Mixture base setting

[Michael]

I'm going to look at a non runner in a few days. They have done a lot of work to it and they want to put on a FD next. I am going to poke around on it and one of the things I want to check is the mixture. Does anyone know how many turns gets you close? In other words, can I tighten it fully, back it out say 7.5 turns and be in the ballpark enough that it will start and run long enough to go into closed loop?

[dn010]

I'm not sure if there is a way to count turns to get close but I did once read somewhere that you jump the RPM relay to keep the fuel pump running, pull a few injectors and turn the screw until it just stops spraying fuel. I can't remember if it was from a Volvo manual etc. but I did use this method and it worked for me.

[dmcnc]

^pretty much what he said:

After assembly of the fuel system, run the fuel pump and depress the air flow sensor plate for a couple of seconds to bleed air out of the fuel distributor. Remove one injector line from the top of the fuel distributor, and while looking into the injector port in the top of the fuel distributor turn the mixture adjustment screw clockwise until the port just starts to fill with fuel then turn the mixture screw 1/2 turn counter clockwise. Reinstall the injector line, start the engine and adjust mixture when it reaches operating temperature. This is the Bosch recommended procedure for initial mixture setting and adjustment.
Ref: Bosch K-Jet Mixture Setting (http://www.cisflowtech.com/frequently-asked-questions/testing-k-jet/k-jet-mixture-setting/)

[Ron]

I'm not sure if there is a way to count turns to get close but I did once read somewhere that you jump the RPM relay to keep the fuel pump running, pull a few injectors and turn the screw until it just stops spraying fuel. I can't remember if it was from a Volvo manual etc. but I did use this method and it worked for me.

:thumbup: THIS!



^pretty much what he said:

After assembly of the fuel system, run the fuel pump and depress the air flow sensor plate for a couple of seconds to bleed air out of the fuel distributor. Remove one injector line from the top of the fuel distributor, and while looking into the injector port in the top of the fuel distributor turn the mixture adjustment screw clockwise until the port just starts to fill with fuel then turn the mixture screw 1/2 turn counter clockwise. Reinstall the injector line, start the engine and adjust mixture when it reaches operating temperature. This is the Bosch recommended procedure for initial mixture setting and adjustment.
Ref: Bosch K-Jet Mixture Setting (http://www.cisflowtech.com/frequently-asked-questions/testing-k-jet/k-jet-mixture-setting/)

This doesn't seem right to me??

Removing an injector line at the FD can spew quite a bit of fluid from just rest pressure.
With the key on or the RPM Relay jumped, things could get exciting.
Or am I missing something??

$.02
Watch the for the injector(s) to fire. Then barely nudge it CCW (1/2 turn is too much).

[dmcnc]

It's exactly what I did when I installed a new FD, with no issues. This is the procedure for resetting a new FD so there is no rest pressure, at least not until after the procedure.


:thumbup: THIS!




This doesn't seem right to me??

Removing an injector line at the FD can spew quite a bit of fluid from just rest pressure.
With the key on or the RPM Relay jumped, things could get exciting.
Or am I missing something??

$.02
Watch the for the injector(s) to fire. Then barely nudge it CCW (1/2 turn is too much).

[dn010]

run the fuel pump and depress the air flow sensor plate for a couple of seconds to bleed air out of the fuel distributor.[/URL]



This is the procedure for resetting a new FD so there is no rest pressure


If I am not mistaken, running the pump and pressing the plate will get you pressure in the fuel distributor.

In my quick search of any K-jet related vehicle manual I have, it doesn't say anything other than "...it's set from the factory" and then gives adjustment procedures. Another quick search here brought this up:

http://dmctalk.org/showthread.php?16116
Keep your new copper washers at home and go with Dave Swingle's advice. This is exactly what I did probably 5+ years ago even before this post so this information must be floating around somewhere in the D community.

[Ron]

It's exactly what I did when I installed a new FD, with no issues. This is the procedure for resetting a new FD so there is no rest pressure, at least not until after the procedure.
Now I'm confused-
Where is the pressure filling the port coming from during this procedure??

