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KF question for the tii pro's


jdamm

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hi guys,

ive been searching the forum and there is alot of info on the KF pump but i haven't found anything to answer my questions,

so a bit of back story: early 73 2002tii with a 72' pump. engine was rebuilt about 10k miles ago and had oil pressure issues(prob sorted) by previous owner, now i have recently started a light resto(as they all start out), pulled the head off to start checking out the motor,to cut a long story short my clys are glazed and you can still see the hone marks,it did run very rich.

so i downloaded a manual form BMW NA about how to set throttle,warm up regulator,throttle timing etc and read it a few times, started looking at the warm up regulator(auto choke thing on the back of the pump), mine is not extending 10mm as it should and i haven't been able to find a replacement.

 

so my first question is- can i remove the warm up regulator and lock the position of the mixture arm on the pump or retrofit a standard choke pull to the cabin?

 

secondly- someone has adjusted the mixture screw and i want it back to factory so can i re position this with an exaust analyzer/o2 sensor and air fuel mix gauge? based on fixing the position of the mixture arm 1st?

 

nobody here in new zealand seems to be capable/knows how to servicing a KF pump but there a few who used to but the gear they used and supply/demand has diminished and the gear has been sold off....

i would like to avoid rebuilding it as i would have to send it to the US or germany but im running out of options and probably cash if it has to be rebuilt ahahhaa

 

any help would be great!

 

 

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To start, you need to purchase and install a wideband 02 sensor.  This will help you properly tune your tii.

 

How often is the coolant changed in your car?  If old or unknown fluid, I'd pull the hose from the top manifold (the piece that bolts to the cylinder head) leading down to the warm up regulator to see if any build up is restricting or blocking the flow of coolant.  Sometimes that hose is completely blocked.

 

I would not remove the warm up regulator and install a manual choke cable.  The KF system is very good when everything is working properly.

 

There are two mixture screws on the tii:  one under the lid of the throttle body housing for adjusting the IDLE mixture and a 2nd one on the KF pump that is used to adjust the mixture across the entire engine RPM range.  The 2nd one should not be randomly turned without knowing a baseline or you could cause damage to the engine (especially if you lean out the mixture too much). 

 

The tii is sensitive to ignition timing, valve clearances and spark plugs.  Make sure all of these things are addressed before making random adjustments to the fuel injection system.

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As I understand it, the important thing about the warm-up regulator is that when warm, the rod extends out far enough that the lever it is attached to is no longer impacting the mixture.  In other words, the 10 mm is not crucial in and of itself, it's whether the rod is out far enough to insure the lever is it attached to isn't impacting mixture.   That's why that "top hat" piece is adjustable.  Maybe you can adjust your way there, maybe you can't.  

 

However, if the rod with the top hat is not coming out of the regulator far at all, then you're right, the regulator is bad.  They do go bad.  There are places that rebuild them:  http://www.2002tii.org/kb/933

 

If you are starting to troubleshoot, I would do these things:

>Make sure all 4 of the filters/screens in the fuel system are clean

>Make sure the throttle linkages aren't worn out - that the ends don't have tons of play in them.  That can screw you up.

>Make sure the linkages are the correct length

>Sync the pump to the throttlebody

>Make sure your valves are adjusted correctly

>Timing set correctly

>Good plugs with the correct gaps

 

And what Jim said.  :)

 

Scott

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In theory, I think what you're saying is possible, however, the old saying "in theory, theory and practice are the same thing, but in practice, they're not" looms large.

 

I believe you are correct that the warm-up regulator and the so-called "verboten screw" are not only intimately related, they're two different mechanisms for doing the same thing. That is, the warm-up regulator simply lifts the enrichment arm which causes the KFish pump to squirt more gas, and, as the coolant warms up, the arm drops down until it comes to a stop at a place dictated by the verboten screw. Well, it's more complicated than that; the warm-up regulator is also metering in extra air through slots in the piston in the WUR to accompany the extra fuel. Because of that, I don't know how well the choke cable idea would work, as that would only move the enrichment lever to squirt extra fuel without also moving the piston in the regulator to supply extra air.

 

If you look here on the FAQ, you'll find four or five places in the United States who rebuild the KFish pumps. You might try contacting all five and asking about the cost to rebuild ONLY the warm-up regulator. It might not be prohibitively expensive.

