engine and drivetrain Adventures in 73 Tii throttle/afr tuning

[gliding_serpent2]

Over the next little while I will be using this thread to document my tuning progress/experiences.  This will be a bit long winded,but lets start with some background...

 

In 2012/13 my tii was fully (mechanically) rebuilt by non (2002/Tii) experts, and then tuned by someone who knew more than the first guys (a benz guy). My car has a stock engine but with the canadian/euro spec 9.5:1 pistons. Aside from finding the timing chain master e clips in the oil, and having a passengers side engine mount bracket break (because another bracket that stops the forward movement of the mount was not installed...), the car has done well. Aside from adjusting the idle speed a touch, i have left things alone.

Gus Pfister rebuilt my pump/warmup regulator to spec, and my tuner had to make new throttle linkages. I had no point of reference, but the car ran well. The car usually started first or second try cold, and immediately when warm. Idle was around 800rpm.

Last year i had to bump up the idle speed as it was becoming low and going up and down a bit. in the last year, cold starts have become slowly and progressively worse, but the engine cranks over "ok". I think my battery is weak, and this would make sense given the progressivly worse cold start issues.  Plus, the batter was charged post winter and it started on 1st try. It does start better after it has run recently.  2-3 tries if driven in the last few days vs maybe 3-6 after prolonged rest.

Afr's are measured by an aem gauge. cold starts are very rich as expected. When the car is warm, afr's are in the 11-13 range on light throttle, with a sudden jump to 15 with maybe 60-95 percent throttle. WOT is in the 13.5 range, closer to 14 when the engine is hot and if uphill. Air filters still look pretty good. My goal is a richer wot and near full throttle, and maybe lean out the light throttle (ie try to get everything near 13, maybe a little leaner on light throtttle).

I have the factory kugelfischer manual (gave it to the tuner, learnign now that he probably did not use it). I am no expert, but I opted to start running through the factory setup starting with removing the throttle linkage on the KF pump. "Adjusting the pump throttle/linkage" section. Rough measurements had it near a cm longer than the 85mm factory spec. So I began to shorten it to find out that it it's shortest, it was still 87-88mm.

So my first thought is to get it shortened, and press on through the factory setup. Now, i am a non expert (but smart enough to know i do not know enough). A trusted mechanic (who should be doing this work... But i want to learn) has a saying that goes something like "you need to know the difference between scratching your a$$ and tearing out your a$$hole". This situation of whether or not I should leave well enough alone makes me thing of his words. 

So question number one is do i leave this longer than OEM spec linkage alone? or do i plow through until everything is oem spec (and get it shortened)... So that i will have a better point of reference for the future?  My personal goal is to get everything OEM, otherwise future tuning will be a bit haphazard.  . 

Notes to ponder.
- Ensure sufficient fuel pump pressure to kf pump (fuel filter?) re issue of near full throttle being so lean. 
- verify clean air filters (should be fine as things not going rich)
- clean fuel injectors?

- verify battery is fine re poor cold starts (it is less than 80% according to my battery tender, and that is one day after a 1.5hr run). 

- given the cars starts better after recient use, I assume my alternator is fine. 

- I assume warmup regulator is fine as Gus rebuilt it to spec recently.  . 

 

 

Thanks for any help/words of wisdom along the way. 

Edited July 5, 2015 by gliding_serpent

[gliding_serpent2]

So I hooked up a basic battery tender plus charger to my battery. After running the car for 1.5hrs yesterday (with headlights, and at times fog lights for the second half) the batter is at less than 85% charge according to the charger (it is not much more accurate than less than 85%, or full). This would confirm that my battery probably needs replacing as I suspected. My cold start issues have been progressively worse over the last two years, so this only makes sense. Plus, after winter storage it started on the first go with the battery getting a charge pre-start. Combine that with prolonged crank times to start it after the car has been without use for long periods... and the answer is evident.

