Braking problem - malfunctioning ABS

ChrisSlicks · 03-18-2010, 12:03 PM

Quote:

Originally Posted by pgrmstr

Also, from previous posts, someone had stated that the ABS fuse a a 3 in 1, which also included VVEL, so you would need to cut just the ABS piece so the other two stayed intact....but I'm not sure.

That is correct. Ordering a spare might be a good idea.

Quote:

If there is another device (fuse/sensor) that can effectively do the same thing, that would be useful!

Removing a wheel speed sensor should do the trick.

Quote:

I only autox my Z twice last year and did not encounter this issue...but the car will be HEAVILY autoxed this season on R compounds so this is of particular interest.

It depends on the smoothness of the track. On a really smooth surface you usually don't run into it, but the old airport we run on has big cracks, off camber surfaces, dips and crests. If you co-drive the car you might encounter pad-fade with the stock pads if the course is brake heavy, higher temp pads such as the Carbotech ones would be a requirement.

Quote:

Additionally, as a left foot brake fan for autox, I am trying to solve the cut off of power when dragging the brake....hoping the ABS disable would solve both

That's a good question. I don't think it will as it doesn't have anything to do with ABS. You will most likely have to disconnect the brake pedal switch (which will take out your brake lights as well).

Valentino · 03-19-2010, 04:40 AM

So witch fuse I have to pull to disable the ABS?

ChrisSlicks · 03-19-2010, 10:53 AM

Quote:

Originally Posted by Valentino

So witch fuse I have to pull to disable the ABS?

If you want to pull the fuse, you will need to get a spare 3-in-one fuse with the correct values, and then cut out the center fuse of the 3. As I recall the other 2 items on the fuse were power windows and VVEL. I'll go make a note of the number.

ZKindaGuy · 03-19-2010, 11:41 AM

Quote:

Originally Posted by Namir

What exactly do you mean by "skate"?

Your wheels would lock up and you were unable to turn while under hard braking? Was the ABS not pumping the brakes for you after you locked up the wheels?
No sounds or ABS flashing lights?
I would for sure contact your dealer as the ABS is a safety feature that needs to be working at all times. You could have a faulty ABS sensor that needs to be replaced and this sort of thing would clearly be under warranty.

Wait a minute....before contacting the dealer I think consideration has to first be given to the fact that he was doing x-events and that more precise details need to be given as to what exactly he was doing at the exact moment he noticed the ABS abberation.

It is entirely possible that the forces being created as a result of his driving reaction to the course could have created a wheel "reaction" that falsely simulated a condition that would normally trigger the ABS system as if the true condition that would trip the sensor trigger had actually happened (though it didn't).

In that case the ABS action would be entirely normal and is not something the dealer or Nissan should even get involved in since the car was being driven outside the normal driving parameters the car was primarly made to be driving under. That is the assumption of the risk on the owners part since the owner is driving the car in conditions beyond the intended use.

What we don't need is some stupid and pre-mature knee-jerk reaction by these drivers who want to push the envelope with their car that starts some kind of media bandwagon witch hunt like is happening to Toyota and Honda.

kannibul · 03-19-2010, 02:23 PM

Quote:

Originally Posted by travisjb

Here's another idea... softer anti-sway bars! Very stiff anti-sway bars are going to cause the inside wheel to lift and 'overspin'. When this happens on the rear axle WHILE BRAKING, that's precisely when our problem seems to occur. Compounded by the fact that the rear end is light... Inside rear corner picks up, inside wheel spins faster than outside, ABS reacts to the extreme wheel speed difference by assuming the car is spinning on ice and it uses a VERY AGGRESSIVE slow speed ABS that is locked in until the car reaches nearly a complete stop.

So now I'm contemplating using the softest setting on the rear sway. It will cause more understeer, which I will have to manage some other way. Like perhaps with a square tire setup (275 widths all the way around).

Just a working theory.

I'm very curious to know if anyone has had this problem with the stock sway bars. I'll have to go back and check notes from early last year before I got my sways.

More chassis stiffening might help too.

travisjb · 03-21-2010, 02:42 AM

I'm definitely generating too much heat in front brakes. Used a paint temp sensor kit from Stillen and found the max front rotor temp at the track today to be somewhere north of 560C. The caliper temp was much more reasonable, which is credit to the design and robustness of the AP Racing calipers. Time for some brake ducting!!!

spearfish25 · 03-21-2010, 08:30 AM

What's the final word on the ABS fuse manipulation? Could be interested in doing this...

ChrisSlicks · 03-21-2010, 09:23 AM

Quote:

Originally Posted by spearfish25

What's the final word on the ABS fuse manipulation? Could be interested in doing this...

