Coils, spark plugs, O2 sensors and fuses - the adventure!
07-26-2016, 07:28 PM
#1
Drifting
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Join Date: Dec 2001
Location: Sackville, Nova Scotia
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Coils, spark plugs, O2 sensors and fuses - the adventure!
Hi all,
I recently bought a 2006 Cayenne S (for a very good price, I may add - there may have been a reason for this).
Here is how the story goes.....hopefully all this info will be of help to others - there is a lot of it!!!
1. Bought car - it had a "Service Interval" warning and a slightly lumpy idle when it was raining out. The car also had a new battery (h8 - 850 cc), as the old one died - but when they replaced the battery, it wouldn't start, but they fixed it because "some wire under the seat" was bad. That battery drained on the lot before I bought it and had to be charged up. This is the no-name battery in it now...
Took the car for an oil change to rid the Service Interval warning and planned on doing the coils to remedy the choppy idle when wet. I noticed two of my coils were not screwed down all the way - cylinder #2 and cylinder #6. #2 didn't even have a screw in it.
2. After getting the car back from the oil change, I get a CEL. Having no reader at the time, I took it into Porsche and had them reset the light. They showed codes for a misfire on cylinder #2 (no surprise) and one for the O2 sensor. The tech said they looked at the O2 sensor and asked if someone was "in there" recently because everything "looked shiny". Looking back, I now know how bad a diagnosing this was. Can't they test the O2 sensor or wouldn't their reader be able to give more than a "looks shiny" report?? lol
3. Drive the car for a month or so and the wonky idle is getting worse...showing up all the time. Also getting a jumpy throttle response when cold and wet - like the fuel is being sent in spurts. Time for coils!! Then, I get the CEL again. I go out and get the cheap Chinese Durametric for $40 to at least know what the light is saying. It's back to the O2 sensor warning - no misfires or anything else. At this point, I figure the O2 sensor is throwing a code because of the extra gas/air being blown past it as the coil is going bad. I did not know there was a "Misfire" CEL at this point - wasn't getting any - just the bad idle.
Now......and this point, I want to point out that the car ran good, etc. I did notice the slight hesitation when starting in 2nd gear and read up on it. But, I found the car, overall to be "weak" anywhere under 2000 rpm. Not much throttle response and a boggy feeling when on throttle at low RPM's. Once you were above 2000 RPM, it ran great!!
4. Weather is getting colder and more rainy and one day the car just starts running very badly. The next (dry) day, it's fine again. A couple days later, during a bad rain storm, it runs VERY bad again and this time the CEL flashes!! Shut it down and order coils.
Replaced all 8 coils and spark plugs and it ran great again. For ****s and giggles, I put the old coils back in with the new spark plugs and it also ran great - maybe it was just the spark plugs I thought. Also - when putting the old coils back in, I put the "weaker" coils (as determined by how brown the spark plugs were) all on bank two (cylinders 5,6,7 and 8) for easier access.
5. Drove the car all winter with no more CEL...still had a slightly bad idle and was weak below 2000 RPM (again, I thought this was just how the Cayenne's drove). As the weather got warmer and rain came again, I get the CEL again - O2 sensor again. To my knowledge at that time, the O2 CEL was my warning of bad coils (didn't do a reading when CEL first started flashing - just changed the coils). Car stats running progressively worse to the point of the CEL flashing again. Check the CEL and saw misfires on cylinders 5,6,7 and 8 and "multiple engine misfire". Ah ha, I thought, the weak coils I put on that side are for sure bad.......
Also, during the winter, the battery would get weak due to short trips and I had to get a jump a couple of time. Bought a battery charger/maintainer and would use it often.....thing was, the fully charged battery would only show up as a 12.1 to 12.4 and give a "weak" reading on the meter. When it was too low, my "FWD System Faulty" warning would show up on start up and if it was really bad (almost dead), I would get the PSM icon. The battery died at least 4 or 5 times over the winter (trying to use that damn "REST" button!!). Once it warmed up, the battery was fine and didn't need tending to.
6. Replaced old coils with new ones (and more new spark plugs) and car went back to driving good, but the CEL didn't go out - I had a new warning saying the O2 sensor was "inactive" or "slow response" (0154 code). Bank 2, sensor 1. Maybe all the misfires burned out the O2 sensor? Again, as it would get wet (or REALLY hot out), the idle would get worse. New coils......new plugs and still the bad idle - has to be the O2 sensor!!
