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?

[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

[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.

[-tWv-]

Originally Posted by blue62

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.

Thanks for the reply. Although this car is intended to be a project car, engine timing is a bit outside my wheelhouse. I am also a bit impatient and want to enjoy the summer weather with my new Boxster!

Have an appointment with a local mechanic on Wednesday to get a diagnosis. I’ll definitely report back as we make progress.

[blue62]

Originally Posted by -tWv-

Thanks for the reply. Although this car is intended to be a project car, engine timing is a bit outside my wheelhouse. I am also a bit impatient and want to enjoy the summer weather with my new Boxster!

Have an appointment with a local mechanic on Wednesday to get a diagnosis. I’ll definitely report back as we make progress.

Hope I have helped in some small way.
Yes do keep us posted.
Hope things turn out well for you.

[-tWv-]

Originally Posted by blue62

Hope I have helped in some small way.
Yes do keep us posted.
Hope things turn out well for you.

Originally Posted by blue62

Hope I have helped in some small way.
Yes do keep us posted.
Hope things turn out well for you.

So got the report back from the shop today. They took a look at the timing and everything looked good there from a mechanical perspective. Current diagnosis is there is an issue with the variable valve timing, specifically with the timing chain tensioner/actuator. Unfortunately that little part is incredibly expensive ($1300 on pelican parts) and about 10 hours of labor to get it put in. Total bill is just over $3k .....

I’m going to go through with the repair because his diagnosis matches with the symptoms I’m seeing. There are misfires on all 3 cylinders (1-3) but the engine starts and runs ok so not likely a spark plug or coil issue. It only really feels like it’s struggling in certain gears/rev ranges. Seems like the one cylinder bank is advancing/retarding timing without the other and causing it to run very poorly/low on power.

It’ll be done in the next couple weeks and I’ll report back. Really hoping this fixes the issue as I want to get out for a real drive on the Blue Ridge Parkway!

[-tWv-]

Originally Posted by blue62

Hope I have helped in some small way.
Yes do keep us posted.
Hope things turn out well for you.

Got the report back from the shop today. Looks like everything looks good from a mechanical perspective on the timing. Unfortunately, that means there’s some sort of deeper issue and the mechanic thinks it has to be the timing chain actuator/tensioner. This part alone is over $1200 and it’s about 10 hours of labor to put it in. Bill just over $3k ....

I’m going to go ahead with it because his analysis makes sense from what I’m feeling with the car. It starts and drives just fine so I don’t think I’m getting a consistent misfire. It seems like it occurs in specific gears/rev ranges and just feels like the car is very low on power. My assumption is this is occurring due to one cylinder bank advancing/retarding valve timing and the other not acting similarly. He’s going to work through getting to the cams and will report if there’s something simpler going on (ex: the plastic guides on the tensioner failed instead of the whole part).

Hopefully this is it and I can get out on the Blue Ridge Parkway in the next couple weeks. Wish me luck.

[blue62]

Originally Posted by -tWv-

Got the report back from the shop today. Looks like everything looks good from a mechanical perspective on the timing. Unfortunately, that means there’s some sort of deeper issue and the mechanic thinks it has to be the timing chain actuator/tensioner. Unfortunately this part alone is over $1200 and it’s about 10 hours of labor to put it in. Bill just over $3k ....

I’m going to go ahead with it because his analysis makes sense from what I’m feeling with the car. It starts and drives just fine so I don’t think I’m getting a consistent misfire. It seems like it occurs in specific gears/rev ranges and just feels like the car is very low on power. My assumption is this is occurring due to one cylinder bank advancing/retarding valve timing and the other not acting similarly. He’s going to work through getting to the cams and will report if there’s something simpler going on (ex: the plastic guides on the tensioner failed instead of the whole part).

Hopefully this is it and I can get out on the Blue Ridge Parkway in the next couple weeks. Wish me luck.

When your mechanic is talking about the timing chain tensioner/actuator (so you and I are on the same page). I am going to assume he means the Variocam actuators.
Did he test the function of the actuator??
I can test the function of mine with my Foxwell scanner.
I run the RPM's up to I think it is 1500 RPM and I watch the exhaust cams jump in advance by 25 degrees.
Or I go to the testing functions and actuate them with the scanner and The engine responds differently so I know if they are working or not.
Your mechanic should be able to verify if the actuators are functioning or not

As you stated:
There are wear pads on the actuators so if they are worn out the actuators can be fine and still not advance the cams properly.
Wear pads are cheap actuators expensive.

Hope this info is of some help.
Keep us posted with the out come.

[-tWv-]

Originally Posted by blue62

When your mechanic is talking about the timing chain tensioner/actuator (so you and I are on the same page). I am going to assume he means the Variocam actuators.
Did he test the function of the actuator??
I can test the function of mine with my Foxwell scanner.
I run the RPM's up to I think it is 1500 RPM and I watch the exhaust cams jump in advance by 25 degrees.
Or I go to the testing functions and actuate them with the scanner and The engine responds differently so I know if they are working or not.
Your mechanic should be able to verify if the actuators are functioning or not

As you stated:
There are wear pads on the actuators so if they are worn out the actuators can be fine and still not advance the cams properly.
Wear pads are cheap actuators expensive.

Hope this info is of some help.
Keep us posted with the out come.

You are correct, talking about the VarioCam actuator. He’s going to test the actuator function today and confirm there’s a cam position mismatch before moving further.