After a night of charging, the battery had reached the 85+% charged. Again, a new battery is in order.

Now to the AFR's...

Edited July 5, 2015 by gliding_serpent

[gliding_serpent2]

So given that my throttle linkage is not OEM (Or at least I am not sure it is), can someone who has theirs at 85mm total length (as per the KF manual) measure it from mid linkage hole to mid linkage hole (if that makes sense).  Accuracy to a mm is fine.  

 

Thanks for any help. 

[jgerock]

The linkages are center to center, not overall length. Get it close and call it a day.

[gliding_serpent2]

Well that is easy then. Error in interpetation.

[PaulTWinterton]

Yes, do everything by the book.   It's a fun process once you've been through it all.  I use the BMWtii_pump_guide_v1.pdf as my source material.  It's on the FAQ somewhere, I'm sure.

 

- confirm linkages (center to center) are correct lengths.

- confirm pedal to pump stop adjustment is correct.

- confirm intermediate shaft, and tuna can adjustments are correct.

- confirm all air hoses are connected and in good shape.  No leaks.  That includes seals between air intake components.

- confirm fuel pump pressure at the KFish inlet with a gauge and/or vol/min into a bottle.

- confirm your WUR is adjusted correctly and disengaged at operating temperature.

- confirm all fuel filters are good.

- without sending your injectors for electrostatic cleaning, you could try injector cleaner.  Not sure how effective that is.  They are probably ok.

- oh yeah, don't forget about engine timing and DWELL.  Very important for hot starts, and overall performance.

 

Concerning your poorer starting, consider that your starter may be in need of a rebuild ($200) or replacement ($200).  Original starter should turn the engine over very quickly.  A weak starter can present as a weak battery. 

 

You have the luxury of an AFR.  I can't comment on that.

 

I tune the Air/Fuel screw by feel, starting at the factory setting and adding/subtracting air to get optimal engine performance throughout the range.  Can't say that's a good thing, but my engine runs smooth throughout the range and starts fairly well at all temperatures.  I'm only getting 24mpg (highway), but I attribute that to 98,800mi on the engine.  Dreaming of an engine rebuild.

 

Hope some of that helps.  Have fun.

[OriginalOwner]

gliding,

 

(sigh)  all that work is giving me a headache .........

 

so naturally I have an idea, and now isn't that scary:  just bring your tii out here to SoCal and park it at Le's place.  Then you and I will sit back and drink fine wine, in the shade of course, while we watch Le work his magic and make everything perfect.  He did it for me, no reason he can't make your tii as good, if not better.

 

While he tunes-up your tii, we can also slip over here for our own variety of a tii tune-up .......

 

 

Cheers,

 

Carl

Edited July 7, 2015 by OriginalOwner

[gliding_serpent2]

Thanks for the list Paul.  And OriginalOwner, interesting you mention Le.  I spoke with him a few years ago and I still remember his wise words (or a variation of them).  He said that he learned to work on his Tii because some day the older experts would retire and he would be forced to work on it himself.  

 

It is time I became the expert in tuning my own car.  Mind you, the wine idea sounds great, but how about you bring your car and Le over to the far Atlantic coast of Canada.  He can teach me how to do it.  I will provide beer.  My experience is limited, but I am keen to learn. 

 

"See one, do one, teach one." 

Edited July 7, 2015 by gliding_serpent

[achman]

I found that by replacing the original Tii starter with an E30 M3 high torque starter, my car started much much quicker, especially when hot.

The original Tii starter is not the great at starting the car, and after years of use, is even worse.

If your battery is not brand new and your connections perfect and everything tuned just right, in my experience, it has trouble starting the car, especially when warm.

The new starter is a known upgrade and works great. Just FYI

[gliding_serpent2]

I got a rebuilt e30 m3 starter two years ago. Warm starts are great. The issue was cold starts after long periods not running. I got a battery tender, but a new battery is in order. Plus, i need to drive it more. 2 young kids makes free time a challange.

