Rough idle, loss of power on accelleration, IMS?

[Schnell Gelb]

How to check Cam Timing with a Misfire:

You need 2 Tools imho:

1. Durametric -to read Actual Values and Deviation. Also check the specific misfire codes.

2. The Baum or LN tools to physically  set  or check the timing of the 2 Camshafts.

The problem is you may have a flashing CEL so running the engine any longer than necessary is bad.

You can eye-ball the half-moons and the Inlet notch to get maybe +/- 20 degrees Crk. Almost useless.

Before you consider removing the Camshaft Cover to investigate ,do some research or start a separate Thread because access is awful with the engine in place.

Check the many easier issues like basic maintenance, MAF ,Vacuum Leaks. For example the AOS hoses/connectors/seals.

Disclosure: I am working (again I am embarrassed to say!) on a Bank 1 misfire and am investigating every alternative to removal(again!) of the Cam Cover.

Mine is a 2001 S with a recently rebuilt engine.Codes are P0300,0301,0305 .These are Porsche Codes 62,63,67 per Durametric..

In my case the Actual Value for the timing (cold)on Bank 1 at idle is negative 10 degrees. Bank 2 is less than 2 degrees. It runs rough stinks of gasoline and has a flashing CEL with codes as above. New plugs.coils,injectors,new CkPS,new cam to cam timing chains but a suspect  Variocam Actuator. Strangely the static Cam  Timing is perfect.

The IMS to Cam chain is original but 'good' the chain tensioner seemed very strong when I did this same job a month ago.

 

If you must remove the Cam Cover - the best write ups have recently lost all their photos due to the Image Hosting Providers going awol.

Insite had the best and it was linked and used  many times .But without the photos it is not as usful. The FSM has the basics.

For example:

http://986forum.com/forums/performance-technical-chat/26418-diy-setting-cam-timing-m96.html

Maybe someone on RennTech has a solution ?

Pelican has a useful Section intended for the 996

http://www.pelicanparts.com/techarticles/Porsche-996-997-Carrera/16-ENGINE-Camshaft_Swap_and_Valve_Train_Repair/16-ENGINE-Camshaft_Swap_and_Valve_Train_Repair.htm

or the Boxster version - but you already have the book?

http://www.pelicanparts.com/techarticles/Boxster_Tech/16-ENGINE-Camshaft_Swap_and_Chain_Tensioner/16-ENGINE-Camshaft_Swap_and_Chain_Tensioner.htm

1.Just be careful about Wayne's ambiguous use of "Chain Tensioner". Sometimes Wayne means the Variocam Solenoid+Actuator assy., sometimes he really means one of the 3 actual  Chain Tensioners.

2. I don't understand why he removes the Camshaft Sprocket (Figure 8) from the Exhaust Camshaft with the IMS-to-Cam chain  still under tension. For Bank 1 that you are concerned with ,the big nut for the Chain Tensioner is easily accessible on the underside of the engine . Why not remove it before trying to remove the Sprocket ?

3. Note Fig 18 - one of the few remaining photos showing the correct (8) link spacing between the cams.Mark the 'divots' with a paint pen.New chains may not have the helpful colored links !

4. It may not be a Timing error if the notch of the Bank 1  Inlet cam notch points slightly upward (& toward the passenger side rear wheel) with the engine at TDC and the Exhaust cam correctly positioned with the LN tool.The FSM shows the notch at roughly 2.45 , not 3.00.

5. Access requires removal of many other parts. Then need to drop the engine as far as possible. If you are not using a lift ,this would be difficult.

Edited July 25, 2017 by Schnell Gelb

[Morissey]

On 7/24/2017 at 4:18 PM, Schnell Gelb said:

Cam Timing - maybe, but it would have to be a common component to both Banks if 1,5=Bank 1 & 6=Bank 2 are causing the codes.

That is why I suggested the basic cam timing check by removing the green plugs.

Vacuum leak  is still a possibility if the misfire is caused by an excessively lean condition in those cylinders.

The plug color may give clues?

My speculation is not authoritative so best for you to gather evidence and let the smarter guys comment.

Checked the cam timing and both banks are on the mark aligned with the timing notches while flywheel at TDC.

Plugs: No oil, no foul firing signs, looks they are in good shape (approx. 20K miles on them)

Coils: Boots bone dry, clean, elastic and overall look great. Resistance measures correct and consistent among all including one pack from a cyl that did not trigger a code for good measure.

 

 

[Schnell Gelb]

There is still the vacuum issue. But you would have to use a smoke machine because of the flashing CEL

You could try disconnecting the MAF. If that helps the rough running try the voltage and resistance test for the MAF.

I am trying to exhaust the list of easier items for you.

" Checked the cam timing and both banks are on the mark aligned with the timing notches while flywheel at TDC. " I presume you mean you confirmed the exhaust cam is in the correct position. What about the Inlet cam notch ?