7. Replace drivers side, pre-cat O2 sensor. As I'm driving away from the shop, the damn CEL comes back on. Now it is no longer a "slow response" warning, but rather an "unknown fault". Same number though (0154). WTHell!! I pulled all the spark plugs and clean them up (maybe they are dirty from the O2 sensor not working correctly??). Drive a few days, idle gets bad - BAM!! Misfire on 5,6,7 and 8 and multiple misfires. So, I guess those other coils weren't bad - it was just a coincidence I put them on cylinders 5,6,7 and 8. Now, I'm just pissed. New coils, spark plugs and O2 sensor and still misfiring???? ...and why only 5,6,7,8. I start my Rennlist searches.
Turns out, there are two fuses for each bank that cover the coils and injectors (#7 and #8 in the water box fuse panel in engine bay). I pull the fuses and they look fine. I replace them anyway. A couple days later, same 5,6,7,8 misfire.
(at this point, I also started getting a P0441 Evaporative Emission Control System Incorrect Purge Flow warning - perhaps that's the problem I though???)
8. The more I think about it, this HAS to be electrical. The former owners seemed to be chasing the same problem with the "shiny" O2 sensor and new coils (the ones in the car were a newer part number). Maybe they gave up on it and sold it - thus the great price.
So, my thinking is the water box is, well, getting water in it. My alarm horn is sporadic....and it's under the water box, soooooo......I start pulling fender liners...
Stick my finger up in the drain holes and dry as a bone. No leaves...nothing.
That's it, I'm pulling the damn water box!!! As there is VERY limited information of removing the water box, I had a hard time when it came to actually pulling the relay/fuse carrier plugs out of the housing. I did manage to pull both wiring harnesses out and I sprayed De-Oxit on each fuse/relay prong and down inside each plug.
Here is the water box with the wiring harnesses unplugged....
Now, at that point, I had not removed the wiper arms/top trim. I think with those removed, you can get at the box better and fully remove it. I was frustrated and just plugged everything back in.
Side note - I had pulled the negative battery cable in front of the drivers seat and used that plastic piece to keep the wire from the ground. After I pulled all the wiring harness, I notice one of them made a small spark - I look and the ground wire fell off the plastic piece and was hitting the ground. I basically pulled all the grounds off with the battery hooked up. Oh no, what would happen when I try and start it??? Yikes, did I blow up the PCM???
9. So, all the fuses/relays had been pulled and cleaned, along with the plugs, etc. I put the key in and start the car - I immediately get the "Oil Level Sensor Workshop" warning and the oil temp gauge is at dead zero. I also lost my AC??? I pull the negative again and re-set the PCM. Warning is gone....for about 15 seconds and comes back on. I'm stumped...but it turns out that fuse #11 is for the oil level sensor, AC and secondary air pump, but my fuse, again, is fine.
I check the CEL with the reader and I get....
P0418 Secondary Air Injection System Relay "A" Circuit Malfunction
P0419 Secondary Air Injection System Relay "B" Circuit Malfunction
Some 2259 (?) warning also related to secondary air pump
0230 Fuel Pump Circuit Malfunction
(no "unknown" O2 sensor or incorrect Purge flow warnings anymore though???)
I open the water box again and pull the fuses/wipe them, etc. and put it back together. Now, the "Oil Level Sensor Workshop" light is gone and I have my AC back - still getting the secondary air pump/fuel pump circuit warnings though.
Back to the no more O2 "unknown" warning. I think it went away because I had pulled fuse #17, thinking it was a spare and used it elsewhere. Fuse #17 if the pre-cat O2 sensor fuse - didn't seem to make a difference it was out??? I put the fuse back in, re-start car and the "unknown" code returns, along with the other ones.
Pull all the fuses/relays again, do the video game "blow on it" trick and put it back together. No more fuel pump code/O2 sensor code - just the secondary air pump codes.
So, it seems to me that the lil row of fuses in the water box (7 to 18) are not getting the right juice or something.
Fuse #7 (bank 1 coils/injectors) - seems ok
Fuse #8 (bank 2 coils/injectors) - well, I had all those misfires on 5,6,7 and 8, even with new coils.