[jgerock]

Yes, do everything by the book.   It's a fun process once you've been through it all.  I use the BMWtii_pump_guide_v1.pdf as my source material.  It's on the FAQ somewhere, I'm sure.

 

- confirm linkages (center to center) are correct lengths.

- confirm pedal to pump stop adjustment is correct.

- confirm intermediate shaft, and tuna can adjustments are correct.

- confirm all air hoses are connected and in good shape.  No leaks.  That includes seals between air intake components.

- confirm fuel pump pressure at the KFish inlet with a gauge and/or vol/min into a bottle.

- confirm your WUR is adjusted correctly and disengaged at operating temperature.

- confirm all fuel filters are good.

- without sending your injectors for electrostatic cleaning, you could try injector cleaner.  Not sure how effective that is.  They are probably ok.

- oh yeah, don't forget about engine timing and DWELL.  Very important for hot starts, and overall performance.

 

Concerning your poorer starting, consider that your starter may be in need of a rebuild ($200) or replacement ($200).  Original starter should turn the engine over very quickly.  A weak starter can present as a weak battery. 

 

You have the luxury of an AFR.  I can't comment on that.

 

I tune the Air/Fuel screw by feel, starting at the factory setting and adding/subtracting air to get optimal engine performance throughout the range.  Can't say that's a good thing, but my engine runs smooth throughout the range and starts fairly well at all temperatures.  I'm only getting 24mpg (highway), but I attribute that to 98,800mi on the engine.  Dreaming of an engine rebuild.

 

Hope some of that helps.  Have fun.

Good suggestions but using the factory settings is only a good starting point.  

 

Another important part are the various springs and bushings.

 

These cars are old and parts may have been mixed between the tii models.  You may have to vary from the factory settings to get your car to run well.    One thing that is NOT pointed out in any publication I have seen is to make sure the lid for the throttle body (tuna can) is installed correctly.  There is a pin on the underside of the lid which should be positioned so the vertical throttle shaft (with cam) does not lift up during full travel.

[xferboy]

The issue was cold starts after long periods not running.

 

Mine is/was doing the same.  The valve at the back (pressure maint) seemed to help a bit.  Still not as good as I think it could/should be.  The linkages on mine are quite worn, so 'resting' my foot on the accelerator seemed to help this.  Parts are on order, but you know the fun of waiting on deliveries from the US.

 

Monkeying with the timing seemed to help too.  I marked the original spot with a paint marker then played a bit.

[gliding_serpent2]

I have some linkage slop for sure.

This is all really good stuff folks. It is nice to return to such a knowledgable forum after a 911 hiatus (that crowd knows their stuff also... Mazdaspeed3 forums... Not so much).

Edited July 7, 2015 by gliding_serpent

[PaulTWinterton]

Parts are on order, but you know the fun of waiting on deliveries from the US.

 

On ordering parts...I just ordered from W&N.   They shipped on Friday and the parts arrived at my door 5pm Monday.   Germany to westcoast Canada.  Wow!  33 euros shipping.  Just have to make a decent size order to justify the shipping cost.

 

They seem to keep good inventory.   I'm confident they would have the common tii injection parts available.

 

Another tip: on the bottom of the throttle body is the pivot for the butterfly shaft.  It should have a plastic cap on it.  Usually missing.  Hardware stores carry packages of plastic caps for furniture legs.  I think 3/4" caps are the right size.  Fits perfectly and seals off the chance of air sneaking in.

[lilmo]

   One thing that is NOT pointed out in any publication I have seen is to make sure the lid for the throttle body (tuna can) is installed correctly.  There is a pin on the underside of the lid which should be positioned so the vertical throttle shaft (with cam) does not lift up during full travel.

 

I believe there is a ridge on the underside of the lid of the tuna can with 2 gaps that forces you to align it correctly.  The ridge also helps keep the little gasket from slipping toward the interior of the can.

 

N