# Cis issues



## phippscody (Oct 24, 2014)

Hey guys, I'm new to vwvortex, and I was just wondering if you knew where to buy a 1992 jetta GLI 16V CIS electronic gasket kit and or inner air box sensor plate seal kit. When I pump the sensor plate gas is running into the air box. Should this be happening?


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## nbvwfan (Aug 15, 2007)

You need the control plunger o-ring.
You might be able to find that from German Auto Parts, Parts4VW's, VW Parts place or similar vendors.
The plunger seal tends to dry out then fail under pressure.
Caution,
There are many procedural approaches to servicing your CIS-E system.
Do research, ask, questions, get a Bentley, and work systematically when solving or repairing whats faulty.
A lot of people give CIS a bad wrap, some know nothing about how it works, but a few do, and will help if you can follow some tips.
Good luck.
:thumbup:


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## phippscody (Oct 24, 2014)

So to clarify there should not be gas leaking into the air box for any reason? Could this be causing a lean/rich and running issue


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## Prairie (Aug 5, 2008)

Your diaphragm/vacuum pressure regulator may be "gone" and spilling he fuel into the air cleaner element.


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## phippscody (Oct 24, 2014)

Thank you very much for the help. I've disassembled and replaced the control plunger o-ring with a beefier tighter fitting one, which has solved the issue of gas leaking into the air box. My next question is in regards to the sensor plate position while at idle. With the box apart we can only get a stable idle with the sensor plate being held ~5mm above the bottom edge of the venturi. At this position the adjustment screw is beyond its range of upwards travel. Is this an issue with the spring supporting the sensor plate or a larger problem? Any help is much appreciated.


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## nbvwfan (Aug 15, 2007)

You need to set the "rest position" and the control plunger stop depth.
In changing your plunger o-ring, you probably set it too far down.
The magic number is 19mm from the metering portal to the pivot bearing and a corresponding 19mm from the tip to the plunger to the base of the fuel meter.
You adjust the mixture screw to have about .5mm of freeplay when the system is pressurized all while the sensor plate rests at a "nickel thickness" below the first angular cone transition.
This is the basics of dialing in most variants of CIS.

:thumbup:


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## phippscody (Oct 24, 2014)

So I just recently swapped my rusted out banjo fittings and accumulator. My CIS injection settings are set to the Bentley manual standards. No luck, the car does not want to fire up or keep an idle. It fired up when the settings were completely wrong in which the sensor plate and control arm were completely out of whack and were not properly adjusted. Do any of you VW professionals out there no what I am doing wrong? Any advice is much appreciated.


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## nbvwfan (Aug 15, 2007)

phippscody said:


> So I just recently swapped my rusted out banjo fittings and accumulator. My CIS injection settings are set to the Bentley manual standards. No luck, the car does not want to fire up or keep an idle. It fired up when the settings were completely wrong in which the sensor plate and control arm were completely out of whack and were not properly adjusted. Do any of you VW professionals out there no what I am doing wrong? Any advice is much appreciated.


You probably need to adjust the control plunger stop depth and dial in mechanical base mixture.
What I would do:
Re-Check rest position, are you at "nickel thickness".
If so, pull the meter off the pivoting backplate. 
Check that the plunger stop depth is 19mm from the base of the meter. 
If it is then I would try backing it out about 1/4 turn. You are now leaning the base mixture about 1/2 point A/F.
Put it back together and turn the mixture screw about 1/4 turn CW, this adjusts the new stop depth.
See if it still has some freeplay with the plunger pressurized, you are aiming for about 1/2mm of uptravel before feeling plunger resistance.
Start it, and see if it will fire.
Adjust the idle air screw accordingly (CW to drop idle CCW to raise it)
If this makes it worse try the reverse as I may have it backwords.

What you are looking to set is the "Zero" of "the floating body principle" to the base idle mixture.
To little freeplay and it is hard to start, too little and it dies, all while the plunger position meters the running volumetric mixture.

Another approach (from the Bosch Factory calibration manual):

Set rest position and plunger stop depth to 19mm
Remove one line at the CIS metering head
Pressurize the system a few times
Turn the mixture scre until fuel starts to weep out of the orifice (backing it off if it flows when pressurized)
Once you get initial flow, turn the mixture screw 1/2 turn CCW
Re-install the line and start the car and adjust the Idle air screw


Post a reply of your results 
_Maybe this method can be stickied if it is successful_


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