200 10V stumbles, poor mileage

[David Michael]

Hi Konstantine - See my replies below:

Dave
On Mon, Dec 21, 2009 at 4:34 PM, Konstantine Bogach <kbogach at comcast.net>wrote:

> Dave, thank you very much for such detailed response.
>  Can you explain in more details on how to do the measurement in your item
> 2?  Which points to hook O-scope to?
>
==>I made a harness that plugged in between the distributor and coil, and
that harness had bare leads on it that I used to connect the o-scope. You
could also use "back probes" to connect to the connector pins at either the
dizzy or coil. I can't remember which lead is the Hall output - you'll have
to check the Bentley.

> Duty cycle sweep is same as before, maybe a little wider (35-65).
> Air meter plate is always a suspect because you can't see it.  Can I reach
> it through air filter box?
>
==>You cannot get to the roller bearing easily, but maybe at an angle- but
it makes it easy to check to see  if the plate is moving smoothly. You want
to do it both with no fuel pressure and with the fuel pump energized (only
do the latter briefly, otherwise you will fill the engine with gas ;-)  )

> Can coil be bad even resistance test is good?
>
==>They can go bad when hot?

> Need to check air cleaner too.   I have no garage and have to wait next
> weekend - I need at least daylight if not warm weather.
>
> Thank you.
> Konstanine.
>
>
> On 12/19/2009 10:50 PM, David Michael wrote:
>
>> Konstantine,
>> On and off I have had several bouts of fixing my poorly running 200 10V.
>> Some of the issues it sounds like you are familiar with, but here are some
>> things I learned:
>> 1. Air leaks. Double, then triple check. Use Scott M's site as a guide for
>> where to look.  Injector seals, valve cover gasket, rubber "igloo" and
>> intake hose clamps all good places to look. All are easy except for the
>> injector seals..
>> 2. I fought a poor drive ability problem for very long time before I found
>> that the Hall Sensor in the distributor was sending false signals. I finally
>> found that when I hooked an O-scope up between the distributor and coil, and
>> found there were random "ghost signals" inter-spaced with the sine wave. New
>> dizzy fixed a world of problems.
>> 3. When you set your idle mixture duty cycle, make sure you also set the
>>  idle valve control current with the bypass air screw. It's best if you have
>> two meters - one for the mixture duty cycle and one for the bypass valve
>> current. If you cannot set the idle air valve it to 430MA, look for the
>> reason why......
>> How steady is the duty cycle at idle? It should not swing by more than
>> about 30%
>> 4. I had a very strange problem where my control pressure regulator was
>> not constant - it would randomly change the control pressure by ~5psi. But
>> that affected the part throttle accelerating, not idle. New WUR fixed that.
>> 5. Make sure your air meter flapper plate moves without binding - there is
>> a roller bearing under the fuel distributor plunger, and mine was
>> occasionally sticking.  I fixed it by spraying some  lubricant through the
>> idle mixture setting hole. You have to bend the tip of the lubricant can
>> little red hose at 90 degrees to do this. It would be better to remove the
>> fuel distributor from the AFM but that is a PIA.
>> 6. You need to find out if your car is hard to start because there is too
>> much fuel or too little. I did have  a drippy injector once, and it would
>> cause hard starting after 15 minutes - but you could also smell gas. It also
>> had no affect on idle.
>> 7. Other things I have done that may or may not have helped: New coil, new
>> plugs, new TDC sensor, new air cleaner
>> Good luck
>> Dave
>> 90 200 qa 240k
>>
>
>