running on 2 cylinders....grrr
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raygreenwood
- Posts: 11906
- Joined: Wed Jan 22, 2003 12:01 am
I know. The spec books have a few things that you have to work around though.
(1) They recommend hideously low tire pressures
(2) We have much better rolling tires now
(3) We have good fuel
(4) The state of tune on the factory engines (or as they come from the dealer)....was pretty slack. You used to see a wide range of gas milage just from car to car of the same spec. I think they listed the milage a little low to cover their backside.
Also....at this point...getting better than stock plugs, and a bettre than stock ignition system and tuning a little tighter will go a long way. Ray
(1) They recommend hideously low tire pressures
(2) We have much better rolling tires now
(3) We have good fuel
(4) The state of tune on the factory engines (or as they come from the dealer)....was pretty slack. You used to see a wide range of gas milage just from car to car of the same spec. I think they listed the milage a little low to cover their backside.
Also....at this point...getting better than stock plugs, and a bettre than stock ignition system and tuning a little tighter will go a long way. Ray
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MGVWfan
- Posts: 825
- Joined: Fri Jun 11, 2004 9:23 pm
One thing going against us is E10 (10% ethanol) that the EPA forces upon the bigger metro areas (like Dallas and Houston). With 10% ethanol, that's 10% less gasoline, and lower energy content, so to compensate I found I had to bump the fuel pressure a bit to get it richer across the board. Unless you've got a "modern" (O2 sensor closed loop control) FI system, and relatively high compression (like 9.5:1 or better), E10 will cause fuel economy to drop just due to the lower energy content. But, yeah Ray, my D-Jet is a bit "tweaked", shall we say? 
Oh yeah, I found that gutting the original (bad in my case) PCV valve and inserting a PCV valve from a 199x(?) Honda Civic (little inline brass-looking thing) in the line I got rid of the PCV valve induced "flutter" in the MPS. It's a progressive valve, and seems to be calibrated close to what my T4 needs for PCV flow. I'll see if I saved the part number somewhere in my 4" binder of T4 schtuff...
Keep at it VWFye, you'll get there.
Oh yeah, I found that gutting the original (bad in my case) PCV valve and inserting a PCV valve from a 199x(?) Honda Civic (little inline brass-looking thing) in the line I got rid of the PCV valve induced "flutter" in the MPS. It's a progressive valve, and seems to be calibrated close to what my T4 needs for PCV flow. I'll see if I saved the part number somewhere in my 4" binder of T4 schtuff...
Keep at it VWFye, you'll get there.
Lane
73 VW 412 (the Nomad, dropped valve seat land now, argh!)
67 MGB (Abingdon's Finest)
76 Plymouth Duster /6 (runs like a top)
99 New Beetle 2.0 (never gives any trouble)
04 Golf TDI (45 MPG)
09 JSW (love it, love it, love it!)
73 VW 412 (the Nomad, dropped valve seat land now, argh!)
67 MGB (Abingdon's Finest)
76 Plymouth Duster /6 (runs like a top)
99 New Beetle 2.0 (never gives any trouble)
04 Golf TDI (45 MPG)
09 JSW (love it, love it, love it!)
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raygreenwood
- Posts: 11906
- Joined: Wed Jan 22, 2003 12:01 am
The idle will depend upon what you have been able to do with stabilizing the idle timing and limiting overall advance. If you tighten up the advance weights, bushings and the breaker plates...put in a pertronix and get your idle timing stable so it does not jump around...and can remain accurate at 10-12 BTDC at idle....you can do fine with 850-1000.
But...in order to do that...you must have total control over PCV. You must get rid of the PCV valve and put in a fixed orifice with D-jet. L-jet does not really have a problem with it....but the MPS of D-jet does.
15:1 may be just a little lean at idle. Maybe 14+.
But what really matters...is what the AF increases to the second you hit the throttle. If AF ratio does not increase enrichment fast enough off the line...you get flat spots. 15:1 could be fine ...especialy if its required to help you stay in the 13.5+ range in the sweet spots at WOT and part throttle.
On D-jet...you need to have advance starting by about 1100....all in by 27-28. If your idle gets too close to 1100....and if have a wandering idle due to wear in the s]dizzy...you pop in and out of advance without having the fuel mixture to support it. It won't hurt you...just that once it starts it causes a wider range of surging.
The really critical adjustment....once you get PCV straight...and once you get the dizzy tight.....is the outer full load stop adjustment in the MPS. The copper diaphram is really the first point (actually the quickest) of reaction when you crack the throttle off the line.
If that adjustment is too tight...you get a lean misfire right off the line. Too loose...and you get black smoking flat spots.
