924 CIS metering

[svandamme]

Hi guys,

i managed to pinpoint the problems in my green bugger to the fueldistributor/metering plate

and bolted in a replacement

the thing that puzzles me is the replacement is from a later type 924, and is missing a connector on the metering housing


green one near the plate

according to the haynes manual , it's the air sensor connector
but couldn't find much information on what exactly that gizmo does

the engine cut's out when i don't short the wires that were attached to the old one

but at the moment, the car runs well, except it won't idle at all
and is a pain to start cold

does anybody know what this plug does? would that cause the idle going wrong?

[Don 944 LA]

He He thats a good one...

I'll let Brando handle this one

He knows all about that thing.

[svandamme]

Originally posted by Don 944 LA
He He thats a good one...

I'll let Brando handle this one

He knows all about that thing.

that scary huh?

[Don 944 LA]

There is a sensor/switch under the round plate that gets actuated when the plate is all the way down. There is an adjustment with a feeler gauge, unsure of the specs.

Basically, it controls the fuel pump.

[svandamme]

so how did they do it on the later models, since that one doesn't have that switch at all,

does it hurt to short the bugger out?

on a different side , i've actually plugged it into my 5th injector , it kinda solves my hotstart problem...

now i'm waiting till the lean green machine is stone cold, so i can mess around with the engine while it's cold, see if i can figure out the cold start with the current wiring...

[Brando]

The plug on the side of the air flow sensor (yeah, called an afs, when it's not?) is what turns the fuel-pump relay in the cab, thus turning on the fuel pump to pressurize the system.

Let's do a little testing. With the plug hooked up, and the AFS hooked up and everything put together, take the air filter portion off. You should then be able to reach inside the airbox and feel the bottom side of that plate. Turn the ignition on, and lift up slightly. You should feel pressure pushing the plate down against your fingers. You should also hear a "click" noise and hear fuel running through the lines. Don't do this too long, though, as you're pouring fuel into the engine by doing this.

And please, only connect the right connectors to their plugs!!! They do different things on the engine components and if you swap them around your chances for success plummet off the bottom of the chart.

If you're having hot/cold start issues, look at diognosing these things:

Cold-Start Valve, if you've swapped those connectors around in the engine compartment, chances are you have the wrong one going to the cold-start valve. This thing drops some extra fuel in (like the AAV allows more air) but only for about 3-5 seconds so it idles properly. Follow the testing procedure to see if yours is good or bad. Also clean it.

Auxilary Air Valve (mine was bad), between the injector lines and intake manifold. You'll see from the black air intake boot near the manifold a small tube that goes to the AAV. It has the black connector on the back. The AAV is a heat-sensative valve. As the ambient air temperature reaches a certain level, a disc with a 'window' turns and closes. When it's colder, it opens to allow more air. Take it off and test it with an Ohm meter. Should have i think 3.5 Ohms. If it reads -1 or open it's bad. If it reads fine electrically, put it in a plastic bag and leave it in the freezer for 15 minutes. Take it out and look through the hole, it should be wide open. If not, this be your culprit (or one of them).

Warm-up Regulator, Another common culprit for hot/cold start problems. Read the manual on testing this, as it's a real PITA to get on and off. Pretty much it's a sensor that if the coolant temp is at or above a certain level, it disables the Cold start valve and also manages fuel pressure. If there's an air bubble in the coolant by this thing, bleed the coolant system.

That's usually about all to consider with hot/cold start issues. I hope i didnt forget anything.

[Don 944 LA]

Hey Brando ....

Whats this ????

LOL ....

[Brando]

That!!! Is the tool to adjust the flap's up and down thinga-hoozit. I forget what it's called... You reach in there wiith a small hex-head wrench, turn that, and it adjusts how far up and down the flap goes. Only adjust it while the car idles!!!

[svandamme]

Brando , you seem to know your **** allright

i don't have that plug on my replacement unit, it's from a later model 924 , at this time , i have to short it out, or nothing works.
is there something else i need to get from the donor car to make things correct ( accordig to later spec? ) a relay or a sensor somewhere else in the engine bay?

[Brando]

You got the AFS from a L-Jetronic car. Yours is K-Jetronic. There's not much you can do besides replace the whole engine wiring harness and injection system to switch over or "upgrade" to an L-Jetronic system. You'll need the AFS for your car.

[Brando]

What exactly went wrong with your original AFS? Usually issues come from the fuel distributor going bad or getting gunked up. The little needle valves inside wear or stick, thus not allowing fuel through the system or uneven amounts.

http://www.specialtauto.com/

New/rebuilt Warmup regulators and fuel distributors.

[svandamme]

the car started running badly , went from bad to worse
only ran on 3 cyllinders by the time i got home, couple of backfires and dead as a duck

when i lifted the plate by hand, it worked, but that's not practical to drive with so i got another unit from Porsche parts scrapper, 100 bucks

with the new unit and those wires from the missing connector shorted , the car runs fine , except the cold/warm thing that i needed to figure out
but i don't think that has anything todo with the connector, since i already had cold/hot issues before

i know the parts place has a yellow 77 donor standing around
so i'll trade the unit for that one, at least now i can drive there

[Brando]

If things still progress badly, fill the gas tank about 50%, then put in 2 things of Techron fuel injector cleaner. Chances are unless your lines are brand new, they're a bit gunked up too. Injectors as well. For the next month put in a can of injector cleaner once a week. That should help.

When you have the time/money take your injectors to get cleaned. You mentioned dropping a cylinder and backfiring. Mine did this too. I had them cleaned and checked the opening pressure (~2.5 bar) and guess what... That's right, one injector was worse than all the others. After a nice cleaning it idles good

[svandamme]

wildo, must say i've got my self to blame on this,
i was paying to much attention to the 911, and the 924 got jealous
gave some hints that it wanted attention , which i foolishly ignored

thanks Brando,
good info

what about that 6 cyllinder 944 in your title, did you drop a flat six in a 944 ?? got any details on that??

[Brando]

You're welcome svandamme. Glad to help a fellow 924 driver. Certainly not enough 924s in driveable shape around...

My avatar is a joke (<- click)

[svandamme]

lol , the avatar looked like you actually had done it
now must say , that would definately be a hefty modification
and i wondered how that would have been possible , with the flat six beeing kinda wide...

but i agree, it's a cool thing to imagine: what if a flat 6 went into the 9x4chassis ?!?

regarding drivable 924's , come to holland , there's a lot of em here
but not many from 77 though , most of those rusted till they turned into parts, i like mine because it's and old timer , and thus taxfree
saves me about 1500 bucks a year in taxes and insurance> i can buy me one every year and still be cheaper than most other second hand cars...
i hope to get it in better shape in the future , got some rust to fix , i'll try to get panels from later year cars, when my finances recoverd from my 911 restore... right now , it's for cheaps...
but it's a fun car, not a friggin VW polo , or a honduh civic

[SoCal Driver]

Brandon had Groked the 924!

[Brando]

Heheh... not really

[Don 944 LA]

Originally posted by FR Wilk

I think I see the problem. Someone cut your thinggy in half!

I hate when that happens !!!!

[Brando]

I guess that explains why he's losing a cylinder...