Jeff928S4

2006 Cayenne S - 200,000 klms (or 125,000 miles).

I've had a bad start issue for over a year. Sometimes it would start right away, other times it would turn over and then just stop. Turning key back to start position and re-trying would usually get it started. Starter was making "whirring noises". Figured it was on it's way out.

Starter finally gave up (would not turn over at all - just nothing when turning the key - starter tested as dead). Got a new Bosch re-manufactured unit.

New starter worked "faster", but was still getting the odd bad start. Progressively was getting worse to the point where when the car did start, it made a grinding noise so loud it sounded like the car was going to blow up. Now at the point where you have to try to start it and if it doesn't work, I have to remove the key entirely and try again. It also stated to crank, but would continue to crank until car started (like a normal starting car that is out of gas). Eventually I got a "crankshaft position sensor" warning. Car also then stated running very badly (which I figured was the crank sensor), but it turned out to be a leaking PCV hose. See that thread here.....https://rennlist.com/forums/cayenne-...l#post17491585

Read just about every thread on bad starts from all over the internet. Here is what I know...

1. Battery is only 9 months old. H8 AGM. Previous new battery only lasted a year. I don't drive more than 4-5 min spurts with the odd highway trip for 15-20 mins, so the alternator doesn't get a chance to re-charge the battery. Alternator was replaced last year. Since installing new battery, I leave it on charger every night so as to not have it run down low and kill a cell like the last battery. Battery sits between 12.5 and 12.7/12.9 (after leaving it on charger).

2. Starter was replaced a few months ago.

3. No wire damage under seat - never had a leak - all drains are clear.

4. Crank Position sensor recently replaced.

5. When I get it stated after a few failed attemptst, sometimes one of headlights will also not be turning on and I also get a "license plate light warning" and the same side license plate light will not turn on.


So - here is what I did when I did some testing.

First thing I did was pull the starter relay ("433" in the waterbox fuse panel) and jumped it.
With the starter relay jumped, the starter turns over immediately and just keeps turning the engine over and over again - no strange noises at all.

Then I figured it doesn't start this way because the brake pedal isn't being pushed (from what I understand, the car won't start unless the brake is pressed and the key is turned). Jam a piece of wood against the brake pedal and jump relay again - no start, just starter turning engine over and over again. I thought if the starter was engaged while the brake was pushed, it would start, but that is not the case.

Then I turned the key to the "on position" (not fully turned like when you are starting the car) and jumped the starter relay. Starter makes whirring/banging/crunching noise and car eventually starts.

So.....I'm wondering...

1. If the starter runs perfectly when the starter replay is jumped, does this mean the starter is good?

2. Why is the starter making all these noises when I jump the relay with the key in the on position, but doesn't make the same noises if the key is not inserted?

3. It seems that the key in the on position starts up the fuel pumps. Turning the key all the way to the right engages the starter. What does pushing the brake pedal engage?

I've replaced the key fob battery. Tried the taking the key completely out and restarting but still isn't helping any more. I'm at my wits end.

Could it be a bad ignition switch? From what I've read, they only go bad and cause the key to get stuck.
Could it be something to do with the brake pedal?

Most posts I read have solved the problem with a new battery or a new starter. I may go and pick up a H9 battery and try that, but, like I said, my current battery seems fine. I've started the car with a weak battery. A weak battery just causes a slower crank in my experience. I don't want to have the intake pulled again to try a different starter, only to have it do the same thing again.

It just seems to me that something in between the ignition and the starter is not correct. Any thoughts????

Jeff928S4

Well....a very quick update.

Just got off work and after fighting with the car to start again, I headed to go get some groceries.

On the way there, the car started running rough again (thought maybe my tape job on the wonky PCV hose gave way). Got groceries and managed to get it stated again. On the way home, the car "bucks". I was like "ok - that's new...". Pressing the pedal didn't seem to be working (like I was out of gas). Car finally kicks back in just feet from my driveway and I make it home and pull in the garage. Tape job on PCV hose was still intact.