Getting the TPS tightened up and properly adjusted is also critical to off the line adjustment of the MPS. If you are trying to get your full load stop setting adjusted and your TPS is poorly adjusted....it might be adding fuel in...and masking the poor adjustment of the MPS.
I have not found a factory manual yet....not even Bentley...that gives correct adjustment procedures for the TPS. They always are non specific in reference to late and early models and to models with fuel cut-off. They also have no info for trouble shooting slack in the fork system or for locking the throttle plate before setting the switch to "0". Ray
But...in order to do that...you must have total control over PCV. You must get rid of the PCV valve and put in a fixed orifice with D-jet. L-jet does not really have a problem with it....but the MPS of D-jet does.
15:1 may be just a little lean at idle. Maybe 14+.
But what really matters...is what the AF increases to the second you hit the throttle. If AF ratio does not increase enrichment fast enough off the line...you get flat spots. 15:1 could be fine ...especialy if its required to help you stay in the 13.5+ range in the sweet spots at WOT and part throttle.
On D-jet...you need to have advance starting by about 1100....all in by 27-28. If your idle gets too close to 1100....and if have a wandering idle due to wear in the s]dizzy...you pop in and out of advance without having the fuel mixture to support it. It won't hurt you...just that once it starts it causes a wider range of surging.
The really critical adjustment....once you get PCV straight...and once you get the dizzy tight.....is the outer full load stop adjustment in the MPS. The copper diaphram is really the first point (actually the quickest) of reaction when you crack the throttle off the line.
If that adjustment is too tight...you get a lean misfire right off the line. Too loose...and you get black smoking flat spots.
Getting the TPS tightened up and properly adjusted is also critical to off the line adjustment of the MPS. If you are trying to get your full load stop setting adjusted and your TPS is poorly adjusted....it might be adding fuel in...and masking the poor adjustment of the MPS.
I have not found a factory manual yet....not even Bentley...that gives correct adjustment procedures for the TPS. They always are non specific in reference to late and early models and to models with fuel cut-off. They also have no info for trouble shooting slack in the fork system or for locking the throttle plate before setting the switch to "0". Ray
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vwfye
- Posts: 1010
- Joined: Sun May 21, 2000 12:01 am
the L jet set up i have has no timing bounce at idle... i mean less than 1 degree's worth! i timed it per spec on the sticker at 7.5 btdc with the vacuum disconnected and hose blocked and my 850rpm idle was producing 14.8 a/f and at part throttle it was 14.1 and at WOT it was 13.6. all this sound okay to you?
Notchback mid-engine speedster
Little Giant Killer 3
Little Giant Killer 3
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raygreenwood
- Posts: 11906
- Joined: Wed Jan 22, 2003 12:01 am
Yes...actually it sounds great. I would bring the idle up to about 10 BTDC. I have found that it is better for off the line power in both L and D jet. Just be wary that it does not bump your total advance up. If your total advance is getting over about 30 BTDC....28 would be better.....you can install a limiter on the vacuum advance can (the #917 cans that came on teh 411/412 and some 914 1.7's had a limiter screw)....and also limit the retard as well. Ray
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raygreenwood
- Posts: 11906
- Joined: Wed Jan 22, 2003 12:01 am
Yes....you will be around 40 btdc once you advance your idle timing. I have written about how to do the limiter several times and is somewhere in the archives.
In short...this is how to do the vacuum side of it. You need to get one of those aluminum expanding inserts that you use for thin panels. You will have to keep the screw ID small like about 1/8". This is so that the insert itself is not too long. You may even have to trim the inside end length. Select the proper size drill bit. Put a depth stop limiter on the bit so you do not damage the vacuum can. Drill the hole at low speed in the dimple on the front of the vacuum can. Clean out shavings. Install insert and torque down so it expands with a short bolt. Seal with high temp silicone. Install a proper length screw with a lockwasher. Done.
The mechanical curve is easy to limit as well once you take out the breaker plate. You basically can use stops or set screws to limit the movement of the weights. Piledriver went into better detail in a post just in the last couple days. I have also in the past. Ray
In short...this is how to do the vacuum side of it. You need to get one of those aluminum expanding inserts that you use for thin panels. You will have to keep the screw ID small like about 1/8". This is so that the insert itself is not too long. You may even have to trim the inside end length. Select the proper size drill bit. Put a depth stop limiter on the bit so you do not damage the vacuum can. Drill the hole at low speed in the dimple on the front of the vacuum can. Clean out shavings. Install insert and torque down so it expands with a short bolt. Seal with high temp silicone. Install a proper length screw with a lockwasher. Done.
The mechanical curve is easy to limit as well once you take out the breaker plate. You basically can use stops or set screws to limit the movement of the weights. Piledriver went into better detail in a post just in the last couple days. I have also in the past. Ray