16 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCH996.2 Positive deviation
Leading reported evidence
Install prior
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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0
Unsuccessful attempts
1
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Read evidence and context
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1
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Performed · outcome unconfirmed · Original poster
The car has a IMS solution installed prior to his ownership.
Leading evidence: 'Install prior' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Install prior' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed · Original poster
Since I last posted he has changed the oil to Motul 8100 and took the car for a few 10-15 mile spirited drives, totaling about 85 miles throughout the week.
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Suggestion · Original poster
What could cause this value to change + .32 degrees in only 85 miles?
Replace timing chain guide pads and or the adjuster
Suggestion or failed attempt
No successful repair reported for this finding.
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Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Suggestion · Original poster
Could a bad camshaft actuator cause this or is he looking at tear down to replace timing chain guide pads and or the adjuster on the camshaft?
Discussions that performed work without a confirmed outcome
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0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Performed · outcome unconfirmed · Original poster
Since I last posted he has changed the oil to Motul 8100 and took the car for a few 10-15 mile spirited drives, totaling about 85 miles throughout the week.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
16 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Hey all,
Ive searched and searched and searched but can not find any information on POSITIVE deviation on a gen 2 car.
Bank 1 7.16
Bank 2 -1.16
This cars owner is a friend of my dads, recent purchase, 2003 C4S, 85k. He has no service history on the car... The car has a IMS solution installed prior to his ownership. The car runs great, no check engine lights. He had a friend scan his car with a durametric and found the above deviation numbers. What could cause this and is it something to worry about as they are outside the spec +-6?
As you noted, Porsche directives state that M96 engines should NOT exceed 6˚ of deviation between bank 1 and bank 2. Top notch shops like Flat 6 Innovations have a stricter tolerance at 4˚ between both banks. This could be caused by a stretched timing chains, excessive chain guide wear, worn out tensioners, for example. I wouldn't ignore this problem. You should have this engine serviced asap. This problem is not like a rash that will go away on it's own in time, you must get it serviced.
B3,
through my research on this and other forums on this issue, those worn components typically cause negative deviation numbers. Would these same worn out components cause positive deviation as well?
On gen1 cars the vario cam pads seem to be the main cause of deviation numbers. Gen2 does not have this same system, is there a pad that is typically the culprit on vario cam plus engines?
Mk1 cars have the 5-chain M9X engines and the Mk2 engines have a 3-chain design. The mk1 has the chain adjuster/actuator unit inside the heads. The actuator on the 5-chain is well known to eat wear pads which in turn affects your camshaft deviation. The 3-chain engines also have chain guide pads that wear out. (see picture) Regardless of how you feel about neg vs pos deviation. You have more than 7˚ of deviation. You need to put this fire out when it's small not when it's a raging fire.
B3,
Thanks for all the info.
This is my dads friends car that he recently purchased with no service records.... SMH.
I�m just trying to help him out as neither of them are very tech savvy and wouldn�t post on a forum.
I have seen under his car and it looks like the IMS solution I�ve seen. Oil feed line, blue fittings, Napa oil filter, etc. No sticker anywhere and nothing comes up where you search the vin on LNs site.
Are those three pads replaceable without removing the heads?
What were the camshaft deviations BEFORE he purchased the car? Could you please take some pictures of the car, especially at the oil filter and such. Happy to help!
A stretched chain or worn chain guides will indeed move the cam position more negative. A positive deviation on a 3 chain motor means the Vane Adjuster was either has not been set correctly at some point, or the Adjuster is sticking and not returning to rest point. Any Vane Adjuster problems on a 3 chain engine, start with an oil change, there are very tight clearances in the Adjuster and dirty oil will cause sticking.
Porschetech,
Thanks for the additional information. Since I last posted he has changed the oil to Motul 8100 and took the car for a few 10-15 mile spirited drives, totaling about 85 miles throughout the week. After we were able to check the deviations once again and found bank 1 at 7.48 and bank two -1.33. He has stopped driving the car. Could a bad camshaft actuator cause this or is he looking at tear down to replace timing chain guide pads and or the adjuster on the camshaft?
What could cause this value to change + .32 degrees in only 85 miles? Is it safe to drive the car or should it immediately have the engine dropped and retimed?
Varicam+ 3.6L engines found in the Mk2 996 cars eliminated the camshaft chain adjuster (i.e. actuator) units. Look at the diagram I posted. This is a 3-chain engine.
The timing is far enough out, that it will effect cylinder pressures on bank 1. You can re- time in the car, if you have the required tools, and patience.
Installing the IMS Retrofit products without using g the proper procedure could result in the timing being advanced, especially if the engine was not perfectly set to TDC, crank pinned, and cams locked.
B3, I was speaking of the solenoid that controls the camshaft adjuster on vario cam plus engines. But thanks for the clarification!
Hmm I wonder if that is what happened on this car. Sucks for the owner! I understand you have a series on Amazon on the complete rebuild of this engine and you can also purchase it in stages. Would Stage 16 show everything we would need to know on the timing procedure if we decide to tackle it? Would we need the same tools as shown in the video?
I really appreciate the help, Jake!
Yes, cam timing is covered, but from an engine building perspective. The procedure would be the same as I show in the video, but won't be as easy with the engine in the car.
