MOT fail

[Louis]

Been for my MOT today and unfortunately the car failed on 3 things... Handbrake efficiency, lambda reading too high, and headlight too low.
I just fitted a genuine (used) cat to the clio, but kept the existing lambda sensors, however I'm led to believe that the post cat sensor may be failing as I get the EML light. I've not had chance to properly drive the car after fitting the cat, and went pretty much straight to the MOT station, so it could be that it wasn't hot enough? The CO was 0.03 (0.20 is the max), HC was 10 (200 max) but the Lambda read 1.077 (1.030 is max). Natural idle speed it was 0.01 CO.

Also I just fitted genuine renault handbrake cables as the NSR was snapped. I had adjusted them to about 5 clicks, but got 15% efficiency (min 16%!!). I've had all my rear carriers apart today and tried cleaning up the sliders/brake pads so they move better. However I'm getting a problem where the piston is coming out, but then wont go in by itself unless pushed. Both sides the piston winds in/out easily enough when apart and both move on the pressure of the pedal. I adjusted the handbrake cable to about 4 clicks, and the OSR wheel doesn't move at all, but I can move the NSR even when the handbrake should be tight on. But then pulsing the brake pedal locks it up more.

Do i need a new caliper? I can move the handbrake lever on the OSR and watch the piston come out, but on the NSR it doesn't seem to move. The mot station wanted £49 to strip and rebuild my rear brakes but i've done this today and it doesn't seem to have helped so glad I didn't pay!
A little stuck as I just want it through MOT! Kind of feels like it's binding at the back when driving, and when i jack up the back the wheels can feel stiff until I put a screwdriver between the pads which I presume is pushing the piston back.

Sorry for the wordy post, appreciate any help!

 

[oVerboost.]

Going by that, replace the pre-cat lambda or question the catalyst itself (doubtful though), the post cat lambda wouldn't cause your car to fail any MOT as it really does very little.
Did they get the engine really hot before testing? Or was it sat around for ages before they did the emissions test? Sometimes a good old fashioned Italian tune up can be the difference between a pass and a fail.

Caliper wise, if you've tried adjusting and aren't getting any joy from it - I'd bite the bullet and replace the caliper. The cables fitted are 100% for your model of Clio?

 

[RichValver]

just had mine mot'd, was told the cat needed to get upto temperature for it to work efficiently. Apparently a common problem on the clios. Mine was like 1.04 before getting it to temp

 

[Louis]

It's been running a decat for all my ownership so far, and the EML was always on then as it was tied up out of the way and the post-cat blocked off. When I use Torque (Fairly unreliable I know) it gives me bank 1 sensor 2, so i presume post cat? It could just be it's not had time to properly adjust to when i've fitted the cat, although I did clear the code and the light came back on fairly readily. The mot station is literally down the road from my house, so no it didn't get 'really hot'. I think next time it'd be worth just taking it for a hard drive? Just got to be careful with it already being out of MOT.

I'm pretty stuck on the caliper situation, as I presume i'd have problems with the piston not moving out under pressure of the pedal, which i dont have? Unless just the handbrake lever is knackered. Although it will 'engage' handbrake it isn't as solid at the otherside. Could it be down to the bias valve?

 

[Louis]

I'm fairly trusting of the cat tbh as it's a genuine part not a pattern part. Is it normal for HC/CO to be so low? Seemed weird to me.

 

[STEVE.M]

I`d check the compensator valve is not seized before replacing the caliper.
@Louis`

 

[flebay]

I`d check the compensator valve is not seized before replacing the caliper.
@Louis`

The 182 brake bias is controlled by the ABS module so it won't be that, compensator on the 172cup only.

 

[Louis]

It doesn't seem like the pads move too freely. The retaining clips seem to hold them quite tight, is that normal? What would usually make the piston return to it's existing position? I did notice when working on one side, that the other side seemed to work better. So could this be the compensator? Nothing was noted on my MOT... @STEVE.M

 

[Louis]

The 182 brake bias is controlled by the ABS module so it won't be that, compensator on the 172cup only.

Ahh okay.

The pads just feel like they're binding after handbrake/brake was applied whilst the back end was in the air. As if the pistons weren't properly disengaging. New brake fluid required? Never changed fluid before, but I don't see it being too hard?

 

[flebay]

lambda reading too high

Lambda reading generally indicates a leak somewhere in the exhaust.

 

[flebay]

Ahh okay.

The pads just feel like they're binding after handbrake/brake was applied whilst the back end was in the air. As if the pistons weren't properly disengaging. New brake fluid required? Never changed fluid before, but I don't see it being too hard?

