I've been getting intermittent misfires on that cylinder, only in low RPM. Revving the engine past 2.5k or so the misfires go away. Sometimes can go several hundred miles without a misfire being recorded, sometimes much less. This has been an on/off occurrence for the last 100 miles or so. A restart generally cures the misfire for a while. I tried coil and plug replacement, that didn't solve it. Given some research on this website, seems that intake lifters periodically being stuck in the open position can be a cause of the misfire. I've received a response in another thread that lifters can be replaced in the car, but also that it is very difficult with limited working room, so engine removal is recommended. While that probably makes sense for a shop, I am thinking that for me it may make more sense to try it with the engine in the car even if more difficult since I don't have a lift and removing and reinstalling the engine on the floor doesn't seem appealing, particularly if can be avoided. However, I can't seem to find any DYIs on camshaft or even valve cover removal with the engine in the car.

 

The response you got back was from Jake Raby. If you don't know who he is just be assured he knows what he is talking about. He is a Porsche engine reconstruction specialist of renown. When he says something you should listen. Doing lifters in an M96 engine is NOT like doing them on a Chevy V8 or a Honda four cylinder engine...

 

You can do it with the engine in the car. Not a job for a novice though. Cam timing on the way back out is important too. You need some tools. You might as well do some other things like changing the pads and solenoid but that is budget dependent.

 

If your talking about replacing the lifters I would questions whether it can be done in the car, have you managed that?, I don't think you can get the cam covers off and the cams out with the engine in the car. Honestly having done the job removing the engine isn't such a big job as it sounds. And with the engine out you can undertake all the other preventative PITA jobs with ease such as the AOS

 

It is possible. My car’s lifters (and chain pads) were raplaced last year by local Indy, and engine was in the car.

 

One more thing to add. I have a C4S. Does the wide body help in this case with the extra room?

 

Had the same thing happen to our 996 4S. Chased around the coil, injector, etc. I told the mechanic to look at the lifter. Sure enough, it was a sticky lifter. Replaced while in the car. I still have that lifter as a paperweight.

 

RGS, did you end up replacing a single lifter or all 6 of them. Curious if this is a very rare failure and might as well leave the other 5 intake lifters in or if it is more common failure and might as well replace all 6. Also, do exhaust lifter fail? They are much less expensive than intake lifters, but they are simple bucket design and in my BMW experience those last a very long time and are not a failure item.

 

We replaced the bank. While You’re in There. It was the intake lifter. The inner rod, for lack of a better term, was sticking. Almost scored and seemed to be tapered to create the sticking. I do not believe the exhaust lifter to be a common failure point for the reasons you mentioned.

 

Agree that the exhaust lifters are pretty bullet proof and have remained unchanged, the inlet lifters have changed part # from what was fitted when built which means a design/supplier change

 

I have removed the camshafts to replace the Cam Variator Hydraulic Tensioner with engine in the car. After the cams came off, the lifters just slipped out with a magnet. On bank 1, the cam holding tool fits easily, and the other bank you would have to slightly drop the engine to make room.

The cam covers come off after you remove the exhaust headers and the mufflers, and of course the bumper has to come off.

If you want to do a lot more work on the engine, then by all means take it out of the car. Clutch work, AOS, cooler, starter would all be easier with the engine out. But if all you need is access to the lifters, you can do it with engine in.