Fuse #9 (camshaft adjustment) - seems ok
Fuse #10 (coolant fan, etc.) - seems ok
Fuse #11 (ac/oil sensor/air pump) - doesn't seem to be working that great - no fuses blow, but the item it covers stop working/give warnings
Fuse #12 (secondary air pump/after run pump) - I dunno?
Fuse #13 and #14 (fuels pumps) - I dunno?
Fuse #15 (main relay) - seems ok
Fuse #16 (not used on S model)
Fuse #17 and 18 (pre-behind cat) - seem ok.
Now, here is the kicker - even with all these new warnings, after unplugging all the fuses/replays/wiring harnesses and cleaning them, the car runs FANTASTIC!!! It's a completely different car. Crisp at all RPMs, shifts better, faster throttle response, and it just sounds different - more of a growl to it. It now drives like I thought it would when I bought it - VERY peppy. Night and day compared to how it ran before.
So, what should be my next step? Battery? The current showing on the current battery as of right this second is 12.14. If I charge it to full, it may get up to 12.4, but never any higher...and that 12.4 starts to drop as soon as I drive it. I can't see the low voltage just starting to cause these warnings now.....there was no sign of any "circuit" warnings before I opened up the water box.
Or, do I pull the box fully and inspect for a short somewhere - I'm guessing the replays are all good still????? Do I rule them out? If a replay went bad, wouldn't the fuel pump/air pump just stop working????? What about those big-*** fuses for the air pumps (Fuses #3 and #4 - do they blow??).
I also have the option of just buying a used water box off ebay for $100 and spice it into the wiring harnesses.
Not sure where to go next - car runs incredible (even in the heavy rain - no more misfires at all), but I'd like to get rid of these air pump codes.
Hope all this info helps someone at some point!!!
I recently bought a 2006 Cayenne S (for a very good price, I may add - there may have been a reason for this).
Here is how the story goes.....hopefully all this info will be of help to others - there is a lot of it!!!
1. Bought car - it had a "Service Interval" warning and a slightly lumpy idle when it was raining out. The car also had a new battery (h8 - 850 cc), as the old one died - but when they replaced the battery, it wouldn't start, but they fixed it because "some wire under the seat" was bad. That battery drained on the lot before I bought it and had to be charged up. This is the no-name battery in it now...
Took the car for an oil change to rid the Service Interval warning and planned on doing the coils to remedy the choppy idle when wet. I noticed two of my coils were not screwed down all the way - cylinder #2 and cylinder #6. #2 didn't even have a screw in it.
2. After getting the car back from the oil change, I get a CEL. Having no reader at the time, I took it into Porsche and had them reset the light. They showed codes for a misfire on cylinder #2 (no surprise) and one for the O2 sensor. The tech said they looked at the O2 sensor and asked if someone was "in there" recently because everything "looked shiny". Looking back, I now know how bad a diagnosing this was. Can't they test the O2 sensor or wouldn't their reader be able to give more than a "looks shiny" report?? lol
3. Drive the car for a month or so and the wonky idle is getting worse...showing up all the time. Also getting a jumpy throttle response when cold and wet - like the fuel is being sent in spurts. Time for coils!! Then, I get the CEL again. I go out and get the cheap Chinese Durametric for $40 to at least know what the light is saying. It's back to the O2 sensor warning - no misfires or anything else. At this point, I figure the O2 sensor is throwing a code because of the extra gas/air being blown past it as the coil is going bad. I did not know there was a "Misfire" CEL at this point - wasn't getting any - just the bad idle.
Now......and this point, I want to point out that the car ran good, etc. I did notice the slight hesitation when starting in 2nd gear and read up on it. But, I found the car, overall to be "weak" anywhere under 2000 rpm. Not much throttle response and a boggy feeling when on throttle at low RPM's. Once you were above 2000 RPM, it ran great!!
4. Weather is getting colder and more rainy and one day the car just starts running very badly. The next (dry) day, it's fine again. A couple days later, during a bad rain storm, it runs VERY bad again and this time the CEL flashes!! Shut it down and order coils.
Replaced all 8 coils and spark plugs and it ran great again. For ****s and giggles, I put the old coils back in with the new spark plugs and it also ran great - maybe it was just the spark plugs I thought. Also - when putting the old coils back in, I put the "weaker" coils (as determined by how brown the spark plugs were) all on bank two (cylinders 5,6,7 and 8) for easier access.
