Tuesday 10 August 2021

Porsche 996 911 - Ticking noise on startup? Checking spark plugs and investigating carbon fouling on 2 of them.

 Bit fed up with this car... one step forwards, 5 steps back. 

After letting it sit for a week... tried starting it yesterday and hearing a ticking noise 🙄 and instant stall. Won't start it again!

Let's do a few basic checks.

Today got the mufflers off and coils/spark plugs out. Having done it before, only takes 30 minutes or less for both mufflers out, and same amount of time for coils/plugs.

Wheels didn't have to come off, but it was a nice day... gave them a real good clean - the three I could remove anyway, the front right will have to wait for another day.

Spark plugs out - wondering why 4 & 5 are carbon fouled while the rest look fine? Literally 0km driven and maybe 10 starts out of these plugs.  All were wet from fuel, which you'd expect for multiple attemps to start the car.

typically carbon fouled plugs indicate
  • rich (too much fuel, not enough air)
  • lots of idling/low speed driving (nope that car hasn't idled or driven for months!)
  • faulty ignition system, retarded ignition timing... ???

Tomorrow is some borescoping with my $5 scope (don't know how well that will work) and a compression test.


Sunday 8 August 2021

Fix porsche cayenne rear hatch boot trunk falling down - replacing gas struts DIY for cayenne 955 9pa

 Day 3 of lockdown #6 and no end in sight. Guess I've got a little free time to do those little chores I've been putting off.

The rear hatch on the cayenne has been falling down for a while now, and I've had replacement parts sitting around waiting to be installed.

You need

  • Replacement gas struts for the rear hatch and rear window
  • Flat and Philips screwdriver, Torx bits

Prop up the rear hatch with something and hold replacement parts triumphantly.

Skipped a few photos - but pull on the rear centre roof trim (with the little light in it) and unclip the light. Then remove the screw hidden behind a little flap on the side panel, pull off side panels. That'll expose this white bracket which is held in by 3x torx screw. Remove it and set aside.

Pull down the rubber gooey flap hiding the gas struts. To remove, get your flat screwdriver and pry ovv the metal retaining clips at both ends. To get to the rearmost clips, look at the external hinge and you'll be able to access them easily.
The large strut is for the bootlid, and smaller one for the glass window. Replace both - don't try to save a few bucks by only doing the bootlid!

Before installing the new struts, you need to lift off the retaining clips, but not remove them entirely. Slide them towards the ball end of the strut using your flat screwdriver, they'll stay attached, then you can slide them into place once installed to lock them in securely.

Mission done. Bootlid is held up high with no drooping.

Friday 6 August 2021

Porsche cayenne 2004 (955, 9PA) brake booster faulty repair - P1914 P1431 - fix for almost free!

 So the other day, was driving the trust cayenne home from work and got yet another fun fault message

which never sounds like a good thing in a old 2 tonne 4WD. Plus of course warning lights for empty windscreen washer and an airbag fault - things which I'll fix later on.

Code reader shows P1914 (Brake booster pressure sensor) and P1431 (Brake booster system).
One thing about old european cars - whenever there's a problem with them (and there's lots) it's an opportunity to learn something new.

Basically the brake booster system makes it easier to stop this 2 tonne 4WD - reduces the amount of braking force needed by your leg to slow/stop the car. A bit of wiki knowledge later, and know we know the engine vacuum (from intake) magnifies the force when pushing the brake pedal.

Further google-fu shouws this a reasonable common problem - the best link I found was to https://www.renntech.org/topic/31161-brake-booster-faulty/ which had many contributors commenting they had a crack in the vacuum line to the brake booster - so we can understand why we have that error message.

Search for "porsche cayenne brake booster three way pipe" for the most likely culprit - but don't buy any parts until you've confirmed the source of the problem!

To access the brake booster, it's tucked in around the coolant reservoir, windscreen washer filler and torque arm. Remove the plastic covers using a coin to twist open the big plastic locks and remove the single bolt tucked under the windscreen filler cap.

Fortunately, was able to easily identify a big crack in this vacuum line to the brake booster - it was just under the torque arm, behind the air intake box.

Pretty important to fix - with this vacuum leak, it'll cause the brake booster pump to run a lot more than usual, causing it to overheat and fail. I'm sure that'd be an expensive part to replace!

The lower plastic pipe came off easily because of the crack.

Now, we're in lockdown #6 in Victoria, Australia, with no end in sight... the price for a new three-way tube is something like $200 of course. Anyway, I grabbed a bit of 1/2" ID heater hose (always handy to have in any garage) and some spare hose clamps. Pop a little WD40 in the hose, and slide it over the cracked part of the tube, making sure all the cracks are covered by the hose - and attached the other end over the one-way valve (that disc thing with large barb attachment). Snug up the clamps, but not too tight.

Turned on the car, felt around for any vacuum leaks (the first time I put the hose on, it didn't go down far enough to cover the crack). Used the code reader to reset codes, and all is good again!

However, if you read the renntech contributions, there could be more than one crack at any attachements of the three-way hose. There's also other vacuum connections to/from the brake booster, and a vacuum leak at any of them will cause a similar fault message. WOuld recommend replacing the three way hose if more than 1 crack is found - so when the next brake booster error message appears, will do another check and order the part.

2004 cayenne turbo white smoke - not AOS but broken crankcase breather hose DIY repair

 So the other day noticed a huge amount of white smoke when starting the car cold, and a very high idle (1500rpm) when in neutral or park. R...