Alzheimers or what?

[PKN]

I have been posting for some time about serious multiple misfires on one bank of cylinders. The problem was intermittent but always on cylinders 5-8. Eventually, the problem got so bad I took it to a local independent dealer.

Before this point, I had refreshed all vacuum connections,unwrapped and re-wrapped the wiring to all of the coils and injectors, replaced the coil packs and plugs - all on the one side reporting the problems. I didn't do both banks immediately, but planned to "catch up" the work later when the problem was resolved. Oh...I also replaced the fuses 7 and 8 in the e-Box.

So the dealer put on his PWIS and after 20 minutes or so comes back and asks which side I had replaced the coil packs and plugs. Drivers side, said I. He went back out to the car and returned with the key a few minutes later, talked with the boss and left.

The boss then told me that I was a good mechanic, had diagnosed the likely fault and taken the right steps - on the wrong bank ! He also said that I should only replace coil packs and plugs in a full set (which I knew anyway). I was a bit embarrassed and got out of there after paying $40 for the diagnosis.

When I got home, I pulled the error logs from my Durametric and also the cars manual. I am not crazy, the reported errors are on cylinders 5-8 and they are on the drivers side. Being a careful kind of cove, I then started pulling the coil packs and plugs on the passenger side to find the plugs were absolutely shot and bright white with lots of residue. It seems very likely that the problem was indeed on the passenger side bank.

Either....

1. My Durametric is wrongly reporting errors on the other side or

2. The manual is incorrect and the plugs are numbered 1=4 on drivers side, 5-8 on passenger side

3. There is a problem on the other bank which my Durametric could not identify

4. I am completely nuts.

I have ordered the remaining coil pack and a full set of Beru plugs and cant wait to see if it fixes the problem which has plagued me for weeks if not months. In the meantime, I open up the floor for suggestions, comments, insults...

Steve

[JFP in PA]

I have been posting for some time about serious multiple misfires on one bank of cylinders. The problem was intermittent but always on cylinders 5-8. Eventually, the problem got so bad I took it to a local independent dealer.

Before this point, I had refreshed all vacuum connections,unwrapped and re-wrapped the wiring to all of the coils and injectors, replaced the coil packs and plugs - all on the one side reporting the problems. I didn't do both banks immediately, but planned to "catch up" the work later when the problem was resolved. Oh...I also replaced the fuses 7 and 8 in the e-Box.

So the dealer put on his PWIS and after 20 minutes or so comes back and asks which side I had replaced the coil packs and plugs. Drivers side, said I. He went back out to the car and returned with the key a few minutes later, talked with the boss and left.

The boss then told me that I was a good mechanic, had diagnosed the likely fault and taken the right steps - on the wrong bank ! He also said that I should only replace coil packs and plugs in a full set (which I knew anyway). I was a bit embarrassed and got out of there after paying $40 for the diagnosis.

When I got home, I pulled the error logs from my Durametric and also the cars manual. I am not crazy, the reported errors are on cylinders 5-8 and they are on the drivers side. Being a careful kind of cove, I then started pulling the coil packs and plugs on the passenger side to find the plugs were absolutely shot and bright white with lots of residue. It seems very likely that the problem was indeed on the passenger side bank.

Either....

1. My Durametric is wrongly reporting errors on the other side or

2. The manual is incorrect and the plugs are numbered 1=4 on drivers side, 5-8 on passenger side

3. There is a problem on the other bank which my Durametric could not identify

4. I am completely nuts.

I have ordered the remaining coil pack and a full set of Beru plugs and cant wait to see if it fixes the problem which has plagued me for weeks if not months. In the meantime, I open up the floor for suggestions, comments, insults...

Steve

<----- FRONT

1 - Ignition module, cylinder 1, bank 1

2 - Ignition module, cylinder 2, bank 1

3 - Ignition module, cylinder 3, bank 1

4 - Ignition module, cylinder 4, bank 1

5 - Ignition module, cylinder 5, bank 2

6 - Ignition module, cylinder 6, bank 2

7 - Ignition module, cylinder 7, bank 2

8 - Ignition module, cylinder 8, bank 2

I have not seen the Durametric call the wrong cylinders, but that does not make it impossible either. That said, did you rescan it when the problem returned?