[blue62]

Originally Posted by -tWv-

You are correct, talking about the VarioCam actuator. He’s going to test the actuator function today and confirm there’s a cam position mismatch before moving further.

Good luck let us know how you go.

[-tWv-]

Originally Posted by blue62

Good luck let us know how you go.

Mechanic confirmed today that bank 1 camshaft position is off by about 20 degrees as compared to bank 2. Bank 1 has all the CEL codes, so solidifies the variocam actuator theory. He’s going to start tearing ‘er apart tomorrow.

[blue62]

Originally Posted by -tWv-

Mechanic confirmed today that bank 1 camshaft position is off by about 20 degrees as compared to bank 2. Bank 1 has all the CEL codes, so solidifies the variocam actuator theory. He’s going to start tearing ‘er apart tomorrow.

Good luck with it.
Let us know how you go.
I always like to hear end results

[-tWv-]

Originally Posted by blue62

Good luck with it.
Let us know how you go.
I always like to hear end results

So the saga continues... he got the valve cover off and found that the cam timing was actually off by 1 tooth. The VarioCam actuator looked good and didn’t look like it needed replacing, so buttoned the car back up and test drove.

He said car ran well (no codes at all) after the first test drive but he noticed the water pump was leaking pretty bad so I told him to go ahead and replace that while the car was in the shop. After replacing the water pump he test drove again and now the car is throwing a camshaft sensor (P0341) code. He replaced the sensor and the code is still showing up. He has checked the cam timing and both banks are advancing together so doesn’t seem like an actuator issue. Additionally, the car runs well when cold but starts to run poorly and feel sluggish when hot. I don’t think this has anything to do with the water pump install, it just didn’t show up until he got a true test drive with the car all the way warmed up.

He’s keeping the car over the weekend and looking into it more next week, but I’m sort of at a loss for what this could be. I guess this could be an electrical issue with the connection itself causing it to not function properly. Another thought was something is wrong with air/fuel mixture when it gets up to temp (maybe MAF, O2 sensor, injectors...?), but no clue why that would throw a camshaft position sensor code.

Any ideas?

Mechanic is going to keep troubleshooting so will post back if we figure it out.

[blue62]

Originally Posted by -tWv-

So the saga continues... he got the valve cover off and found that the cam timing was actually off by 1 tooth. The VarioCam actuator looked good and didn’t look like it needed replacing, so buttoned the car back up and test drove.

He said car ran well (no codes at all) after the first test drive but he noticed the water pump was leaking pretty bad so I told him to go ahead and replace that while the car was in the shop. After replacing the water pump he test drove again and now the car is throwing a camshaft sensor (P0341) code. He replaced the sensor and the code is still showing up. He has checked the cam timing and both banks are advancing together so doesn’t seem like an actuator issue. Additionally, the car runs well when cold but starts to run poorly and feel sluggish when hot. I don’t think this has anything to do with the water pump install, it just didn’t show up until he got a true test drive with the car all the way warmed up.

He’s keeping the car over the weekend and looking into it more next week, but I’m sort of at a loss for what this could be. I guess this could be an electrical issue with the connection itself causing it to not function properly. Another thought was something is wrong with air/fuel mixture when it gets up to temp (maybe MAF, O2 sensor, injectors...?), but no clue why that would throw a camshaft position sensor code.

Any ideas?

Mechanic is going to keep troubleshooting so will post back if we figure it out.

So in a previous post you stated that the cams on one bank were out of sync. with the other bank by 20 degrees when the actuators were supposed to kick in.
In your newest post you state that your mechanic found no issue with the actuator but the cam timing was off by one tooth.

Did he correct the timing issue????
How did he correct it???
If the cam timing issue was not fully resolved it could be part of the ill running issue when fully warmed up.

Sounds like your P0341 code didn't show until after valve covers were removed and water pump replaced. new sensor didn't fix it.
I would look at the wiring very closely sounds like some wiring got pinched or disturbed in some way.

[-tWv-]

Originally Posted by blue62

So in a previous post you stated that the cams on one bank were out of sync. with the other bank by 20 degrees when the actuators were supposed to kick in.
In your newest post you state that your mechanic found no issue with the actuator but the cam timing was off by one tooth.

Did he correct the timing issue????
How did he correct it???
If the cam timing issue was not fully resolved it could be part of the ill running issue when fully warmed up.

Sounds like your P0341 code didn't show until after valve covers were removed and water pump replaced. new sensor didn't fix it.
I would look at the wiring very closely sounds like some wiring got pinched or disturbed in some way.

Yes he corrected the timing issue before he replaced valve cover etc. The car is now not misfiring at all and in time, just running poorly at operating temp.

Agree with you on the wiring, he’s checking the to ensure nothing was disturbed during the timing correction/other work in the past before I bought the car.

[blue62]

Well with the timing issue resolved your making progress.
The ill running when warmed up is kind of a mystery.

It would be interesting to have a scanner hooked up to it and see if it begins to run poorly right when it first goes into closed loop. or not.

My first thought was a possible bad MAF sensor but lots of times you see the engine hunting at idle when cold. With a bad MF.

Another thought is:
What readings is the DME getting from the coolant temp. sensor after the engine has been warmed up.
If the coolant temp. sensor is showing cold or low temp. when the engine is warmed up then the DME will still be on the cold start map.(rich in fuel) even though the engine is at operating temp.
If that were the case it also would probably not go into closed loop when warmed up.
May be something to look at.