Mda123

Hi all,

So my 955 05 Cayenne S is being a naughty boy today and refuses to start embarrassing me in front of the neighbors.

Turn the key and it cranks fine but will not fire up fully, jut the starter motor keeps wuring. needle flickers around 200 revs but will not fire up properly.

No check engine lights, but it did on one attempt come up with 'Low oil pressure' but it only did this once in 10 tries perhaps. Oil level is fine.
Last time I was in it was about a week ago and it was rather abused if I'm honest chasing friends in faster cars around the city. short fast bursts kind of thing, and after a while it did start to bog and lose revs on accelerating, loss of power. But after parking for a couple of hours it was absolutely fine when I came back. Not sure if this could linked.... was taken out on one short trip after this actually and was fine..

It has also done this in very heavy traffic before. An hour of traffic jam just rolling forward and it has started to really bog down and lose revs on acceleration with a rough idle too, almost hard to pull away like it was about to stall, but again, no CEL and park it for a while and its perfect when come back to it...... but still a concern.

Also after a full tank fillup once it did struggle to start and needed an accelerator pump to do so, so possiblly weak full tank vent line or something? could that cause this no start?

It's an 05 Cayenne S 4.5, just gone over 90k miles, new battery, coils done 12k ago.

It's just had a Facelift and Techart Magnum kit fitted to so im really really not keen on having to spend anymore money on it, so help would be much appreciated!

Many thanks!

touareg

Fuel pump failure, pull the primary fuse.

Shannon123

A good read on it
http://www.renntech.org/forums/topic...p-replacement/

Mda123

Cool guys! thanks a lot for the help. I pulled the fuse for the primary pump (fuse 14 I believe) And it still wouldn't start..... however I am parked on a side incline, driver side (rhd) up on the curb and with low fuel, 20 miles range, if this would make a difference? Ie. fuel not getting to one sides pump?

Shannon123

Maybe the gas is the entire issue ? Hopefully it is ! Might try to get 5 gallons in it somehow and retry .
I have no direct experience with this.....hopefully, someone will chime in with a timely helpful idea.

Of course....at some point, when this is resolved, we need some of the techart update pics.

Good luck

Shannon123

Hey guys.....been chatting with MDA123 and he has not yet remedied this......

Any other ideas on what could/ should be done next given the troubleshooting thus far ?

ciscorp

When you were running around town fast, did you ever floor it and the engine just missed or bucked while it was floored? If this happened at anytime it could be the Crankshaft Position Sensor located on the bottom of the flywheel cover on the drivers side. About a $60 sensor. The code doesn't seem to show up on the CEL until the sensor gets really bad. This sensor controls many things and acts like a distributor for reference to the ECU.

Then again Bad Gas and/or very low fuel tank levels can play tricks on any injected engine. A clogged dirty fuel filter gets worse with low fuel tank levels as well.

Was it hard to start after refueling?

Mda123

So today I had a good look at it, pulled fuse 14 for the primary fuel pump and still did not start, then pulled fuse 13 also no start. So I decided to check the coils for fun and 4 were cracked 2 badly cracked so maybe that can explain some rough running... but not the no start.... as should still start with some bad coils i think?
Also had a guy plug his laptop in and check for error codes.... and no codes found at all which i thought was strange.
Then I put some more fuel in with a jerry can to 1/4 tank and tried starting with fuse 14 removed again, and eventually it came to life, with a big bit of smoke........ It seems rough and noisy to me now though but then again I havnt driven it for 2 weeks so maybe im being paranoid :P is everyone elses Cayenne quite loud and ticking at idle?
Anyway I have ordered 2 new fuel pumps and coil pack and will document installing them for anyone else with similar problem

Mda123

Yes that did happen.... on accelerating seemed to not respond and lag.... hmmm I'll have to check this too then, will replace fuel pumps and see if same symptoms, but some coils are cracked so maybe its that...

Also yes when filling with a full tank you have to dab the accelrator to get it to start up, put half a tank in and its fine

ciscorp

Makes me wanna say "Where do you buy your parts?"
Sounds like your making progress and will have it up and running soon.

There should have been misfire codes reported but maybe they are not readable with your code reader.

From your description after refueling you need to replace your Purge Valve. It is most likely stuck open. So when you refuel the gas vapors are pushed into the manifold and flood the engine. Half a tank not as bad. Hold the gas pedal to the floor to get more air and she will start a little easier. Purge Valve is about $90 and is on top of the motor and runs down the drivers side.

Replace your coils and plugs and after driving 50 miles, floor it to see if the engine still starts to buck or miss to check the CPS. At 90,000 your due for a CPS and O2 Sensors at 100,000 miles if they have never been replaced. Whats your computer read out for the average miles per gallon? The 4.5 L can get 16.+ miles per gallon in town with new O2 Sensors.

The fuel pumps may be fine. The purge valve is creating the hard starting. A near empty gas tank also creates a lot of fumes.

Do you have cat bypass exhaust pipes installed?

Keep us posted on your progress.