# Air Flow Meter / Fuel Distributor Interchange Question



## marsmann (Dec 18, 2005)

Problem: fuel lines rusted out and gave way to leaking fuel on my 89 GTI 16v (all stock configuration, cis-e system).

I found an identical (in appearance) air flow meter, regulator and fuel distributor. Fuel distributor part numbers are identical, as are all the other part numbers I can see. Flipping it on the underside, I can see it is an '86 year stamping. The only noticeable difference I can see if the air plate, and its associated movement or travel.

the one in my 89 GTI (date stamped 88) has the air plate that has the huge swing (assuming that is for the higher revving 16v). the other one has only an inch or less of movement.

Are these interchangeable? Is the relation to movement from the air plate on the 86 version with its fuel distributor and plunger the same as the wider movement found on my existing car?

Are the pressure regulators any different also? 

thanks in advance!

p.s. my Bentley does not go into this detail, and the chiltons and haynes are useless in this regard.


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## Butcher (Jan 31, 2001)

CIS has no idea what size engine you have under the hood. It just delivers the right about of fuel to the air being drawn in. As long as the air flow housing and distributor are paired together, then you should be fine 

As for the DPR, if they are the same part number, you should be fine. If they are not, then you may have some issues.


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## kwak (Apr 7, 2005)

If the airflow meter housing has the same part number then the plate should have the same range of lift. The definitive way to check the housing is by measuring the inner diameter of where the air cone steps from one diameter to another. For example, don't measure in the middle of a ramp where the angle is constant, measure where the angle does an abrupt angle change. Compare the airflow meter housings that way.

If the housings are identical then figure out why the 86 has less range of lift to the airflow metering plate. With the housings upright in normal position, check the height of the plate at rest. See the Bentley manual for specs. Then look underneath and see if the depth of the "idle mixture" screws are the same. Then see if you can see where the fuel distributor plunger makes contact with the arm and see if the height is the same. The Bentley is good at walking you through what the mechanical measurements should be.

If the new airflow meter only allows for an inch of lift then you are going to lose a lot of top end in your 1.8L 16V.


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## tolusina (Oct 19, 2004)

You'll do best if you work under the assumption that withing any series/production run, the sensor plate housing assembly and the fuel distributor are matched within each series.

The advice above regarding the diameter inside the cone is spot on, also the height of each of those steps. If they don't match, don't swap less than complete assemblies.

As Butch pointed out, CIS neither knows nor cares what displacement engine is pulling air through the system.

BUT, the fuel distributor does 'know' and 'care' about the amount the metering piston raises relative to plate lift. 
That part is locked into specifically engineered parameters that are far beyond anyone without fuel and air flow measurement capabilities to mess with.


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## marsmann (Dec 18, 2005)

Thanks guys.

Excellent info. I really appreciate it.

I took another look at everything today and while the fuel distributors and the plastic air filter housing share the same part numbers, there are some differences. Just for reference, here are the part numbers. Differences noted in bold and underline:

Replacement Part:
*Plastic Air Filter Top*
027 133 837 J 
027 183 
46 074 85 910 


Original Part:
*Plastic Air Filter Top*
027 133 837 *F*
027 183 *B*
46 074 *908*


*Replacement Fuel Distributor*
0 438 101 005 

*Original Fuel Distributor*
0 438 101 005


*Replacement Air Flow Meter Plate Value(?)*
1.9+0.5 

*Original Air Flow Meter Plate Value(?)*
1.9+*1.1*


I uploaded a brief video to show each side by side. I'm not sure what the values on the air flow meter plates refer, but if you notice they both sit at the same position, but the original on the right has the typical lift, while the other on the left barely moves. It basically just stops at a quarter inch of movement. Otherwise, they look identical and I "should" be able to swap these out but without the lift, I see no way for the car to register the right amount of air and send fuel. Thoughts?

The original one does not have the screens inside any of the banjo bolts, and the 3mm hex for the CO2 mixture has been drilled out. The replacement part is very original, as it has all of the screens in all banjo bolts and the CO2 mixture screw undrilled, which I like.

As for plate and cone dimensions, they are both 119mm wide across the tops, and approximately 78-80mm at the plate. So both are identical sizes.


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## tolusina (Oct 19, 2004)

Technical term for the assembly on the left is boogered, busticated.

I may be a stuck piston in the fuel distributor, you'll have to remove the fuel distributor to find out.
DO NOT score the piston or the entire fuel distributor is junk.

Above I mentioned how components of a series are interchangeable.
This is absolutely untrue regarding metering pistons, each was hand fitted to the distributor it was installed in.

You'll want the anti-tamper plug easily removable, way early CIS used a dipstick looking thing for easy removal with a rubber stopper to both seal the hole and keep it in place.

Anti-tamper plugs, I've worked with a few............









A minuscule collection of the total I've dealt with in the past.


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## marsmann (Dec 18, 2005)

Tolusina, looks like you are correct.

I was assuming this was the normal movement of the unit on the left. I kept fidgeting around with both of these after my last post and I did notice that the plunger, or piston, appears to have been stuck. Initially when pushing on it the arm had sufficient resistance that any additional pressure "felt" wrong, like if you were forcing it or possibly breaking it. But I kept looking for gunk or something on the arm itself that might be binding and at one point I just applied enough pressure and it broke free.

So now, the lift and swing are identical to the original one. But it feels loose now, like if I flip it upside down the plate arm just drops. The original does this too, though.

On the one hand, now I know these two really are compatible/swappable as they have the same part numbers for the most part and movement. But on the other hand, having freed the piston and having a loose arm plate -- does this leave any area of concern? Looks like I am going to pull the distributor body off either way but just looking for any gotchas with what we know at this time before I tear into it...

thanks.


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