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Hello all, new to Porsche and the forum for that matter (1st post) , experienced in Mercedes though. 

 

I have just acquired a 2004 Porsche Cayenne S that won't start. I get an intermittent Immobilizer on the dash but if I tap the key and try again it goes away and the car will crank but not start, that's another issue though (I think) - I need a new key anyway. 

 

I check the fuel rails and have no fuel/no pressure. I pulled fuse #14 to force secondary pump on and it did not change. While the fuse was out I checked to see if the fuel pumps were getting voltage and with the key in the ignition and turned on (but not cranked) I get 8.4 volts. Does anyone know if this is correct as I was expecting 12 volts across the fuse, with the voltage regulation happening on the pump. There is a new battery in the vehicle (tested and it has 774 cranking amps).

 

If the voltage is incorrect would this NEW battery be to blame OR could it be tied to the immobilizer, which I doubted because I would think it would send NO voltage.  

Correct voltage  Yes/No? 

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44 minutes ago, John Komar said:

Hello all, new to Porsche and the forum for that matter (1st post) , experienced in Mercedes though. 

 

I have just acquired a 2004 Porsche Cayenne S that won't start. I get an intermittent Immobilizer on the dash but if I tap the key and try again it goes away and the car will crank but not start, that's another issue though (I think) - I need a new key anyway. 

 

I check the fuel rails and have no fuel/no pressure. I pulled fuse #14 to force secondary pump on and it did not change. While the fuse was out I checked to see if the fuel pumps were getting voltage and with the key in the ignition and turned on (but not cranked) I get 8.4 volts. Does anyone know if this is correct as I was expecting 12 volts across the fuse, with the voltage regulation happening on the pump. There is a new battery in the vehicle (tested and it has 774 cranking amps).

 

If the voltage is incorrect would this NEW battery be to blame OR could it be tied to the immobilizer, which I doubted because I would think it would send NO voltage.  

Correct voltage  Yes/No? 

 

Welcome to RennTech :welcomeani:

One of the functions of the immobilizer is to shut off the fuel system, so if you are getting intermittent codes for the unit, I'd start there.  Your voltage reading also is questionable, you should be seeing around 12V.

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Would you know definitively if the immobilizer shuts down power to 0 - zero volts. 

I'm going to get different leads on my meter so I can get a better reading on the fuse block, I'll update once I can verify voltage without questionable leads. 

 

Thanks for the reply 

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28 minutes ago, John Komar said:

Would you know definitively if the immobilizer shuts down power to 0 - zero volts. 

I'm going to get different leads on my meter so I can get a better reading on the fuse block, I'll update once I can verify voltage without questionable leads. 

 

Thanks for the reply 

 

The immobilizer functions by shutting off power to both the fuel system and the ignition.

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Well after testing the motor cranks very slow (sometimes not at all) and the voltage drops across the board to 8 volts from 12.6 at the battery. Had the battery load tested and all was good I am now suspecting that the starter may be drawing to much current. At this point I may be having more than one issue, 1st of which is to check the starter and get the voltage drop figured out then onto fuel pumps or it may just be the large current draw and once addressed everything else may fall into order.  

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13 hours ago, John Komar said:

Well after testing the motor cranks very slow (sometimes not at all) and the voltage drops across the board to 8 volts from 12.6 at the battery. Had the battery load tested and all was good I am now suspecting that the starter may be drawing to much current. At this point I may be having more than one issue, 1st of which is to check the starter and get the voltage drop figured out then onto fuel pumps or it may just be the large current draw and once addressed everything else may fall into order.  

 

Check the voltage drop across your primary battery cables, it may just be an internal resistance issue, which is not uncommon.

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With still a no start situation I pulled the battery back out and had it tested and it was rated at 1000 cold cranking AMPs but only had 440 and voltage drop of 1.2 volts. This was a new battery, but never load tested. They suspected that maybe the battery was bad (parts store). When the rain stops I'm going to try the new battery and see what happens. 

I also got a code CAM timing sensor BANK 1 error, so I put in a new cam timing sensor on both banks, haven't tested it because of battery issue. I changed both CAM sensors not that both were bad but while I was in there it was easy to just do both and with my luck I'd fix one and the other would go.