 

Regarding the "verboten screw," there are two schools of thought. One is that, as its name implies, it should never be mucked with, and once it is, you're lost (LOST!!!). My understanding is that, when you screw it in, it causes the pump to inject a fixed number of CCs of extra fuel per X number of strokes of the pistons inside the pump. The way it was explained to me is that, once the car is warmed up and at idle, that extra fixed number of CCs of extra fuel is a much higher percentage of the small amount of fuel at idle than it is when you're driving, and certainly than it is at wide open throttle, so it's easy for the car to run monstrously rich at idle when the screw has been screwed in.

 

But the other school of thought is that, 42 years and lead-deprived Ethanol-enriched gas later, many of us with air fuel gauges report the cars running unnervingly lean unless the screw is twisted in to enrichen the mixture (effectively making the car act like it's in warmup longer).

 

John Jones ("kaptanoglu") had a post about six months ago that did a better job than most describing the seat-of-the-pants procedure many of us with air-fuel meters use to tune tiis, which is basically to:

 

1) Use the verboten screw and the air-fuel gauge to get the mixture sufficiently rich at wide open throttle (or at least not so lean that you cringe);

 

2) Loosen the pinch point on the throttle shaft leading up to the "tuna can" and rotate the half-moon cam one way or another to get the mixture in the ball park at driving conditions other than WOT (trial and error; air fuel gauge is a godsend for this as well), then

 

3) Futz with the height of the hat on the warmup regulator to get it to start and warm up acceptably. 

 

Everything Jim and Scott said about linkage adjustment, ignition timing, and valve adjustment is true. These are all necessary prerequisites to getting a tii to run well.

 

Good luck!

 

--Rob Siegel

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the KF pump is like having another engine under the hood.  it is great fun figuring out how to tune it to your car.  No plugs or points but you have linkages and adjustments that all play a role.  It is very basic once you understand what impacts what.  As stated above an O2 sensor is very helpful as you navigate your way.  There is plenty to read on the FAQ and elsewhere, I read it all twice and still find out new tidbits that I missed.  Once understood "eureka" - even then there is always room for improvement unless you reach the pinnacle of being a tii guru.  it is an elusive goal but at 63, i figure I can give it another 20 years before i give up

 

have fun - that is what it is all about

 

Jeff

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thanks guys for the great info, ive been schooling up on everything tii lately (well kfish,linkages, throttle timing and ignition timing mainly)

and its a VERY big topic and has sooo many across topic links as you'd expect from german engineering, this resto has just become quite complex(in the engine bay atleast). i was hoping i could try something like i suggested to simplify the tuning set up some what and to try and avoid the well known check list tii's need to function well, because i have a few tampered items in my engine bay(luminetion elec. ignition but no vac advance on the dizy, metric mechanics 292 cam and the KF pump.

once again thanks for the help!

once its all put back together and i can reset everything i will ask  for help if i get stuck.

 

PS:

CgeraldT- by "cores" do you mean entire WUR or just the internal actuator? 

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Your 73tii should not have a vacuum advance mechanism on the distributor-please post the Bosch number stamped into the housing. If the unit has been replaced, it may not have the correct advance curve for the tii engine. There are several other posts about tuning a tii with a 292 degree camshaft. It will be interesting to hear more about your engine specifications.

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I noticed that the Technical Articles have been inaccessible for weeks...not sure what the glitch is there but I can't get that area of the FAQ to load. I mention this because I scanned and posted a good tii tuning article a few months back that you may find helpful. Let me know if you don't have it and are interested...I'd be happy to email it to you.

COOP

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jgerock- ok i wasnt sure about it as some of my shop manuals refer to it having vac advance or tuning for vac advance and the thing having the LUMINETION sys added to the big question mark, i wasnt sure which was the culprate... but the stamping is (0231129037 jfr4) i hadnt got that far on the dizy subject yet because im waiting for the motor to be finished to start setting it up properly to the check list and once its done i can confirm the parts for you as i dont have alot of info/sizes/figures of what was/is in it. it has a e21 head,m3 oil pump,LS pistons,modded sump with baffles and MM 292 cam, thats all i can tell you at present.

 

CGerardT- ok thank you regarding the WUR, i cant afford to replace that at that price right now so ill have to put it on my list....try use what i have...

 

COOP- yea i downloaded your article and ive read it along side the shop manuals i have, trying to work out the kinks, my linkages were all the wrong lengths too! it will be a great help when i put it back together thats for sure!  

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