924Board.org

bnoon · Last edited by bnoon on Wed Dec 30, 2009 12:07 pm; edited 5 times in total

I thought it would be kind of fun to keep a journal here of my project resurection 924 turbo all in one place. Project plan is to rebuild it into a capable weekend cruiser and make some performance improvements along the way, then sell it in a year or two for something else to rebuild.

Things I've already done:

Fixed firing order
Checked cam timing and verified that it is a new timing belt
Replaced fuel pumps (previous owner did it)
Replaced pressure acclumulator
Replaced fuel filter
Started rubbing out the paint (it will get a full repaint at some point, but I've got to make it look better in the meantime)
Replaced charge tube bracket (previous owner purchsed one from ideola but never installed it)
Cleaned, washed, deodorized the interior
Fixed/lubed the power windows (previous owner had disassembled the passenger's doorand left it's bits in the hatch)
Ran some speaker wire to the two hatch wells where the dual 8's or 10's will go.
Tested fuel system again and WUR failed test, removed it from the intake manifold to wait for replacement.

List of things to do:

Order/Replace WUR Done 12-26-09
Fix/upgrade grounding
New tires Done 12-26-09 Got new/used 928 S4 rims/tires from ebay for $275
New paint
Fix shifter slop Done
New front engine seals
Fix oil leak at turbo feed lines (and inspect turbo for wear)
Inspect/replace axle seals and CV boots on rear axles
Rebuild center console and heater controls (stereo will be period correct Alpine 7390 tape deck, unsure on speakers yet)
Fix passenger side power window >>>Completed
Build door pods for door speakers Done, pics coming soon
Build speaker boxes and mount amp/s

There will be more to add to the to do list that I'll add/update as I go. Here's some pictures to get started.

Hood during rub out initial stage.

Passenger side prior to rubbing compound.

Driver's side after 1st stage, still need to polishin 2 more stages and then wax.

Also, a couple of short videos. First one, before I tested fuel pressure, showing how it ran. I had already checked/corrected firing order (they had it counter-clockwise) and verified timing belt was new and on properly.

http://www.bnmotorsports.com/porsche/1.MOV

This one is after I tested pressure, then replaced the pressure accumulator, pressure is now correct. I think after thinking about it more though, I need to rebuild the fuel distributor along with the air flow sensor itself because it may be a little gummed up and not operating smoothly, which could be why it can't open on it's own when I rev it. Thoughts?

http://www.bnmotorsports.com/porsche/2.MOV
_________________
'80 924 Turbo - SOLD!
1986 Porsche 944 Turbo - SOLD!
Porscheless

Smoothie · Posted: Mon Oct 26, 2009 1:58 am Post subject:

Looking good.

Looks a lot like my original color (LA6V "Lhasa Green Metallic"), or is yours charcoal? (I'm partly color blind.)
Fuel pressure wouldn't normally be corrected by replacing the fuel accumulator, but it is concievable - if there were a clog in the old one..

Here - I've rudely stepped in and sub-sized (and re-brightness and re-contrasted) you -

_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

bnoon · Posted: Mon Oct 26, 2009 2:07 am Post subject:

It's charcoal color with black interior. The images are alreay 50% smaller than what they come out of the camera at, what do you want?

Garage shots I don't tend to color balance/filter/etc, but have fun if you like. There will be a LOT more pictures added as projects get completed.

Also, the pressure accumulator (if I'm using the right term) will help stabilize pressure as the engine runs. The pump builds initial pressure against the pressure regulator, but the accumulator is what helps keep the pressure constant. Without it, pressure drops suddenly as you try to rev, which is what was happening to mine. I can now rev it smoothly without the pops and sputters like before. The old one actually leaked!!!

Now, to rebuild the fuel distributor/air meter to open smoothly. Leaving to buy this now Viton o-ring kit from Harbor Freight Tools.

EDIT: There, I knocked the pics down another 25%, are those small enough for your 15" monitor?

_________________
'80 924 Turbo - SOLD!
1986 Porsche 944 Turbo - SOLD!
Porscheless

Smoothie · Posted: Mon Oct 26, 2009 2:16 am Post subject:

[Yes, good job.]

After viewing the flicks...

The need to prop open the air meterer is certainly due to a very large vacuum leak somewhere in the intake plumbing between air meterer and throttle. There should be a large rubber "boot" connecting the bottom of the air-meterer-fuel-distributor assembly and the turbo. Make sure that's there and that is is completely intact with no splits. Next is the connection between the turbo's outlet and the lower charge tube - often the bracket that holds the lower charge tube to the front of the block is missing or unfastened. There should also be a large o-ring sealing that joint.
When all vacuum leaks are eliminated, intake vacuum will pull the air metering plate open and provide the correct A:F mixture.
Air metering plate and it's housing = "MAF sensor" on these cars.

