924Board.org

[foxtg557]

So I finally got my engine running without it shutting itself off. So I took it for it's first test drive. It lasted for about 20 - 30 seconds of decent driving before it started rocking front to back heavily and started stalling. After stalling, waiting a minute or so, starter up, starts up good, does the same good drive for 20 or so seconds before the rocking and stalling occurs again. I'm trying to find the problem here, this car has not been driven in years, so I'm sure theres plenty of things which could be wrong.

Another thing, which could be causing the issue - vacuum lines, when I got the car there were lines all over the place, not going anywhere, and plugged up with wine bottle cork :S... I have been unsuccessful in finding a diagram which shows where these lines are suppose to go, any help would be greatly appreciated !

Thanks,
Dave.
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77 924, It Drives !

[2Fast]

Those vacume lines could be why it is stalling.....The 924 has exhaust recirculation.....So, it could very well be "smoking the engine out". That is very cool that you got your car to drive though!
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=====>Alex<=====
1979 Porsche 924 NA 5spd
1979 Parts Porshce 924 NA 5spd

[foxtg557]

Haha, yeah i definitly had a big smile on during those 20 seconds of drive time. I know i need to get those vacuum lines sorted out, any idea where I could get a diagram? And I wouldn't mind replaceing the intake boot that's on the air flow sensor and the intake boot on the throttle body, anyone know where I could find replacements for those?
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77 924, It Drives !

[Chewtoy]

What all have you done to the car since it was sitting?

It does sound like an air or fuel issue. I would lean more to a fuel issue actually.

These cars can be quite testy if the CIS isn't working decent on them.

you mentioned wanting to replace the boots, is there tears or holes in them?

As for the vacuum lines, they all run accesories. you can get away with blocking them all except the brakes and distributor for advance for testing. And actually you can block those but I would really only do that just for testing purposes.
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'77 Yellow 924

[Ozzie]

Not sure what your local requirements are but here in Oz we only have this setup.

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

[Chewtoy]

OZ,

Your brake booster line 'Y's off and goes into the intake duct?

Otherwise same setup I have except mine goes straight into the intake. It used to have a vacuum canister in the passenger fenderwell but was damaged during an accident the previous owner had so I removed all of it.
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'77 Yellow 924

[Ozzie]

Thats right and you can only fit the "Y" one way.
Scared the crap out of me fitted the other way, no booster.

Crankcase breather goes to either the intake join or the air box.
I now have mine on the air box.
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

[foxtg557]

2Fast: The smoking out the engine thing could be an issue - there is an intake just to the left of the throttlebody and down - it's attached to the intake manifold, it's a big hole that sucks a lot of air, it's wide open - no clue where it goes, so atm I've plugged it, seems to have made no difference, but it could have been sucking exhaust back into the engine - smoking it out like you have suggested.

* I can idle the car for just about as long as I like, I can rev it up and down etc. It's the driving part that has become the issue, When im driving it do I get those symptoms of decent drive for 20 seconds then crapping out. When it stalls, I can restart right away, but I've found that waiting 20 - 30 seconds before I restart it will give me more power when i resume driving...

Another thing, maybe related or might help someone pinpoint an issue - Theres an electrical 2 wire connector on the air flow sensor right by that air lifting plate. When it's plugged in, my car will fire up and die instantly... When it's unplugged, my fuel pump will run constantly while either - the key is in the on position or while the car is running, and the car will idle / rev / and drive as described. Currently I've left it unplugged...

I'm suspecting fuel issue here ?

Chewtoy - The car has sat for as far as I know, 6 years total. I have had it for 2 years, it's sat while i've worked on it over these past 2 years.

I have done

new oil pan, alternator, fuel pump, exhaust, cleaned a lot of ground wires, replaced the 3 ( i believe it was 3 ) big ground wires. Replaced fuel / air filters, new battery, tried to seal up any vacuum leaks, new fuel injectors... I might be missing some things. A lot of diagnosis as in taking fuel pressure readings havent been done as I am very unequipped .
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77 924, It Drives !

