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Old 09-10-2020, 12:52 AM   #1
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986 Misfire 1 2 3 on idle - Variocam?

Hi,

Apologise in advance if this has already been covered. I did have a good look through the forum first. I have a 1998 986 2.5 manual with 48k on the clock. It flew through MOT and the only issue is that on idle the MIL light comes up. On scanning it points to misfire on bank 1 2 3. A quick scan at the Porsche specialist says it's the variocam but without further testing or taking the engine apart they cannot be sure. They did say I could still drive it and live with the problem. Is that recommended or should I get it sorted? Has any got this problem and live with it? Other than this it actually drives great!

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Old 09-10-2020, 06:10 AM   #2
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Hi,

Apologise in advance if this has already been covered. I did have a good look through the forum first. I have a 1998 986 2.5 manual with 48k on the clock. It flew through MOT and the only issue is that on idle the MIL light comes up. On scanning it points to misfire on bank 1 2 3. A quick scan at the Porsche specialist says it's the variocam but without further testing or taking the engine apart they cannot be sure. They did say I could still drive it and live with the problem. Is that recommended or should I get it sorted? Has any got this problem and live with it? Other than this it actually drives great!
If it was my car!!
I would First look at the coil packs for that bank.
Look for hairline cracks in them.
They can be tested with an Oms meter but I don't know the values.

You could also swap all the coils from one bank to the other to see if the misfire follows.
If the misfire code does follow to the other bank then you know the coil packs are bad.

If you continue to drive it with misfires you will destroy the Catalytic converter.
They are very pricey to replace.
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Old 09-10-2020, 09:41 AM   #3
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Thanks for the reply. I was told that if it was the coilpacks it would misfire individually but it misfire all banks 1,2 & 3 which suggest it could be the variocam?
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Old 09-10-2020, 11:43 AM   #4
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Hi thanks for your reply but if it's the coil pack surely it wouldn't affect the banks 123? Chances of that happening are very little.
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Old 09-10-2020, 04:18 PM   #5
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Hi thanks for your reply but if it's the coil pack surely it wouldn't affect the banks 123? Chances of that happening are very little.
What is the code or codes you got when you scanned the OBDII.
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Old 09-11-2020, 05:58 AM   #6
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Thanks here it is using a foxwell NT644 scanner. I understand that porsche uses PIWIS Scanner?


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Old 09-11-2020, 06:56 AM   #7
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Thanks here it is using a foxwell NT644 scanner. I understand that porsche uses PIWIS Scanner?


So all of your codes are misfire codes for cyl. 1-2-3 on the right hand bank.
I see no codes that point to issues with camshaft position or (variocam) issues.

You stated that your car is a 1998 with 48k on the clock.
48k is low mileage so variocam or cam position issues at that mileage although possible would I think be rare.

Now your coil packs (if they have never been changed) are 22 years old.
Perhaps they are beginning to fail.

So following good diagnostic processes always go with the simplest things first then work your way up the ladder step by step to the most complex.

A very simple first test that you can do yourself at no cost.

Is to switch all the coil packs from the left bank to the right bank and vise-versa.
If the problem is the coil packs then you should get codes for misfires on the 4-5-6 side.

When you do this clear all your codes before restating and test driving the car.

If the codes do not move to the 4-5-6 bank then you have proved for certain your coil packs are good.

If the codes come back for the 1-2-3 bank then I would look for a problem in the wiring or wiring connections that feed the coil packs on that bank.

Three questions:
How old is your battery?
Was any recent work done to the car before this problem?
Did the Porsche shop tell you why they suspected the variocam system?

Last edited by blue62; 09-11-2020 at 07:47 AM.
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Old 09-11-2020, 12:02 PM   #8
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Quote:
Originally Posted by Tinkerer View Post
Thanks here it is using a foxwell NT644 scanner. I understand that porsche uses PIWIS Scanner?


FWIW I had a similar list of codes come up with 78k on the clock and a new variocam actuator was the solution along with a timing adjustment (my chain had skipped a tooth). Thread here: Help Diagnosing Slew of CEL Codes

Not saying that for sure is the issue but it was also a bit of a surprise for me to be at relatively low miles.

Last edited by -tWv-; 09-11-2020 at 12:06 PM.
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Old 09-11-2020, 01:36 PM   #9
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Thanks for the response. Yeah the Porsche shop suspected the variocam? They plugged in a computer and said this is likely the case they didn't tell me the code but wouldn't know for sure until they give it a strip down.

Coil packs have been changed. It's has comprehensive service history and new Yuasa battery.
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Old 09-11-2020, 01:57 PM   #10
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tWv
You also had a cam timing ,cam chain position code with your issue.
The OP shows no cam timing or cam chain position codes
Only misfire codes on one bank.
So it will be interesting to see what happens if he switches the coil packs.
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Old 09-11-2020, 02:21 PM   #11
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This is the a recent invoice if that helps looks like new coil packs have been tested but problem still persist.
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Old 09-11-2020, 03:04 PM   #12
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This is the a recent invoice if that helps looks like new coil packs have been tested but problem still persist.
Is it just me... or is that a laundry list of throwing parts at a car?

Best wishes on a less costly outcome.
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Old 09-11-2020, 03:29 PM   #13
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This is the a recent invoice if that helps looks like new coil packs have been tested but problem still persist.
Interesting:
I see why the shop is looking at cam timing.
I would want to verify proper camshaft timing at this point.
Along with proper function of the variocam system.

You could have an issue with the wiring harness from DME/ECU to the coil packs
the connections to the DME/ECU or the DME/ECU itself.

Testing all the above shouldn't be to hard for a shop to do.

As for living with the problem and continuing to drive the car.
It's not something I would do.
But it's your car and something only you can decide.
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Old 09-11-2020, 03:35 PM   #14
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Originally Posted by Starter986 View Post
Is it just me... or is that a laundry list of throwing parts at a car?

Best wishes on a less costly outcome.
Looks like they used "new" parts to test with, as they refitted all of his original parts.
Testing with known good parts is one way to go, if you have that resource.

Last edited by blue62; 09-12-2020 at 06:41 PM.
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Old 09-14-2020, 03:01 PM   #15
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Thanks for all the comments, very useful tips.

I spoke with another boxster specialist who said it could be the variocam shaft? Which parts cost 375 plus VAT from porsche plus some seals etc, incl labour it's about 1k pounds total. If they diagnose and it's what they suspect they will just take the diagnosis cost off the fixing cost. That's reasonable right?

Is there anything else worth doing whilst they are there? They said it will cost more on the pre 2000 model it's more difficult to access?
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Old 09-14-2020, 09:36 PM   #16
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That invoice was from the previous owner. Is it just me but it look like the garage was taking him for a ride? I don't think all that takes 20 hours labour? Surely 1-2 hours max!

I'm not a trained mechanic but think I could do it for all that for less than 20hrs .
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Old 09-15-2020, 01:19 PM   #17
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Maybe it`s just me, but I`m not sure what the specialist is referring to as a variocam "shaft". The variocam unit does not have rotating parts. Looking at the price perhaps he meant the solenoid, the price seems reasonable. To replace that you need to pull the head cover, so if it tops at 1k I think that`s pretty cheap.
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Old 09-16-2020, 01:35 AM   #18
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Thanks for your response. Yeah I think I must have misheard it it's the variocam solenoid. Would that affect 1 bank or both sides? Are there 2 solenoids?
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Old 09-16-2020, 09:50 AM   #19
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Thanks for your response. Yeah I think I must have misheard it it's the variocam solenoid. Would that affect 1 bank or both sides? Are there 2 solenoids?
There`s one at each bank.

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