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

[0257]

Btw, in getting KF pump lever hole #1 (idle position) to line up reliably, the one obscure piece of advice that made the biggest difference was the bit highlighted in yellow below:

No matter that you replace all the ball joints in the linkage, there’s always a bit of slack across all 6 (including a bit in the intermediate block-mounted pivot, new bushings notwithstanding).  Lightly depressing the firewall lever (even if only 1/16”) before tightening the collar on the intermediate shaft seems to take up that slack and help keep the idle position of the KF lever more reliably centered.

 

Sadly, achieving micro-alignment has done nothing to keep my light accelaration AFRs running into the 17-18:1 range….  Still fiddling with the various settings to address that.

[ray_]

1 hour ago, 0257 said:

 

 

Sadly, achieving micro-alignment has done nothing to keep my light accelaration AFRs running into the 17-18:1 range….  Still fiddling with the various settings to address that.

Check ignition. Could be a miss.

[0257]

Taking Dlacey’s advice, I procured a MATCO leak detector and put it to work to locate source of lean acceleration.  Maybe this is it?  WUR hose plugged, MATCO detector set on highest pressure setting.  This is the only leak, right from the bottom of the tuna can bushing….  I had the bottom bushing replaced but did not bother with the top bushing, as the machinist thought it would be difficult to get to.  I wasn’t thinking then of air leaks, only eccentric rotation.

 

Enough to drag my light acceleration AFRs all the way to 18?  Any way to address this short of bushing replacement?

 

Even with the car idling in the high 9s AFR, the plugs look pretty good, maybe even too clean.  In the two photos below you can see both sides of the plugs after yesterday’s 30 or so miles of mixed driving.  Up to 100 mph on empty road, pulling like a beast, no audible pinging.  After settling in, 4th gear WOT at 4000+ rpm swinging from mid-13s to high 12s.  I think it could probably be a little richer.  Cruise is in the 14s in 4th and 5th, mid-13s to high 12s in the middle gears.  I’d like to see cruise in the 14s through the gears, but I’ll take it in just 4th and 5th if it’s best I can do.  Idle is averaging sub 10(!).  Car doesn’t seem to mind and look at the plugs.  If anything, they’re a bit light, even after  stop and go driving.

So: is that tuna can air leak my problem?  Interestingly, while I know the WUR leaks when connected, it does not really change my numbers perceptibly.

[cda951]

8 hours ago, 0257 said:

Taking Dlacey’s advice, I procured a MATCO leak detector and put it to work to locate source of lean acceleration.  Maybe this is it?  WUR hose plugged, MATCO detector set on highest pressure setting.  This is the only leak, right from the bottom of the tuna can bushing….  I had the bottom bushing replaced but did not bother with the top bushing, as the machinist thought it would be difficult to get to.  I wasn’t thinking then of air leaks, only eccentric rotation.

 

Enough to drag my light acceleration AFRs all the way to 18?  Any way to address this short of bushing replacement?below you can see both sides of the plugs after yesterday’s 30 or so miles of mixed driving.  Up to 100 mph on empty road, pulling like a beast, no audible pinging.  After settling in, 4th gear WOT at 4000+ rpm swinging from mid-13s to high 12s.  I think it could probably be a little richer.  Cruise is in the 14s in 4th and 5th, mid-13s to high 12s in the middle gears.  I’d like to see cruise in the 14s through the gears, but I’ll take it in just 4th and 5th if it’s best I can do.  Idle is averaging sub 10(!).  Car doesn’t seem to mind and look at the plugs.  If anything, they’re a bit light, even after  stop and go driving.

So: is that tuna can air leak my problem?  Interestingly, while I know the WUR leaks when connected, it does not really change my numbers perceptibly.

 

I don't think that is your issue, at least not the way it appears to be. If the throttle shaft bushing air leaks were a thing, the idle mixture/quality would be most affected. However, throttle shaft wear in general, in addition to slop/wear throughout the system is the most likely cause of your issue, in that the D-cam influence is affected in the light load range. For this reason, I have a throttle body being rebuilt by @Einspritz as we speak.

