Failed MOT

[liquid079]

The list this year wasn't huge but I'm still not looking forward to repairing bits of the car on the road in the wet and cold, failed today on:

Nearside front power steering components leaking
Offside front power steering pipe or hose leaking
Exhaust emissions carbon monoxide content excessive

I had a good look at the offside power steering and could not find a leak anywhere, my rocker cover gasket is weeping slightly so I was thinking maybe mot man thought the oil running down was from the power steering?? On the nearside the steering Gator below one of the pipes has a little fluid on it but I can't really see where it's coming from unless the metal pipe has a split in it

I was surprised at the emissions, as last year CO was 2% and this year it was 3.5% even though the motor seems to be running better than ever, with decent MPG. I don't really know where to start with this as I replaced the air filter a couple of months ago and have only done 6000 miles since the last MOT so any suggestions would be much appreciated.

Dan.

[liquid079]

It's an M20 if that helps

[Brianmoooore]

We can't help you from here regarding the alleged steering fluid leaks. You should have asked the tester for more details, or clean everything off and run the engine.
Any details of the other gas test results?
Wouldn't be an M20 if it didn't have a few engine oil leaks.

[liquid079]

Ah thanks Brian, I did ask the tester but he was very unhelpfull, I think he may have just seen oil on the pipes and assumed it was steering fluid. Just for info, I never have any oil spots left under the car even after being parked for a week, and the steering fluid level doesn't drop.

MOT Exhaust Emissions Test Results:

CO=4.59% Max 3.50%
HC=187 ppm Max 1200 ppm
Idle speed=Pass
Smoke level= Pass

If the CO level is measured at idle then I may know how to sort this?

Got to go to work now, I'll update later.

Thanks, Dan.

[TheRu]

Ah thanks Brian, I did ask the tester but he was very unhelpfull, I think he may have just seen oil on the pipes and assumed it was steering fluid. Just for info, I never have any oil spots left under the car even after being parked for a week, and the steering fluid level doesn't drop.

MOT Exhaust Emissions Test Results:

CO=4.59% Max 3.50%
HC=187 ppm Max 1200 ppm
Idle speed=Pass
Smoke level= Pass

If the CO level is measured at idle then I may know how to sort this?

Got to go to work now, I'll update later.

Thanks, Dan.

Was the engine cold when they tested the emissions?

[liquid079]

Hi TheRu.

I dropped the car off at 07:45 and they done the Emissions test at 14:04, although I thought they were supposed to warm the car up before they tested it?? Does make me wonder though as since I fitted the Miller MAF(over two years ago) it does sound like it's overfueling slightly on fast cold idle(1100rpm-2000rpm), but only for a minute or so. I assumed it just needed a different chip, but it the last two emission tests with flying colours at the same garage.

[Brianmoooore]

Those gas readings suggest a slightly rich idle mixture to me - something around 14:1.
As the mixture goes from the lean side of stoic. (where it should be) to rich, the CO shoots up long before HC increases significantly.
Adjustment of the bypass screw in the AFM would be the standard fix, if the ECU's coolant temp. sensor checks out OK, but you say you have a MAF fitted.

[liquid079]

I reduced the idle speed a little while ago as I found it a little high with the Miller Maf fitted(1000rpm) so I might rise the idle a little(and adjust the TPS accordingly)-the throttle butterfly gap is smaller than the factory setting at the moment.

I've been trying to get a remapped Chip from Miller for sometime now with no joy, although --alpina-- on here has been very helpfull.

[Brianmoooore]

How did you reduce the idle speed? It's controlled entirely by the ECU, to whatever value is set in the software.

[liquid079]

Well,
basically I just closed the throttle butterfly, apparently there should be a tiny gap, although mine may have been just a small gap. This is only to stop the butterfly sticking but it brought my idle down by about 150 rpm.

[Brianmoooore]

If you close the throttle butterfly, the ICV should open further to compensate. The idle speed should remain constant with all settings of the stop, until the butterfly is open enough tom raise the revs above the specified idle, after which it will rise, since the ECU can do no more to control it.
It sounds like you have a fault with your ECU or ICV, or the ECU isn't getting the message that the throttle is closed.

[liquid079]

That's strange then...

My ICV has tested fine many times in the past with the Multimeter, as has my TPS and I have a spare ECU. When warm the car both idles and runs smoothly, and I have measured my fuel consumption on several long journeys in the past 5-6 months and averaged 31-34mpg, so it surely can't be overfueling that bad.

I'm going to clean the MAF sensor, check a few things, sort the steering out, and get it back in for it's free re-test by next wednesday and see what the results are.

Cheers, Dan.

[Brianmoooore]

How do you set idle CO with your MAF conversion?

[liquid079]

I can't adjust the CO levels, but as I've raised the idle slightly I've adjusted the TPS to suit. So now when the TPS clicks, and squirts in a load more fuel the throttle butterfly is slightly further open letting slightly more air through, I guess the ICV stops letting much air through once the TPS clicks??

Anyway my idle is now 800rpm cold and 1000rpm warm.

[liquid079]

Just thought I'd update this.

After cleaning up the entire power steering rack/pipes I didn't find a single leak so the MOT tester obviously made it up .

Put it back in for its free re-test today and it passed so raising the idle sorted the problem, annoyingly they didn't say what the emissions were this time.