Imo000

If the valves open and close early that there will be no contact between the piston and them. That’s how you can have deviation and no bent valves. Happened to a friend of mine. When he put his engine back together, he missed the cam timing on Bank 2 (intake cam) and had it off by one tooth. Took use some time to finally be 100% sure that the issue was mechanical and not something sensor related. After pulling the valve cover and checking the cam timing it was clear that he missed it by 1 tooth. His intake valves on Bank2 were opening and closing too soon. Engine was misfiring in that bank but no bent valves. After he re set it, the engine ran perfect and has been ever since (since Christmas).

Schnell Gelb

Great anecdote - And the key is it was both misfiring and showing excessive deviation on Durametric on the same Bank ?

Porschetech3

Sounds like the little green o-ring has failed on the cam adjuster and stuck at full advance(25 degree crank).The extra 2 degrees was probably just initial setting. Schnell Gelb is an expert on this subject !!

Mike Murphy

They need more time now to test. They pulled the oil filter and did not find metal (good). There was some tiny small debris, looking like silicon sealant, some chain guide material, and some other very hard dark black plastic bits. Very small. The was one big problem, though, the bypass control valve was missing from the canister. Oh my. That must mean that oil was not being filtered, and possibly why now the actuator for the cam could be stuck.

However, they are getting strange results or maybe a combination of things. They checked base timing to be good (crank to IMS, and ISM to camshafts). However, bank 1 solenoid showing 60 ohms compared to bank 2,which is 11.7 ohms. When they manually activate from the DME solenoid bank 1, from rest, there's 10V and 12.5V when activated. Bank 2 is 0V at rest and 12.5V when activated

Therefore, there are testing the DME, as someone already pointed out is a common issue.

The good news is that they are running a battery of tests instead of replacing parts.

EDIT: They just called me to tell me that it's either a bad wire or the ECU. After they removed the DME from the equation, all solenoids and timing are in good shape. So, mechanically, I think we are in good shape.

Paul Waterloo

I have my old OEM filter assembly if you want it. I am not sure if the bypass valve is in the plastic part that houses the filter or not, but I think it is.

Imo000

They should have tested the wiring for the solenoids a long time ago. The proper process is that you start at the solenoid (with a 9V battery) and work your way back. That’s how I did it.

Was the bypass valve in the filter housing removed? You can get a new one, comes with a filter, from your dealer for very cheap.

Mike Murphy

I agree. I told my former mechanic (who quit and now drives a truck) exactly how to do it. Shame on me for using him I guess. But Midwest Performance Cars could have checked this, too, although I didn’t go an explain how to do it, for fear of appearing to know more than they do (that’s extremely annoying when a customer comes off as an expert). However, they only did a 1-hr initial test, so the 2nd time round, they are spending more time doing it properly. Maybe they won’t charge me for all the hours they consumed because they could have tested easier/quicker, we will see.

As for the bypass in the filter, they already reinstalled the filter and included the bypass valve.

Paul Waterloo

Going back to this, you did not check the cam deviations after you had the check engine light, so you don't know if Durametric has ever read them wrong before, especially based on Porschetech's post about the 24 degrees + the 2 previous degrees recorded. Just curious to see if this is correct, and if so, the Durametric most likely is reading correctly.

Mike Murphy

I actually did, thanks to you letting me borrow the Durametric. So yeah, Durametric appears to have read the correct values.

Mike Murphy

So the most recent update from Chis and MPC is this:

- the mechanical base timing is correct- the resistance of each solenoid, spec = 13.6 ohm. Bank 1 = 15.4 ohm, B2 = 11.7 ohm- checking voltage with the solenoids connected and manually activating through the DME, B1 = 10.4v then up to 12.46 when activated. B2 = 0V then 12.46V when activatedWe believed the B1 solenoid was shorting in the wiring or at the DME, or the DME was attempting to activate the solenoid to compensate for an issue between the B1 exhaust and intake came.- measuring resistance, we found no short to ground in the wire from the DME to the B1 cam solenoid- with the solenoid disconnected, the engine seems to run a bit better- when manually jumping the solenoid, the solenoid activates correctly- with the timing okay & solenoid activating, we're pointing at the DME which is likely shorted internally causing the B1 cam solenoid to stay activated with 10.5V. 996 DMEs are no longer available new, only remanufactured by Porsche. Given the time and cost, we're looking at options to have your DME removed and sent out to be rebuilt. The risk is if the re-builder blows out any pertinent information or VIN specific information.We'll likely have some options and pricing for you tomorrow.

Schnell Gelb

ECU Doctors in Florida may be a useful resource??

Mike Murphy

Yeah, I may give them a try.

Mike Murphy

So my bill to investigate all this stuff came to about 7 hrs of labor. Does that seem too high or normal? The DME for my cab has to have the service position access and all that tracing of wires and cam timing stuff took a lot of time they said.

Paul Waterloo

I can't say it sounds unreasonable. If it took 3 hours I would say you are the luckiest person in the world. I know when I am troubleshooting something, it takes a lot longer than you think.

Paul Waterloo

Mike: Did you ever resolve the issue? Let us know!