[PKN]

Thanks JFP - I had already checked that the manual supported my view. Durametric is looking into the issue for me. If the problem is still there after I replace the remaining parts, I will go back to quiz the mechanic

Steve

[JFP in PA]

Thanks JFP - I had already checked that the manual supported my view. Durametric is looking into the issue for me. If the problem is still there after I replace the remaining parts, I will go back to quiz the mechanic

Steve

It is entirely possible that you correctly coded the first side you worked on, after which the other side crapped out, just by a coincidence of timing. These vehicles are well known for having coil pack related misfire issues; when we get one in, we always recommend doing all the coil packs and the plugs. That is often cheaper, and easier on the digestive system, then a repeat of the entire process.

[njrbd]

Had a similar situation on my V6 cayenne. Threw a misfire for only 1 cyl , so replaced that and everything seemed fine for about 40 miles. Then she threw a cel for 2 more cylinders. Ended up replacing all 6 and no issues since. Good luck!

[PKN]

Unfortunately, I took a Durametric reading just before I took the car down there and it was still showing the cylinders 5-8 as problematic. In fact, when I looked at some actual values for cylinder misfires I could see them racking up on the same cylinders as I watched. Very curious. I will report back when I get the new parts in (probably this weekend

Steve

[PKN]

I am utterly frustrated. I replaced all of the plugs with new Beru ones and the remaining 4 coil packs. The Durametric is now reporting a constant misfire on 5 and a few on cylinder 6. As requested, I logged the session and mailed to Durametric. Monday, I will go back to the indie and see what they say but this time will look at the scan while they are doing it

Steve

[binger]

HI Steve,

Did you replace with OEM coils or aftermarket coils?

[wvicary]

Are the coils electrical connectors securely connected?

[binger]

Are They Original Equipment Manufacturer parts or aftermarket?

[PKN]

Porsche parts only and I double checked everything when I assembled it. My suspicion is still a bad connection somewhere but not sure how it hits two cylinders (though 5 is now missing most of the time)

Steve

[binger]

Before this point, I had refreshed all vacuum connections,unwrapped and re-wrapped the wiring to all of the coils and injectors, replaced the coil packs and plugs - all on the one side reporting the problems. I didn't do both banks immediately, but planned to "catch up" the work later when the problem was resolved. Oh...I also replaced the fuses 7 and 8 in the e-Box.

One clue you said you "unwrapped and re-wrapped the wiring to all of the coils and injectors"? Also what were the original codes you pulled.

[PKN]

Binger

The original codes suggested a problem with coil pack 7 and/or a short in the coil pack system. I checked the wiring by unwrapping the insulation but found no problem in the wiring and so re-wrapped. The fuses were also good in the E-box though the problem went away for a couple of weeks after replacing them which I suspect is coincidental. The connectors all seem tight. What is very odd is that the problem migrates from cylinder to cylinder but always on that bank. Today, I plan to lube the silicon seals in the connectors and re-connect them. I will also use one of the coli packs I removed to check for a spark outside the cylinder. At least I will be able to see if the spark is strong and/or not present at all.

Because I don't know how the computer detects the misfires, I still am not sure if the problem may be related to the injectors. Can you shed any light on this and how I might be able to discount injectors as the problem. I have not seen anything on the Durametric which points in this direction.

Steve

[binger]

Unless you have a proper Ignition Spark Tester do not just let the coli jump to ground. This could damage the Ignition system or the DME. Also I would not lube any connectors seals as your just adding one more problem in to the mix.

OBD II codes let us know if an injector or 02 sensor coli etc. The codes to point us to where the problem might be. Then we have to test that system to prove if it is good or failed. That is why I ask about the exact codes you were getting.

Back to basics, I would take a coil from one cylinder that is not misfiring and swap it for the one that is. This is a low tech way to be sure that the new coil is not defective. If that cylinder is still misfiring now you have to look at the connecters, wiring on that bank. That is if the codes are not fuel related.

[PKN]

Thanks for hanging in here with me. I spent a couple more hours on it today and it looks like the problem is in the fuse box. The misfires are moving around between cylinders 5-8 and so I opened up the top of the E Box and started tugging at wires that I could get to. Occasionally, the problems cleared up, only to come back after 10 minutes driving. If somebody can advise on the best way to remove this fuse box, I will check out the connections underneath it. Also, does anybody know if any of the colored connectors next to the fuse box carry the coil wired for this bank and if so, which?

I checked cylinder 5 plug using one of the old coil packs running a separate ground from the plug and it has a nice strong spark. I can also hear the injectors running nicely using a screwdriver between the injector and my ear.