The ABS actuator fuse in on the 3-in-one fuse as described. Unfortunately I couldn't figure out where to buy one from, and I couldn't see how you could remove the center piece of the fuse without destroying it. You might be better off disconnecting a wheel speed sensor as that will shutdown the ABS computer.

Valentino · 03-21-2010, 09:44 AM

Ya the wheel speed sensor sounds less complicated. So do you have any idea how to do this?

SkyZ · 03-28-2010, 06:31 PM

i believe its a simple plug in unit. find the sensor, trace the wire and unplug it.

spearfish25 · 03-28-2010, 08:02 PM

Has anyone seen if disabling the ABS solves the icing issue? I was looking through the service manual to see where the speed sensor are located and of course ABS was in a nearby section.

If you disable the speed sensors, you'll be messing up the VDC/TCS system as well (possibly the icing problem, but maybe it's just the ABS system alone).

The manual also states the pulling the ABS harness will disable the system and then we can just threshold brake. Could be useful at the start of a track day, then just reconnect when done.

Valentino · 03-29-2010, 06:11 AM

^ +1 REP

I'll try this next time when I'm on the track.

kannibul · 03-29-2010, 09:04 AM

WHen this happens, are you guys progressively braking, or jam-braking?

Basically, are you loading the weight of the car on the front wheels progressively, or, are you slamming the brakes quickly?

The first is the correct way...and you're less likely to trip ABS in any instance. The front wheels are about 70% of your braking force, and by loading up the front suspension FIRST, then you end up with more downforce on those wheels, allowing them to do their work better without tripping ABS.

That said, perhaps the car is too soft in the front, and nose dives hard enough to allow the back wheels to trip into ABS. If you're turning a bit, perhaps it's enough to where ABS trips on one wheel, kicking off ice-mode?

It could also be related to the inertia sensors in the car - perhaps they are reaching their limits and not reading the car correctly.

travisjb · 03-29-2010, 10:41 AM

don't think it is the inertia sensors, mine are disconnected

no. not 'slam braking'... controlled braking

yes, it is the differential wheel spin

bullitt5897 · 04-05-2010, 11:08 AM

Ok, so Semtex, StormCrow and Myself met up yesterday to do some braking tests and see what the stock 370z could do 60-0 and what a BBK 370z could do...

Well fully stock the 370z stops 60-0 in approximately 64 feet with no problems except brake fade after 3 stops. The third stop was about 68 feet.

so what does this tell us... Something we all already know the Magazines are full of $hit...

Now to the problem... The BBK 370z would redoubtably lock up the brakes faster and begin to slow faster than the stock Z then BAM "ice mode" would kick in and send the car an extra 40+ feet before allowing the brakes to reactivate. We tried several different processes to eliminate the problem but to no avail. We even disconnected the ABS harness and tried a test run at about 40mph and lets just say its was smokey!!! then we went for the 60-0 and with no speedo it was hard to gauge speed. At this point I decided not to lock the brakes but to progressively brake and it still locked the brakes to the point I said F' it and let off. I now have two flat spots on my right rear tire...

so all in all you need the ABS as you will lose your speedo and the intelligent key starts acting funny and will not turn off the car! It literally took me like a full minute of pressing the off button to get the car to shut down.

Now the question is... is there a way to dial back the abs? Giving us a larger margin for wheel speed deceleration?

but its gets even more weird... I took the car to a different road surface and the car did just fine...

03-19-2010, 04:40 AM	#77 (permalink)
Valentino Enthusiast Member Join Date: Jan 2009 Location: RaceTrack Posts: 349 Drives: SOLD 09,370z,M6 Rep Power: 305	So witch fuse I have to pull to disable the ABS? __________________ Lou Fusz Nissan \| KW V3 \| SPL rear camber and toe bolt \| OS Giken LSD \| Nismo Diff cover \| Engine Oil cooler \| F.I. TDX Cat Back 18" Resonators \| F.I. Resonated Test Pipes \| Injen cold air intake \| COBB AccessPORT \| JWT Clutch Flywheel \|

03-21-2010, 02:42 AM	#81 (permalink)
travisjb A True Z Fanatic Join Date: Jan 2009 Location: GSO Posts: 2,803 Drives: VIR Rep Power: 188	I'm definitely generating too much heat in front brakes. Used a paint temp sensor kit from Stillen and found the max front rotor temp at the track today to be somewhere north of 560C. The caliper temp was much more reasonable, which is credit to the design and robustness of the AP Racing calipers. Time for some brake ducting!!! __________________ 2009 370Z #104 For Sale

03-21-2010, 08:30 AM	#82 (permalink)
spearfish25 A True Z Fanatic Join Date: Mar 2009 Location: Naples, FL Posts: 4,117 Drives: to work Rep Power: 1856	What's the final word on the ABS fuse manipulation? Could be interested in doing this... __________________ 2013 Cadillac V-Wagon, RIP Z

