512 BBi ignition problems

well, those screws are not covers for anything. The hole that is unplugged is direct access to the bar that links to the air plunger. There is still three possibilities..a stuck or improperly adjusted FD (larry fletcher..where are you..he is the guy who rebuilt it) a stuck open WUR or possibily faulty auxiliary pressure regaulators. I tend to think it is the first two.

>>The hole that is unplugged is direct access to the bar that links to the air plunger.<<

Those holes "must" remain plugged except for brief periods needed to access &amp; adjust.

Coach,

Normally during a diagnostic process, parts and/or possibilities have to be eliminated and/or ruled out as the culprit. To eliminate possibilities a data base needs to be built, I'm not sure I'm seeing that here.

Could you list the hard data we have compiled so far for our review?

Regards, JRV

Hmmm..

JRV, He is saying he didn't feel the adjustment screw at the bottom of the shaft (per his email).
There has to be an adjustment of some sort, but it is possible that the builder left this off? Which would explain the way-out-of-whack fuel delivery. But, I'm not sure the FD would even operate w/o having it's internals missing...

Coach, did you inspect both sides? You can use a 3mm allen wrench to touch the adjustment point (may be almost impossible to see). I just did this on my lotus, you can't see anything down that shaft due to the angles. BUT, you can feel the screw engage with the long end of the key. I just set the idle and mix adjustment... car runs like a scalded ape now!

I'll email coach here in a bit.

Thanks
James

Hi James, glad to hear you are having success. I'd like to say the same for CoachI at some point.

I can't imagine the screw always being missing as idle mixture could have never been set, there is no spec or automatic adjustment. The engine never would have idled anywhere in the ballpark if at all.

The lack of some definative data is making this far more difficult than it needs to be imo. HenryK just went thru this entire tuning/diagnostic procedure on his Boxer and had good results.

Yes at my level I can find a starting point and solve problems by guessing, however this is not the place nor can every problem be solved by throwing darts at the board. And honestly I use my experience to guess what tool to use and what test to perform first, not what part to replace first. Believe it or not the more experience one has the more adverse to guessing one becomes.

Best Regards, JRV

Here is what we have established so far:

1) Car runs rich. explosion of unburnt fuel can be heard in the exhaust. Blueish smoke from the drivers side bank, which is passenger side due to the crossover

2) Passenger side FD was rebuilt, which makes sense to start there. Both of the above conditions can be caused by a fault in the FD.

3) Passenger side WUR does have a cross over to the drivers side WUR. Fault between FD and WUR(1), or WUR(1) itself would explain rich condition (on pass side of the engine).

4) Multiple sources confirm that mixture adjustment screw is between the AM and FD housing, protected by a single brass, removable screw.

5) Idle adjustment must be made in conjunction with mixture adjustment to get ballance between both banks.

6) Process for trouble shooting will start with inspection of the AM plunger. Then a static fuel pressure test at WUR(1). If both check out, we will move on to the FD adjustment screw. If it is infact there, then C0% adjustment will be made at the idle mix screw. Final step will be to ballance idle on both sides. If the problem still occurs, then we will look further into more detailed solutions.

Effectivly, all we have done thus far on this car is take the adjustment screw off. Now, the problem of "is it there?" has popped up. If the adjustment screw is missing, then the troubleshooting process cannot continue. If it is infact there, then the troubleshooting process must move forward into the fuel pressure checks and so on.


So, thats where we are. Sound about right?

James

>>3) Passenger side WUR does have a cross over to the drivers side WUR. Fault between FD and WUR(1), or WUR(1) itself would explain rich condition (on pass side of the engine). <<

Ok...

...the crossover balances Fuel Pressure side to side, so a FP problem on one side affects BOTH Banks on cars with C/O Pipe still in place.


If you don't have easy access to an Exhaust Gas Analyzer, then make your checks for the screw because it is simple, then check for ignition spark on all 6 cylnders on the problem side, because that is also simple, done with a spark test tool from Pep Boys.

These things can be easily checked and definative conclusions drawn. Boxers split the ignition system in the Distrib so it's important to know that strong quality spark exists to all cylnders and this test is easy. The basics of engine running condition diagnostics go like this, 1- spark 2-fuel 3-compression. Those are the 3 things that enable an engine to run, or prevent it from running.

Regards, JRV

Yep. I think coach is going to change out the plugs for new NKGs just to be on the safe side.


James

JRV,

Spark is getting to all cylinders, new NGK plugs all around.

Is the adjustment for the FD under the brass screw? Coach says he cannot feel/find it to make the adjustments. I don't know where else it could be, since thats pretty much where all bosch K-jet cars are.

James

James,

all the adj. screws are in the same location, between the plate &amp; FD itself. It is possible someone has re-installed the sealing plug over the access screw that must be removed to reach inside to the adjustment screw itself.

As far as the screw being brass...the factory sealing screws are steel...recessed into the access hole. Of course it's possible someone has changed how the hole is plugged.

Regards, JRV

actually, James and JRV these screws are NOT brass, but are steel. No one reinstalled the sealing plug because I can insert a very small allen wrench and physcially move the bar and see the air diaphragm move. I can push it up and down, through the hole that is plugged by that small screw. And by the way I have ordered new iridium plugs and will change into those soon.