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.

 

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.

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.

Checking fuel output before filter, and new 996 fuel filter installed

 

Before installing new fuel filter, tested quantity delivered by fuel pump before it enters the filter. Connected a hose to the fuel line, and activated the fuel pump for 30 seconds - got way over 850ml which is a good result.

 

New Mann fuel filter WK832/1 to install. Fairly simple... hardest part was getting the retaining metal band connected properly to the metal bracket.

Primed fuel lines to the engine - holds better pressure then before by about 0.5bar.

However, no change to startup - kicks over instantly, but then rough idle again sounding like fuel starvation. Next thing to do - remove fuel injectors and check for blockages.

porsche 996.1 changing fuel filter

 So... I don't actually have a fuel pressure problem I think - the fuel pressure gauge shows 3.8bar with fuel pump on/engine off, holding at 2.8bar for hours after.

Anyway, I'd ordered a new fuel filter off amazon which should arrive tomorrow, so spent today getting thte old one off.

Since the car was already on jackstands, remove a bunch of 10mm plastic bolts to remove central undertray.

Fuel filter is here. Remove the bracket holding coolant pipes, disconnect ground wire to fuel filter. Squeeze and remove the clamps for the filter inlet and outlet - have a pan or something to catch the fuel.

Push the filter backwards and slide it out between the coolant pipes.

This old filter was manufactured March 2013.

This shows the colour of the fuel that came out of the filter - pretty black! Replacement is the opposite of removal as usual. I don't think this will solve my starting then stalling issue, but good to replace with a new filter anyway.

Checking past work... is my new fuel pump bad or something else? 996 fuel pump low pressure and flow quantity

 On another cold rainy lockdown day, decided to run some basic tests to see if the work I've done so far is OK.

1) Vacuum test - unable to detect any leaks (will talk more about my homemade smoke machine later if I feel like it!)

2) Removed airbox, restart - no good

3) Removed airbox, removed drive belt, no good

4) Replaced everything except MAF, no good

5) Replaced everything and bypassed fuel pump relay with jumper wire - no good

6) Swapped MAF for a dodgy cheap yum cha china MAF bought from aliexpress - no good. Put back the Bosch unit

7) Swapped in two spare car batteries from my other cars - no good.

Then thought I might as well check the new fuel pump.

Porsche workshop manual specifies 850ml in 30 seconds output - this is well short!

Engine off, powered fuel pump on - only 2.2bar of pressure instead of the 3.8 it should have!

SO, is it a bad new fuel pump, or is there something else? Now need to check

• Check fuel filter - just ordered a replacement part, only $35 delivered for a Mahle filter, but won't arrive for a week. Change it out, then recheck pressure and flow. Try starting car.
• If still no good, check for low voltage to fuel pump (should be at least close to 12V). Perhaps a bad ground, loose connection, or bad wiring. Or maybe the voltage is fine.
• Obstructed fuel lines - visually check as much as possible for any crimps, bends, folds etc that would obstruct flow.

Making progress? Wouldn't call it that, but need to get this fixed anyway. What a saga.

Major service complete - still stalling!

 Welcome to lockdown #5 in Victoria, thanks to Glady's royal f#ckup with NSW "gold standard" contact tracing and quarantine.

Anyway, done some minor work in the last few weeks.

Pulled both exhausts off in preparation to a major service - replacing spark plug tubes, spark plugs and coilpacks. Might as well polish the exhaust tips while mufflers are off. Easy to remove - 17mm bolts on the cross pipe, and 13mm bolts x3 holding the muffler on.

Polished with 400-3000 sandpaper, then an orange cutting pad and wool fine pad with metal polishing compound. Nice!

Pulled off the old coilpacks - very old 996 items, plus some pretty well used NGK spark plugs.

Spark plug tubes are a fiddly and annoying thing to remove. I made a little tool with a long bolt and washer to tug the spark plugs tubes out, also had a 1" boat plug with sandpaper wrapped around it. A combination of both tools was able to remove all the spark plug tubes.

A view through cyl 1.

New coils are a Beru coil, comes with new E10 bolts.

Bought some spark plug tubes from ebay delivered from USA, did take ages to arrive. Cheap though.

Finally, some Bosch FGR6KQE spark plugs

Installed tubes, spark plugs and coils. Fitted up the original heat shields, using some new spare M8 rivets to space the heatshield away from the new coil packs.

Started everything up - had a great super smooth idle for 2 minutes... then it stalled. Restarted and stalled again immediately.

Tomorrow.... smoke test the intake system looking for leaks. If that's good, then go back a step of two - swap in another battery, then byopass fuel pump relay and check again.  If still no good, will remove fuel injectors and check for any clogging (eg if the old old fuel lines are perishing internally and blocking up the injectors)