RLTC - Failure

[Pig]

After me singing the praises all these years of how great RLTC is and just because its on, it doesnt mean the driver will rely on it, today i was proven wrong. (it is great but i do rely on it)

 

I was coming off a round about in 3rd gear as the road was almost straight i planted it with RLTC on wet, the ass end came flying round and I caught it very late into the slide. Was not ready at all as was expecting the RLTC to catch it first like it should have done.

 

I then tried a few straight line pulls, 2nd, 3rd and 4th and it was fine. Then 5 mins later did another 3rd gear straight line pull and it span the wheels up to the limiter and then started working as i kept foot half burried to see what it would do.

 

Very strange, anyhows i have asked dave to check the wheel speed sensors for me as im pretty sure i have a problem with one as ABS doesnt work.

Does anyone know if wheel speed sensors are expensive?

 

Jon

[Chris Wilson]

From Toyot, yes, very. The more adventurous might try one from a different car, and try and engineer a secure mounting and splice the lead. The stock ABS ecu will self diagnose to a certain extent. A `scope on the sensor pins at the ABS ecu is the best way to test them though.

[hogmaw]

Has happened to me too. RLTC does kick in most of the time but it is not 100% reliable. I always drive as if it's not there, it's not something you can expect to rely on.

[jevansio]

Have you tried the RLTC diagnostic where it flashes each of the wheel speed sensors in turn via the light on the controller?

[Pig]

I have a digital adjuster and all wheel speeds show up fine.

I dont know if that answers your Q jay but i didnt really understand it

[jevansio]

Ahh right Jon, you have the new fancy LCD screen one???

 

I had the old black box where you turn the knob to each of the settings 0%, 5%, 10% & 15% and it flashed what the RLTC was seeing as the wheel speed via he little LED on the box.

 

I just thought if it was getting a dodgy input from one wheel that might show up which wheel (for example one might not be working at all)

[dandan]

I think there is a factory ecu ABS diagnosis possible that will highlight sensor issues

[RedM]

I've mentioned it before but (if I understand Terminator correctly) if you are on more or less a straight line RLTC will reduce your setting by 5%, maybe even as much as 10%.

 

This means that with zero slippage dialed in you could end up being on a much more relaxed setting.

 

See Phil's post below with the pertinent point in Bold. Thread here:

http://www.mkivsupra.net/vbb/showthread.php?t=80970

 

Sorry mate don’t get on here as much as I used to do. Others will read into that what they will.

 

Cant see anything glaring in the screen shots.

 

There are always at least two components to slip, rotational and lateral. RL can and will only respond to rotational slip and in response, cut injectors progressively to reduce power to the driven wheels.

 

The contact patch friction level is critical, if the momentum of the car was slightly upwards biased on one wheel the coefficient of friction at that point would be considerably reduced. the lateral component would suddenly become much less than the rotational causing the car to move side ways. A secondary effect would be the generation of rotational slip causing RL to kick in. As lateral forces out weighed rotational RL could not help. Sounds like drive skill came in handy.

 

Don’t forget 5% is added to all slip levels in a straight line so even on wet you may not have turned quite enough for RL to recognise a turn and thus reduce allowable slip to 0%. This can be altered but may cause the car to bog down in corners

The fact that you then tried to replicate the situation unsuccessfully suggest this was a one off set of external factors, not a fault of RL.

 

Might be a line worth investigating.

[Pig]

I've mentioned it before but (if I understand Terminator correctly) if you are on more or less a straight line RLTC will reduce your setting by 5%, maybe even as much as 10%.

 

This means that with zero slippage dialed in you could end up being on a much more relaxed setting.

 

See Phil's post below with the pertinent point in Bold. Thread here:

http://www.mkivsupra.net/vbb/showthread.php?t=80970

 

Thats interesting to know, however in my case it wasnt the amount of slip it aloud it completly stopped workng for a short period of time.

 

I also adjusted the slip to 25% to see what the impact would be and the 2 we completly different.

 

Jon

[imi]

This is a bit concerning. For your sake John, I hope that there is a lose connection somewhere as i cant for once believe that RLTC is more of a hit and miss solution........FFS, they have it in the 250K gumpert.

[Ian C]

There are extensive logging and diagnostics that you can do. You can check the error codes of the ABS system - I've posted on here before about that I think, enjoy your search

 

Also, with a laptop + serial port + RLTC software, you can hook the unit up to the lappie and watch the reports from the wheels sensors in real time. I had problems with mine once and jacking up the back of the car and running it in gear showed a messy RPM signal and dirty speed sensor data. Hooked it up to TACH instead of IGF and problem solved for the RPM signal. The diagnostics are a rolling graph in realtime of the sensor outputs, RPM, and the level of cut the RLTC unit decides upon. This helped diagnose a problem with the ABS sensor signal, in that it kept spiking from about 15mph to anything up to 200mph hahaha, no wonder it'd randomly cut the engine out.

