'84 VW K-Jet

[ray greenwood]

Searoy....That is a thought, but not what these are for. The spring load on an injector...when operating properly is designed to break free of the seat at a specific pressure. These are to balance the pressure on each injector line to its opening point. This takes up for variations in spring pressure from one injector to another. The drawback of having some injectors wildly different than others, is that by tuning to their spring tension...you could actually run one cylinder leaner...wether you want to or not. These are for very small adjustments...but they make a world of difference. Lots and lots of cars had these adjusters. Whats even better...but very hard to find, were early model european injectors for CIS, that had a knurled barrel adjustment on the injector to be able to adjust the seat pressure on the injector. I have no idea what they were actually used on, or if they are even available. It has been since high school since I held one in my hand. I would bet, that an interprising machinist with a handful of old injectors could figure out a way to do this either with an internal shim, or a knurled o-ringed expanding barrel....now thats the way to get real tuning on CIS! Ray

[dbltrbl]

Here seems to be alot of knowledge about CIS systems, ill ask some questions under this topic too. Not vw related but i hope someone answers...

I have installed CIS injection from Mercedes Benz 280 to my Vauxhall 3,4 litre straight six, engine has haltech direct fire ignition system and turbocharger with intercooler ofcourse.

Fuel system is basic CIS (with before mentioned individual trim possibility) so only electrical parts are fuelpump and coldstart injector.

Now im running with about 15 psi and engine seems to be working just fine, i havent had chance to drive with lambda meter connected (more than 10 inch snow on ground) but i will soon.

So now to my question:

What ways there are to enrichen the fuel mixture if i notice that engine is running too lean?

Are there any fuelpressure regulators i could use, more pressure when boost goes up.

Can counterpressure regulator be modified to add fuel? i have regulators from mercedes, volvo and renault.

Mercedes model uses only manifold pressure
Volvo model uses only temperature, and Renauld model uses both to adjust controlpressure.

What happens if airmeter valve hits "bottom"?
engine gets all the air that turbo can feed and no more fuel?, i have notice that if i adjust controlpressure down (and adjust mixture screv to leaner) the airmeter valve moves much easier and viceversa. So if controlpressure is high it causes resistriction before turbo, not a good thing, but it prevents airmeter valve "bottoming"

Im not sure if it will bottom out or not, but valve is ment to engine that has about 180 hp and now it should feed twice that.

has anyone had "bottoming" problem?

So many questions


Kristian

[ray greenwood]

Hello, you need to have some sort of control pressure regulator. Most have an electrical hook-up with a bi-metallic strip. They can be adjusted internally...but its tricky. This is what helps to keep the metering plate from bottoming out by keeping a minimum system pressure on thetop side of the plunger. Also, it reduces pressure on the plunger during cold start to allow more free movement...hence more enrichment when cold. Also, there should be a clip, or tab that keeps the plate from dropping below the "horizon" so to speak. Other enrichment methods also include th use of simple pressure switches that utilize a grouning wire to the cold start valve as a fifth injector. You would also have to regulate that pressure. Another simple, but not easily controllable method is to use an extra fuel pressure regulator, rising rate type, on the fuel pressure inlet main for the fuel distributor. This bleeds pressure at high vacume (idle) to keep you fuel pressure on the distributor at a normal rate. When vacume dumps, it drives up fuel pressure across the board which corresponds to higher flow at the injector. Also thevery best addition is the lambda unit with frequency valve, that bleeds main line fuel pressure up and down according to exhaust co content. Of course thereis the overall fuel mixture with the hex screw on the plate lever fulcrum. Ray

[Bare]

Interesting discussion..
From my personal experiences with the Bosch CIS system (purely amateur;-) on my Rabbit and Saab, I can safely say that the parts are interchangeable..sure looks acts and feels like the identical/same system? the Saab enrichment system for Boost condition is simply a microswitch on the throttle arm that powers up the "cold start" injector (blue one) at WOT. No extra regulation involved that I've ever noticed.
Am unsure of the benefits of the dopey Lambda system as the primary purpose of the thing is to ensure a fuel rich mixture for the Catalytic... something it does.. barely. I believe all CIS fuel distributors have the hole for the 3mm Hex key adjustment, just that some have the hole temporarily filled with an easily removed aluminum plug. I used to believe, along with others apparently, that the pre Lambda air metering housing (flap valve assembly) being of significantly larger opening size/diameter was preferable for performance usage.. made NO difference whatsoever when I finally went to the bother of switching one.
Just some thoughts that someone may find useful.

[dbltrbl]

ray:
now i use counterpressure regulator from volvo, it has only bimetalstrip adjusting, it has electrical connections too, but i dont use them now, so it doesnt adjust counterpressure when engine gets hotter.

the model renault uses has also manifold pressure sensing, but its ment for nonturbo applications so im unsure if it works with turbo, i quess it could be modified.

so there are regulators that add fuelpressure when chargepressure rises?
any websites where i could see one?

could pressure bleeding (normal driving) bleed pressure to about 3 or 4 bar? i dont like the idea of rising pressure higher that i use now (about 5,2 bar) because if fuel press has to be rised to about 6 bar for example, it lowers fuelpumps flow (and i soon notice that i need another pump allso...).

so can i lower normal pressure for example to 3,5 bar and richen mixture from hex adjuster?



Kristian

coldstard injector is useable, but one such injector doesnt give so much fuel, some say it only gives fuel to about 40 hp, it depends of the used pressure ofcourse, and other thing that should be considered is which cylinders get the extra fuel and which doesnt, some get richer mixture than others.

[Bobtail]

The cold start injector works two ways it injects more fuel when open and it lowers the counterpressure so the paddle lifts up further changing the air to fuel ratio.

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www.centralvwaudi.com

[ray greenwood]

Bobtail is correct, that is...if your coldstart is plumbed to the control pressure side. It is a good way to go, but hard to meter. Rising rate regulators, like you find on L-jet can also be used on the main pressure side to bump pressure up. When I say increase pressure...its not much...cause not much is required. 2-3 psig is a large amount of enrichment. The control pressue regulators can be tweaked, by taking them apart and bending or shimming the bi-metallic strip closer or farther from its cold set point...which is low pressure. It drives a diaphram which closes a restricting orifice. You will need to tweek and play with a guage on it to see where it works best...but its easy to do. Ray

[dbltrbl]

here is my injection system, please dont laugh, its first i have ever done...
http://home.talkcity.com/ThePits/turbob ... uisku.html

Kristian

[ray greenwood]

Bare, the SAAB does have an interesting system. There are actually three seperate enrichment circuits used over the years in SAAB. The micro switch/cold start is actually the simplest. Mine does not have that one. Mine has a differntial impulse pressure switch over near the fuel distributor which triggers an impulse to the lambda unit which cycles the frequency valve injector at a different rate to bleed injection mainline pressure up and down. Some years had both systems. There are a lot iof parts that fit rabbit and Audi's in this car. Ray

[type3]

Kristian, silly question, but what engine is that?

cheers,
type3

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http://www.t3uk.org.uk
http://www.vwtype3.org.

[ray greenwood]

No laughing at all! Its clean...and it should work as well as anything with K-jet when you get it tuned out. Nice! Ray

[dbltrbl]

type3: its Vauxhall 3,3 litre (made in UK), its basically copied from 50's chevy truck engine (weights 250 kgs!).

Not VW related at all, but i posted link here anyway, sorry about that.

Kristian