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Old 02-28-2012, 09:35 AM   #1
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Track Days, Check Engine Light, Cam Deviation

I have a 2002 Boxster base with 59Kmiles.
I have been tracking it since last year, with a total of 8 track days on it so far.
Last month, on the way back home from the track, a yellow light in the instrument cluster blinked a couple of times and then stayed off.
I couldn't see which light it was (can't see well anymore without my reading glasses ), but once home, I guessed it was either the windshield washer (wishfull thinking) or the check engine light.
Tracked the car again this Sunday and had a eventfree drive back home. But yesterday morning, on the way to work, the check engine light flashed a couple of times again.
This morning, I hooked up the Durametric and found the following:

Engine Fault Codes:
P0300 Porsche Code # 62 Missfire, damage to Cat.
P0301 Porsche Code # 63 Missfire, Cyl. #1, damage to Cat.
P0306 Porsche Code # 68 Missfire, Cyl. #6, damage to Cat.
P0306 Porsche Code # 66 Missfire, Cyl. #4, damage to Cat.

Ignition Range 2 = 0; No over-rev

ABS Fault Code:
5525 Incorrect data transfer with DME Module

Camshaft Position 1 Deviation -7.27
Camshaft Position 2 Deviation -8.20

Interesting observations regarding camshaft deviations:
1) Both readings were indicating zero (0) until the engine warmed up a little (until steam started coming out of the exhaust). No, there is no intermix issue here; I am talking about the overnight condensation in the exhaust system burning off.

2) Both readings remained rock steady during a short drive around the block. I had cleared the engine fault codes before the test drive and the stayed clear.

3) When I had just purchased the Durametric, I had looked at the camshaft devations and remember them being different. I'm not sure but probably -1 and -6 respectively.

So, what could all this mean? I need help narrowing down the problem before attemting any repairs.

TIA


Last edited by seventythree; 02-28-2012 at 10:22 AM.
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Old 02-28-2012, 09:45 AM   #2
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Would a faulty coil pack alter the cam deviation (timing) in any ways using sofware/dme perhaps?

Similar to you, I have neg6 deviation on the CamPos1 (row car) and then O2 generated codes occasionally.
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Old 02-28-2012, 11:19 AM   #3
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No, coil packs cannot alter the cam deviation values.

The car obviously has misfires on cylinders 1 and 6, which is more than enough to cause the car to code and trip the CEL. The bigger issue is the cam values, which are both out of range (+/- 6), usually a sign of excessive slop in the cam drives. This can result from a myriad of causes, including the VarioCam units, tensioner pad wear, the tensioners themselves, etc.; or from the beginnings of an IMS issue. But as you have indicated that the deviation values remain steady, I would think that the IMS is not the issue here.

Unless you are prepared to get deep into cam timing diagnostics, with some potential for opening up the engine should your tensioner pads or VarioCam units need work, you need to take this car to a qualified indy for further assessment.
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Old 02-29-2012, 07:11 AM   #4
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Originally Posted by JFP in PA View Post
No, coil packs cannot alter the cam deviation values.

The car obviously has misfires on cylinders 1 and 6, which is more than enough to cause the car to code and trip the CEL. The bigger issue is the cam values, which are both out of range (+/- 6), usually a sign of excessive slop in the cam drives. This can result from a myriad of causes, including the VarioCam units, tensioner pad wear, the tensioners themselves, etc.; or from the beginnings of an IMS issue. But as you have indicated that the deviation values remain steady, I would think that the IMS is not the issue here.

Unless you are prepared to get deep into cam timing diagnostics, with some potential for opening up the engine should your tensioner pads or VarioCam units need work, you need to take this car to a qualified indy for further assessment.
What constitutes misfire? Wrong timing of spark (Ingition), or detonation? How is misfire sensed?

Also, how could cam timing being out of spec cause misfire?

Thanks
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Old 02-29-2012, 07:49 AM   #5
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Quote:
Originally Posted by seventythree View Post
What constitutes misfire? Wrong timing of spark (Ingition), or detonation? How is misfire sensed?

Also, how could cam timing being out of spec cause misfire?

Thanks
JFP may be quite busy looking after customers. I would definitely heed his advice. In my amateur opinion/guess, The misfire problem code could be independent of the cam deviation. You have to consider the possibility cam deviation is not necessarily the cause/ putting out that code. There maybe an independent misfire issue.

You might want to investigate the chain tensioners they are probably clogged up.....get them replaced and see what that does to the cam deviation....the deviation is pretty high though!


I am not sure I would drive the car without having it checked first. I would hook up the durametric and keep close tabs on the deviation if you have to drive it. If it starts dancing around I would shut it down and flatbed it

....hope you get to the bottom of it!
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Old 02-29-2012, 09:59 AM   #6
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What constitutes misfire? Wrong timing of spark (Ingition), or detonation? How is misfire sensed?
Engine misfires are detected by small unexpected changes in the crankshaft rotation speed.
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Old 02-29-2012, 10:20 AM   #7
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Engine misfires are detected by small unexpected changes in the crankshaft rotation speed.
oook. that doesn't sound too good mate

How much are we talking about here for changing the supportive timing mechanism aprox? Excluding the engine drop work and labor... how much would it be for a NEW chain, the variocam tensioners, external chain tensioners, green caps, and other related blah stuff...sealant etc?

Just about 1k? 2k? less more?
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Old 02-29-2012, 10:36 AM   #8
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What is the firing order? Thanks
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Old 02-29-2012, 11:22 AM   #9
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what is the firing order? Thanks
1-6-2-4-3-5 Unless severe, cam timing issues typically do not cause misfires, we have seen cars as far out as 8-9 degrees that were otherwise running fine.

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Last edited by JFP in PA; 02-29-2012 at 11:48 AM.
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