[968rz]

You really need to check your fuel pressures, if I'm right, the two wires you mentioned are for the pressure regulator. Are fuel lines attached to it?
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Rick
79 924 coupe Petrol Blue 3spd auto (wife's DD)
93 968 coupe Amazon Green 4spd Tip (my DD)

[Chewtoy]

Ok, then the basics were done. Which is what I was curious of.

Still think it sounds like a fuel delivery or air intake issue.

The Item you are referring to on the intake is not listed in the book I have. I remember seeing it on my old engine as it had completely rusted away. I plugged it just as a precaution but it didn't have any effect on the running of the engine.

The wire you are referring to goes to the CIS. My understanding is minimal of the system, but seems I am learning pretty rapidly with mine.

A quick run down of what I know is this:

As the engine turns it pulls air through the intake and intake tubing. Inside that box attached to the air filter is a "flapper" valve. As more air is sucked in it lifts that valve more, and in turn delivers more fuel. With that in mind it is critical to make sure that there is no leaks within the intake or tubing so that the flapper valve is drawn correctly.

I don't know how the fuel distributor works, would love a run down of it sometime myself. All I know is that it doesn't matter where the injector lines connect to it. Which just confuses me even more.

Anyway, check your "flapper" valve operation, make sure it moves freely and isn't getting pinched. I saw a simple test on another thread to check it's functionality. I'll see if I can find it for you and paste it here.

I look forward to hearing what is found from it, and will let more knowledgeable members assist from here.
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'77 Yellow 924

[968rz]

The thing on the left side of the intake is your EGR valve, if you plug both holes (at the intake and the pipe that goes down to the exhaust) you can run with out it but it might ping a bit with cheap fuel.
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Rick
79 924 coupe Petrol Blue 3spd auto (wife's DD)
93 968 coupe Amazon Green 4spd Tip (my DD)

[foxtg557]

968ez - The connector im referring to connects to the CIS - where the air sensor / fuel distributer things are. As to my pressure regulator, there is a connector there, it is plugged in, and there are fuel lines connected...
I agree, I really do need to check my fuel pressures and see what's going on. Since I am poorly equipped, pressure testing is difficult, are their any good tests for the poor mechanic?
And I'm not referring to the EGR valve, i'm referring to some hole about 3/8th's wide, sucks a lot of air, if u look straight down onto the intake manifold of my 924 there it is... but I believe it is a non issue, I have it plugged up.

(as mentioned, with regard to that connector on the CIS which I have off - which makes my fuel pump constantly run - My engine only runs / idles / revs / kinda drives while my pump is constantly run. )

I'm begining to suspect a lack of fuel pressure while driving, this is leading me to believe that since my fuel pump is new and my fuel filter is new, then all that's left on the fuel line are the accumulators ( i believe I have 2 20 cc accumulators ), the fuel distributor, and the fuel pressure regulator. I believe my fuel distributor is working properly, which leaves the other two - which deal with fuel pressure and could be an issue ...

Chewtoy - I think your right, I can plug the hole im referring to, it doesnt seem to have much effect on the engine.

You are correct in your understanding of the CIS system, I have become pretty familiar with it's basic operation over these past couple years. I have checked my CIS, checked that air sensor plate (flapper) and it is in good working order, moves freely and all that.

As far as I know with that fuel distributor, when the air sensor plate flapper thing lifts, the distributor allows fuel to go through all four fuel lines to the injectors.
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77 924, It Drives !

[968rz]

Sorry, 79s must be different, I don't have wires to my dizzy other than the pressure reg or the hole (i thiink?) but any vacuum leak is bad.
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Rick
79 924 coupe Petrol Blue 3spd auto (wife's DD)
93 968 coupe Amazon Green 4spd Tip (my DD)

[Chewtoy]

I think you both are right, just referring to a different item.

The electrical wire connects to the CIS just under the boot at the flapper end. Which is what fox is talking about.

The EGR connects to the back of the top of the Intake. which is what 968 is referring to.

The third item in on the no. 3 cylinder runner in the valley of the intake. And that I have no idea what it is. the engine I have now does not have that item and it was rusted away on my old one.
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'77 Yellow 924

[foxtg557]

Agree's with chewtoy - the hole is on the # 3 cyl on the intake... but anywhoo, still not sure as to why my car dies when driving .

Still open to opinion ^_^.
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77 924, It Drives !