 

As an aside, there is one chunk of road by me, coming off a roundabout onto a bit of new dual carriageway, where I can step the back end out in 3rd if it's wet. Did it, straightened up, did it again, gave up trying. That's happened twice. I think it's a combo of road surface, wetness, gentle curvature and the camber angle of that bit of road. The car ends up slipping sideways and as RLTC can only cut power to equalise wheel speeds, it may be the case that momentum of the ass of the car makes it continue to slide on a wet road. Lifting off was the only way to catch it. Probably not relevant to your situation Jon but another affirmation that it's note Pokemon and cannot catch them all. Seriously, do you boot it in the wet even with RLTC? I daren't, I still accelerate expecting it to go at any moment...

 

-Ian

[SUPRALOOPY]

All noted and I will check it all out. In a safe and controlled situation..LOL

[imi]

I dont have a 100% confidence in the system anyway and with threads the situation isnt being helped.

 

I think ill have to take on Ian's advice and look into this myself rather than relying on someone else. shame I dont have any roads nearby where I can put the system to the test safely.

[Branners]

For many years RLTC has been installed in a very large number of cars including Supras. Its pretty much infallable but relies on information from the ECU and ABS sensors which we all know on a 15 year old car can get a little iffy. When you have 5 or 6 units tapped in to your ECU to control boost, fuel cut, speed cut, mph conversion and fuel control it can get a little cluttered.

 

I lost my fuel cut defenser on my UK spec but it went in such a way as to cut the whole engine as soon as it came on boost. Driving normally was fine, but as soon as it hit boost it stopped the car dead. Who could have guessed.

 

I wouldn't want people to start thinking RLTC is unreliable. It has no doubt saved many Supras from an early grave and I dont doubt that it has saved the life of a few Supra owners too, people dont dont realise how well it works and how often its giving a helping hand.

 

JB

[gaijin]

Not much help this.I too have RLTC fitted and the same thing has happened to me lately.Coming off roundabouts maybe putting on the power a wee bit early and the back end wanting to switch places.At the moment i put it down to the greasy road conditions here in NI,Salt and grit are being laid at night to combat the frost and ice leaving a scum on the road surface.There has been little rain to wash it off;so i take it very canny,RLTC or no.A new Shelby Mustang passed me the other day;i was severly tempted to tramp on but i bit my tongue and just trunddled along(chicken)

[Pete]

I've had this a couple of time but only on spilled diesel and frozen water. If the road is slippy, oily or icy then RLTC will not help you at all.

[Branners]

I should also have mentioned that the out of the box RLTC DAT file is far removed from a DAT file setup and modified to your specific car.

 

Make sure the settings are optimised for your wheel and tyre set and that all the different hard and soft cut points are set properly.

 

There are people on the forum who can help with this.

[Pig]

Thanks for all the replies, especially Ian.

Branners, totally agree with the poss mixed up signal, one of m signals hasnt worked from day one and had to be connected to somewhere else, i think the same thing Ian said above.

 

Mine has been setup by Matt Harwood so know its been setup properly

 

 

All noted and I will check it all out. In a safe and controlled situation..LOL

 

Thanks mate, good luck. I managed some home DIY this weekend next step I might even be able to clean my own car

[Terminator]

As John has said RL is very reliable, and the experience of a few users should not put other off the product. With a a well set up RLTC in your car full throttle round a round about in driving rain is quite possible. However RL is only as good as the data it gets from the car. And the suitablitiy of the internal dat file. It is worth getting ABS signals checked before condemning RLTC. Ensure the RPM feed to the RL ECU is dedicated, with no other after market add ons sharing the signal.

 

If you are checking RL files ALWAYS go to the RL Web site and down load the very latest version of the software. It has been a few years now but there is one version of the RL software that changed data in the dat file. I speak from experience as I was inches away from the car ending up in a ditch, all four wheels ended up on the verge.

 

The was also an issue with some of the early digi units, they caused some settings to change when first connected to the main unit. You would need to get your Digi unit serial number and contact RL to check if you adjuster required attention. I believe there is a very simple firm wear fix.

 

Very rarely the injector drivers in the RL unit can fail, but this will cause massive misfires and leave the car unusableagain I speak from experience.

 

 

I have not had any traction control since my big single build and despite all the extra power and torque have found the car very well behaved, admittedly single power is far more predicable particularly with a manual box. If I ever go back to an auto or tiptronic, the first mod would be RLTC, as it is too easy to be caught out at the second turbo transition point in auto mode.

 

If you want me to check over your dat file, once you have ruled out ABS sensors, drop me a pm.

Edited January 4, 2009 by Terminator (see edit history)

[Pig]

 

If you want me to check over your dat file, once you have ruled out ABS sensors, drop me a pm.

 

Thank you. I will keep this updated while we check out the sensors.