944 MOT Emissions Failure

[Paul Fraser]

As above plus the LHS handbrake efficency. The examiner said it was just over and that maybe that it just needed a good run. That's not an option so any other suggestions to 'encourage' it through its MOT? I'll check the spark plug gaps (I think they are probably at 0.6 rather than 0.7 of mm the way I measured it last time, but I doubt that is all that is causing it).

PS It is a 1984 with about 140,000 miles on it.

 

[Fred Hindle]

Either lean out the mixture or take it for a spirited run for a few miles to blow the crap out of the system, then take it for the MOT with the engine still hot.
Cheers,

Fred

 

[Paul Fraser]

How do you lean out the mixture on electronic ignition?
PS Car had a twenty minute run on way to garage...

 

[sawood12]

You can adjust the mixture by an adjusting screw on the Air Flow Meter (AFM). This component should be a unit that connects directly to the air filter box. It's best to do it at a garage with the sensor up the exhaust so you can bring it in within the corrent tolerance band.

 

[Paul Fraser]

You just beat me too it: found it last night in the Porsche Maintainance Manual. Initially I thought it was just for 85.5 cars onward but my air flow meter has the adjustment hole. I'm thinking about going out to check the avometer readings on the AFM and the injectors, but it has just started to snow very lightly... Hope it doesn't lie.

 

[Paul Fraser]

Checked the plugs -- gap was about 0.5mm so I increased that to 0.75, that will hopefully help. Checked the AFM, all voltages correct and found the mixture adjustment bolt on the AFM for the MOT.
Spent the rest of the afternoon (till it got dark and beyond) trying to get the sodding handbrake to work properly. Put in new handbrake shoes on the failure side but couldn't get the two sides to balance. The RHS has no extension at all on the automatic adjustment spreader screw at the top of the handbrake shoe assembly and the LHS has been screwed out a couple/three turns until it is just starting to bind with the handbrake off. Right hand side is full on when handbrake applied but LHS slips. Think the only thing left to adjust is by the compensating bow where the handbrake cable splits to left and right hand sides -- anyone adjusted this part before -- is it adjustable?

 

[Paul Fraser]

Had a look this morning and the compensating bow is about as inacessible as an inaccesible thing can be. Further, I knocked a hole in the underside of the sill when letting the car down off of two jacks -- it fell off one. Doh!