My 996 3.4 C4 Cab project.

Last weekend I bought a 51 plate 3.4 C4 Cab with Tiptronic. I’ll be honest, it broke down on the way home and I’m currently in dispute with the auction house I bought it from, but that la another story. It has various faults which were not disclosed and I’m after honest but helpful advice with regards to sorting them (run a mile isn’t helpful, I’m past that option sadly). The gearbox only uses 1st, 2nd and reverse whether in manual or auto modes. In the last 10 years the car has covered approx 1000 miles. Is it likely that new transmission oil/filter will help at all? What else could it be? Cylinder 1 has a misfire. This afternoon I got under the car and changed the coils between 1 and 3 cylinder. Cylinder 3 still runs fine and 1 is still missing, so it doesn’t seem like the coil is at fault? I’m hopeful it might be the spark plug but the fear is it could be compression issues. Next step will be swapping the sparks between cylinders to rule sparks out. Any other suggestions? The brakes are awful, I’m hoping fully flushing the brake system will improve the brakes, fingers crossed. It needs both front window regulators replacing, but I’ve done these on other cars. The only thing g I’ve spent out on so far is a new battery (in the hope it would clear the gearbox issue). Watch this space, I’m really hoping I don’t get burned badly in this…….

I wish you luck and good fortune! I’d first plug in a decent code reader and see what shows up. Maybe Compression test the cylinders before you start throwing any more money at it if swapping spark plugs doesn’t work. Sorry I can’t offer any suggestions on a Tip ‘box. If it’s a lemon try to get a refund.

Sorry to hear your issues. Unfortuantley beyond my technical skill level once you get past coils and plugs. Do you have a code reader? That might help you narrow down the symptoms. Brakes are soft compared with modern cars, but a fluid flush can help - what do the pads and discs look like? Check the rear of the discs as well, sometimes tney look good on the front but can be deteriorated on the rear. Might also help if you add your location as there may be someone local that could offer help? Good luck and keep us posted on your progress.

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I basically code reader brought up P0301, cylinder 1 misfire.

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I have an Autel reader that I bought off a mechanic friend. It’s great for average cars but doesn’t have any Porsche software downloaded. I’m based near Chester.

If the car is misfiring and the engine check light is on, it will go into limp mode and stop the box from changing up. Sort the misfire and clear any fault codes and see where its at after that. There are numerous things that can affect the tip ecu , wheel speed sensors, brake abs unit, amongst other fault codes ,the gearbox itself is most likely ok.

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Oh wow, so fixing one issue ‘could’ sort both out??? That would make me very happy!!! And yes, I do have ‘check engine’ light.

Some minor progress today. A new spark plug in No1 cylinder cleared the misfire! I still have the gearbox issue of not changing beyond 2nd gear. It flashes 4 and D in the selector, so it’s still not happy. I also have the ‘check’ light lit, so need to get it read properly. But it sounds lovely at least………

have you disconnected the battery after replacing the plug to do a system reset on the gearbox? sounds like its still in limp mode.........

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I’ll give it a try!

Well this weekend I replaced both window regulators and the drivers window motor. They now work pretty spot on. Tomorrow I’ll visit my local Porsche retailer, Cheshire Oaks and order the parts for the Tiptronic gearbox fluid change which I’m really really hoping will help with the gearbox fault. Fingers crossed. The car isn’t as it was advertised and I was disappointed with my 1st Porsche purchase, however with each job I fix, I’m loving it a bit more. I just hope I can get it running and changing gears proper.

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As for the auction who was it and is the link still live ? On the gearbox , if it is still only using 1st, 2nd and reverse, and you are getting flashing D and 4, then the box is clearly still unhappy and storing a fault. At that point I would be careful about pinning too much hope on a fluid and filter change alone. If the fluid is old and the car has barely moved in 10 years then it is worth doing anyway, but I’d see that as sensible baseline maintenance rather than a guaranteed fix. The good news is that Tip boxes will often restrict shifting because of an electrical or control issue rather than because the gearbox itself is mechanically finished. So before condemning the transmission, I’d want the car read properly on something Porsche-friendly and see what the Tip ECU is actually complaining about. As already mentioned, wheel speed sensors, brake switch / ABS faults and related control issues can all upset the Tip. So where I’d be now is: misfire sorted, clear that from the list read all fault codes properly, not just generic OBD engine codes see what the Tip control unit is actually storing do the gearbox fluid and filter because after 10 years / 1000 miles it is overdue regardless then reassess before assuming the box itself is bad it's key get proper Porsche-level fault reading on the Tiptronic side before spending too much money in hope rather than evidence. The fact the misfire was simple is encouraging. Hopefully and typically the gearbox turns out to be something simple like a sensor rather than hard parts.

Brakes, thankfully easier to sort but time would have had an impact given a length of inactivity I would go in with low expectations for a simple fluid flush magically fixing them. It absolutely needs doing, but if the brakes are “awful” I’d be looking closely at: seized sliders / pistons old pads corroded discs tired flexi hoses fluid that is ancient So again, flush it, but don’t be surprised if it needs more than that. Genuine Porsche & Aftermarket Brake Pad & Disc Packages | OEM Braking Kits | Design911 parts.911uk.com

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That’s exactly what I was thinking. I was chatting to one of the techs in Porsche this morning and they said the same, get the service done, then get the codes read and looked at. From that point I’ll have a proper idea what needs doing and how much more needs initially investing into it.