I only mentioned the rest pressure because we've seen how much that will leak when a banjo breaks, etc....To compare with the pressure that procedure uses to "...fill with fuel then turn the mixture screw 1/2 turn counter clockwise".
It doesn't say whether to use the key or relay, but since it is not gravity feed at all, you'd about have to use one or the other to get it to fill. There could be ~4 Bar of pressure there. No?


If I am not mistaken, running the pump and pressing the plate will get you pressure in the fuel distributor.That will get you fuel out of the injectors. No need to press the plate -- The FD would fill (and pressure the plate up) anyway.


In my quick search of any K-jet related vehicle manual I have, it doesn't say anything other than "...it's set from the factory" and then gives adjustment procedures. Another quick search here brought this up:
http://dmctalk.org/showthread.php?16116

Keep your new copper washers at home and go with Dave Swingle's advice. This is exactly what I did probably 5+ years ago even before this post so this information must be floating around somewhere in the D community.

+1

======

Maybe this will help:
When you activate the pump, the FD gets line and control pressure (both ~4.9 bar, depending on temp). If you do nothing else, the plate will be firm and the plunger, etc. will have the injector port pressure just below where the injectors open (~4 Bar). This is where setting the screw comes in. You simply turn the screw CCW to make sure the injector doesn't spray, turn it CW until it barely starts to spray, then nudge it CCW until it stops -- Ya want the port pressure just below the point at which the injector(s) open.
Just enough to fill the port is way too low for a base setting. (Not to mention spewing @ ~5 Bar. Or more, if you do press the plate.)

Injector port:
Rest = ~3 Bar
Pump On = ~4 Bar
Fully Pressed Plate = 120 liters/hr (min).

:dunno: :burnout:

[Bitsyncmaster]

I would recommend you put all six injectors into jars. I guess it would then be a good idea to press the plate to purge the lines of air. Then you just turn the mixture screw until the injectors just stop leaking fuel. Of course all this is done with the RPM relay jumped.

If you leave any injectors in the engine your going to pool a lot of fuel somewhere.

[Michael]

If you leave any injectors in the engine your going to pool a lot of fuel somewhere.

Only if you continuallly press the metering plate.

Thanks all for the help. Sounds like I could get close with the advice here. I will probably just jump the relay and pull one injector line off the head to set it.

[dn010]

Only if you continuallly press the metering plate.



It depends on how far off the adjustment is. If it is off lean it won't do anything, if it is off set too rich it will drip/spray even without the plate pressed.


This is the Bosch recommended procedure for initial mixture setting and adjustment.
Ref: Bosch K-Jet Mixture Setting (http://www.cisflowtech.com/frequently-asked-questions/testing-k-jet/k-jet-mixture-setting/)

Are you able to reference this from Bosch for us so we know for sure?

I've never seen any 'official' recommended procedure for setting base. You're quoting a repair website and then telling everyone - this is it - the procedure - Bosch recommended. I think we'd all feel better if we saw something from Bosch themselves stating it because it seems unnecessarily messy and dangerous as opposed to simply removing an injector and controlling where your flammable liquid goes.

[dmcman73]

It depends on how far off the adjustment is. If it is off lean it won't do anything, if it is off set too rich it will drip/spray even without the plate pressed.



Are you able to reference this from Bosch for us so we know for sure?

I've never seen any 'official' recommended procedure for setting base. You're quoting a repair website and then telling everyone - this is it - the procedure - Bosch recommended. I think we'd all feel better if we saw something from Bosch themselves stating it because it seems unnecessarily messy and dangerous as opposed to simply removing an injector and controlling where your flammable liquid goes.

Even though this is for Porsche kJet, Page 32: http://www.type17.ch/downloads/Injection/Bosch%20-%20K-Jet%20-%20Workshop%20Manual.pdf

Can't get anymore official then a Robert Bosch manual.

[dmcman73]

And, you don't need all the fuel lines off the distributor, only one. Place shop rags around it for spilled fuel. This just base lines the fuel distributor. If you're reusing old injectors, it'll be hard to baseline since they may be a little worn.

