engine and drivetrain Adventures in 73 Tii throttle/afr tuning

[jgerock]

You may have to adjust the cam position again.  Remember that the vertical post thru the throttle body is not on the same orientation as the butterfly.  The cam has a specific profile that needs to be adjusted for running while under load.  Loosen the clamp, rotate the cam towards the front of the car just a little bit, readjust the idle co and idle rpm and take it out for a spin.

[gliding_serpent2]

You are right.  I did that again this am.  I adjusted the throttle body shaft again, but made sure to take slack off of the pedal/linkages before final tightening.  I also set things to be richer with the eccentric cam partly obstructing the hole for the 4mm pin.  Running this way, i had initially thought my problem was fixed.  I only moved it.

 

idle and low throttle are afr's of 10.5:1.  As throttle progressivly increases, things lean out, but to a max of 14:1 near wot, and again with wot, it goes to 13-13.5:1.  Just like before, instead of ranging from 12-16, it is 10-14.  So i just moved my problem, but at least it is a lesser of evils.  At good cruising and 75% throttle, things are 13:1, as opposed to over 15:1.

 

so this makes me think about why my fuel delivery is lagging the throttle body.  The static idle and wot are fine, as they are set.  I do wonder if the throttle body shaft is out of round, or, more likely, there is a vacuum leak.  One person at the car event  i went to suggested that.  It might be worth getting a smoke machine.  As he said, vacuum leaks tend to be worse in part throttle applications as wot is vacuum independant.  

 

Besides, i am also chasing mixture issues in my 911, and a smoke machine would be a good tool to have.  

 

Either way, my car was quite popular!  I gave a few rides by request.  

 

I may also talk to ireland engineering about Petronix (or their tii mechanical distributor with electrical points)

 

 

 

 

 

 

Edited May 7, 2016 by gliding_serpent2

[gliding_serpent2]

This is a bit of an odd thing.  So i drive back, and then my car wants to stall whenever it idles.  Again, making me think the distributer is causing some (probably unrelated) fault.  

 

I opted to lean out the idle to 13:1 when i got home, and to readjust the idle speed.  It did not reslly change the afr spread from light to full throttle, but idle is not so rich, so the illusion is that things got tighter.  

 

Also, after 4 or so hours of driving today... My fuel pump (in the back) now sounds like it is spitting and angry.  Like it is struggling to suck fuel from a straw, except that my tank was 3/4 full.  It was a rebuild unit (volvos of the era used the same one).  

 

I will go for another drive.  At the moment i suspect my fuel pump is in the fritz, i might have a vacuum leak, and my distributer needs a tune-up.

 

the joys of old cars.  

 

Man do i want a e30 m3.  

 

And after a cooldown, the fuel pump sounds fine.  Thoughts?

Edited May 7, 2016 by gliding_serpent2

[xferboy]

2 hours ago, gliding_serpent2 said:

This is a bit of an odd thing.  So i drive back, and then my car wants to stall whenever it idles.  Again, making me think the distributer is causing some (probably unrelated) fault.  

 

I opted to lean out the idle to 13:1 when i got home, and to readjust the idle speed.

I had similar:  Idled ok, driving, off throttle/clutch in, stall.  Restarts and then idles OK.  I've bumped the idle a bit (not much), adjusted AFR, seemed to help (i forget which way now, it's been a couple weeks)

 

Since then I remembered one set of tuning instructions (that I have to use more), surging idle = rich, rev's drop below set idle after throttle burp = lean (which could be above)

 

Just more info to muddy the water   Use or don't use, up to you

 

[gliding_serpent2]

Yeah, for sure. I tuned it out, but what was odd was that it was fine to begin with. Then I drive on the highway for a while, and then some b roads fun, and after 1.5hrs of driving, idle is trying to stall out on me.  Something changed, and I am assuming it is distributor related.   

Edited May 8, 2016 by gliding_serpent2

[MatthewCervi]

9 hours ago, gliding_serpent2 said:

Yeah, for sure. I tuned it out, but what was odd was that it was fine to begin with. Then I drive on the highway for a while, and then some b roads fun, and after 1.5hrs of driving, idle is trying to stall out on me.  Something changed, and I am assuming it is distributor related.   

If you suspect something is wrong with your fuel pump--and from your description it sounds like there could be--then I wouldn't do any more adjustments on the fuel system or ignition until you get that resolved.  You'll be going around in circles if the fuel pressure and volume isn't consistent.

[gliding_serpent2]

2 hours ago, MatthewCervi said:

If you suspect something is wrong with your fuel pump--and from your description it sounds like there could be--then I wouldn't do any more adjustments on the fuel system or ignition until you get that resolved.  You'll be going around in circles if the fuel pressure and volume isn't consistent.

