‘74 tii fuel delivery issues: last mile? Or rabbit hole?

[0257]

35 minutes ago, ray_ said:

 

And I wonder if ethanol-laced gas is contributing at that point...

 

 

Assuming the lean condition is not occurring under significant load, I think I'd grit my teeth... and never subject the motor to the condition that allows for lean readings

 

 

Well, you might swap injectors 1 and 2. Still seems like a vacuum leak, though. 

 

Go, drive!

 

Cheers,

Appreciate those thoughts. I’m running 90 octane rec (ethanol-free) gas, so I’ll be interested to see how a tank of regular works.  And after today’s cruise and that last post I went out in the garage and pulled the plugs again to have a look, and vwa-la:

They all look the same, and all look about right, with no new wet on the threads now.  Maybe I just have had a tendency to under-tighten no. 2, creating a vacuum leak?

[ray_]

1 hour ago, 0257 said:

Oh, NOW you tell me.

You might try putting that 700 point at 5 degrees as well.

[ray_]

And don't pull the plugs for another 10k miles.

 

 

And, they look a bit light on anti-seize.

 

 

Edited October 10, 2022 by ray_

[cda951]

Fix the wacky timing curve within the idle to 1200 RPM range and enjoy the car.

Edited October 10, 2022 by cda951

[0257]

7 hours ago, cda951 said:

Fix the wacky timing curve within the idle to 1200 RPM range and enjoy the car.

After re-reading your advice to Gliding Serpent on the topic of KF “lag” for, oh I don’t know, maybe the 12th time, I am finally at peace with those readings and am going to do just as you suggest.  And get one of DLacey’s wax elements into my WUR as soon as they’re field-tested.

[jimk]

12 hours ago, 0257 said:

2.  Partial acceleration in 2d and higher gears still gives super-lean readings (up to 18:1) for anywhere up to 8-10 seconds.  If I increase throttle to over 2/3 it drops fast, and in any event it always drops into that sweet spot around 14.7

I don't think KF has a throttle pump (acceleration enrichment) function as a carb or a tuned EFI has.  Without any there is a momentary lean condition.

[Stevenola]

58 minutes ago, jimk said:

I don't think KF has a throttle pump (acceleration enrichment) function as a carb or a tuned EFI has.  Without any there is a momentary lean condition.

With no dumping of raw fuel from any accel pedal movement, that's probably why it got relatively good gas mileage for its performance back in the day.

[0257]

In case you thought this was over… did all the tuning and driving yesterday with the air filter off (no wonder Zouave seemed to be breathing so free!).  Put all that kit on today, and it seems to have transformed all our tuning.  Idle in high 9s to low 10s.  Cruise from high 11s to low 13s.  WOT pretty much the same as yesterday.  Removed front air filter and gained a full point, maybe more, at idle.  Cruise up to mid 13s, bumping higher. Interestingly, the mid-throttle high-AFR lag was at least as pronounced as yesterday, maybe moreso.  I guess maybe you have to tune these things with the air filter on!  It seems the air filter is pretty dang restrictive if that’s the case.  Thoughts?

[cda951]

13 hours ago, jimk said:

I don't think KF has a throttle pump (acceleration enrichment) function as a carb or a tuned EFI has.  Without any there is a momentary lean condition.

 

Yes, this is the eternal bugaboo with the 2002tii. The solution for most is to adjust the relationship between the D-cam and throttle butterfly until the hesitation is diminished, but this often results in overly rich running at very small throttle openings. 

 

I was chatting with a well-regarded Ferrari technician several years ago about such things and he mentioned that the Ferrari cars with the Bosch CIS/K-Jet fuel injection system used the cold-start injector as an acceleration pump. Obviously this a very crude system, as distribution to the individual cylinders would not be ideal, but it got me thinking. One of my tii friends who has a moment switch for his cold start injector mentioned that he noticed a difference if he hit the switch during initial acceleration . . . .

 

Obviously EFI is the ultimate answer, but I had thought about a switch to the CSI operated by a combination of throttle position and manifold vacuum to fill the gap in the KF system. The answer is still EFI, but whether I try this or go to a fakey Alpina A4S system remains to be seen, I'm just a nerd for mechanical fuel injection

[jgerock]

On 3/30/2022 at 7:01 AM, dlacey said:

 

Healthy gap over here

I see the return spring has started to wear out the retainer pin. Keep an eye out on that before the spring wears completely thru it.

