[T3] Ken's lean exhaust

[KENNETH ROGERS]

Phil,

I will follow Jim's and your advise. I will not open up the pressure sensor.  I had no intention to do this.  I have a 'C' pressure sensor coming. and will install it.  All components will then match.  
Right now, after tuning the 'B' pressure sensor also installing one range hotter spark plugs the motor starts right up, idles perfect, accelerates without a pause, hesitation, or knocking (pining), and can really wind out as it shifts smoothly.  It is automatic.  At idle, 12.75:1.  It never goes lean anymore. I doesn't go way rich either. The exhaust looks and smells clean.  It seems to me running just a litter hotter.  Could this be from using one range hotter plugs?  I will go back to the normal heat range plugs and see if there is any difference per Jim's advise.  But why?

I have just learned from Jim and reading the Samba that the FI's have a 4 mm intake manifold gaskets and do not use 1 mm thin ones.  As you know it causes problems.  Mine are 4mm thick.  Good!  Looks like they are NLA.  Someone should knock a bunch out.

The car runs the best it ever has ever since I really started to concentrate on the FI section.  Ray, the T4 specialist,I have read on the Samba has made many comments about FI's.  I learned so much from him.  I must not forget to mention Jim Adney who really has heart, soul, and the brains who is keeping me on course. Thank you Jim. Thank you Phil.  I appreciate you input on AFR's and comments.

There is so much to learn about the Bosch D-Jet system. One book missing in my T3 library is Henry Elfrink's, Volkswagen Type 3 Technical Manual 1971. Next to impossible to find. I do have his FI manual. I feel like a baby just starting to walk and I want to run at this so bad. I want to know all the do's and don'ts. I want to best as I can to understand our T3's fuel injection system and know what we are talking about. Once I get there I want to help others. Carbs are cool, but to keep FI on the car is admirable.

Kenny Rogers  
----- Original Message -----
From: "Phil Hof" <phil.hof at ostronic.org>
To: "type3-vwtype3 org" <type3-vwtype3.org at lists.vwtype3.org>
Sent: Sunday, May 7, 2017 1:06:21 PM
Subject: Re: [T3] Ken's lean exhaust

—————————————
I will echo Jim’s comments, sorry for the repetition.  I’ve had good luck using an Innovate A/F meter but I seem to be one of the lucky ones.  I’ll share what I found but I also agree that chasing fractions of A/F points with a meter is probably not the best approach unless all else is spot on.

You have a lot of “all else” to clean up before going there.  Mismatched FI components will just never work.  Your lean condition under acceleration is a good example.  AS Jim posted, your mismatched system has no way to perform full throttle enrichment.  All you have (maybe) are the extra injection pulses driven by your throttle valve switch.

So lets start with a list of the part numbers for your major components:
ECU
MPS
TVS

One final word… do NOT open your MPS up unless you are going for major surgery and have a reliable A/F meter that reacts instantly.  On the C/D/E systems, that “plug” is NOT just a plug; it’s the full load enrichment adjustment!  Idle is not affected by that plug.  One of the two inner adjustments controls idle.  Another internal controls part-throttle mixture.  Then the outer plug controls full load enrichment.  There is considerable overlap and interactions among these three, and you will spend hours of trial and error, not just with the A.F meter, but also with drivability under various conditions.

I’ve got mine pretty well dialed in, though not perfect.  I invested in an expensive meter, the expensive MPS rebuild kit (Porsche prices), and frankly have been lucky that worked out consistently.

I now see about 14:1 at idle, on the verge of a lean hunt. Midrange cruising is about 13:1.  When I floor it, it spikes to 10:1 for an instant, then levels out at about 12 as the revs increase.  Form what I’ve read, this is about ideal.

My engine is higher compression after the rebuilds and 1776, so it took a bit of experimenting, and I also removed the vacuum advance.  It knocks under load and overheats with it in place, since it drives timing at high speed to something like 40 degrees BTDC, way too much for my compression, even on premium.  Effectively, I have “009-like” timing, and get slightly worse fuel economy and throttle response at low to mid rpm.  I may experiment with different mechanical advance springs or weights, since this distributor model MUST be timed at TDC for the injection timing to be right.  Experiments for the future...

I feel you will get more improvement by eliminating all vacuum and exhaust leaks, and being VERY picky about dwell and timing.  I have found that only a few degrees makes a HUGE difference in throttle response, probably due to the dual effect on ignition and injection timing.  My point hold-down screw doesn’t seem to hold very well, and every time the car seems to buck when floored at 2000 rpm, run hot, or hesitate, I find it has slipped.  I’ll probably send a spare distributor to Jim and/or Glenn to have its various components cleaned, checked, and adjusted.

So tio summarize, let’s get the right parts on your car, check/tighten the connectors, work on leaks and timing, and ONLY then think about fiddling with the MPS.

-Phil
----------------------------

_______________________________________________
VWType3.Org mailing list - type3 at vwtype3.org
To unsubscribe or change subscription options, visit:
http://lists.vwtype3.org/listinfo.cgi/type3-vwtype3.org
If you need more help, contact: gregm at vwtype3.org