[Michael]

The way I interpreted it was only one line needed to be removed and that didn't seem too bad but I guess it's just as easy to remove an injector.

I assume that the engine needs to be cranking in order for an injector to fire rather than just jumping the rpm relay and removing a line from the distributor.

[dmcman73]

The way I interpreted it was only one line needed to be removed and that didn't seem too bad but I guess it's just as easy to remove an injector.

I assume that the engine needs to be cranking in order for an injector to fire rather than just jumping the rpm relay and removing a line from the distributor.

You don't need the engine to crank to get the injectors to spray, just jump the fuel pump. No injector should spray or leak at rest with the fuel pump jumped, they should spray once you start pressing the metering flap down which pushes the plunger inside the distributor up to allow fuel to pass.

[Michael]

You don't need the engine to crank to get the injectors to spray, just jump the fuel pump. No injector should spray or leak at rest with the fuel pump jumped, they should spray once you start pressing the metering flap down which pushes the plunger inside the distributor up to allow fuel to pass.

Got it, thanks. I would be a little worried about filling up the other cylinders with fuel though. IDK, I think the best method mentioned is to crack a line at the FD. I can handle a little gas running off, it's not like we got any hot exhaust to worry about.

[dmcman73]

Got it, thanks. I would be a little worried about filling up the other cylinders with fuel though. IDK, I think the best method mentioned is to crack a line at the FD. I can handle a little gas running off, it's not like we got any hot exhaust to worry about.

If you're only removing one line from the distributor to do the "official" adjustment, I would still remove the injectors for the rest of the cylinders and put them in glass jars, or better yet, baby bottles. There is still a chance that the injectors will leak into the cylinders while your making the adjustments. That's just me.

[dn010]

Awesome, thank you for this!


Even though this is for Porsche kJet, Page 32: http://www.type17.ch/downloads/Injection/Bosch%20-%20K-Jet%20-%20Workshop%20Manual.pdf

Can't get anymore official then a Robert Bosch manual.

[Ron]

Trying not to step on any toes here...

The OP wants to work on a non runner that has a lot of work to it. It is more possible that the adjusting screw has been previously turned way too far rich or that any FD is defective. In either case, following this procedure is prone to spraying fuel into the engine compartment, or worse, your eye.
Anyway, his stated goal is to get it close. That procedure will work. But pulling one injector, making it weep and then barely backing it off is the way to get it the closest. It's faster and a lot safer.

[Michael]

Thanks Ron. The guy never got back to me which is suits me just fine.

I'm not exactly waiting by my princess phone twirling my hair hoping the quarterback calls to take me to the prom. I'll just go to the docks and wait for the fleet to come in.

[Ron]

Thanks Ron. The guy never got back to me which is suits me just fine.

I'm not exactly waiting by my princess phone twirling my hair hoping the quarterback calls to take me to the prom. I'll just go to the docks and wait for the fleet to come in.YW!

An aside-
Speaking of phones, the firefighter instructor in me was having nightmares over this, so I PMed you my phone#...But you didn't call?? Thenn, my password quit working on Today. Once I found the recovery page (it is not on all pages asking for a password, as posted BTW;-), I could not figure out the random question (which is always the same BTW ;-). What "has whiskers, a tail, and shits in a box for..."?
I tried:
cat
a cat
Cat
A cat.
meow
Meow
pussy

I was beginning to wonder if you still love me...

[Michael]

YW!

An aside-
Speaking of phones, the firefighter instructor in me was having nightmares over this, so I PMed you my phone#...But you didn't call?? Thenn, my password quit working on Today. Once I found the recovery page (it is not on all pages asking for a password, as posted BTW;-), I could not figure out the random question (which is always the same BTW ;-). What "has whiskers, a tail, and shits in a box for..."?
I tried:
cat
a cat
Cat
A cat.
meow
Meow
pussy

I was beginning to wonder if you still love me...
I thought you were wanting to personally scream at me for a rules violation.
Send me your user name via PM and I will hook you up.

