Durametric help

[Jkienzle]

I have a miss fire # 4  in rough running cylinder #4 is higher then the rest but not sure what reading is . All cylinders are about the same low # but #4 is 10  to 13  

[Ahsai]

A healthy reading should be less than 1 / second square at idle (after fully warmed up).

 

Have you tried replacing your sparks plugs and coils? You can swap the coil with another cylinder and see if the misfire follows the coil.

 

Did you just get the car with this problem or the problem just developed recently.

[Jkienzle]

This is a   Reoccurring  issue I’ve had it keeps coming back always #4 .I have changed  plugs/coils /Maf / injectors/ each time I change out a part it runs great and in a month or so cel on again 

[Ahsai]

Have you performed any compression and leak down tests? What are the exact error codes?

[Ahsai]

What are the cam deviations, FRA and RKAT on each bank? Just a sanity check...

[Jkienzle]

Yes compression is good on all .All  about 210 psi but  #  6 a little weaker at 195 and plug shows a bit of oil .The codes are p0300 and p0304  . Miss fire clears up at higher rpm  I have not done leak down test 

[Ahsai]

What year is your 996? You may need to check the injector and coil signal with a scope. If those are normal, then it's likely a mechanical issue such as a bad lifter.

[Jkienzle]

2003 C4S I took it to a local shop that said he had Porsche software but turns out he does not .He was unclear how vario cam system worked so not in a hurry to go back to him .

[Ahsai]

In the meantime you may also want to attach a vacuum gauge at the intake vacuum to see if the needle are bouncing. That will tell you something mechanical is bad such as a burnt valve, broken valve spring, bad lifter, etc.

[Jkienzle]

I’ll look at cam deviation in durametric .If I run rpm up it clears up and runs fine . Does not make any noise like lifter or broken spring . Thank you Ahsai for your input 

[Ahsai]

Check out this thread. Not saying this is your problem but definitely a possibility.

 

https://rennlist.com/forums/996-forum/861911-stuck-lifter-symptoms-misfire-on-cylinder-4-intermittent.html

 

Another one

 

https://www.6speedonline.com/forums/996/297370-solved-misfire-idle-p0305-2002-lifter-replacement-bank-2-p1325.html

[Jkienzle]

i got some new codes this time  p01362 and p01371  how can I Diagnose  further with durametic  

[Jkienzle]

[Jkienzle]

[Ahsai]

Excellent. I'm not too familiar with those codes but per the DME 7.8 diagnostic info for 996  P1362 is  intake valve of cylinder #4 does NOT switch to small lift i.e. stuck at large lift. That makes sense because at low rev, the intake valves should use small lift and they change to large lift at higher rev. That's how variocam+ works. You mentioned misfires occur only at low rpm. That's because the lifter #4 is stuck at high lift.

 

P1371 is a general lifter code for any cyl #1-#6 do not switch to small  lift.

 

I think it's time to remove the bank 2 cam cover and inspect all the intake valves.

 

BTW, can you check the "Cam deviation" readings of both banks? Are they solid and remain constant regardless of revs? This does not change the above but I am just curious about the general health of the engine.

Edited April 22, 2019 by Ahsai

[wyovino]

Bore scoring? Cylinder 4 is textbook bore scoring victim for MY2003.

[Jkienzle]

I think this is it #s done move 

[Ahsai]

Great numbers. Spec is 0 degree +/- 6 degrees so yours are way within spec.

 

You may want to read or re-read the two threads I mentioned before. They have identical symptoms and intake valve failure.

[Ahsai]

11 hours ago, wyovino said:

Bore scoring? Cylinder 4 is textbook bore scoring victim for MY2003.

 

While the cylinders may be scored, I doubt bore scoring will trip the very specific intake valve lifter codes.

 

It sucks that one cannot inspect the lifters without removing the cam cover, which involves a lot of labor. That's why the factory manual recommends replacing ALL the lifters (intake and exhaust) of the bank that is affected. The logic is if one lifter went bad, it's possible the others could follow since they wear similarly and are subject to the same operating conditions.

 

If the mileage is high, it will also be a good opportunity to replace the timing chain pads.

[Jkienzle]

Yes I think I should remove cover it sounds like lifters to me .I will have to park it for a bit no time are good place to do it .Thanks again for your help Ahsai

[Ahsai]

You're welcome! Let us know how it goes.