 

I have tried every iteration of D- cam adjustment there is, and the only way to completely  eliminate the typical mid-throttle lean spot is to have pig-rich light-throttle mixtures, so I am excited to get that sorted out soon. In the meantime I have the D-cam adjusted to provide the best compromise between the two conditions, and that has been perfectly acceptable for the last two fun road rallies that I have done in the 2002tii.

[Einspritz]

Smoke coming from the top D-cam bushing indicates to me that the smoke is following a path from throttle body through the top butterfly bearing to the upper can.

 

The lower bearing is closed off because there is a rubber cap on the bottom..... or should be.

 

These bearings are not sealed, although I do use sealed bearings to ameliorate that possibility.

 

That said, I don't think it is significant enough to be your absolute problem. I'll need to go back and study your observations more.

[ray_]

Ignition.

 

?

[dlacey]

I think it's time to switch off the lambda gauge and enjoy the car...seems like it's running very well ?

[ray_]

2 hours ago, dlacey said:

I think it's time to switch off the lambda gauge and enjoy the car...seems like it's running very well ?

I've made that suggestion also.

 

?

[0257]

6 hours ago, ray_ said:

I've made that suggestion also.

 

?

I am starting to agree that it’s time to just enjoy this car.  It has never run better since I’ve owned it.  Though Ray, you’re making it difficult to decide whether I’m declaring victory or defeat!

[0257]

Stevenola and I spent some time tuning the KF yesterday.  Zouave has been running well, but with dirty slimy nasty low (like 9:1 or lower) AFRs at idle, piling up gasoline residue around the spark plug threads.  Above idle it ran pretty well and the plugs surprisingly clean, though rich at WOT (high 12s down to low 12s) and almost as rich cruising.  No amount of d-cam or a/f screw fiddling could get the idle leaner than low 9s without incredible surging, and an idle screw that didn’t reach the d-cam.  

 

Since I had fiddled with the verboten screw already, this suggested to me that I needed to bring that screw lean a bit.  I had marked it as best I could before fiddling with it, but was unsure I had returned it to its original spot.

 

So I screwed it out about 1/10 of a turn.  Without moving the d-cam we got the a/f screw to a place where the car starts well and idles smoothly at 1000 rpm.  Timing on the 123 as follows:

 

When Zouave’s engine is cold the AFR gauge still pegs 9:1 at idle, but warm idle is 11-12.5:1.  I’ll take that.  WOTs in 3d through 5th gear on the cam (3500-5500 rpm) are acceptable (low 13s down to mid 12s, but mostly between 13.1 and 12.7).  Again, I’ll take it.  AFR on steady cruising at 3000-4500 rpm in 2d through 5th gear is eerily consistent between 14.5-15:1, mostly right at 14/7.  I like that fine.   And the car feels good, like it’s breathing deeply in all gears.  I have driven it over 50 miles hard with these settings, and from a general behind-the-wheel standpoint I don’t see how I can improve the way it runs by further KF tuning.

 

Two issues remain, though:

 

1.  After a half hour of spirited driving, when the engine is good and hot, the idle wants to cycle.  No so much surge, as it doesn’t go far above 1000 rpm. Rather, it tends to rise slightly, get lean (14+:1) and drop to 700 or so; then it recovers, climbs again, drops again. I hardly dare fiddle with the a/f mixture screw any more, as getting idle mixture out of the basement is sooo hard.  Thinking perhaps of (1) lowering the idle speed into the 950 rpm range to hopefully avoid bumping up against the timing change (5 degrees advances to 12 between 1000 and 1200 rpm) or (2) dropping idle speed a bit to avoid hitting that timing change.  Suggestions?

 

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 when — I’m not sure how to describe this — the engine gets close to equilibrium. Eg, if I have depressed the accelerator pedal deep enough in third gear to reach 55 mph, the AFRs drop right into the cruise zone as Zouave approaches that speed.  Never any stuttering or hesitation; if there’s any pinging going on, its sub-aural and neither Steve nor I can detect it.  Unless this sets off alarms among you gurus, I’m about ready to flip the off switch on the AFR gauge.

