924Board.org

[Racing]

Thought i´d get a little more hardcore this time out.
Those that are in understanding-kewl-those that are not-hey..you´ll always learn something.

Started to check things more thorougly.
Turned out that the separator diaphragm NEEDS to be stock thickness as there are 4 individual "rests" for the flapper/adjuster valves to rest on,to make the valve flow the right amount of fuel needed at different settings.
Stock thickness is 0,15mm(divide by 25,4 to get fractions)
Not only that,but the diaphragm also NEEDS to be made out of nitrilic rubber that can withstand the rigors of todays fuels.
Same thing goes for the 2*6mm o-rings.
With that said...

First stop was to make a new gasket from the 0,7material i picked up at the local warehouse.
Didn´t work for crap.
Made a new one from 0,5mm material that good friend supplied-same deal.
Rendered me idle and such,but wouldn´t take the gas or boost.

Fiddled around with CO settings as well as load screw settings to no avail.

Alrighty.
Got fed up with trying to dig up the diaphragm needed(Bosch won´t sell you a new diaphragm.Whole FD ONLY.BIIIIIIIIIG surprise) and scrounged up a used head from a Ford escort that at least around here runs the KE-jetronic(In other words have the aluminium housing needed).
Took that apart,and it showed that in OEM form where the flapper valves rests there are intendentions.In other words the OEM rubber is recessed where the flappers go.Also checked that the same FD;s from an Audi 80 would work(guess they´re called 2000 in the US)

Anyways.
Sorry to say the OEM rubber "ripped" a little when i took the deal apart,and as a result... yeah well...
Tried it anyways and sure enough.
Engine behaviour changed dramatically as there at least weren´t any through holes in it.Just shavings gone from the tope side of the rubber.
This left me with cross leakage from the plunch out to the chambers-which TOO would affect injector pattern.Jesus are these thing delicate...

In fact this hole deal comes down to just that.
Injector pattern,and apart from chamber pressure it is a function of system pressure and control pressure.

The problem lies in that you friggin NEED a total seal between the chambers-not only the halves of the CIS unit.

Practical findings then.
Yanked the injectors for each time i had the FD apart and true enough.Pattern would vary.(Took it apart approx 10 times yesterday)
A lot.

When i started to get the FD to seal one could attest this easily by checking at the wideband lambda as well as the CO/HC tester.

Best numbers has been 0,8%CO 26ppm HC,and when this thing screws up the CO can be adjusted to approx the same value while the HC-understandably enough-goes out the door at something like a 1000-1500ppms.
When this happends the performance goes in the toilet.
Car will studder and smell unburnt and the exhaust temp will skyrocket-even at idle.
Speaking of which it has turned out that when things DO work i get an exhaust temp @ idle of approx 110deg C and when things go awol i´ve seen ém as high as 280sh-300.

When i got it right the AF gauge of the WB would stand rock steady-otherwise it would fluctuate approx 5/10ths.Idle and load alike

Timing is stills completely static at 25,and have in mind that i´ve overhauled the dizzy too-Shimmed for axial play aso.(In other words it´s as stable as can be expected from a dizzy controlled spark)

So.
What´sthe conclusion here?
Basically this..
Cheapest and simplest way to scrounge up the pts needed is to visit the local junkyard as far as i can see.
No matter how you look at it the CIS system was used way up in the 80,s and chances are that the diaphragm from a car that is younger as well as that it has had the FD run cooler then it does in our cars will be intact and ready to refit to your own damaged one.
No biggy to agree on that putting the CIS unit per our cars WILL make it take heat like it wouldn´t in an NA car like the escort mentioned or an Audi.
Altho i hurt the diaphragm i took out of the escort unit it looked WAAAYYYYY better then the one that was in my FD from the beginning.

Modus operandum then.

When taking the dizzy off the car you need metric spanner 12 and 17 and a single blade screwdriver that FITS the three screws that hold the FD to the housing.
Take notice of the copper seals that go on each end of each banjo fitting.

When lifting the unit from the housing IMIDIATELY put one hand in between the FD and the housing to catch the fuel metering piston.
This can not be emphasized enough!!!!


CAUTION
When working on the FD of the CIS unit make sure that;
1/You have an absolutely clean work area with good lighting.
2/That you have an absolutely clean work area with good lighting.
3/That you have an absolutely clean work area with good lighting.
4/Shut off all phones and such to be left alone without disturbance.
5/Have the "other" FD unit needed at hand.
6/Have the Tx 30 bit needed
7/None lint rags around(old t-shirt works)
8/Have mineral assembly grease around
9/HAVE LOTS OF TIME! THIS CAN NOT BE RUSHED OR EMPHASIZED ENOUGH!!!!
10/You need a small plastic mallet or similar
11/A can of engine builders spray tack(spray bomb gasket glue.Made by Loctice as well as Permatex)
12/Some source of compressed air.
13/That you have an absolutely clean work area with good lighting.
14/You MIGHT need a hole punch(the variety used to make holes in belts)to punch three through holes in the new gasket.This depends on variety of gasket used.Check differences between gaskets by laying them atop each other.Holes are for control pressure and therefore EXTREMELY important.


Put the metering piston aside on your work bench where it won´t get disturbed or fall down or something.


