Having Worries About My Fuel/air Mixture

[trialster 0]

hey, just wondering if anyone knows how to set the fuel/air mixture correctly. at the moment the mixture screw is 8 and a half turns out from fully shut.

 

anyone got tips/hints regarding how far out this screw needs to be?

 

btw its a 1.9, and it feels slightly down on power! my old 1.6 seemed alot quicker.

 

thanks

 

Will

[simonb 0]

OK. Firstly, what colour are your plugs? The car feeling slow could be down to a number of things so I would first of all check the condition of these. They should be a nutty brown colour if the mixture is OK.

 

BTW that mixture screw you are referring to only adjusts the mixture at idle and will have no effect on fueling through the rest of the rev range.

[trialster 0]

OK. Firstly, what colour are your plugs? The car feeling slow could be down to a number of things so I would first of all check the condition of these. They should be a nutty brown colour if the mixture is OK.

 

BTW that mixture screw you are referring to only adjusts the mixture at idle and will have no effect on fueling through the rest of the rev range.

all new plugs im afraid! hehe.

 

suppose i need to take it to arolling road to test it, i haven't driven a 205 gti in a while so maybe i'm a bit out of touch, but for some reason my mates 205 xr (75bhp) seems almost as fast as mine (128bhp, from factory)

[simonb 0]

Well I would still recommend checking the colour first as they will still change colour pretty quickly after fitting.

[trialster 0]

Well I would still recommend checking the colour first as they will still change colour pretty quickly after fitting.

ok, cool!

 

do you know the traits of a rich and lean exposed spark plug ?

[trialster 0]

ok, i just checked the plugs..

 

they are a kindof white colour, with a hint of brown!

 

any ideas?

[simonb 0]

Brown is good. Lean mixture will result in white plugs. Any chance of a photo to have a look?

[trialster 0]

Brown is good. Lean mixture will result in white plugs. Any chance of a photo to have a look?

sorry, no photos, but its about 85%white and 15%brown.

 

i'm guessing a leak on the intake side of things will create a lean mixture?

 

i'm going to take apart the intake system, clean it all, and then put it back together with new gaskets.

[simonb 0]

That's the obvious thing to check for yes but it could be so many other things. From my experience all of the pugs I have had seem to have been running a little lean at first.

 

If you still have no joy, check that you are getting the correct fuel pressure at the rail and also test the AFM (Airflow Meter) with a multi meter. This has been covered loads of times on the forum and so a search should bring up some result on how to do this. If the AFM is in need of a referb, the ECU will be getting incorret signals from it and this will in turn effect the amount of fuel injected.

 

HTH and good luck.