2003 Ford Focus RS - sensors question ?

[Jackstrath]

So, sun was out, logs taken... and some interesting data....

Im getting spikes in wheel speeds? Not sure why? Its even saying its activating the LIMP switch but doesnt say what for?

Also i set the sensors as 5v and thermistor and both didnt work, i was getting zero wheel speed? Put them back to 5v Bipolar and it works again?

[stevieturbo]

I can see spikes on vehicle speed. I do not know what you are using for vehicle speed.

RL and RR do not appear to have spikes visually on the log, but RR is counting up spikes when it happens. Which also seems to impact gear display.

gear display should really be derived from a driven wheel, although spikes there too would mess things up.

Not sure the best way to mitigate spikes, whether more teeth per reading, or I think there are some ways of generally ignoring the spikes, but I never really got much into it, as my spikes were always at higher speeds, so not something easy for me to test and diagnose.

Although as said, the spikes only appeared when I moved my driven wheels to the X10, I never had any when direct to the ecu.

Limp switch, not sure what activates this. If you go into the Cal and Goto limp, you can see the various entries relating to Limp Switch. That might help you find something. Or it could be getting received via CAN from something to do with the box ?

[Jackstrath]

Vehicle speed is set to AVG REAR on speed select.

Worth noting, the cars set up;
Front Left wheel speed sensor is the sensor i added using the brake bell bolts to count. The Front Right is the same, These are the only two inputs i have for wheel speed on the car, there is nothing on the rear axel at all counting rev's. Both these sensors on the front driven axel, both are inputted into the Rear Left and Right Pin assignments, this is for soft wear on the syvecs for the DSG control which requires them to go into the rear wheel speed inputs.

I currently have 12 bolts for reading speed input with it counting 1 per reading, like you say maybe putting that up to counting 3 would work better?

Limp one is a weird one, i think its a torque trip that flashes up on my dash... from CANBUS like you said, LIMP_SLOT //Slave an23 TRQLIM_SLOT //Slave an24

What would cause RR to count spikes but not have on the log? Seems an odd one? Might increase the spike count....

I think im going to need to compose an email to the Dutch lot to ask how sensitive the soft wear is to spikes and differential speed... iv now got it in my head that potentially as im a FWD car im seeing bigger differences in wheel speeds across the axel due to the steering....

[stevieturbo]

Not sure what causes the spikes, obviously it is seeing some sort of voltage it thinks is a reading or something. Even at 750Hz though it's too slow to see anything. Really it'd need an oscilloscope.


No idea if expanding the voltage thresholds will help, or make it worse. Or indeed turning the filter on. But filter on with mine worked ok at lower speeds, it did not like high speeds.

But you could definitely play with the tooth per reading etc and filter off/on

Looking at SCal again, it looks like the spike detection is purely for health monitoring, too many spikes and you can deem a sensor fail. It looks like it serves no other purpose. So probably not of any use to you here, other than it is allowing you to see there has been spikes more easily.

Although loss of traction might impact it a little, you could maybe just use RL as vehicle speed, at least then vehicle speed would not see the spikes.

Does the DSG side use RR ? RL ? or vehicle speed itself ? Or all ?

Or are the spikes not impacting the DSG side of things, you're just concerned about them ?

[Jackstrath]

I could try bump it up to 1000hz, iv since realized the logging time is per MB not total

Yeh i think il play about with tooth per reading next and see how it responds.

In the instructions it says the TCU needs to see both sides of the driven axel, im not sure if me changing it will make much odds as i suspect the signal go's in to the TCU from both sensors, Il email about that i think and ask.

The box keeps going into limp mode with the errors relating to both left and right speed signals so something not tying up right, it could be a case of me having the vehical speed averaging the rear, maybe it doesnt like that? I shall send an email and see what comes back to me!

[stevieturbo]

If it is direct receiving right and left speeds, then vehicle speed is probably not an issue.

You need to sort the spikes, whatever is causing them.

Try filters on..didnt work well for me, but you never know

Try higher numbers of teeth per reading, then it might ignore or not see any short spikes ? Don't know.

As said, 750 or 1000Hz, probably isn't going to make much odds now, even at 750 there is no distinct square waveform. But 1000hz can only be better for this

There are no dropouts now ? Did you change anything there ?

[Jackstrath]

Yeh il double ask the question, never know they might of had something similar!

Il try filters and higher number of teeth and see what happens!

So here is the next weird part.....
I changed the speed input signals to 5v, went for a drive and the car wouldn't shift out of 1st, pulled over and hastily changed it to thermo, same again.... wouldnt change out of first... so put it back to what i knew gave me signals, 5v bipolar and went on my way...
Now iv just looked at the config, and just went out to double check as i thought the copy saved was wrong but its not.... but as i was planning on the sensors working at 5v input, I have the high threshold set to 3V and the low set to 2V...... but off course on 5v Bipolar it never drops below 2.5v..... so no idea how that even worked? Unless its uses the high voltage as the count? but that could be accounting for the spikes! Another thing to try i guess!

[stevieturbo]

It may only look at one edge.

But would do no harm to have voltages that make sense both ways

[Jackstrath]

So played about with the thresholds again, and tbh the logs are looking good? I managed to set up the VCDS to log as well but a bit confused as to why there is multi options for the same thing? Like Transmission output speed, there is output speed, output speed 1 and output speed 2? Even the both transmission output speeds are vastly different in readings? So although i can log i have no idea what im really looking for other than spikes or dips but there is nothing jumping out at me!

Iv attached a log which i think looks nice and clean, all things considering. Iv spoke with someone on facebook and looking to redo the speed sensors, move them onto the Outer CV Dia. This should remove any concern about bearing float screwing with the sensor readings.

[stevieturbo]

your wheel speeds look fine there,

Vehicle speed looks fine, no dropouts or spikes ?

Most of the channels in the VCDS log follow the same pattern, no idea what they are though as never really used it or logged a DSG.

Is it still giving errors ?

Obviously the Syvecs log is in mph the VW in kph ?

Could that difference cause it to be annoyed ? would it maybe want speed in kph ?