Fuel distributor rebuilding (and re-sealing) can be tricky. I'd leave it until you're real sure something's wrong with it. The fuel pressure regulator is built into it - near the attachment for the line that returns fuel to the tank. That may need attention, but doesn't involve complete disassembly of the fuel distributor.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Smoothie · Posted: Mon Oct 26, 2009 2:28 am Post subject:

Yes, the fuel accumulator does act as a damper, smoothing any pulsating affect of the fuel pump/s, but normally a bad/leaky one will only cause the hot start problem. Mine ran fine on a shot fuel accumulator. That's fine, you had a different experience - it's just the first one I've heard of causing a running problem.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Smoothie · Posted: Mon Oct 26, 2009 2:38 am Post subject:

Vac lines and fuel distributor (w/lambda) flow -

_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Smoothie · Posted: Mon Oct 26, 2009 2:55 am Post subject:

There's also a large vac line from the bottom of the air metering housing to the purge valve (#7 in the vac line diagram). That could also be causing a large vac leak if it's missing/disconnected.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

bnoon · Posted: Mon Oct 26, 2009 6:51 am Post subject:

Yeah, the vacuum lines have been getting replaced in bunches. I need to remove and inspect that black tube coming from the air meter again. I had it off for a few moments while I had everything pulled out of the way to get the timing cover off, but I didn't concentrate on looking for cracks in it. I'll take a look at it again before I tackle the fuel distributor since it's easier. Thanks folks!
_________________
'80 924 Turbo - SOLD!
1986 Porsche 944 Turbo - SOLD!
Porscheless

bnoon · Posted: Mon Oct 26, 2009 8:21 am Post subject:

Checked for air leak on the black tube between the air meter and turbo and I put on the bracket for the charge tube (previous owner purchsed one from ideola). Neither was leaking or improved the situation.

This time I was paying attention to the air moving past the disc in the air meter and there was a large amount of vacuum moving past my hand while holding it open. There's enough vacuum that it slows the closing of the meter disc when running vs when it's shut off. It's actually getting better the more I open the door manually time after time, which is telling me something needs cleaned and/or new o-rings and could more easily be attributed to it not being ran very much in the last decade. This is starting to be fun.
_________________
'80 924 Turbo - SOLD!
1986 Porsche 944 Turbo - SOLD!
Porscheless

Smoothie · Posted: Mon Oct 26, 2009 12:50 pm Post subject:

Toooo high control pressure might be part of the problem. That would be caused by the WUR (warm-up regulator, aka- control pressure regulator) being clogged or rusted shut, and/or lines to-fro it being clogged, or a clog where its' return line meets the fuel pressure regulator in the fuel distributor.
Excessive control pressure would present too much back pressure on the air metering plate, causing it to return toward its' closed position.

I would also try running some Techron fuel injection cleaner through it. That should help things along if you're dealing with some kind of gunk/varnish in the fuel system.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

bnoon · Posted: Mon Oct 26, 2009 11:51 pm Post subject:

Hummm, I'll have to check that out. I don't know where exactly the WUR is located since I haven't researched it yet (repair manuals are at home right now). I've seen a couple for sale from ideola I believe, one from a running car if I remember right. Is there a WUR test? Seems I remember a voltage test that lasts 10 seconds (IIRC), but I don't recall a flow test (may have missed it).
_________________
'80 924 Turbo - SOLD!
1986 Porsche 944 Turbo - SOLD!
Porscheless

Dankoneon81 · Joined: 30 Sep 2009 Posts: 136 Location: Mercersburg PA

you could always take that small block i see sitting in the back ground and stuff it in between the wheel wells and not worry about it.

_________________
95 Neon gutted PnP MS2E turbo
94 Toyota sr5 the work horse
78 924 bone stock for now coming soon MS2E

Smoothie · Posted: Tue Oct 27, 2009 1:18 am Post subject:

Yeah the WUR is pretty well buried, but you don't need access to test it. It's attached to the rear of the intake manifold. There'll be 2 fuel lines and a vac line attached to it. The vac line causes it to open up, lowering control pressure, which causes the fuel distributor to send an extra rich mix to the injectors at wide open throttle.
The rest of the time it varies control pressure based on temperature - that pressure is lower while cold which causes the mix to be enriched during warm-up. The elect. is for a built in heating element - the element along with radiated temperature from the engine cause the WUR to close to a point as the engine warms up. -So the elect. test, while useful, doesn't test the most important function - that is the fuel pressure. To test that, you need a CIS fuel pressure tester. JCWhitney sells them at approx. $60. They test both primary (aka- system) pressure and control pressure. The tester hooks up right at the top-center of the fuel distributor.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

bnoon · Posted: Tue Oct 27, 2009 11:00 am Post subject:

Smoothie · Posted: Tue Oct 27, 2009 2:00 pm Post subject:

When hooked-up correctly, and with the testers' valve opened, you're testing control pressure.
With valve closed, you're shown primary (aka- system) pressure.

CIS fuel pressure tester hook-up -

Here the valve is open and control pressure reading shows as 53 psi (engine warm) -

Circled fittings are the ones to use -

80 psi would be low for an '80 931's primary pressure. That should be between 84-94 psi.
Your control pressure (warm) should be 50-55.8 psi.
Your control pressure (cold) should be 29-34.8 psi.
_________________
"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox