Hey guys,
I know this has been covered many times, but not sure if my issue is the same

My car started running rough few days ago.. went to the garage, got diagnosed it's crankshaft position sensor (signal too low). Got that changed today, and guess what, the problem persists! It's not throwing any faults at the moment.

1) Garage was struggling to fire her up after changing the sensor, so they considering the fuel filter in the tank? DO you think this would be logical to get that changed? Is there a pressure they could potentially measure and see if it gets enough fuel?

2) I instructed to check the notorious coils.

3) This will probably sound silly, but heard that bad battery may cause lots of problems and not sure whether it's Porsche itself or the battery but the starter seems to start really slow and then after a good second picks up the speed and fires up. I have honda accord and chrysler 300c (diesel) and their starter just kick in at full speed straight away. Still not sure if it's a battery or starter.. If it's a battery, would you think this might be related to rough running?

Any advise would me much appreciated

 

Need to know how many miles are on the car.

Does it sound rough, or does it feel rough? Torque arm on the top of the motor can make the car shake at idle if it's failed. They seem to go around the 80K mark. When was the last time you put in new plugs?

The garage should know how to test for fuel pressure. If they don't - take it to a Porsche specialty place. Otherwise, you're going to just pay for them to make guesses. If the car has good fuel pressure, no reason to think it's a filter or pressure problem.

How old is the battery?

 

thanks for the advise wrinkledpants!
86k miles.

it sounds rough.. you press the accelerator and it wouldn't respond as it should.. the car is basically un-drivable..
Not sure of the plugs as only have the car for couple of months. Will be ringing porsche garage to find out as the previous owner was servicing car at porsche.

Unfortunately, don't know how old is the battery either...

 

It`d be worth checking, there should physically be a date stamped on it somewhere, pretty sure it was a "week/year" configuration e.g. 32/10

Would be worth testing it too while you're in there if you have a voltage meter but the only true way to test is with a dedicated battery tester that quotes AH IMO

It`d also be wise to check for a second battery below the spare wheel to ensure it hasn't went south and is dragging the entire electrical system down with it, unlikely but worth a look.....

 

plugs shoulda been done at 60k, so if they weren't....

 

now I'm getting worried..
battery changed 2013 (Varta), so theoretically it should be OK'ish ..

spark plugs changed at 38k and 70k...

Ignition coils is the only obvious issue which wouldn't throw a fault?

 

Coils would likely throw a misfire, but might not. I'd check the part number on the coils to see how close they are to the most recent version.

Otherwise, I'd start with a fuel pressure test. Might have them do a throttle body adaption, too. Turn the ignition on, but don't start the car. Let it sit for 15 seconds or so, and you'll hear the throttle body snap open and closed a couple of times. After it stops making noise, wait another 10 seconds for it to finish. Shut off car, restart.

Could also be a failing camshaft position sensor. Sometimes they won't throw a code for awhile, despite the car having symptoms (running rough).

Nothing to be worried about. Some issues take a bit more time to figure out.

 

Might be the fuel pump. There are two fuel pumps because the tank is lobed with the driveshaft cutting down the middle. Hence there are two fuses (under the hood near firewall) that can be pulled individually to see check. If your primary is going then pulling the fuse will force the secondary to run. If thats the problem you will know right away because it will drive normal. I forget what the fuse numbers are.. going to have to search.

 

thanks guys,

wrinkled pants, thanks for the info regarding the adaptation. Will forward this to the garage..
camshaft position sensor was changed yesterday..

endless_corners, fuse numbers would be brilliant, would pass them to the garage.. i've read somewhere about fuse 13?

They are going to check live data today, so would imagine they would be able to identify if the pump is not running as it should?

 

According to this post:
https://rennlist.com/forums/porsche-...l#post11549226

it's fuse 14. Will give it a shot, just wondering if the tank has to be full or something as I only got one quarter of the fuel left..

 

That's pushing it but you may have enough to tell. I don't know the exact level at which the secondary can't pump anymore.

 

I would go for it anyway... because its always fun to figure things out before the indy. If it run normally when you pull — go add fuel right away. Then shop online for your own damn part and dont pay mark up.

 

Don't rule out coils just because they don't throw a CEL. I just spoke with a tech at Sunset Porsche and he claims that they can gradually degrade and the ECU compensates but can only do so much. They are a wear item, and by the time they throw a CEL, they have completely failed.

Best of luck with your diagnosis.

Cheers,
TomF

 

thanks for all your support guys.

Went to the garage, took the car to the petrol station to fill the tank up. The petrol station was like a mile away but was quite a challenge to get the there as the car would just not respond to throttle..

Got back, pulled the fuse 14 out, but the problems remained. Hook up diagnostics and found multiple misfire fault, and some other specific cylinders misfire. Decided it's the time for spark plugs check... Mechanic didn't like couple of the spark plugs so got all 8 ordered straight away. Now the ignition coils.. Was hoping to see them all cracked (as in some pictures on the forum), however it wasn't the case.. all on the right hand side seemed to be OK, however on the left side (where torque hand is) we found two of them with slightly melted connections.. I could even see some rainbow kind of a colour inside which would indicate the was some high temperatures there.. so got them all ordered and will see where we are on tuesday when they arrive..
I feel like we are getting somewhere! If this fails.. I'm dreading to think it might be a trip to Porsche...

 

after all this positive thinking nothing happened after changing the plugs and ignition coils..

This really makes me worried now.. The symptoms are exactly the same.. when the engine is cold it's not even running on idle.. At the beginning we thought it's fuel pressure related and considered the fuel filter but I was playing with the throttle for a good 15min until the required temperature was reached and the car started idling on itself.. after another few minutes the revs started went up and ended up idling 1500rpm. It's probably a limp mode?

No faults on my mechanics bosh kts650, but he says Piwis is using same device, so looking into installing a software on his machine to see if we can see more info..

Any more ideas what could be checked over.. ?