MOT Fail (CO emissions and handbrake)

[zcacogp]

Chaps,

To my significant shame, my S2 has just failed it's MOT. Emissions too high (CO of 4.6, should be <3.5) and handbrake efficiency low.

Handbrake I am guessing is a matter of just taking it apart and seeing whether the pads are worn and whether anything is jammed up, not moving as it should and so on.

CO is more of a concern. It was last serviced about 3,000 miles ago, and had new plugs then. It had new leads and a new rotor arm and dizzy cap last year and was fully hot when it went to the MOT station. What else could cause this? Is it time to stump up for a new air flow meter? (If so, does anyone have one?)

Thanks for any advice,


Oli.

 

[ukmastiff]

O.K I don't want to see any " it wouldnt have happened if you owned a turbo posts " []

On a serious note : check air filter , fill with fuel and some good quality injector cleaner type petrol additive , thrash car to death . Re take MOT ( with air filter out for good measure) []

This has made a massive difference when I have failed on CO2 ( in a non Porsche)


Regards

Mas

 

[PSH]

My first port of call would be to give the fuel system a good clean out, Forte do the best product but you can get similar cleaning products from Halfords. If the engine is good this alone should bring your C0 down below to what's required for an MOT.

Pete

 

[Copperman05]

Mine did the same 2 years ago, Promax very slightly lowered the idle and it passed. Worth knowing I suppose if nothing else works.


Edd

 

[zcacogp]

Chaps,

Thanks for the answers. I'll take the rear drums off and see what's happening (or not happening) in there; it seems that sometimes driving the car a few yards with the handbrake on can clear debris that has built up on the surface. And I'll check the levers and cables and whatnot.

Fuel cleaner? Interesting. Thanks for the tip. I'll buy a bottle from Halfords and see how I get on.

Mas - the car was pretty hot when it went in (had a good thrash for 30 minutes before going to the MOT station), and the air filter was cleaned when it was serviced. However I agree that taking it out can help ... perhaps that's the way forward.

Oh, and an oil leak I thought I had fixed has come back with a vengeance. Oil pressure sender leaking around the crush washer seal. Arse - that's a complete pain in the bum to get to. []

Thanks for your input chaps. Off to get my hands dirty ...


Oli.

ETA: I've just found two naughty words that get through the swear filter on here - arse and bum! Great, I must use them in posts more often!

 

[tref]

When mine failed similarly it turned out to be the temperature sensor - don't rely on the "cold" temperature resistance being right... it is a pain to check it, so I almost said "that must be ok" because it was the correct resistance when cold, and it is a pita to get to twice. turns out the resitance was out (and only a little) when hot. Changed the sensor, MOT passed no problems.

Oh... changing the sensor didn't fix the handbrake - I had to do that the same way as you suggest!;-)

Regards,

Tref.

 

[Cater_Racer]

Good Luck Oli

 

[pauljmcnulty]

Unless you're sure it's the handbrake shoes then the cable is far more likely to be the problem. Shoes don't wear out unless the cable's making them bind, and if they come loose with broken springs you'll know it. Adjusting them is easy, but again they don't often need adjusting as they shouldn't wear. The handbrake shoes only hold a stationary car, so why would the friction surface wear out?

 

[zcacogp]

Chaps,

Thanks for your various replies. I've now dismantled the drums at the back and discovered that the amount of rust in there was astonishing! I'm more than a little surprised the handbrake did anything when the tester put it on ... I've cleaned the rust off the inside of the drums and the outside of the shoes, but the surface is pitted and grotty. I'm hopeful that it will suffice, but having tested it since doing the work it doesn't seem to be much better. In fairness, I didn't adjust the handbrakes once cleaned so there could yet be an improvement, but I fear it may be new rear disks/drums time. Out of curiosity, how do you know whether the fault is jammed up cables? When I pull on the handbrake it feels springy (as opposed to dead, like a jammed cable), but is this a reliable test? Is there any other way of telling?

Gerry, thanks, I'm hoping it doesn't come down to luck! []

Tref, thanks for the tip about the temperature sensor. That's worth trying. I can't imagine it is expensive. Whereabouts is it on the S2 engine? Do you happen to know if there is an adjustment screw on the AFM?

Edd, thanks for the idea about lowering the idle speed. Not quite sure how (/why) this would work, and I suspect the problem with mine is beyond this sort of fix. Thanks anyway.

Another question. While I had the rear drums off I took the calipers off as well and tended to a small amount of plate lift on them. I will need some new caliper nipples soon - anyone have any idea what size they are? I know they work on an 11mm spanner; does this mean they are 11mm nipples?

Thanks for your advice chaps.


Oli.

 

[BlackMagic]

If you are suffering high CO2 at idle look at the fuel pressure releif valve. As they fail/wear the pressure tends to go up and not down and at idle the ecu doesn't really adjust the mixture. So too higher pressure means too much petrol and then high CO2.

