Does anybody know anything about....

[Judderi]

Well ive had problems lately with my motor not running right so i took it to a propper bo garage. They just rang me and said it was 2 things.

1. The air mass meter needed re-setting

2. The timing needed doing.

I had already guessed the timing was out but i wasnt aware that the mk2 16v K-jet had an air mass meter?  Does it? Is this part of the metering head or something?

[davidhawkins_78]

That's the  'flap' in the top of the metering head isn't it ?!?

[Judderi]

Do you mean the round disk that moves up and down when the air whooshes past it? Surely they cant mean that. Ive always wondered how exactly the metering head works. I know the higher the flap lifts the more fuel it supplies but how?

[mk3miniturbo]

As far as I know the air mass meter is like a gate.  The wider open it is, the more air can flow through it.  And it increases the electrical current going through it.  The ECU will read the current and adjust the injectors accordingly.  All cars with a fuel rail, like the golf have one. You can alter the spring in them to fool your car into over fueling.  Or buy a cheap cr*p resistor off e-bay for about a quid which does the same.

[tobz.]

On a k-jet it's much more basic than that, the flap is raised by the engine sucking the air in when you open the throttle. The air mass meter (flap) progressively opens a valve as it rises allowing more fuel to flow to the injectors. The system is a constant injection system (CIS) meaning that fuel is allways flowing from the injectors. The amount is controlled by the system pressure which is determined by the position of the air flap.
Hope that clarifies things a bit. I understand the air mass meter is a right pain to set up correctly.

[tobz.]

Check out these two sites for a really in depth description of how it all works:

http://www.auto-solve.com/mech_inj.htm

http://www.users.bigpond.com/INTERJECT/KSITEPLN.HTM

I found them really handy when trying to diagnose a fault on my last valver.

[Judderi]

I understand the air mass meter is a right pain to set up correctly.

Thats why i picked a BOSH credited tuning garage to do the work. If they cant set it up propperly then theres not much hope in the world!

[Diluxe]

any ideas how much getting the air meter setup correctly will cost?

as my car seems to need a bit of a prod on the accelrator to get it fired up.

[Gambit]

i can only assume he means setting the CO% as the little adjuster screw that sets the CO% sets the air meter flap when its at idle - hence how you adjust the CO%

so tell him to set the timing and check the CO% & adjust if nessecary

the only other reason u'd need to set the air flap is if it was sitting off centre, and you can see that just by taking the top off