For sure.  But if it is a fuel pump problem, i wonder why the afr numbers/issues would be so consistent, yet the idle rpm so variable after a period of use.  I still think multiple small issues are at play.

 

But given that it is a rebuilt unit, i think i will source a new one.  Could also be as simple as a gas tank needing flushing, and the noise began when the tank got closer to empty (i filled it at 1/4th... After six months with fuel stabalizer).  

Edited May 8, 2016 by gliding_serpent2

[gliding_serpent2]

Fuel pump and fuel filter on order.  The other can be a spare.

[gliding_serpent2]

oh balls

 

Good news is that i know what my problem is... An intake leak.  A smoke machine solved that one.  

 

Bad news is that the leak is my warmup regulator (rebuilt in 2012).  I can see the leak around the top sealant... But more comes from underneath.  

 

Any words of wisdom for removal?  While you are in there thoughts?  

 

Edited June 21, 2016 by gliding_serpent2

[gliding_serpent2]

Rookie mistake.  I did not verify the warmup regulator had extended to the full warm 10mm.  It should let in air in a cold engine.  Mind you, they checked it as soon as i drove in and engine temps were mid gauge.  

 

I should probably repeat and verify the 10mm... But as the only source of smoke... It still needs a rebuild in my mind.  It was leaking where it shouldn't.

 

useful link:

 

 

Edited June 21, 2016 by gliding_serpent2

[gliding_serpent2]

Looking at the prices of a warmup regulator swap/rebuild.  Makes webbers look good again.  I have a nice pair of 40's for my car that I would love to swap for something smaller....

 

I will sleep on that.  

Edited June 21, 2016 by gliding_serpent2

[saaron]

4 hours ago, gliding_serpent2 said:

Looking at the prices of a warmup regulator swap/rebuild.  Makes webbers look good again.  I have a nice pair of 40's for my car that I would love to swap for something smaller....

 

I will sleep on that.  

That's crazy talk...just stop it.

 

Scott

[jgerock]

I'm with Scott- do NOT swap the KF with Webers!  Do I need to visit you?  

[cda951]

14 hours ago, gliding_serpent2 said:

Rookie mistake.  I did not verify the warmup regulator had extended to the full warm 10mm.  It should let in air in a cold engine.  Mind you, they checked it as soon as i drove in and engine temps were mid gauge.  

 

I should probably repeat and verify the 10mm... But as the only source of smoke... It still needs a rebuild in my mind.  It was leaking where it shouldn't.

 

 

 

 

You should repeat the smoke test with the engine at operating temperature and the warmup regulator piston fully extended to 10MM.

 

If there is still a leak from the bottom, a mirror should be used to verify whether the leak is coming from the WUR itself or from the attached hoses. When I first bought my tii a few years ago, the bottom of the WUR was epoxied. Not sure if it was to seal in air or coolant, but neither leaked from it so I left it alone at first!

 

When I rebuilt my engine, I sent the KF pump to Gus at Pacific Fuel Injection. He went through the WUR at the same time as the pump rebuild, and said that he got it to function as well as it could, because mine was faulty and replacement thermostatic elements are no longer available. It now functions pretty well, but when the temp gauge is reading about 1/3, there is a lean spot in the WUR and the idle is slightly rough. But, cold start is easy and it runs great stone cold and at operating temp, so I don't worry about it too much.

 

Because your issue seems inconsistent, have you tried pumping the brakes numerous times while observing idle speed/mixture? Leaky brake boosters and/or hoses are fairly common on these old cars and are the cause of many an odd idle issue . . . . .

 

Chris

Edited June 22, 2016 by cda951

[gliding_serpent2]

I am not so concerned about my idle.  

 

For me, the concern is the engine leaning out with more throttle (a4-6 point swing on my cauge from light to near full throttle, then going back again to 13:1 at wot).  Air leak was suspected as part throttle has the most vaccum.  

 

I did not think to verify the warmup regulator was 10mm... But i drove the car hot into the bay and we were diagnosing it with smoke within 15 minutes.  

 

Plus, no smoke exited from any other location.  And although smoke exited from areas of the regulator i could not see, if also exited from the epoxy seal from one area on the top that looked broken down.  

 

Even if things cooled off a bit... I think the answer was evident.   

 

I found an air leak thread by the hackmechanic where he quickly described an in vitro test of the warmup regulator.  I will do that as my final test... And if there is no easy fix... It needs to be rebuilt (again) by gus.  It was last done 4 years ago.

 

arent the hoses to the warmup regulator filled with coolant? 

 

I was thinking about trying a hack fix with epoxy before i send it across the continent for who knows how long for the tune of 500-700$.  

 

 

 

 

Edited June 22, 2016 by gliding_serpent2