I second the jammed cable for the brakes. Get someone to lie underneath and see if the cable is moving freely at both drum when you lift the hand brake.

William

 

[zcacogp]

Thanks William. I take it the fuel pressure relief valve is the same as the fuel pressure regulator?

Handbrake cables - I'll check. Not sure who I can get to pull the lever tho' - the missis is at work all day! Maybe a neighbour.

Thanks again.


Oli.

 

[zcacogp]

OK, update on this; having cleaned up the inside of the rear drums and re-assembled, I have checked the cable with a friend sitting in the car. It seems to be moving fine; you can see the join in front of the rear axle moving when the handle is pulled, and both side cables seem to pull fine.

I've re-assembled it and adjusted it very carefully, and it now works better than before. Whether it's good enough to pass the test I'm not sure but we'll see. I'm going to take it back to the MOT place this afternoon and see what they say. Fingers crossed ...


Oli.

 

[zcacogp]

'Nother update ... it's passed. Cleaning up and adjusting the handbrake brought it up to spec and all is well. The garage doing the MOT carelessly (so carelessly!) put the exhaust probe in the wrong car when they did the test so that was OK, but it is clearly an issue that needs addressing. I'll update this thread as I find out more.

As a point of reference, Brembo calipers (S2/turbo) use M10x1 bleed nipples and M10 fittings on the end of the brake lines.

12 months ticket feels good!


Oli.

 

[robdimond]

I didn't want to crow about it until I heard yours had passed as well Oli, but mine passed today as well. So two more of the best 944 model are on the road for another year now!

 

[PSH]

well done guy's...

Pete

 

[zcacogp]

Rob,

Very good news about your MOT - glad to hear it! I bet it isn't giving quite as much grief as my S2 is at the moment ...

I have an MOT. That's good. I have also put some Redex injector cleaner in the fuel tank and adjusted the wiper on the AFM, and it seems to run more smoothly now than before. That's also good. However it still smells as if it is running rich, which isn't good, and I've just ordered a new Fuel Pressure Regulator which should be the last piece of the puzzle (famous last words, eh?)

It did about 200 miles over the weekend, and it was clear that the brakes were binding slightly ... until I got to the motorway, when there was a drumming noise for a while, which ended with a bit of a 'clonk'. Drumming noise ceased, all was much smoother, but it appears that there is play on a rear wheel when the handbrake is applied. So that'll be the drum needing to come off again to look at the shoes. It also seems to have developed a brake shimmy when the brakes are applied at high speed (unrelated to the handbrake issue? Just co-incidence that it happens now?) which is very annoying.

I also saw a pretty large oil leak when it was up on the MOT ramp, so I removed the oil pressure sensor (about 4 months old) and re-fitted it, hoping that would solve the problem. Judging by the three (large) oil marks under the car when parked up over the weekend I can only assume it hasn't, and that there is something else amiss as well.

Don't misunderstand me - I still love my S2. But the path of true love doesn't seem to be running smoothly at the moment. []


Oli.

 

[robdimond]

Oli,

I have a similar list of niggles. I still need to do the water pump, belts and front seals... still not had a free weekend with decent weather. I've almost got all the parts now... just need a heater rail to replace the butchered one that's in there at the moment (plumbing fitting in the middle to shut it off!). Now have quite a significant oil leak from the front which is contaminating the belt, which now has three years on it. Need to do front pads and discs as well... and sort out caliper plate lift at the same time. Then there is a poor repair to the driver side sill that I didn't notice before...

At least MOT man was happy with my new fuel lines and CV boots... gives me the confidence to keep going!

Rob

 

[Hilux]

The garage doing the MOT carelessly (so carelessly!) put the exhaust probe in the wrong car when they did the test

You are winding us up?

 

[zcacogp]

ORIGINAL: Hilux

The garage doing the MOT carelessly (so carelessly!) put the exhaust probe in the wrong car when they did the test

You are winding us up?

No, not at all.

It was >cough< very very careless. >cough< >cough< []


Oli.

P.S. The coughing has nothing to do with the emissions it was pushing out at the time, or the new Fuel Pressure Regulator I am just about to fit ...

 

[PSH]

ORIGINAL: zcacogp

ORIGINAL: Hilux

The garage doing the MOT carelessly (so carelessly!) put the exhaust probe in the wrong car when they did the test

You are winding us up?

No, not at all.

It was >cough< very very careless. >cough< >cough< []


Oli.

P.S. The coughing has nothing to do with the emissions it was pushing out at the time, or the new Fuel Pressure Regulator I am just about to fit ...

Actually I've seen this done at MOT stations.... I'm surprised this particular station didn't pass you Oli as this type of thing only really happens at MOT stations who deliberately use another car ( already checked for emissions) for the emission test, thus getting a car that would otherwise fail threw it's own test.

Pete