Steve

[voodoocat]

I am utterly frustrated. I replaced all of the plugs with new Beru ones and the remaining 4 coil packs. The Durametric is now reporting a constant misfire on 5 and a few on cylinder 6. As requested, I logged the session and mailed to Durametric. Monday, I will go back to the indie and see what they say but this time will look at the scan while they are doing it

Steve

FYI, I didn't waste my money on Beru plugs, used NGK Iridium BKR6EIX. 4 years and 40000 miles later, still running strong, not a single misfire.

I do recommend genuine coil packs, knockoff coils have inferior boot rubber that hardens, get brittle and misfires.

[binger]

Hi Steve,

Sounds like you have wiring, connector issue. Your going to need the schematic for your car to trace from the coils to the fuse box. Then you will need to do some voltage drop testing on each conductor that leads to the coils in question.

[wvicary]

I have seen the contact area that engages the fuses in the fuse block become overheated, lose tension and create an intermittent connection.

[PKN]

Today, the car behaved reasonably well. Misfires seemed to occur mostly at closed throttle. Raising the idle just a couple of hundred revs stopped it. I will be servicing the old girl tomorrow and plan to clean the air tube from the turbo on the drivers side at the same time. I know she has been blowing oil up to the intake and want to make sure that I am giving the cylinders at the front of the car their best chance to fire. Wvicary = what would you recommend to deal with the fusebox issue? Electrical contact cleaner? Can you tell me how to remove the fusebox so I can check the connections underneath?

Thanks again to all of you for your advice.

Steve

[wvicary]

I use a dental pick to gently bend the fuse contact terminals together.

[PKN]

Thanks - I already did that so I am wondering if it could be a bad connection under the fuse box....

Steve

[binger]

You can have one of three things. intermittent open, high resistance, or a bad ground. Trying to fix your issue by bending the connectors in the fuse box is a band aid fix. You need to get the the root cause of your issue.

You need the schematic for your car to trace from the coils wires to the junction box then the fuse box. Then you will need to do some voltage drop testing on each conductor that leads to the coils in question. Also look at the fuses for the coils check the connectors tips for hot spots.see picture below.

Here is a case study on a car that would not charge. The shop replaced 3 alternators and 3 batters before I was called in to diagnose the issue. After several hours of tracing and testing I found a cheap fuse did not open. The thing that threw me off, It did not fry any of the wires that led to the fuse / junction box. Here is what I found. It got so hot for extended periods it melted the internal parts of fuse / junction box. Once I replaced the fuse with a quality part the fuse would open. If I put the original fuse back it would not open and would work intermittently until it got too hot. The fix was to replace a $700.00 fuse / junction box.

I am not saying this is your issue. However you have to be a detective and prove each system for faults or no faults to eliminate throwing parts at it or jumping to conclusions.

[PKN]

That is good info and a salutary tale. I did check and clean the grounds. I have changed the fuses on several occasions now and see no signs of overheating or damage on the fuse or the topside of the fuse box.

The schematics do not unfortunately show the connectors in the junction box, only the lines from coil packs/injectors to the fuses but I will trace them from the color codes. At least my problems are presently intermittent on one cylinder only (5) and only at idle which might indicate a ground problem somewhere. It also occurs to me that the O2 sensors are cleaning themselves up since I changed out the coil packs and plugs and the problem might eventually sort itself out (clutching at straws now).

In the meantime, I have started a service which will now not be completed until tomorrow because I was given the wrong oil filter. I will also clean the air intake and turbo pressure pipes out in the event that the remaining issue is due to oil contamination. I will clear down all off the codes after I finish and take her for a long run and report back with my findings.

I really appreciate the support from you guys. This has been such a trial that I suspect a dealer visit would have brought me to the edge of bankruptcy.

Regards

Steve

[wvicary]

It's odd that it only occurs at idle.... maybe injector not operating correctly?

[PKN]

I finally finished the service and then removed the inner wheel arch to get at the turbo pressure pipe which was covered in oil thanks to a leaking Henn joint. The hose elbow contained about a quarter pint of oil which had been making its way as a mist through the cooler into the throttle body. I have ordered a new pressure tube from and O ring from Andraya and will re-assemble when it arrives. It is a great opportunity to clean everything up but I am not looking forward to putting the wheel liner back in - it was a bugger to get off.....

Steve