I went to inspect the fuel pumps and noticed that someone was in there before me and instead of cutting the carpet at the perforations they took a razor knife and just made 2 straight cuts in the rear carpet (hacks) so I'm suspecting they changed the fuel pump #1, I'll just wait and see on this one.

No other codes came up when I ran the diagnostics, the only issue I see was a very slow cranking motor which could have been the battery which we'll see if the new battery resolves later today.  As a side note when cranking (slow) I could smell fuel after a few cranks, no leaks visible just the slight aroma of fuel.  

 

 

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Well it took awhile to get back here so I'll go over everything I did and what happened. (It takes a while to get parts)

 

#1. Put in new battery and it cranked but slowly.

#2. Removed the cover over the fuel pump #1 on the drivers side and found a broken piece of the fuel regulator in the tank which should have been on the passenger side images below. With the carpet sliced I suspected someone was in there and a hack at that - a cut carpet should have been a good indicator.

#3 Replaced both fuel pumps, regulator and filter. 

#4 She came to life......

#5 Starter is grinding when cranking but it starts and runs. 

#6 Ran for WEEK -- no issues ran very good then on the 7th day CEL

#7 Check engine light comes on but it is still running and starting fine - code reading EVAP purge valve error.(ran like this for 2 days)

#8 Shut off truck and went to restart then it cranks but "won't start".

#9 I knew I had a CEL purge valve error so I picked one up a the dealer and replaced it  I also replaced starter - longer job then expected. Someone had replaced the coolant tubes and when they replaced the intake manifold they used the security torx wrench, the one with the hole in the center and broke them off in the intake manifold bolts. I had to use a pick and small hammer to chisel them out so I could remove the manifold. You would have thought after breaking one you would stop but no keep going to make someone else life miserable. 

#10 So right now it is dead - It will crank but not start - we have new fuel pumps, battery, starter and purge valve, and cam sensors.It will just spin up but not start. Reconnecting the batteries I get a CAM sensor error "A" bank 2 when I reconnected the battery but once cleared it does not come back.

 

With it not throwing any codes and 58 PSI on the rail and a starter that spins up fast I don't know what else to look for, like I said when it ran for the week it ran strong no indication of problems at all everything worked great and I liked the truck. If anyone has a suggestion I'll try it - or the next stop is going to be the dreaded dealer. 

 

 

 

regulatorCrop.jpg

regulatorCapCrop.jpg

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Another day - 

Checked voltage into the coil packs 12V when cranking - pulled a few plugs they are dry no fouling and not flooded. Tested for spark -good.

 

So it appears that something is preventing the injectors from opening up and supplying fuel as there is 58 PSI on the rail (gauge connected, no guessing) and power to the coils.

 

It may be something in the DME at this point no other reason, weekends coming up so I'll sit on it and think this through. 

 

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3 minutes ago, John Komar said:

Another day - 

Checked voltage into the coil packs 12V when cranking - pulled a few plugs they are dry no fouling and not flooded. Tested for spark -good.

 

So it appears that something is preventing the injectors from opening up and supplying fuel as there is 58 PSI on the rail (gauge connected, no guessing) and power to the coils.

 

It may be something in the DME at this point no other reason, weekends coming up so I'll sit on it and think this through. 

 

 

Refer to my July 19th posting above...……….

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Thanks for the response. 

 

If we're in Immobilizer land then it's to the dealer on Monday (its the point where you throw money at maybe) . The other parts needed to be replaced as they were clearly bad but once you get into the unknown that's the point where a dealer or independent pro can save you money. I'll let you know the out come so at least if someone runs into this thread it may help them. 

 

 

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9 minutes ago, John Komar said:

Thanks for the response. 

 

If we're in Immobilizer land then it's to the dealer on Monday (its the point where you throw money at maybe) . The other parts needed to be replaced as they were clearly bad but once you get into the unknown that's the point where a dealer or independent pro can save you money. I'll let you know the out come so at least if someone runs into this thread it may help them. 

