macadamianut

Can I just remove the belt cover to check alignments?

I don't know so much about vibration under accel., but it sure feels like it hesitates in two spots. Almost feels like what a bad TPS would do. One is right on the bottom (like as soon as the clutch pedal is released an you get on the gas from a stop light) and the other is near 4000 rpm. Maybe described as a distinct "hole" on the bottom and a "surge" on top.

To test the solenoid, is it okay to hook up any 12v battery? Or something less powerful?

In the process I found that the plastic vacuum hose coming in to the top of the heater valve has rubbed itself nearly open against the side of the valve. Will be fixing that too.

RajDatta

Another thing to check in the area is your hall sender. Due to its location above the header, it tends to get brittle and break. This could potentially be causing some of your problems.
You can sometimes have a misaligned balance shaft sprocket and not know it. You can test by trying to stick something into the two notches on the balance shaft. One of them should have the woodruff. Check Clarks Garage for instructions on this.
Not 100% positive if testing with a battery would have any adverse affect. I would assume it to be safe. When was the last time you had your ignition system overhauled. Some of these hesitations could be bad distributor cap/rotor/wires.
Do you have another 968 oner that lives close to you. Maybe swapping some parts to test might help.
Raj

macadamianut

Raj, thanks. No history on the ignition combo. Was on my list for this summer before the transaxle issue surfaced, figured that was the really important one. The hall sensor plug seemed fine when I pulled it for extra valve cover clearance. jpk and miles968 are close, but I really hate to bother anyone if I can take care of it myself. I had an independent Porsche tech do the belt service, so I am unfamiliar with the procedure, I will look up the DIY so as to get the belt cover off and check alignment/cam timing.

I had planned on using an old 12v motorcycle battery to test the solenoid, I hope that won't fry the thing. Is there a distinct positive/negative on the sensor? Color of wires running to it indicative?

Will order valve cover gasket, grommets and plug hole seals to seal her back up tight.

What spark plugs have you all decided are the best??? I replaced mine 10k ago with Bosch platinum + 2's. Don't know if this is a bad plug for the car that is complicating or is directly responsible for the rough idle?

RajDatta

Mac, I think it should be easy to determine the hot lead. Just disconnect the variocam plug on a car and rev it to 1500 rpm and you should see a 12v signal on one of the leads.
If the Indie is reputable, I am sure he checked the bs sprocket orientation. This is what I would recommend. Do a good tuneup, which should include plugs, dist/rotor. Check the wires for cracks. Also, consider servicing your injectors, it makes a huge difference. I have used Bosch WR7DTC in the past and they are oem. I don't think they are made any longer. You should try to run copper instead of platinum plug.
Also, it would help getting a 2nd opinion on how your car runs in comparison to other cars.
Raj

Jfrahm

You can use a 9v battery, like from a smoke detector. It does not matter which side is positive if it is not in-circuit.

-Joel.

macadamianut

Tested solenoid with 9v. Click off with no problem (car battery disconnected.)

Forgot to mention that the other day I noticed what sounded like a pressure (or vacuum, I'm not sure) leak from near the firewall end of the engine, immediately after cold startup. Is there a vacuum control for the variocam that could have anything to do with my clatter? I do not have a lift, so self-services are on the limited end and I'm hoping the that it doesn't turn out to be the oil pickup tube.

RajDatta

Vacuum leaks are never good but your vacuum leak should have no effect on how your variocm operates. The fuel pressure regulator does have a vacuum connection. I would check into that area and fix all the vacuum leaks.
Raj

FRporscheman

Try running the engine with the variocam unplugged. My friend's 968 makes a variocam noise at 1500 but it sounds perfect with it unplugged. That's a sure way to test your solenoid.

How about a bad lifter?

macadamianut

It would appear that I am being overly cautious (****) at this point.

Special thanks to jpk for stopping by to listen with his "auto stethoscope, calibrated ears, etc." He has helped me to know how these cars "normally" sound and idle. We did discuss that the 5w-30 Mobil1 I last put in might be on the thin end, and as such it might benefit the car to revert back to 10w-40, etc. So hopefully, I am only dealing with sorting the transaxle now. Yea!!!!! (Wait, what? How much??)

Thanks to all for the helpful advice and suggestions.

Jfrahm

My black car makes a 'braaap' noise when the variocam switches. If the variocam is unplugged the noise goes away. Some say this is indicative of a cracked oil pickup causing low oil pressure to the variocam unit. This is something I need to check out. My blue car does not make this noise.

You can hear the noise by blipping the throttle in neutral. Brap-brap as the RPMs go up/down. Pull the variocam harness and the noise goes away.

-Joel.

RajDatta

Do you mean the J-tube that connects the oil feed to the variocam unit? If so, it is an easy swap. You can do it with the cams and variocam intact. Remove the valve cover. Just need the two crushwashers and the checkvalve o'ring.
Raj

JDS968

Sounds like an Irish mechanic

Jfrahm

No, my J tube is fine. The suggestion I got was that I had a cracked oil pickup tube in the oil pan. I do not quite make the connection between that and the variocam rattle, but anything is possible I suppose. If this tube is cracked it might get worse (but it hasn't) or break completely and leave me stranded one day.

-Joel.

RajDatta

There is a connection. The oil pickup tube, if cracked will suck in air. The variocam unit is pressurized via oil pressure feed. That is why when you retime the cams, you are supposed to pressuze the variocam unit via compressed air.
If you are sucking air into the oil pickup, the variocam unit will lose some of it's oil pressure when it is getting activated, because instead of oil pressure, its getting air.
Does it make sense? The oil is fed into the variocam via the Jtube.
Raj

jpk

Raj - wouldn't you be seeing big fluctuations on the oil pressure guage if the oil pump was sucking air?