 

3.  Plug no. 2 burns much lighter than the other 3. It looks like a plug from an EFI car, light buckskin, whereas the others look a little grayer.  Not sure if this is related to the fuel system, the valves, or something else.  I have adjusted the valves to a fare-thee-well.  Given the attention I have lavished on new ignition bits I’m hoping it’s not a plug wire.  I worry it could be the corresponding suction valve on the KF.  I haven’t messed with the suction valves, as Gus at Pacific rehabbed those in 2015.  Thoughts?

[Stevenola]

1. Your timing curve should be 800-1100 at 5 degrees not 800-1000.  Eliminate the 1200 point.  I thought I did that.  This will bracket the 1000 rpm idle speed.

[0257]

2 minutes ago, Stevenola said:

1. Your timing curve should be 800-1100 at 5 degrees not 800-1000.  Eliminate the 1200 point.  I thought I did that.  This will bracket the 1000 rpm idle speed.

Oh, NOW you tell me.

[ray_]

8 minutes ago, Stevenola said:

1. Your timing curve should be 800-1100 at 5 degrees not 800-1000.  Eliminate the 1200 point.  I thought I did that.  This will bracket the 1000 rpm idle speed.

I've been staring at that for the last 5 minutes.

 

Anyway tii's aren't spec'd to idle below 950 IIRC.

[0257]

3 minutes ago, ray_ said:

I've been staring at that for the last 5 minutes.

 

Anyway tii's aren't spec'd to idle below 950 IIRC.

Oy!

[ray_]

23 minutes ago, 0257 said:

Stevenola and I spent some time tuning the KF yesterday.  Zouave has been running well, but with dirty slimy nasty low (like 9:1 or lower) AFRs at idle, piling up gasoline residue around the spark plug threads.  Above idle it ran pretty well and the plugs surprisingly clean, though rich at WOT (high 12s down to low 12s) and almost as rich cruising.  No amount of d-cam or a/f screw fiddling could get the idle leaner than low 9s without incredible surging, and an idle screw that didn’t reach the d-cam.  

 

Since I had fiddled with the verboten screw already, this suggested to me that I needed to bring that screw lean a bit.  I had marked it as best I could before fiddling with it, but was unsure I had returned it to its original spot.

 

So I screwed it out about 1/10 of a turn.  Without moving the d-cam we got the a/f screw to a place where the car starts well and idles smoothly at 1000 rpm.  Timing on the 123 as follows:

 

 

Two issues remain, though:

 

1.  After a half hour of spirited driving, when the engine is good and hot, the idle wants to cycle.  No so much surge, as it doesn’t go far above 1000 rpm. Rather, it tends to rise slightly, get lean (14+:1) and drop to 700 or so; then it recovers, climbs again, drops again. I hardly dare fiddle with the a/f mixture screw any more, as getting idle mixture out of the basement is sooo hard.  Thinking perhaps of (1) lowering the idle speed into the 950 rpm range to hopefully avoid bumping up against the timing change (5 degrees advances to 12 between 1000 and 1200 rpm) or (2) dropping idle speed a bit to avoid hitting that timing change.  Suggestions?

 

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

 

23 minutes 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 when — I’m not sure how to describe this — the engine gets close to equilibrium. Eg, if I have depressed the accelerator pedal deep enough in third gear to reach 55 mph, the AFRs drop right into the cruise zone as Zouave approaches that speed.  Never any stuttering or hesitation; if there’s any pinging going on, its sub-aural and neither Steve nor I can detect it.  Unless this sets off alarms among you gurus, I’m about ready to flip the off switch on the AFR gauge.

 

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

 

23 minutes ago, 0257 said:

3.  Plug no. 2 burns much lighter than the other 3. It looks like a plug from an EFI car, light buckskin, whereas the others look a little grayer.  Not sure if this is related to the fuel system, the valves, or something else.  I have adjusted the valves to a fare-thee-well.  Given the attention I have lavished on new ignition bits I’m hoping it’s not a plug wire.  I worry it could be the corresponding suction valve on the KF.  I haven’t messed with the suction valves, as Gus at Pacific rehabbed those in 2015.  Thoughts?

 

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

 

Go, drive!

 

Cheers,