Did you work on any area of the engine before this rough running happened ? AOS for example.

[Morissey]

20 hours ago, Schnell Gelb said:

There is still the vacuum issue. But you would have to use a smoke machine because of the flashing CEL

You could try disconnecting the MAF. If that helps the rough running try the voltage and resistance test for the MAF.

I am trying to exhaust the list of easier items for you.

" Checked the cam timing and both banks are on the mark aligned with the timing notches while flywheel at TDC. " I presume you mean you confirmed the exhaust cam is in the correct position. What about the Inlet cam notch ?

Did you work on any area of the engine before this rough running happened ? AOS for example.

I am going for the MAF and vacuum leak checks next.

Should I drain and check the oil?

Yes, I confirmed the exhaust cams (with the notches - 5 chain setup) were at 90 deg. How do I check the inlet ones? Do they have position indicators?

 

Thanks!

[Schnell Gelb]

Camshaft identfication

Be careful ! Read the Pelican diy article.See links in link below. The INLET cam notch is 90 degrees(??) you mean 3 o'clock.

The Exhaust half moons should be vertical AND align with the parting line of the cam cover with the engine at TDC

But make sure you understand the small but vital difference between the reference positions on Bank 1 vs.Bank 2.

Here is an example where despite repeating this mantra confusion still ensued:

 

Edited July 27, 2017 by Schnell Gelb

[Morissey]

3 minutes ago, Schnell Gelb said:

Camshaft identfication

Be careful ! Read the Pelican diy article.See links in link below. The INLET cam notch is 90 degrees(??) you mean 3 o'clock.

The Exhaust half moons should be vertical AND align with the parting line of the cam cover with the engine at TDC

But make sure you understand the small but vital difference between the reference positions on Bank 1 vs.Bank 2.

Here is an example where despite repeating this mantra confusion still ensued:

 

 

I am trying to understand how to check the inlet cams timing and position indications

On the exhaust side, yes the notches on the cam are vertically aligned with the notches on the covers.

I will now look into the DIY link and check the inlet cam positions.

I will come back with my findings. Thanks!

[Ahsai]

To diagnose misfires, the Durametric will be very useful. Most common cause of misfires: bad spark plugs, coils, MAF, intake air leak, fuel pressure. I would not suspect the timng first unless durametric shows > 7 degrees of cam deviation.

[Morissey]

I have checked the timing visually using the helpful post here: http://986forum.com/forums/performance-technical-chat/26418-diy-setting-cam-timing-m96.html

I did the procedure once and all seems correct on the car. I will be doing the procedure again tomorrow and will post photos so you can confirm my finding.

I will then move onto the MAF as I have ruled out spark plugs and coils.

[Morissey]

When checking the bank2 timing with engine on exhaust TDC, the exhaust cam notches are perfectly aligned, but he inlet cam notch is not exactly at 90 degrees. Is this a problem??

 

[innov8]

7 hours ago, Ahsai said:

To diagnose misfires, the Durametric will be very useful. Most common cause of misfires: bad spark plugs, coils, MAF, intake air leak, fuel pressure. I would not suspect the timng first unless durametric shows > 7 degrees of cam deviation.

@Morissey  I can second Ahsai's recommendation. He is correct... get the Durametric (less than $300 or 2 hrs at the local P-dealer). It will pay for itself in saving you time and money.

I purchased one and he has been helping trace the source of the same misfire codes. By measuring actual values, we have eliminated cam deviation, MAF and are now I am going to make a smoke machine out of an old fog machine we used to use for Halloween (and an Ahsai post on another board). In my case, the codes are intermittent amongst the cylinders across both banks but they only happen on a cold start, at idle and when starting off in first gear with low revs... as I pull away, the RPMS drop for a second as I pass 2k and then come right back up and the engine pulls hard and smoothly throughout the rev range otherwise. You can check out my thread here: 

The thread title doesn't really match the topic as it was started while I was still looking to determine what the codes would be. I strongly recommend getting the cable and downloading the software. BTW, I am a 30-year mac user and have been running the program on Bootcamp without any trouble at all. I'll be following your thread to see if one of us uncovers a cause that might help the other. Good luck.

Edited July 27, 2017 by innov8
grammer, typo

[Morissey]

1 hour ago, innov8 said:

@Morissey  I can second Ahsai's recommendation. He is correct... get the Durametric (less than $300 or 2 hrs at the local P-dealer). It will pay for itself in saving you time and money.

I purchased one and he has been helping trace the source of the same misfire codes. By measuring actual values, we have eliminated cam deviation, MAF and are now I am going to make a smoke machine out of an old fog machine we used to use for Halloween (and an Ahsai post on another board). In my case, the codes are intermittent amongst the cylinders across both banks but they only happen on a cold start, at idle and when starting off in first gear with low revs... as I pull away, the RPMS drop for a second as I pass 2k and then come right back up and the engine pulls hard and smoothly throughout the rev range otherwise. You can check out my thread here: 

The thread title doesn't really match the topic as it was started while I was still looking to determine what the codes would be. I strongly recommend getting the cable and downloading the software. BTW, I am a 30-year mac user and have been running the program on Bootcamp without any trouble at all. I'll be following your thread to see if one of us uncovers a cause that might help the other. Good luck.