Good chance the callipers sized inside from rust, best to get a recon or second hand.

 

[Louis]

Good chance the callipers sized inside from rust, best to get a recon or second hand.

Hmm okay i'll try other things first though as it may be simpler. Could it be that the pads need filing? They look fairly new and were a bit of a pain to get in the carriers when i tried, so maybe why the piston isn't moving back properly? Will have another play tomorrow, just want it MOTed then I have more spoke for travelling for parts etc.

 

[Louis]

Lambda reading generally indicates a leak somewhere in the exhaust.

I can't see it blowing anywhere, unless it's leaking on the olive joint as I have put a new gasket/fitting kit on the cat. It's running an aftermarket exhaust, so could one pipe want covering whilst they test the other?

 

[flebay]

I can't see it blowing anywhere, unless it's leaking on the olive joint as I have put a new gasket/fitting kit on the cat. It's running an aftermarket exhaust, so could one pipe want covering whilst they test the other?

It may help bring in down depending on the make/design of the system also try the reading from the other pipe.

 

[flebay]

The retaining clips seem to hold them quite tight, is that normal?

That's normal they need to be to stop the bad rattling around

 

[STEVE.M]

The 182 brake bias is controlled by the ABS module so it won't be that, compensator on the 172cup only.

I`ve been reading too many uninformed threads on CS.

172 Cup has no ABS, hence the compensator, that makes sense.

Somewhere down the line, I`ve been given the impression that 172/182`s have the valve, but 172 Cup has no actuating spring.

 

[Gus]

Wont lie, rebuilding the rear calipers is a f**king nightmare. The front side with the pistons is a doddle. The back bit with the hand brake arm under the big black boot is a pain.

 

[Louis]

Wont lie, rebuilding the rear calipers is a f**king nightmare. The front side with the pistons is a doddle. The back bit with the hand brake arm under the big black boot is a pain.

Be better to just replace the whole caliper i'm thinking? Then it's just fit and bleed? Just don't want it to be something else. One side was 91kgf, the other 89kgf during the MOT test, now after stripping and rebuilding carriers etc it seems that the NSR is loads less than the other side... Will look again tomorrow!

 

[Jonz]

Be better to just replace the whole caliper i'm thinking? Then it's just fit and bleed? Just don't want it to be something else. One side was 91kgf, the other 89kgf during the MOT test, now after stripping and rebuilding carriers etc it seems that the NSR is loads less than the other side... Will look again tomorrow!

if this happened aafter replacing the handbrake cables check the routing of the cables and make sure all the plugs are slotted into the frame properly otherwise one will pull while the other will only pull slightly. It is possible to have damaged the compensator if you've been driving aroud with one snapped cable for a while so it never sits right.

 

[Louis]

if this happened aafter replacing the handbrake cables check the routing of the cables and make sure all the plugs are slotted into the frame properly otherwise one will pull while the other will only pull slightly. It is possible to have damaged the compensator if you've been driving aroud with one snapped cable for a while so it never sits right.

Weathers crap today, otherwise i'd go out and have a better look. I'm pretty sure all the routing of the cables was fine though, and all are properly slotted. Does anyone have a picture of the route for the NSR? Mine goes through the frame near the adjuster, then into the clip, then passes near to the brake lines, then through the other hole and onto the caliper. Again, worth a look! I did notice that the little adjuster itself is just free to move around under the car, and did look to be angled more towards the OSR. Is this meant to stick under the car?

I dont know how long the PO has been driving the car around with it snapped. I've only been driving it snapped for the past month, but it's been sat on my driveway snapped for 2 months before that.

Had a look at the lambda readings too, precat seems fine, but is the postcat reading too high? I'll try switch them over and see what changes.

Should post cat be reading more like 420mv? Torque could be inaccurate though.

 

[Louis]

An update of sorts. From my 1.2 I had a genuine Bosch sensor lying around which i believed to be knackered. I fitted it onto the post cat and I got this constant reading, higher voltage still than the one i took off.

I then also had a real cheap brand new universal lambda lying around from my 1.2 too. I fitted this, and the constant reading seemed closer to what i thought it should be 420mv ish.

Soo, i believe my 2 bosch sensors are knackered hence the throwing of my EML. The thing is, how good are these universal ones? Will they just s**t themselves quickly or cause me any other problems with my car? I will probably refit my decat anyway after MOT time, so if I was to spend £45 on a new bosch lambda, it would kind of be pointless.