 

 

 

Not necessarily; check your crank position sensor.  When the CPS stops registering rotation, the DME shuts off the power to the fuel system and the ignition because it thinks the engine is not turning.  And a bad CPS will not always throw codes.

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27 minutes ago, JFP in PA said:

 

Not necessarily; check your crank position sensor.  When the CPS stops registering rotation, the DME shuts off the power to the fuel system and the ignition because it thinks the engine is not turning.  And a bad CPS will not always throw codes.

 

I doubt its the CPS I replaced it about an hour ago (seriously) as I was thinking same thing.  It wasn't raining and I was bored and it was sitting in box looking at me, my intent was to return it but I had it so why not. It's a Porsche part NEW.  Hardest part was trying to fit my hand behind engine to re clip the wire holders. and it still doesn't go but it started raining again so I had to call it quits. 

 

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Stopped raining so I decided to see if I actually have 12V coming to the injectors and sure enough 12V to the injectors and 12V to the coils - baffled - so it looks like the engine is getting what is requested but not firing. If it was an old car I would say the timing was off. 

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Well a week at the dealer and still it's not running.

They said to take it to the next level is going to be a minimum of $1,200 on top of what they already charged me and there is no guarantee it will run and the estimate will only go up from there unless of course they find something quickly and they can cover it in the $1,200 but like they said no guarantee it will run. 

So I'm having the car towed back to my place and will start going through all of the wiring Saturday morning. I have this feeling it's something stupid that everyone is over looking or at least I hope so or it will be a nice lawn ornament.

 

They did initially mention steering column but ruled that out, then it was crank sensor (I did put in a new one) then changed their mind. 

I'll keep posting till either I get it running or scrap it which I would hate to do as it ran so well initially. 

 

 

 

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It's alive ! 

After spending the weekend going through wiring and grounds it still would not run. So even though I put in new sensors I decided to pull them out and test them to see if they were working and unceremoniously they all checked out. But out of curiosity I grabbed an old Bosch cam positioning sensor I had and while holding it next to the (new) Bremi cam positioning sensor something didn't look correct. I decided to measure them and the Bremi cam positioning sensor was at least 1mm shorter than the Bosch sensor. So I replaced the cam sensors with Bosch sensors and wouldn't you know it, it fired right up. 

It most likely wasn't throwing any codes because the sensors did work I just think that the 1mm made the difference. Had I had an oscilloscope to connect to the sensor while cranking this could have been solved much quicker. Now why it ran for a while I have no idea it could have been just on the upper tolerance limit and with expansion and contraction it pushed it to its outside limit. 

 

The Bremi cam sensor P/N: B5-99660610602 was and still is listed as a direct replacement for the Bosch P/N 0232103022 at half the cost but after this experience I'll buy the Bosch part. 

 

Thanks for watching and just maybe this little nugget of frustration will help someone. 

 

 

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On 8/28/2019 at 4:00 AM, John Komar said:

It's alive ! 

After spending the weekend going through wiring and grounds it still would not run. So even though I put in new sensors I decided to pull them out and test them to see if they were working and unceremoniously they all checked out. But out of curiosity I grabbed an old Bosch cam positioning sensor I had and while holding it next to the (new) Bremi cam positioning sensor something didn't look correct. I decided to measure them and the Bremi cam positioning sensor was at least 1mm shorter than the Bosch sensor. So I replaced the cam sensors with Bosch sensors and wouldn't you know it, it fired right up. 

It most likely wasn't throwing any codes because the sensors did work I just think that the 1mm made the difference. Had I had an oscilloscope to connect to the sensor while cranking this could have been solved much quicker. Now why it ran for a while I have no idea it could have been just on the upper tolerance limit and with expansion and contraction it pushed it to its outside limit. 

 

The Bremi cam sensor P/N: B5-99660610602 was and still is listed as a direct replacement for the Bosch P/N 0232103022 at half the cost but after this experience I'll buy the Bosch part. 

 

Thanks for watching and just maybe this little nugget of frustration will help someone. 

 

 

Nice find and kudos for not taking a stiff one from the stealership. Who knows what new parts or control modules you might have ended up with lol. 

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