Okay, for starters TCS... always off when testing. When I've been running highway blasts, the slip light starts to come on at the top of 4th and 5th gear (Haven't noticed it in 3rd but most the time I am doing 4-5 pulls). Now a few questions.

One, is the car just telling me the rear is slipping? Or is it compensating and adding braking etc? (Or is it telling me the LSD is activating?)

Two, would this be an issue caused by my 18 in. 295's in the rear? I am 265 front. (God I wish I were AWD)

Three, could this have anything to do with my ATS differential?

Or basically is the problem that at around 5000 RPMs in 4th gear I am doing 120 mph with 9 PSI and about 400 RWHP?

Please chime in if you have any ideas

~Josh

 

This is my guess. When I was running tire sizes that the VDC didn't like it would only show up in top speed runs(120mph+) when I was running the 275/35/18 tires rear and 245/40/18 front.

 

I had the same issues come up when I first went FI at high speed runs as well. It seemed like mine was always near 100mph or so and up. My question at the time was, is it really slipping and where does the sensor pick slip up at. Is it at say the rear axle or is it at the transmission. Before I could ever really get an answer back to my questions, it quit doing it. I know this doesn't help you a bit, but I would sure like to know the answer to the question.

 

Lets limit the conversation to TCS. TCS attempts to keep you from spinning the rear tires. That’s all. It does so by cutting engine power, and therefore cutting power to the rear wheels.

TCS has noting to do with LSD.

When the rear wheels spin, TCS will light “SLIP” indicating that TCS is cutting engine power.

 

It probably wasn't slipping and the sensor picks it up via the ABS sensor on the wheels and compares front to rear for the slip light. Wheel size difference becomes more noticable the higher the speed and that is my guess as to why it comes on. Unless you are pushing 500whp or more it is doubtful that wheel spin is the culprit.

 

Well then my big concern is since TCS is OFF... is the bastard activating and pulling power anyway? Or just lighting up and saying "Hi douche, you're tires are slipping"

Anyway to recalibrate for different tires? I mean different versions of the car have different setups (Enthus, Track, Performance)... so I'd think I could do something

~Josh

 

LOL!!!! Just get the properly sized tires and other than that you will be ok unless you are adding IPW via MAP.

 

Well right now I am running 265 front and 295 rear on SSR Comp-H's. I was under the impression that tehy'd be relatively close to the original 17 inch enthus wheels in over all diameter but I might have fuked it up. I dunno. Still, is the light just letting me know or is this thing shutting down power to the engine? Cause with FI I know that can NOT be good.

~Josh

 

What profile tires are you running? Without that it's impossible to tell if the front to rear ratio is correct. Use this calculator to find stock ratio and then find your current ratio. http://www.miata.net/garage/tirecalc.html

 

Ach I don't remember the stock set up. Now I am F265/35/18 R295/35/18


I'm just wondering why this isn't a more standard issue on FI Z's since I am willing to guess just about everyone is running a different size tire. Some on 19's etc. Bleh... I will go beat on her tonight and see if it is still happening.

~Josh