5. Drove the car all winter with no more CEL...still had a slightly bad idle and was weak below 2000 RPM (again, I thought this was just how the Cayenne's drove). As the weather got warmer and rain came again, I get the CEL again - O2 sensor again. To my knowledge at that time, the O2 CEL was my warning of bad coils (didn't do a reading when CEL first started flashing - just changed the coils). Car stats running progressively worse to the point of the CEL flashing again. Check the CEL and saw misfires on cylinders 5,6,7 and 8 and "multiple engine misfire". Ah ha, I thought, the weak coils I put on that side are for sure bad.......
Also, during the winter, the battery would get weak due to short trips and I had to get a jump a couple of time. Bought a battery charger/maintainer and would use it often.....thing was, the fully charged battery would only show up as a 12.1 to 12.4 and give a "weak" reading on the meter. When it was too low, my "FWD System Faulty" warning would show up on start up and if it was really bad (almost dead), I would get the PSM icon. The battery died at least 4 or 5 times over the winter (trying to use that damn "REST" button!!). Once it warmed up, the battery was fine and didn't need tending to.
6. Replaced old coils with new ones (and more new spark plugs) and car went back to driving good, but the CEL didn't go out - I had a new warning saying the O2 sensor was "inactive" or "slow response" (0154 code). Bank 2, sensor 1. Maybe all the misfires burned out the O2 sensor? Again, as it would get wet (or REALLY hot out), the idle would get worse. New coils......new plugs and still the bad idle - has to be the O2 sensor!!
7. Replace drivers side, pre-cat O2 sensor. As I'm driving away from the shop, the damn CEL comes back on. Now it is no longer a "slow response" warning, but rather an "unknown fault". Same number though (0154). WTHell!! I pulled all the spark plugs and clean them up (maybe they are dirty from the O2 sensor not working correctly??). Drive a few days, idle gets bad - BAM!! Misfire on 5,6,7 and 8 and multiple misfires. So, I guess those other coils weren't bad - it was just a coincidence I put them on cylinders 5,6,7 and 8. Now, I'm just pissed. New coils, spark plugs and O2 sensor and still misfiring???? ...and why only 5,6,7,8. I start my Rennlist searches.
Turns out, there are two fuses for each bank that cover the coils and injectors (#7 and #8 in the water box fuse panel in engine bay). I pull the fuses and they look fine. I replace them anyway. A couple days later, same 5,6,7,8 misfire.
(at this point, I also started getting a P0441 Evaporative Emission Control System Incorrect Purge Flow warning - perhaps that's the problem I though???)
8. The more I think about it, this HAS to be electrical. The former owners seemed to be chasing the same problem with the "shiny" O2 sensor and new coils (the ones in the car were a newer part number). Maybe they gave up on it and sold it - thus the great price.
So, my thinking is the water box is, well, getting water in it. My alarm horn is sporadic....and it's under the water box, soooooo......I start pulling fender liners...
Stick my finger up in the drain holes and dry as a bone. No leaves...nothing.
That's it, I'm pulling the damn water box!!! As there is VERY limited information of removing the water box, I had a hard time when it came to actually pulling the relay/fuse carrier plugs out of the housing. I did manage to pull both wiring harnesses out and I sprayed De-Oxit on each fuse/relay prong and down inside each plug.
Here is the water box with the wiring harnesses unplugged....
Now, at that point, I had not removed the wiper arms/top trim. I think with those removed, you can get at the box better and fully remove it. I was frustrated and just plugged everything back in.
Side note - I had pulled the negative battery cable in front of the drivers seat and used that plastic piece to keep the wire from the ground. After I pulled all the wiring harness, I notice one of them made a small spark - I look and the ground wire fell off the plastic piece and was hitting the ground. I basically pulled all the grounds off with the battery hooked up. Oh no, what would happen when I try and start it??? Yikes, did I blow up the PCM???
9. So, all the fuses/relays had been pulled and cleaned, along with the plugs, etc. I put the key in and start the car - I immediately get the "Oil Level Sensor Workshop" warning and the oil temp gauge is at dead zero. I also lost my AC??? I pull the negative again and re-set the PCM. Warning is gone....for about 15 seconds and comes back on. I'm stumped...but it turns out that fuse #11 is for the oil level sensor, AC and secondary air pump, but my fuse, again, is fine.