[Ron]

I thought you were wanting to personally scream at me for a rules violation.
Send me your user name via PM and I will hook you up.:hysterical:
Now what would make you think that? You do know how to prevent it?? :deviltail:

=======

No (I PMed you before all that). I wouldn't do that anyway -- Rich would kick my ass.

PM sent. THX.

[David T]

I don't like using glass bottles, too easy to break. Plastic bottles. You should pull all of the injectors, the one you pull may be clogged or leak at a very low pressure so your adjustment is going to be way off. If you are working on a non-runner the injectors all probably need to be cleaned anyway. If it is way too rich make sure the plunger is not stuck before you start turning the mixture screw. Typically that mixture screw only needs to be turned LESS THAN A 1/4 TURN, usually less than that, that is how sensitive that adjustment is. Never try to "adjust " a problem away. All problems, vacuum leaks, dirty injectors, worn spark plugs, valve adjustments, etc must be done BEFORE you turn that mixture screw.

[dmcman73]

Trying not to step on any toes here...

The OP wants to work on a non runner that has a lot of work to it. It is more possible that the adjusting screw has been previously turned way too far rich or that any FD is defective. In either case, following this procedure is prone to spraying fuel into the engine compartment, or worse, your eye.
Anyway, his stated goal is to get it close. That procedure will work. But pulling one injector, making it weep and then barely backing it off is the way to get it the closest. It's faster and a lot safer.



With any unknown, you're expected to first turn the mixture screw counterclockwise a few turns first so that it wouldn't spray all over the place. Then jump the fuel pump and then adjust the mixture screw clockwise slowly just until is begins to leak, then go counterclockwise 1/2 turn from there. No one in their right mind should ever pull a line off the distributor on an unknown car and trust in blind faith that it wasn't set to rich.

[Ron]

I don't like using glass bottles, too easy to break. Plastic bottles. You should pull all of the injectors, the one you pull may be clogged or leak at a very low pressure so your adjustment is going to be way off. If you are working on a non-runner the injectors all probably need to be cleaned anyway. If it is way too rich make sure the plunger is not stuck before you start turning the mixture screw. Typically that mixture screw only needs to be turned LESS THAN A 1/4 TURN, usually less than that, that is how sensitive that adjustment is. Never try to "adjust " a problem away. All problems, vacuum leaks, dirty injectors, worn spark plugs, valve adjustments, etc must be done BEFORE you turn that mixture screw.
+1

...that is why I just turn the screw 1/2 turn CCW to begin with.

"Sensitive", yes! -- When setting the CO, sometimes it takes me several tries to get it right where I want it.

[dmcman73]

I don't like using glass bottles, too easy to break. Plastic bottles. You should pull all of the injectors, the one you pull may be clogged or leak at a very low pressure so your adjustment is going to be way off. If you are working on a non-runner the injectors all probably need to be cleaned anyway. If it is way too rich make sure the plunger is not stuck before you start turning the mixture screw. Typically that mixture screw only needs to be turned LESS THAN A 1/4 TURN, usually less than that, that is how sensitive that adjustment is. Never try to "adjust " a problem away. All problems, vacuum leaks, dirty injectors, worn spark plugs, valve adjustments, etc must be done BEFORE you turn that mixture screw.

Plastic baby bottles are the best. They don't easily break, they are long and narrow making them easy to fit in areas around the engine and most have graduated marks on it for easier measuring the amount of fuel being sprayed.

[Ron]

With any unknown, you're expected to first turn the mixture screw counterclockwise a few turns first so that it wouldn't spray all over the place. Then jump the fuel pump and then adjust the mixture screw clockwise slowly just until is begins to leak, then go counterclockwise 1/2 turn from there. No one in their right mind should ever pull a line off the distributor on an unknown car and trust in blind faith that it wasn't set to rich.

YES! -- I totally agree!

But, FWIW: That should be noted in the preparation section at least, which it is not.
And I personally don't like the thought of someone accidentally pressing down on the wrench while peering into the port. (Granted, it does "mention" it.)


Safety first!
Stepping off of soapbox... :smile: