GBX

I plan to do a full tuneup on my motor, as I’ve been getting misfires on all cylinders recently. The PO did caps, rotors, plugs and wires 7 years ago, but only about 5,000 Miles but my tech did notice wear on the wires and caps so I guess I’m due. Parts would be as follows:

spark plugs (12)
spark (ignition) wires
air filter
fuel filter
cabin filter set
distrib. Cap X2
distrib. Rotor X2

having trouble finding part numbers on the above. I want to compare pricing. Anyone have those handy?

oil and filter change and brake fluid flush is already done. Anything else to consider doing for a tuneup? Thanks guys!

Churchill

I would be shocked if your wires, with 5K miles on them, show "wear." You can inspect the lower wires, which have sharp bends and are exposed to exhaust heat, for cracks, and you can test resistance through them. But I doubt you need any of the stuff replaced that was done 5K miles ago. Common cause of misfire is using non-Porsche v-belts. Belts cost something like $20 each and can be changed in under an hour. Start there.

Also, FWIW, I am deeply skeptical of "parts changer" techs whose diagnosis of problems does not involve actually figuring out the problem but recommending to the owner a list of parts that can be changed out, with many billable hours for the tech.

P-daddy

GBX

Thanks guys. I’m doing belts too so maybe I’ll hold off on the “tune up” and see how she runs with the new belts.

pp000830

I would just consider caps and rotors.
Misfires on multiple cylinders is quite often a vacuum leak. In such a case replacing expensive stuff won't solve your problem. I would do incremental parts swapping and see what makes your issue go away in the following order:

1. Check for vacuum leaks
2. Verify the distributor belt is in place
3. Replace caps & rotors, clear the code see if the code returns.
4. Replace wires. My wires were replaced 10 years ago and are still working w/o any OBD codes. Clear the code and see if it returns.
5. Replace spark plugs, our cars use extremely high voltage so even a nasty plug will fire.

If you do it all at once you may not solve your problem even though you spent a lot of money.
Better to identify the specific issue first.
Andy

GBX

Extremely helpful. Thanks!!

pp000830

Also, spray out the idle valve with some carb & choke cleaner when you replace the caps and rotors as it may contribute to misfires at idle. The valve is easy to get to and clean on top of the engine and really never needs to be replaced. It functions to adjust mixture at idle.
Andy

BobbyT

+993 what Churchill said: " Common cause of misfire is using non-Porsche v-belts." And they MUST be the ones that have "Porsche" stamped on the belts. Although the OEM belts may be from the same manufacturer, there is something different about the Genuine Article, even though the measurements may all be the same--maybe the flexibility? Some special magic rubber? I dunno, but I'm with Churchill on this one.

fsa

Ditto above.
Dayco non-oem "Porsche" v-belts triggered 3-consistent "misfire" codes.
Remedied with Porsche stamped Dayco belts. They differ in circumference and width, by a few mm, likely enough to trigger sensors. The number of inner belt serrations differs- more on Porsche stamped belts. Seem more pliable.

GBX

Porsche belts are on the car but replacing them anyway as they are showing some wear, along with the tensioner which is cracked and basically shot. Decided to do caps, rotors and plugs. Wires seem fine upon further inspection so wont touch those for now. Engine should be running great after this!

Churchill

Hopefully it's the belts, but may not be.