Immediately shut the car down and try another re-start. Nothing this time - just a whirrr noise from the starter - over and over again No cranking or anything. I open the fuse panel again and pull the relay for the starter and instead of getting a steady attempt at starting like I had when I tried doing this the other day - it's still just the whirrr sound. Put key in/pushed brake pedal....exact same whirrr sound (putting the key in last time resulted in a different sound vs just jumping the relay).

My thoughts went directly to the fuel pump (the bucking was a hint too lol). Left car alone for a bit and when I came back out to and opened the drivers side door - no "fuel pump sound".

I then pulled the two fuel pump fuses - both were ok. Pulled the fuel pump relays and jumped them. Both gave me a mild sound from both pumps (but it wasn't as loud as when you open the door).

Car will not turn over at all - just makes a weak whirrr sound when turning the key. Guessing the starter is still working cause at least I'm getting something vs no response at all when the last starter went.

So, does it make sense that the fuel pump(s) were going bad - would this have cause all those bad starts?
Does the car need to "recognize" there is fuel pressure/fuel available before it will attempt to start?

Getting it towed to shop in the am so they can test the fuel pressure and go from there.

P.S. - anyone know if the Touareg uses the same pumps as the Cayenne? I don't think they do.....

bigbuzuki

Engine starter operation is independent of any fuel pressure logic.

Petza914

Does your interior dome light come on when you open the driver's door?

I believe the brake pedal only releases the current so the starter will rotate, but nothing else. With the brake pedal not pressed, turning the key to the start position does nothing but activate the full accessory position for the electrics. Turning it with the brake pedal depressed, does that and spins the starter.

Your test with the key in and starter relay jumped with the bucking almost sounds like the engine is out of time where the fuel is igniting on the way up the compression stroke instead of at the top of it. If you get it running again, see what the camshaft deviation numbers look like. You may have a bad variocam solenoid or cam position sensor issue (I know you've replaced the crank position sensor from your other thread).

The other thing you may try is to open the driver's door and listen for the fuel pump buzz. If you hear it, don't do anything. Come back 15 minutes later and open the door again, listen for the buzz, then this time try to start it - that will double prime the fuel system before the first start. If it starts better this time, it may point to a weak fuel pump issue and why sometimes it starts well and sometimes it doesn't.

Jeff928S4

Dome light is coming on.

Just went home and tried locking/unlocking doors and restarting - still getting the spinning starter noise.
Did the battery reset - still getting the spinning starter noise.

Ordered a new starter and some camshaft position sensors. Will be installing them myself on Tuesday. Will report back if that makes a difference.

P.S. - one thing I did notice is that my "Auto Lock" function doesn't seem to be working? As in, I set the Auto Lock to on with the column stalk and after I leave the car, the doors auto lock after 10-15 mins - it's not doing that now. Hood has been open since I parked it - wonder if that makes a difference???

Jfrahm

Dying fuel pumps can cause hard starting. Hard starting can cause damaged starters. In the spirit of "horses not zebras" I'd at least test to see if spraying in some fuel or starting fluid improves the starting.

Jeff928S4

Where exactly would I spray in some fuel? I would like to try that, just in case.

Jfrahm

I often use a vacuum line for the vapor recovery system or the EGR system, whatever is handy. Never needed to do it on a Cayenne.

Jeff928S4

Quick update....

I pulled the intake tonight (not as bad as I thought - although I did break that air intake hose that is at the back of the intake - grrrrrr). JB welded it back together for now.

Was just about to try and pull the current starter and low and behold - the positive wire going to the current (also new) starter was not even finger tight. The wire was just flaying loosely - only held on due to the nut keeping it from coming off all together. I'm shocked the car started at all for the past two months.

The nice shiny copper bundle next to it is all black from arching. Calling the shop who did the initial work first thing in the morning and demanding they replace the starter for free. Inexcusable.

As it seemed super hard to get at the nuts to remove the starter, we just tightened up the loose wire, hoping that is what was causing the starter to just spin, but after putting it all back together, the stater still just spins and won't engage.

Would the loose wire arching all over the place burn out the solenoid?
If the shop who did it originally blows me off and if it's too hard for me to get the starter out, without removing the coolant hoses, could I just put the solenoid from the newer one I got on the one that is in the car already?
Is there any way to test the starter with the intake off to see if that works before putting it all back together (like pull fuel pump relay and try and start it)?