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Slam · Posted: Mon Mar 13, 2006 3:53 am Post subject: Vacuum & EGR question.

Well, I took all the emissions control junk out of the 77.5 here. I plumbed in new vac lines for timing advance and retard, off the throttle body and brake booster hose respectively. I took out the air pump and plugged the check valve on the top of the engine. I plugged the vac nipple on the EGR valve. I removed the long vac hose from the airbox to the diverter valve - in fact the diverter valve has been removed. I took off the vac booster and air pump switch (California model) and sassociated wiring, plumbing.

The car started a little hard but seems to run better. It has been sitting a long time as we've been twiddling with other things on it, so I'll ignore the hard start for now. What I did notice right away was that the idle started too low and quickly moved to too high. I adjusted the bypass screw to bring it down around 950rpm or so but I won't know exactly what effect the mods have made till the car gets driven.

Have I removed too much? Does the crankcase need a breather plumbed in? Should I put the EGR system back on line or at least run a vac line to the EGR valve (I could T off the brake booster line)? Ozzie sent me vac diagrams and I pretty much followed what I saw there. Any input would be helpful. The car doesn't have to pass emissions, BTW.

On another note, I sat out with the car for long enough to teach myself how to read wiring diagrams and now the high-beam indicator, the turn signal indicator, the dash lights and the fan motor all work!
_________________
'84 944 - kid blew motor
'83 944 - resting comfortably. For 12 years
'87 944 - sideswiped by trucker
'80 924 - gone
'78 924 - gone
'77 924 - rusting comfortably

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

Wait a second? You didn't plug the crankcase breather, did you? If you did, you'll need to undo this. Route the hose from the breather (near the clutch lever) and run it to the intake (air box).
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
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Slam · Posted: Mon Mar 13, 2006 5:49 am Post subject:

Went out and had another look. I didn't plug the crankcase breather, just plugged the vac stem for the EGR valve. Ozzie's photos show no vac line to the EGR control valve. I did leave the hose between the bottom of the air sensor and the crankcase breather. On Ozzie's diagram this line runs from the elbow in the intake boot to the crankcase breather (odd - it would be unmetered air). I know asking here is totally lazy when all I have to do is pick up the Haynes manual lying on the toilet tank...

So I'm left with:

Vacuum advance from the throttle body
Vacuum retard T-ed off the brake booster
Crankcase ventilation to the air meter
Auxiliary air valve untouched (kinda need that)

Missing anything?
_________________
'84 944 - kid blew motor
'83 944 - resting comfortably. For 12 years
'87 944 - sideswiped by trucker
'80 924 - gone
'78 924 - gone
'77 924 - rusting comfortably

Ozzie · Posted: Mon Mar 13, 2006 5:36 pm Post subject:

That sounds about right with what I have.
The euro models have a different pos for the PCV instead of the airbox. Why- dont know.
You may have to adjust your ign timing to get the best result. Dyno tune it and work out which is best.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

zwoodward · Joined: 07 Mar 2006 Posts: 58

While I'm at my tune up I decided to start removing all the emissions crap as well. Is the Deceleration valve needed or can that be tossed?
Thanks,
Zac
79 924 na

Ozzie · Posted: Wed Mar 15, 2006 7:14 am Post subject:

I dont have one.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance