83 930 - New Toy!

[kostya.lyt]

I've recently acquired an '83 930 and it's having some popping/clicking noise under acceleration. What could cause this? I've found some missing sealing rings on the pressure pipe (both sides - turbo and intercooler), the pressure pipe was easily turning and moving up and down 1/2".

Any thoughts?

Thanks!

[Ronnie's.930]

Man, very difficult to say without more specific details of the sound and when you hear it (could be many things).

Clicking is usually associated with the diverter valve (metal piston in it smacking against the end caps when the seals there have deteriorated and turned to powder), that sound is usually heard when the throttle is suddenly closed (like when blipping the throttle at a standstill). But the sound made by compression loss due to broken headstuds could be described as clicking/popping and that would be heard under acceleration.

Is there any way that you can describe the sound, and conditions when it happens, in a more specific way?

[jsveb]

Detonation, or pre-ignition?

[zcoker]

It could be a broken head stud, similar symptoms. Pull rocker covers and check rocker shafts and, while your at it, check those head studs.

[oilonly]

I've found some missing sealing rings on the pressure pipe (both sides - turbo and intercooler), the pressure pipe was easily turning and moving up and down 1/2".

Well you will have to get that fixed first and then take it back out for a drive.

Just a guess here on what it might be by chance if not your loose charge pipe.
Bye Bye Clicking Sound..A Slow'N'Rusty Pictorial - BOV Housing

[kostya.lyt]

Well, this evening I replaced all of the o-rings and seals on the pressure side, it was missing both of the "seals" that go on charge pipe. It certainly helped the idle considerably, it is much smoother and quieter now.

The bad part is that the popping is still there under acceleration. It doesn't sound like a high-pitched exhaust leak, but a more "substantial" and lower tone exhaust pop. It doesn't pop when slowly building the RPMs to about 3,000 or so, but it does pop at low RPMs with more of a load and under acceleration.

[WERK I]

Originally Posted by kostya.lyt

Well, this evening I replaced all of the o-rings and seals on the pressure side, it was missing both of the "seals" that go on charge pipe. It certainly helped the idle considerably, it is much smoother and quieter now.

The bad part is that the popping is still there under acceleration. It doesn't sound like a high-pitched exhaust leak, but a more "substantial" and lower tone exhaust pop. It doesn't pop when slowly building the RPMs to about 3,000 or so, but it does pop at low RPMs with more of a load and under acceleration.

More than likely a backfire. It's a lower tone because of the long path back (throttle body, IC, turbo, plumbing) to the fuel metering plate. Does it happen only when the engine is cold or all the time?

[kostya.lyt]

Originally Posted by WERK I

More than likely a backfire. It's a lower tone because of the long path back (throttle body, IC, turbo, plumbing) to the fuel metering plate. Does it happen only when the engine is cold or all the time?

All the time, although it seems to get a bit worse when it's warmed up.

[wildturkey]

Head studs?

[totle]

Think Oilonly nailed it.

Check the gaskets in the blow off valve.

[kostya.lyt]

Originally Posted by totle

Think Oilonly nailed it.

Check the gaskets in the blow off valve.

Would this cause a significant backfire?

[krasuskyp]

no, the shuttle valve end seals merely create an audible 'click / clack' when you snap-lift off throttle - you're hearing this UNDER ACCEL, not let-off...

you're either really lean, or your timing is off, or both

go thru the diag basics - need timing light for timing and CIS gauges for mixture...

...but, you can start by turning the air meter hex plunger bolt atop the fuel distributor to try to dial in small incremental amounts of fuel (turn Right for Rich / Left for Lean) and re-try

good luck

[wjfk32]

Pull your plugs out--check/clean or replace
Chk afrs
Chk ignition-coils-box-wires--etc..etc..
Chk Hoses-lines-vacuum

Also-sounds you are running on 5 cylinders or/missing or detonation--not building boost. Similar situation happened in the passed with me. I would clean the plugs. Run well for awhile, then crap again. Changed all injectors-put an msf6al&coil-epoxy..plugs..cleaned distributor-fuel filter-fuel pumps etc..etc.... I did go extreme-but age/parts is a reliability factor. All worked out in the end.

[krasuskyp]

oh, yeah good point - I had wicked popping (misfiring) when my distributor cap got scuzzy...

a vid would help us see what it's really doing, shouldn't be hard to shoot / post one...

[kostya.lyt]

This evening, I pulled the wastegate to be sure everything inside of it was OK, as well as check the seals on the Air Bypass Valve, they were fine. Like some of the responses above, it is looking like some sort of FI or ignition issue (all ignition components replaced less than 100 miles ago). Also, I found the smaller of the two vacuum tubes going to the distributor completely broken near the distributor, this was fixed today as well.

A few questions:

- Can the air cleaner assembly be easily removed without removing too much around it?
- What kind of seal goes between the throttle body and the large cast piece (pardon my ignorance) that the intercooler seals to?

Wastegate...





What should this tube be connected to? It's almost like a "collector" running from fittings coming out of the bottom of the head.



What is this unit? How should the hoses be connected? Currently, one of them is just plugged.

[oilonly]

What should this tube be connected to? It's almost like a "collector" running from fittings coming out of the bottom of the head.

That used to go to your smog pump. I would say make sure it is plugged as exhaust will be coming through there if not.

[patina]

I hate to say it but head studs?

[Ronnie's.930]

Originally Posted by kostya.lyt

- Can the air cleaner assembly be easily removed without removing too much around it?

Yes - a bit difficult to remove some of the bolts due to limited space but can be done.

Originally Posted by kostya.lyt

- What kind of seal goes between the throttle body and the large cast piece (pardon my ignorance) that the intercooler seals to?

The large cast piece is usually called the secondary intake manifold and/or the diverter valve housing - it seals to the throttle body via the following orange, silicone o'ring (several brand options to choose from).

Pelican Parts - European Automotive Parts and Accessories - Porsche • BMW • Mercedes • Volkswagen • Audi • Saab • Volvo • MINI

In picture #3 above - it was originally connected to the air injection pump which is drive by the left cam (pump is on the left side, directly behind the driver's seat) - emissions related device meant to increase exhaust temperature - many people, myself included, remove this system altogether.

[kostya.lyt]

Here's a quick video I took a few minutes ago. Even blipping the throttle at idle makes a popping sound, not near as much when slowly building revs.

Porsche 930 Misfire - YouTube

[DSPTurtle]

Check the seals on the recirc valve before you get too worried.