[jgerock]

Going back to the sloppy linkage points (even with all new parts), I added some thin nylon washers to the two pivot points (cowl and engine block) to help reduce the sloppiness of the components.  The engine block pivot seemed to be the worst culprit, even with new BMW nylon bushings.  You can get the nylon washers in the hardware aisle at a big box store (HD or Lowes).

 

You want smooth action from the entire linkage, but not too tight.  The replacement vertical rod assembly from the pedal arm to the cowl with heim joints is a very good upgrade.  It’s available from a seller here on the FAQ.

 

The “fixed” length short linkage rod is the same length as the second one. 85 mm center to center holes.

[0257]

On 10/11/2022 at 9:05 AM, jgerock said:

I see the return spring has started to wear out the retainer pin. Keep an eye out on that before the spring wears completely thru it.

Happily, Jim, that's a Dlacey photo, and not my linkage!  But I have read your and others' advice on that issue in the past, and my original had some wear in that spot.  So I went and ahead and bought a new piece. Slava faq!

[0257]

On 10/11/2022 at 9:17 AM, jgerock said:

Going back to the sloppy linkage points (even with all new parts), I added some thin nylon washers to the two pivot points (cowl and engine block) to help reduce the sloppiness of the components.  The engine block pivot seemed to be the worst culprit, even with new BMW nylon bushings.  You can get the nylon washers in the hardware aisle at a big box store (HD or Lowes).

 

You want smooth action from the entire linkage, but not too tight.  The replacement vertical rod assembly from the pedal arm to the cowl with heim joints is a very good upgrade.  It’s available from a seller here on the FAQ.

 

The “fixed” length short linkage rod is the same length as the second one. 85 mm center to center holes.

I am going to add some of these washers.  I did already on main pivot (the one that extends from the engine block), as the OEM bushings are sad flimsy things.  But I suspect I may have a little pump to butterfly mismatch, in addition to the pretty leaker warmup regulator (c'mon Dlacey!).  Until I get the WUR fixed I am going to live with this over-lean condition.  I'll test it again once that's done.  Re that replacement vertical rod assembly, an anyone reading name the supplier of that assembly?  Interested.

[bergie33]

8 minutes ago, 0257 said:

I am going to add some of these washers.  I did already on main pivot (the one that extends from the engine block), as the OEM bushings are sad flimsy things.  But I suspect I may have a little pump to butterfly mismatch, in addition to the pretty leaker warmup regulator (c'mon Dlacey!).  Until I get the WUR fixed I am going to live with this over-lean condition.  I'll test it again once that's done.  Re that replacement vertical rod assembly, an anyone reading name the supplier of that assembly?  Interested.

 

@harry6422 was making these.  Last I heard, he was having trouble with time and sourcing materials.  Here is his thread on the upgraded rods:

 

 

[0257]

A little update. With the air filters on the car this time, I leaned out the a/f mixture screw and I think I have got Zouave back to those sweet numbers I referenced last week.  Also, I loosened the set screw on the WUR cone and rotated it clockwise 3/4 turn.  This both puts the top of the cone closer to the factor setting (I had it set higher to compensate for my lazy wax actuator, to bring overall extension up a few mm) and aligns the largest of the three air channels with the air port into the plenum. The result is a smoother start, even though my idle still doesn't change noticeably between cold and warm. 

 

Now the only issue I'm experiencing is a slightly down-surging idle when the engine is warm but not hot.  That is, once I run Zouave hard for a half hour the idle is steady. But during that first half hour I'll occasionally get the surge.  This, if nothing else changes between now and the next time I drive Zouave, is a happy detail.  Other than during surges, when idle can dip down into the high 10s, warm idle is staying between 11.5 and 13 on the AFR gauge, at about 1050 rpm. 

 

Regarding the leaky WUR, I'm not sure that more actuation is the answer for this WUR.   Even at full extension it lets a fair amount of air through.  Looking at the pits in my windshield, I speculate that it picked up a lot of grit living in SoCal all those years. I have acquired a spare, really decrepit WUR and am considering working with Buck Denzer, a really fine machinist and Porsche guy who moved to Sarasota recently, to do a comprehensive fix.  What I'm considering is honing the cone to ensure roundness and a good surface, then sleeving the collar with some space-age material (or maybe just bronze) to get a really tight seal on extension.  This should not be too expensive a fix to engineer, and if it works, and Dlacey's wax element works, a whole lot of warmup regulators could get a new lease on life.  More to come.