Thanks for the post. The thread is still valid for my case as I have rough idle and no power. If I can do a physical check of timing to rule out a chain skip or other internal mechanical issue, I can then move on to other possible cause diagnosis.

[Morissey]

Update:(2001 Boxster s 50K miles)

I have ruled out ignition components, fuel and vacuum as causes with a good deal of confidence. Never say never...

I have checked the physical cam timing and all is per spec.

Cleared all codes and it consistently gets flashing CEL and P0306 only. I have cleared 3 times just to be sure and same code came back.

I plugged in a compression gauge onto cyl 6 and it got up to 60 psi. I tested two other cylinders on bank 1 and they both read 100 psi.

 

Please feel free to give me your diagnostic thoughts.

 

Thanks!

[Ahsai]

Any coolant/oil intermix? Sounds like your problem is in the cylinder #6. Could you do a leak down test and check for leak from the valves and piston rings? Borescoping the cylinder (valves and cyl wall) might give us more clues too.

[Schnell Gelb]

You might want to try doing a "wet" compression test on #6 or a leakdown test.

That may help you identify the source of the low compression

woops, Great minds...

Edited August 5, 2017 by Schnell Gelb

[Morissey]

I will do a leakdown test on #6 and come back. Thanks.

[Morissey]

1 hour ago, Ahsai said:

Any coolant/oil intermix? Sounds like your problem is in the cylinder #6. Could you do a leak down test and check for leak from the valves and piston rings? Borescoping the cylinder (valves and cyl wall) might give us more clues too.

 

No coolant/oil mix. The culprit is definitely #6. When running at idle there is a bit of backfire sound here and there. Thinking valve issue right now, but I will do the proper test.

[Ahsai]

Yeah, does sound like a burnt valve or broken valve spring.

[Morissey]

1 hour ago, Ahsai said:

Yeah, does sound like a burnt valve or broken valve spring.

 

Update:

I am afraid you are correct. I have a leak into the exhaust at TCD on cylinder #6.

What should be my next diag move to determine extent of damage? or is this pretty much a head removal and valve job?

 

Thanks!

[JFP in PA]

4 minutes ago, Morissey said:

 

Update:

I am afraid you are correct. I have a leak into the exhaust at TCD on cylinder #6.

What should be my next diag move to determine extent of damage? or is this pretty much a head removal and valve job?

 

Thanks!

 

What compression pressure or leak down value to you have on that cylinder?

[Morissey]

19 minutes ago, JFP in PA said:

 

What compression pressure or leak down value to you have on that cylinder?

 

I don't know the leakdown value. I could not get my hands on a  tester so I put air directly into the cylinder and looked/listened for the source of leak. On compression test it maxes at 40 psi.

[Ahsai]

Without a leak down tester, it's hard to say because even a healthy engine can have something like 5% leak and you may see even more on a cold engine or if the valve is not completely seated due to the light spring pressure despite nothing is wrong.

[Morissey]

2 minutes ago, Ahsai said:

Without a leak down tester, it's hard to say because even a healthy engine can have something like 5% leak and you may see even more on a cold engine or if the valve is not completely seated due to the light spring pressure despite nothing is wrong.

 

I was afraid you would say that. I am pretty sure the leak is well over 20%. I do need to be for certain, so I will acquire a tester and report back.

[Ahsai]

Sure. Also a good idea to do the test on the other cylinders for comparison.

[Morissey]

14 minutes ago, Ahsai said:

Sure. Also a good idea to do the test on the other cylinders for comparison.

 

Yes, I will test all 3 on that bank. Thanks.

[Morissey]

Coming back with some updates. My hunch was correct. An exhaust valve on cylinder 6 is not seating. My theory was a burnt guide or broken spring. Turns out neither! See attached pic. The object is a thin seemingly grooved piece of metal. I have yet to understand where it came from. I have checked IMS (in great shape, but will replace with LN for good measure) oil filter, oil, spark plugs, and of course the cams, covers and heads. I find nothing to be out of ordinary

 

Both heads are off and with the machine shop for complete crack/leak test and valve jobs. I left everything in tact so they perhaps can try and determine the source of metal debris. While the machine shop does their assessment, your perspectives are welcome.

 

Also, while I'm at this I have determined following additional projects to be worth the time and $. Any feedback on what I may be missing or overdoing is welcome.

Care details: 2001 Boxster s with 50Kmiles

1. Water pump & thermostat (they are the originals)

2. IMS

3. RMS seal

4. Clutch (has ~ 40% left)

5. Oil separator

6. Cam chain rails