I check the CEL with the reader and I get....
P0418 Secondary Air Injection System Relay "A" Circuit Malfunction
P0419 Secondary Air Injection System Relay "B" Circuit Malfunction
Some 2259 (?) warning also related to secondary air pump
0230 Fuel Pump Circuit Malfunction
(no "unknown" O2 sensor or incorrect Purge flow warnings anymore though???)
I open the water box again and pull the fuses/wipe them, etc. and put it back together. Now, the "Oil Level Sensor Workshop" light is gone and I have my AC back - still getting the secondary air pump/fuel pump circuit warnings though.
Back to the no more O2 "unknown" warning. I think it went away because I had pulled fuse #17, thinking it was a spare and used it elsewhere. Fuse #17 if the pre-cat O2 sensor fuse - didn't seem to make a difference it was out??? I put the fuse back in, re-start car and the "unknown" code returns, along with the other ones.
Pull all the fuses/relays again, do the video game "blow on it" trick and put it back together. No more fuel pump code/O2 sensor code - just the secondary air pump codes.
So, it seems to me that the lil row of fuses in the water box (7 to 18) are not getting the right juice or something.
Fuse #7 (bank 1 coils/injectors) - seems ok
Fuse #8 (bank 2 coils/injectors) - well, I had all those misfires on 5,6,7 and 8, even with new coils.
Fuse #9 (camshaft adjustment) - seems ok
Fuse #10 (coolant fan, etc.) - seems ok
Fuse #11 (ac/oil sensor/air pump) - doesn't seem to be working that great - no fuses blow, but the item it covers stop working/give warnings
Fuse #12 (secondary air pump/after run pump) - I dunno?
Fuse #13 and #14 (fuels pumps) - I dunno?
Fuse #15 (main relay) - seems ok
Fuse #16 (not used on S model)
Fuse #17 and 18 (pre-behind cat) - seem ok.
Now, here is the kicker - even with all these new warnings, after unplugging all the fuses/replays/wiring harnesses and cleaning them, the car runs FANTASTIC!!! It's a completely different car. Crisp at all RPMs, shifts better, faster throttle response, and it just sounds different - more of a growl to it. It now drives like I thought it would when I bought it - VERY peppy. Night and day compared to how it ran before.
So, what should be my next step? Battery? The current showing on the current battery as of right this second is 12.14. If I charge it to full, it may get up to 12.4, but never any higher...and that 12.4 starts to drop as soon as I drive it. I can't see the low voltage just starting to cause these warnings now.....there was no sign of any "circuit" warnings before I opened up the water box.
Or, do I pull the box fully and inspect for a short somewhere - I'm guessing the replays are all good still????? Do I rule them out? If a replay went bad, wouldn't the fuel pump/air pump just stop working????? What about those big-*** fuses for the air pumps (Fuses #3 and #4 - do they blow??).
I also have the option of just buying a used water box off ebay for $100 and spice it into the wiring harnesses.
Not sure where to go next - car runs incredible (even in the heavy rain - no more misfires at all), but I'd like to get rid of these air pump codes.
Hope all this info helps someone at some point!!!
Last edited by Jeff928S4; 07-26-2016 at 08:21 PM.
07-26-2016, 08:42 PM
#2
Rennlist Member
before you go much further, have a read here about proper battery voltage for a healthy wet cell battery. Yours does not appear to hold a charge and is either being drained by an active circuit that should be asleep or there is an internal short.
Pull the battery and drop it off at your favorite autoparts store for a battery analysis. They will charge it up and put it through its paces. Please keep us posted.
These modern autos are demanding on the electrical system and the battery has to work hard.
Pull the battery and drop it off at your favorite autoparts store for a battery analysis. They will charge it up and put it through its paces. Please keep us posted.
These modern autos are demanding on the electrical system and the battery has to work hard.
07-27-2016, 01:52 PM
#3
Drifting
Thread Starter
Join Date: Dec 2001
Location: Sackville, Nova Scotia
Posts: 2,362
Likes: 0
Received 8 Likes
on
8 Posts
As an owner of a 928 also, I know about how much a good, maintained battery helps. lol
I think I will pick up a nice AGM battery tonight and put it in and see what that does.......
I think I will pick up a nice AGM battery tonight and put it in and see what that does.......