Help Diagnosing Slew of CEL Codes

[-tWv-]

Hello all,



New member here. I just purchased a '98 986 last week from my BIL who has been daily driving it for the past few years. Recently the CEL light came on and the car has been running poorly (most noticeable is very poor acceleration in low gear). He took it to his local Porsche dealer and they essentially diagnosed the issue as bad catalytic converters and quoted a $6k+ repair bill. He didn't have the money or patience to deal with the car anymore and I told him I'd be willing to do the work, so he sold it over to me.



Looking for some help interpreting these CEL codes and making sure that addressing the catalytic converters is the best first step.



There are 6 total codes reading out (I have an iCarSoft PORV1.0, looks like these are interpreted via their software):



1) 22 - Sensor ageing ahead of catalyst converter, cylinder (4-6)

2) 23 - Sensor ageing behind catalyst converter, cylinder (4-6)

3) 322 - Toothed belt out of position, Bank 1

4) 62 - Misfire emissions - relevant

5) 50 - Cylinder 1 misfire emissions - relevant

6) 52 - Cylinder 3 misfire emissions - relevant



Am I correct in thinking that Codes 1,2,4,5,6 could all be caused by a bad cats blocking up the exhaust flow causing poor O2 readings and misfires? The O2 sensors were recently replaced, so I'm thinking that the readings are correct.



The one that has me a bit worried is code 3 for the toothed belt out of position. Could this be caused by bad cats or is the timing chain truly the root cause?



My current plan is to replace the stock headers/cat with the Manzo headers and see if that resolves the flow issue. Obviously I'll still have codes for the downstream O2 sensors, but I'm hoping that clears up the misfires and pre-cat sensor issues. My future plans are to put sport cats on and extend the O2 sensor cables, but looking to at least get the thing running well for cheap in the short term.



Thanks in advance for any help you can provide.

[mikefocke]

322 - allocation of exhaust cam and inlet cam do not agree, timing chain out of position.

Fix this problem first before you spend anything on any mods.

[-tWv-]

Originally Posted by mikefocke

322 - allocation of exhaust cam and inlet cam do not agree, timing chain out of position.

Fix this problem first before you spend anything on any mods.

Thanks for the input. Digging into this more it seems like the Porsche shop may have just gone for quoting the high dollar amount fix first instead of actually solving the problem. Misfires seem to be related to the timing issue and then potentially still need catalytic converter delete or replacement to take care of the other codes.

[blue62]

when you get an O2 sensor aging code it is telling you that the sensor is responding slowly. Which is what they start to do as they get get older. eventually their response gets slow enough that the DME throws the code. Unlikely that the cats are causing the problem.

If the O2 sensors are new or recently replaced and you are getting O2 sensor aging codes.
I think there are other issues in play.
Were the codes present before they were replaced?
If so were the codes erased after they were replaced?
If they were replaced recently are you positive they are the right ones for the car.
If they were other than Bosch or Porsche (relabeled Bosch) in my mind things get iffy.
Is all the wiring to them and from them to the DME sound?
Are the connections sound?

I would fix the timing issue first.
In fact if it was me I would not drive or even start the car until the cam timing issue was resolved.
Then I would erase all codes and go from there. But that's me.

[-tWv-]

Originally Posted by blue62

when you get an O2 sensor aging code it is telling you that the sensor is responding slowly. Which is what they start to do as they get get older. eventually their response gets slow enough that the DME throws the code. Unlikely that the cats are causing the problem.

If the O2 sensors are new or recently replaced and you are getting O2 sensor aging codes.
I think there are other issues in play.
Were the codes present before they were replaced?
If so were the codes erased after they were replaced?
If they were replaced recently are you positive they are the right ones for the car.
If they were other than Bosch or Porsche (relabeled Bosch) in my mind things get iffy.
Is all the wiring to them and from them to the DME sound?
Are the connections sound?

I would fix the timing issue first.
In fact if it was me I would not drive or even start the car until the cam timing issue was resolved.
Then I would erase all codes and go from there. But that's me.

Still waiting for my BIL to send all the maintenance records but they put a ton of work into the car over the past few years and as far as I’m aware all parts were OEM. I don’t believe the codes were present prior to replacement, it was more of a preventative maintenance thing at that point but I’ll confirm.

The car has been driven a decent amount since the CEL came on with no major issues, but I’m not sure if the cam timing code was present initially. Definitely going to get the timing issue resolved first like you said and then start diagnosing everything else.

Is there any chance this could be a bad camshaft position sensor? Or does the code I have specifically relate to physical timing being off?

[blue62]

Originally Posted by -tWv-

Still waiting for my BIL to send all the maintenance records but they put a ton of work into the car over the past few years and as far as I’m aware all parts were OEM. I don’t believe the codes were present prior to replacement, it was more of a preventative maintenance thing at that point but I’ll confirm.

The car has been driven a decent amount since the CEL came on with no major issues, but I’m not sure if the cam timing code was present initially. Definitely going to get the timing issue resolved first like you said and then start diagnosing everything else.

Is there any chance this could be a bad camshaft position sensor? Or does the code I have specifically relate to physical timing being off?

I am not familiar with your ICARSOFT scanner brand.
But OBDII was standardized in 1996 so you don't need priority brand scanners to read OBDII codes.
Checking the codes with another scanner to prove your cam timing codes and other codes would not hurt.
Especially if the software is in the more common "P" code format.

Yes there is a possibility that the cam position sensor could be bad.
But I don' like to just change parts without confirmation that they are bad.

What I would do is have the codes read with a scanner that uses the more common "P" code format. Because that is what "I" am familiar with.
So I would have more confidence in my diagnosis.
Then if I got the cam timing code again I would check the timing by aliening the manufactures timing marks for the crank and camshafts. That way I would have physical proof of correct or incorrect crankshaft and camshaft timing.