You basically start by cleaning the exterior off.Common oil based detergent goes a long way.Blow off with compressed air and wipe down.
Then turn to the Tx bolts keeping the two halves together.Losen all of them and and keep two of them in place a couple of twists down the windings.
Give these two a GENTLE blow with the mallet with the FD in your hand to make the two halves separate.
When it STARTS to do so,put the mallet down and work by hand.
A gentle small back and forth twisting and pulling at the same time does it.Keep over the workarea.
Keep the FD upside down to make the flappers not fall all over the place.
When apart you will have;
1/Two main pts-the halves.
2/4 white plastic flapper valves
3/4 stainless steel coil springs
4/4 aluminium spring seats.
5/4 o-ring seals for the outlet ports of the plunch.
6/The rubber diaphragm

Start by inspecting the diaphragm and the o-rings.
These are what goes awol.
ANY dents or similar to the o-rings means that they are shot-but no matter as you already have the new nitrilic ones around right
Check the diaphragm.
Hold it up towards a STRONG GOOD LIGHT to check for any porousity(sp?),cracks and holes.Diaphragm might also be distorted,especially so where the flappers rests,and this will ALSO affect performance of the unit.
The dents in the diaphragm where it rests over the flappers is supposed to be there.

Clean out everything in sight with compressed air and wipe it down with one of the LINT FREE rags.Blow it clean again.

Assembly is basically the reversal of removal with a few add ons.

Take the flapper coil springs and dip ONE end in the grease.BE ANAL THAT THE GREASE IS CLEAN OF DEBRIS!!
This end goes towards the valve-to keep the valve on the spring upon reassy.
Don´t worry about the grease as it´s solvent in gasoline.Ie;it´´ll vanish fast on startup.

Spray the DIAPHRAGM ONLY with spray tack on both sides.
Set this to the lower part of the housing where the plunch is still attached.
Let it have a minute or so to let the spray tack set a LITTLE.
Install the o-rings to the outlet ports with the mineral grease.Liberal amount on BOTH sides of the rings.
Likewise lube the top sealing o-ring of the plunch with said grease.

Now take the two halves to each other and focus on the plunch with its o-rings.
You so to say look "between" the halves upon reassy.
Reason is that the o-rings might very well twist ,and god knows what ,when you try to press the plunch back in its housing.
With the grease as a lubricant there should be NO binding of any sort upon reassy and the whole "feel" of it should be that it goes in with a LITTLE force in one fluid motion.
When convinced that you´ve got it right press the two halves together and put the Tx bolts back in one by one.
Same deal here.
They should just slip right in.
Give these a SMALL dab of grease each to to ease when torquing down.

When torquing make sure you do so in a criss cross pattern.
No Schwarzenegger kinda deals here.
If using a bit with a 1/4" ratched apply force with ratchet in one hand and housing in other.That´s all it takes.

Let housing sit half an hour or so before putting it back on housing to let the spray tack set.

Upon reassy to the housing DO NOT OVERTIGHTEN THE BANJO BOLTS.
This WILL make them break.
If you need any appreciable force to make the copper seals do their job,reheat the seals with a common torch until cherry red.
Then reinstall.

After everything´s reconnected start her up and if you don´t have a CO/HC machine at hand,most don´t,seek one out.One way or another.

Tool to adjust CO is a fairly long 3mm allen wrench.
When setting CO to approx 1% you should have a HC that doesn´t go much over 200ppms no matter how shot the engine is if she´s in a fair state of tune.
She should be running whistle clean at idle.No misses or such.
If HC climbs....back to the workbench,cause in that case you F;ed up somewhere upon reassy of the FD unit.
A newly rebuilt engine should show VERY good HC values.In fact to such a degree that she´d more or less pass a sniffer test for state of the art catalyst modern ones.

[wdb]

good work ! now that you learned how to fix the FD , if you happen to take it apart again , pics would be great to help us clearly understand all the details .there are some cheap digi cams avail. like $25 . a reliable source for the nitrile O rings would be useful , anyone where to get them retail , I know there used in hydraulic cylinders . (forklifts etc.)

heres a list of manufacturers of O rings if it helps .

http://www.thomasregisterdirectory.com/seals/oring_seals_0002882_1.html

[CMXXXI]

I bought a US and a Metric O-ring kit over a year ago from this outfit:
http://www.allorings.com/oring_kits.htm.
I see that the kits are only $10 now, I think I paid over $20 back then, but don't regret having the kits on-hand. 30 different sizes, over 350 rings all together in each kit. I don't know off the top of my head if the exact size Racing is qoting is in the kit or not. None the less, $10 is a pretty good deal to have around the house/garage. Having it has sure saved me several trips into town (to who knows how many hardware stores) looking for just the right sized ring.

When I bought, I asked about getting "onesies and twosies" of this size and that, but the response was they only sell as kits, or in lots of 100 (fewer per lot for larger sizes). Nice personable folks...
_________________
'79 Eurospec 931

[Racing]

Got a digi.
Got more FD;s laying around.
Will take pics and post tomorrow.

[johny42]

Keep on educating us, this is great stuff. I owe ya a brew.

John
_________________
Johny
80 931 (all in boxes)
82 931 - making me crazy
84 928S - leaking radiator
86 951 with cam off

[Racing]

Minor correction(shows my age i guess...)
The Tx bit needed is NOT a Tx 30 but a Tx 25.