[DMCForum] Re: 10989
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[DMCForum] Re: 10989

I'm a big fan of disconnecting all the ancillary systems,  getting the
engine to run properly distilled to its basics,  then adding back
whichever ancillary systems you want.  If the engine runs well
distilled,  you'll have no problems with any other systems (that are
properly functioning themselves).

B28F will run without any of the following:
- Idle speed motor (use manifold screws)
- Lambda (just unplug the frequency valve. You do need external fuel
supply to lower chambers of the fuel distributor)
- Spark advance
- Charcoal canister
- Vacuum to CPR (vacuum normally cuts off above 100 some odd degrees
coolant temp anyway)

Unplug them and cap off their connections to the intake manifold. Note
that this will not guarantee no vacuum leaks!  There are still
numerous potential points of leakage:
- Fuel distributor to metering unit
- Idle speed motor to metering unit
- Metering unit to throttle plate unit
- Throttle plate shaft
- Charcoal canister purge nipple (ported under throttle plates)
- Manifold screws (if opened, they are sealed with O rings)
- Throttle plate unit to U pipes
- EGR plate on the U pipes
- U pipes to intake manifold
- Cold start tube itself (idle speed motor, PCV)
- Cold start tube to intake manifold
- Intake manifold to heads

Don't forget that you can have a vacuum leak in the front of the car:
- Brake booster
- HVAC ductwork
- Heater core shutoff valve (routed from HVAC)

Why don't you:
- Cap off the big 3/8" line on the passenger intake rail (power brakes
and HVAC)
- Cap off the 3/16" line on the driver intake rail (CPR, spark advance)
- Cap off the 3/16" line under the throttle plates (charcoal canister
- Cap off the idle speed motor takeoff from the fuel metering unit and
connection to cold start tube
- Cap off whatever the charcoal canister attaches to (can't remember.
I don't have one)
- Close the brass manifold screws
Intake manifold should now (in theory) be vacuum tight. Don't worry
about PCV -- it's basically an intentional vacuum leak throughout the
entire engine. Note that the engine will only run like this if you
crack the throttle plates open. If the intake manifold is indeed
vacuum tight,  you can set base ignition time and adjust the CO screw
(unplug the frequency valve),  then start adding each system back one
by one,  even diagnosing them in the process.

BTW: I've never been a big fan of the F series spark advance cutoff
solenoid.  Europeans didn't use it,  but rather ran spark advance
directly from the ported nipple under the throttle plates.  Much
simpler IMHO.

Bill Robertson

>--- In DMCForum@xxxxxxxxxxxxxxx, "therealdmcvegas" <dmcvegas@xxxx> wrote:
> Marc is most likely right when he says vacuum leak as being a
> problem. Most likely too, the engine was probably tuned WITH a vacuum
> leak in place. Which means that you'll need to re-tune the engine,
> once you get it fixed. It's a pain, but the motor then gets better
> milage, and outputs more power.
> As for the idle speed, do the RPMs decrease to normal when you tap
> the gas pedal? If so, it may be a linkage adjustment, for the arm
> that triggers the Idle Speed Motor, and the vacuum solenoid. Which
> brings me to your next question...
> Yes, RPMs affect engine spark. When the engine is @ Idle, there is a
> solenoid which activates, and cuts off engine vacuum to the
> electrical distributor, to prevent any spark advance. Once the gas
> pedal in depressed, and the solenoid is deavtivated, then spark
> advance occurs as the RPMs & vacuum increase.
> My advice is to start with replacing ALL rubber hoses, and vacuum
> lines. It's cheap, the hoses are available at ANY parts store, and
> you KNOW that it needs to be done. From there, you could also try
> spritzing a bit of starter fluid sparingly around the intake manifold
> joints, rubber hoses, valve covers, and fuel injector seals. If the
> engine revs, you've found the vacuum leak.
> But before you go tuning an engine, you've got to first ensure that
> it's components are up to the job, and are in proper order.
> -Robert
> --- In DMCForum@xxxxxxxxxxxxxxx, mike clemens <rmclemns@xxxx> wrote:
> >
> > Josh's car, moving under it's own power was good, but
> > not near as good as seeing the smiles on his and
> > Cousin Ben's faces when they returned from their spin
> > around the block.  I could have keeled over with a
> > heart attack and they would have kept on grinning and
> > jiving.
> >
> > To expound on his problems---when we got it started,
> > idle was around 2000 rpm and if you tried to open the
> > throttle at all, it would hesitate and try to quit.
> > Let off the gas and it would stabilize at 2000 rpm
> > again.  After we got it warmed up, rpm's leveled out
> > at 2500 rpm, but the throttle worked without much
> > hesitation.  Any ideas on this high idle problem??
> >
> > Second problem----we bled the clutch as per all the
> > advice given by the Forum members and it appeared to
> > work.  Once we got it running, we couldn't get it into
> > gear without pumping the clutch five or six times,
> > then it would go into reverse and all gears.
> > After running a while, we could not get it to shift
> > into reverse at all.  I'm thinking he's got bad seals
> > in either the master cylinder or the slave cylinder,
> > but not sure which, that is allowing the pressure to
> > bleed down.  Any ideas on this??
> >
> > Last question---does the RPM relay have any control
> > (even remotely) over the spark put out by the coil??
> > I'm 99% sure his relay is bad (intermitant open) and
> > while trouble shooting, I noticed no spark from the
> > coil.
> >
> > I really appreciate all the help and encourgement you
> > folks have given in this little quest.  Josh, I know,
> > is thrilled!!
> >
> > Mike      TPS      1630
> >
> > PS:  See Lauren, I told you we'd get it going, and he
> > still wants to hug me, but that ain't gonna happen
> > this lifetime. :-)
> >
> >
> >
> > --- Josh Porter <joshp1986@xxxx> wrote:
> >
> > > I was wanting to let everyone know about my good
> > > news. I drove my car
> > > down to the end of the street on it's own and it was
> > > good. It still
> > > needs lots of work but it is by far the best day to
> > > date. There is a
> > > small problem. My rpm is still at 2500, there is
> > > smothing else that I
> > > am suppossed to ask but I can't remember. Mike will
> > > be able to tell
> > > you.
> > >
> > > I'm telling you it was GREAT!!! I just wich Mike
> > > would have gone with
> > > me, he deserves to drive it more than to tell you
> > > the truth, but for
> > > some reason he won't. Maybe it's because it is a
> > > MANuall:)
> > >
> > > Josh
> > >
> > >
> > >
> > >
> >
> >
> >
> >            
> > __________________________________
> > Start your day with Yahoo! - Make it your home page!
> > http://www.yahoo.com/r/hs
> >


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