If all timing marks fell in spec. then I would be looking at things like the cam and crank position sensors.

Setting up the timing marks so you can check them is a little bit of work but I think the only cash outlay is for the plastic plugs that you have to remove to see the timing marks.

[Blue99]

First of all I’d get the codes using OFFICIAL PORSCHE diagnostic equipment I’m not saying the codes are wrong BUT as you say It’s your machines interpretation of the codes as in 1 tooth out Might not be the correct code
Also if the IMS bearing was done it could be an old code stored

[-tWv-]

So after a couple more troubleshooting sessions the shop has pinpointed the issue as the VarioCam actuator like we originally thought. Mechanic took the current actuator apart and there was apparently some silicone blocking the oil feed port. It’s unclear where this came from but he thinks it’s from a previous time the valve cover came off with a past owner.

He put the car back together and it runs MUCH better now and I was able to drive for an hour yesterday with no codes.

Unfortunately, eventually a CEL code came back for bank 1 timing adjustment. I think the actuator may have been damaged due to lack of oil or is working intermittently. Going to drive it for the weekend if the code keeps coming back we will put a new actuator in and hopefully have this issue put to bed.

[blue62]

Originally Posted by -tWv-

So after a couple more troubleshooting sessions the shop has pinpointed the issue as the VarioCam actuator like we originally thought. Mechanic took the current actuator apart and there was apparently some silicone blocking the oil feed port. It’s unclear where this came from but he thinks it’s from a previous time the valve cover came off with a past owner.

He put the car back together and it runs MUCH better now and I was able to drive for an hour yesterday with no codes.

Unfortunately, eventually a CEL code came back for bank 1 timing adjustment. I think the actuator may have been damaged due to lack of oil or is working intermittently. Going to drive it for the weekend if the code keeps coming back we will put a new actuator in and hopefully have this issue put to bed.

Sounds like your making some progress as things are beginning to improve.
Keep us posted
Waiting for the: damn this thing runs great post

[-tWv-]

Originally Posted by blue62

Sounds like your making some progress as things are beginning to improve.
Keep us posted
Waiting for the: damn this thing runs great post

It’s running way better, but still randomly sluggish off the line which I think is due to actuator just not responding correctly 100% of the time. I had a blast last night cruising through the mountains though, so definitely making progress .

[Tremonte986]

Have you looked at the cam deviation? If it's reading negative more than 9, that will trigger cam.timing CEL and can indicate timing chain guide wear. Could be that the failed actuator accelerated the pad wear. Something to check. And if you don't mind telling, what shop are you using? I'm in Asheville as well. We are lucky to have a decent amount of Porsche shops around here.

[-tWv-]

Originally Posted by Tremonte986

Have you looked at the cam deviation? If it's reading negative more than 9, that will trigger cam.timing CEL and can indicate timing chain guide wear. Could be that the failed actuator accelerated the pad wear. Something to check. And if you don't mind telling, what shop are you using? I'm in Asheville as well. We are lucky to have a decent amount of Porsche shops around here.

At this point I’m only getting a “Camshaft adjustment Bank 1” code and it seems like the actuator is working intermittently. For example, 8/10 times when I start out in 1st gear the car will feel great with plenty of torque. The other 2 times it feels like it’s struggling to rev (no torque) and does not respond to throttle position well at all. Leads me to believe the timing is just not quite right in those instances on Bank 1 causing the sluggish behavior. I think I’m going to have to bite the bullet and just get the actuator fully replaced.

The shop I’m working with is All German Performance on Hendersonville road. Daniel (the owner/lead mechanic) has been great thus far and really fair with pricing out the labor. It’s been a bit of a goose chase trying to pinpoint this issue but I think we finally have it nailed down. Going to get the part swapped next week and hopefully that will be the end of it.

[-tWv-]

Closed out this saga today (hopefully). Ended up having the bank 1 camshaft adjuster (996-105-051-58) fully replaced. Drove the car pretty hard for 2+ hours this afternoon with zero CEL codes and no hesitation at all. I was also hearing a timing chain rattle at startup that is now gone.

In summary the fix for this problem was 1) timing adjustment and 2) new timing adjuster/actuator. I also replaced o2 sensors myself to get rid of those codes. It seems like the bad adjuster allowed the chain to skip a tooth and just was not functioning properly due to oil starvation from the gunk in the feed port. Another big lesson learned here was never trust the first diagnosis of a problem, especially when said diagnosis doesn't make a ton of sense. If we would have gone with the initial Porsche dealer diagnosis I would be out $6k in catalytic converters and likely no progress made at all. Find a trusted indy with good reviews and they will likely be able to get it fixed.

The car is now running great and I'm very happy with the purchase. Was a bit more pricey than I anticipated getting this thing running, but well worth it in the end. Looking forward to enjoying the car for years to come!

[Tremonte986]

Cool deal. Glad Daniel fixed you up. I've only heard good things about him and his shop.

[blue62]

Glad you got it sorted.

[-tWv-]

Originally Posted by blue62

Glad you got it sorted.

Thanks! Also thank you for the help and suggestions. Was able to have a more informed conversation with your feedback.

Put a couple hundred more miles on it this past weekend with no lights and none of the previous hesitation issue. Been a blast!

[blue62]

Originally Posted by -tWv-

Thanks! Also thank you for the help and suggestions. Was able to have a more informed conversation with your feedback.

Put a couple hundred more miles on it this past weekend with no lights and none of the previous hesitation issue. Been a blast!

Glad I could help.
They are fun cars when everything is sorted and working correctly