrie in Ottawa, Canada.
He is doing the test on Friday before the event and reports on his last run that he thinks the rev limiter is cutting in early. I tell him he is just not used to higher speed courses. I make the mistake of not driving it in the test and seeing what is going on. On Saturday I take my first run & the car is on the rev limiter way too early, I am spending 2-3 seconds at a time on the limiter before I have to make a turn. Same for my son. On his 2nd run he reports the rev limiter is engaging at around 5500 rpm. We try shifting to 3rd to do parts of our runs, but not the best idea in an auto-x. We finish the day well off the pace and me being really pissed off about it. I do research Saturday night and find an article online with someone in Europe that has had the same problem. Turns out that the engine computer has gone into "limp" or "fail safe" mode because me, being the genius that I am, unplug the fuses for traction control and ABS. Apparently, the computer reads that the ABS & traction aren't working and is limiting the speed of the engine, thinking something is wrong. So Sunday morning, we plug the fuses back in, turn off the traction control with the button on the dash. and presto, we are up to 7K before the rev limiter kicks in. The reason I have unplugged the ABS/Traction was that I always thought the ABS was too intrusive and the only way to disable that was with the traction control as well. Now when we are autocrossing, the engine has always seemed a bit anemic but I just contributed that to being a little 4 in an overweight car. After getting the flashed DME back from Barrie, it improved some, but again, I thought it was just not a very powerful engine.
We get out on the course Sunday & Wham! Right up to 7K pulling strong all the way, no rev limiter anywhere on the course. For the first time in 5 years I am driving the car with the engine running like it is supposed to. I am a course challenged drive & can get lost on a dragstrip so I did not improve on Sunday. My son took roughly 3.5 seconds off his time from Saturday to Sunday. The course was run backwards from the day before & the general consensus was that it was about 2 tenths faster than the day before. He could not run with the fastest but he was faster or as fast as several others that had beaten him by 2+ seconds the day before. On each of our runs, we did not once encounter the ABS. I guess my son needs a better (smarter) mechanic. It was just nice to see the car perform the way it is supposed to. It was almost like driving a new car! Sorry it was so long but hopefully my mistakes will help prevent someone else here from doing the same thing. I am hoping to do another event this weekend (Glen Regional) and will try to take some GoPro videos & post them.
Thanks for listening!

apexspeedtech 06-12-2018 09:33 PM

Great to hear! I've always wanted to build a little audrino circuit to reverse the polarity on the Traction Control switch so it would be off by default, its on my long list of things to do....

joe1602 06-18-2018 02:09 AM

Here is the link to the autoX from today (6/17/18) at the Seneca Army Depot in Romulus NY


weste46 08-14-2018 03:10 PM

Nice story! This is with an M44 engine? Is the factory redline really set to 7k rpm? We still have the slushbox automatic in the car at this time, and I think that shifts at somewhere around 6.5k.
We are planning to do a dual duty daily driver/autocross build for our compact so we won't be making the car nearly as stiff, but it would help to be able to rev the engine that high!

John Firestone 08-19-2018 02:47 PM

The rev limit should be at 6500 rpm. I know the tachometer can lag a bit, but does it also overshoot?

IIRC, the M44 DME uses the wheel speed from the ABS/ASC unit to detect rough road, so as to not confuse it with engine misfires.

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