03-21-2010, 09:44 AM	#84 (permalink)
Valentino Enthusiast Member Join Date: Jan 2009 Location: RaceTrack Posts: 349 Drives: SOLD 09,370z,M6 Rep Power: 305	Ya the wheel speed sensor sounds less complicated. So do you have any idea how to do this? __________________ Lou Fusz Nissan \| KW V3 \| SPL rear camber and toe bolt \| OS Giken LSD \| Nismo Diff cover \| Engine Oil cooler \| F.I. TDX Cat Back 18" Resonators \| F.I. Resonated Test Pipes \| Injen cold air intake \| COBB AccessPORT \| JWT Clutch Flywheel \|

03-29-2010, 06:11 AM	#87 (permalink)
Valentino Enthusiast Member Join Date: Jan 2009 Location: RaceTrack Posts: 349 Drives: SOLD 09,370z,M6 Rep Power: 305	^ +1 REP I'll try this next time when I'm on the track. __________________ Lou Fusz Nissan \| KW V3 \| SPL rear camber and toe bolt \| OS Giken LSD \| Nismo Diff cover \| Engine Oil cooler \| F.I. TDX Cat Back 18" Resonators \| F.I. Resonated Test Pipes \| Injen cold air intake \| COBB AccessPORT \| JWT Clutch Flywheel \|

03-28-2010, 06:31 PM	#85 (permalink)
SkyZ Enthusiast Member Join Date: Jul 2009 Location: Canada Posts: 382 Drives: 09 370z PG M6 Rep Power: 16	i believe its a simple plug in unit. find the sensor, trace the wire and unplug it.

03-29-2010, 09:04 AM	#88 (permalink)
kannibul A True Z Fanatic Join Date: Jun 2009 Location: Jenks, OK Posts: 2,281 Drives: 370z Touring/Sport Rep Power: 267	WHen this happens, are you guys progressively braking, or jam-braking? Basically, are you loading the weight of the car on the front wheels progressively, or, are you slamming the brakes quickly? The first is the correct way...and you're less likely to trip ABS in any instance. The front wheels are about 70% of your braking force, and by loading up the front suspension FIRST, then you end up with more downforce on those wheels, allowing them to do their work better without tripping ABS. That said, perhaps the car is too soft in the front, and nose dives hard enough to allow the back wheels to trip into ABS. If you're turning a bit, perhaps it's enough to where ABS trips on one wheel, kicking off ice-mode? It could also be related to the inertia sensors in the car - perhaps they are reaching their limits and not reading the car correctly.

03-29-2010, 10:41 AM	#89 (permalink)
travisjb A True Z Fanatic Join Date: Jan 2009 Location: GSO Posts: 2,803 Drives: VIR Rep Power: 188	don't think it is the inertia sensors, mine are disconnected no. not 'slam braking'... controlled braking yes, it is the differential wheel spin __________________ 2009 370Z #104 For Sale

04-05-2010, 11:08 AM	#90 (permalink)
bullitt5897 Premium Member Join Date: Jan 2009 Location: North GA Posts: 6,831 Drives: Twin Turbo Z34 Rep Power: 3682	Ok, so Semtex, StormCrow and Myself met up yesterday to do some braking tests and see what the stock 370z could do 60-0 and what a BBK 370z could do... Well fully stock the 370z stops 60-0 in approximately 64 feet with no problems except brake fade after 3 stops. The third stop was about 68 feet. so what does this tell us... Something we all already know the Magazines are full of $hit... Now to the problem... The BBK 370z would redoubtably lock up the brakes faster and begin to slow faster than the stock Z then BAM "ice mode" would kick in and send the car an extra 40+ feet before allowing the brakes to reactivate. We tried several different processes to eliminate the problem but to no avail. We even disconnected the ABS harness and tried a test run at about 40mph and lets just say its was smokey!!! then we went for the 60-0 and with no speedo it was hard to gauge speed. At this point I decided not to lock the brakes but to progressively brake and it still locked the brakes to the point I said F' it and let off. I now have two flat spots on my right rear tire... so all in all you need the ABS as you will lose your speedo and the intelligent key starts acting funny and will not turn off the car! It literally took me like a full minute of pressing the off button to get the car to shut down. Now the question is... is there a way to dial back the abs? Giving us a larger margin for wheel speed deceleration? but its gets even more weird... I took the car to a different road surface and the car did just fine... __________________ *Shop Cars: 2013 318whp Nismo VspecII 370z SOLD, 2009 1000hp+ 93oct 4.0L TT 370z Fast Intentions STAGE 4 #054*

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