Hi folks,

Just picked up a cheap Stilo for in and out of work. It does have its issues so thought I'd ask about this one.

Basically when I brake it's fine but as soon as I brake fully with foot to floor I get a shudder hitting my foot for the last few metres of stopping and a dodgy noise.

Then tonight I got an ABS warning and the light came on. Now when I brake it's fine with no shuddering.

Can I assume it's an ABS fault as opposed to thinking it was a warped disc or dodgy pad?

Any suggestions appreciated.

Thanks

Hi

At what speed does this happen?

ABS should actually kick in when breaking hard and abruptly. It uses a magnetic ring and a sensor (one on each wheel) to check whether the tires are still spinning, or blocked. Whenever the wheels are blocked there's no control over the car, that's why ABS is invented.
If the ABS-system notices that one or more of the wheel are being blocked, it starts to engage the pump that applies braking in a pulsating manner, making emergency braking a lot more effective. This is the simple explanation of the system, I could be off a bit.

I only notice ABS kicking in when having to do an emergency stop. Since my tires are a bit old and getting slick, the ABS-system kicks in more than when having a good set of tires.

You should read out any error codes, as the 'ABS failure' alone isn't enough. If you can get your hands on an OBD-reader it'll give you codes, which you can work from. It could be signal loss to a sensor, signal loss between the ABS-module and the Body computer, or something else.

It only happens when I'm slowing to stop, ie on approach to a junction, traffic lights etc. Any time when I'm braking right down, it happens from around 20mph down to a stop.
I'm wondering is the sensor playing up and thinking it needs to engage ABS as such.
The ABS light isn't on anymore, it came on once and when I went out the next day it wasn't there.
Leaving it in next Tuesday so fingers crossed nothing major.

I picked a lead up and used multiecuscan, no ABS fault showing but had these other 4:

P0530 - Air conditioner pressure sensor (I know I need it re-gassed).

P0380 - Board relay, thermostarter or preheat. ECU. (Preheat fault, need a new plug).

P0235 - Supercharging pressure (cleared ok, not sure about it?)

P0404 - EGR (cleared ok, not sure about it?)

To top it all off I have a lovely thumping noise when I go round a left bend, comes from right wheel I think, from quiet to right up there noisy on motorway corners!

Is it a JTD?

P0235 - Supercharging pressure
Could be the MAP-sensor.

P0404 - EGR
Could be a smudged up EGR-valve, but that would almost always result in loss of power under 3000 rpm, with quite some smoke coming out of the exhaust.

The sound that comes from one of the tires could be a stabilizer, it's a joint that has rubbers, which wear out over time. Google 'stabilizer joint' and you'll know what to look for, they're close to the suspension springs.

One other simple thing you can check is the plastic ring that's at the bottom of the suspension spring. Normally it wouldn't be touching the wheel but if it's damaged it could, especially when steering. It should be an inch or two above your tire.

As far as the ABS goes, check your brake pedal switch. Park your car with it's rear facing a window, and press the brake-pedal 30 times. Check the reflection in the window to see if the brake lights actually come on each time. If it fails just once out of those 30 times, replace the brake switch.

Thanks for the response, I'll take a look at your thoughts. I do have smoke but only when I put my foot down, like going to overtake or pulling out of a junction quickly. Haven't noticed any power loss but sometimes in 2nd gear there's a lag.

When the mechanic looked at it he said he thinks it's electrical/sensor issue. He plugged in and took it for a drive. Not sure what the reader does but he says it reads speed of the 4.wheels, then he brakes and reads what it does. Basically there was no speed.reading, then all fine, then front would read 10 mph and rear 20 mph. Couldnt get it working long enough to brake! ,

It's probably not an electrical issue, as the sensors are actually reading the rpm of the wheels. If it were a voltage related issue, like when one of the sensors starts to fail, it would more likely give error codes when reading with OBD.

In this case I'd say the difference in MPH is caused by the rings that are being used by the sensors. On each wheel there's a metal ring with magnetic poles. The sensor is a magnet as well which will give out a different resistance depending on which pole it faces (poles on the ring).

As lots of brake-dust and metal comes of your braking system, there is a possibility that dust is now stuck on either the sensor, or the actual ring. Considering the front rings are pressed within the actual bearing, I'd say there's dust between the sensor and the ring.

You could remove the sensor, which will leave you with a hole that opens to the magnetic ring. However it is impossible to clean the ring without taking apart the hub. So I'd advice to dissemble it. Take of wheel > dissemble brake-arm > open the hub. It's a bit of work if you haven't done it before, but it's free and worth a check.

You can always check just one wheel, in this case one of the front wheels.

Good luck and let me know when there's any trouble or questions.

To clarify:

When there's too much metal-dust sticking to the sensor and/or the ring, it will lose some of it's 'magnetic force', hence the difference in mph compared to the rear tires.