error p0300 to p0303, rough idle, rattle past 2200rpm

[Jinster]

For a few days, I have noticed a rhythmic rattling noise that comes from the engine bay when I accelerate beyond 2200rpm. I also noticed rough/fluctuating idle rpm, and the car seem to have this irratic de/acceleration quality as I cruise at a (not exactly) contant speed - which I guess is due to a fluctuacting rpm not controlled by my acceleration pedal.

I also heard some "popping" noise from the exhaust - which I guess is a misfire.

Today, the CEL light came on. It was blinking at first, then became constant. And then sometimes it blinks again, and then becomes constant again.

I checked the codes with a generic OBD2 scanner. Got codes p0300, p0301, p0302, and p0303. No other codes.

I did a search on this forum. And found this seems to pertain to a bad variocam solenoid.

Before I go ahead to order my replacement solenoid, I was wondering if:

1. Anyone know any other causes for this situation? I cannot explain the rattling noise...

2. Does anyone know where this solenoid is and whether it's possible to replace it with the engine in situ?

I have a MY97 tiptronic.

Edited January 1, 2008 by Jinster

[Loren]

If you are sure the plugs and connection to the plugs are fine then it could be a mechanical problem.

Here is what the manual says:

"Possible mechanical causes of faults

Valve lifter chattering.

This is caused by dirt in the valve lifter.

When the Check Engine MIL lights up, a chattering valve lifter may also occur for a certain time. The DME control module registers (sporadic) misfiring at one or more cylinders. The adaptation values of areas 1 and 2 are normal.

Remedy

1. Remove lifter bores, check for damage and blowout oil passages.

2. Replace all valve lifters (engine installed).

3. During the test drive, listen for valve lifter noises.

Camshaft control badly adjusted.

The camshaft control has changed. No chattering noises occur. The DME control unit indicates misfiring for the entire cylinder bank 1 or 2. The adaptation values in area 1 differ in bank 1 and bank 2 (e.g. TRA=0.02/TRA2=0.27), the adaptation values for area 2 are generally normal.

Remedy

1. Reset camshaft control.

2. Road test vehicle. The adaptation values should be normal.

VarioCam does not switch over completely.

Cases have occurred in which the VarioCam of one bank was mechanically faulty. In these instances, the VarioCam had not switched over completely from power to torque valve timing.

An indication of this problem is misfiring detected by the DME control module in the range of 1200 - 1500 rpm occurring in an entire bank. The adaptation values of areas 1 and 2 are normal.

Remedy

1. Replace VarioCam.

2. Road test vehicle."

[juniinc]

Yup, usually it is the vario cam solenoid. but it could also be a bad cam position sensor,cam timing system? I highly doubt it

But check your wiring hardness first!

Solenoid is located on the cam cover, U will need some special tools to take the right side cam cover and housing off to get at the solenoid from a PORSCHE dealer.

Engine can stay , but U will need to remove the exaust manifold,coils, spark plugs, solenoid seal,and the spark plug tunnels. Be sure to replace all your seals and get some silicone seal from PORSCHE, because there is no gasket for it.

Dealer repair cost can be a bit steep on this1 (+$2000)

Good luck!

Edited January 1, 2008 by juniinc

[Jinster]

Thanks guys. Sorry for the barrage of questions but my Boxster has had so many things broken over the years, I could've just bought a 911 with the repair money.

Juniinc, this sound like a lot of work. I am not working at the moment, so I guess I am time rich and money poor. So I'd be interested in having a go (though the biggest thing I have done on the Boxster so far was replacing the water pump). Have you done changed the variocam solenoid before? How long did it take? Do you have any pics to share? I am still trying to figure out where everything is, and the factory workshop manual is poorly illustrated to say the least. Also, when you say check the wiring harness, is there a particular section in the wire path where things tend to break? If I take off the cam cover and all the plug tunnels, would I need to drain the oil first so that oil doesn't gush out when things come off? When you say remove the spark plug tunnels, do they just slide out or something?

Loren, is this from the Mitchelle's Repair Guide or the factory workshop manual? I have both but my Mitchelle's CD seems to be physically corrupt so I can't use it at the moment. And I can't find the relevant section from the factory workshop manual. What do you make of "reset camshaft control"? Does that mean unplug the battery to reset the switches or physically turn the camshaft to reset? I have poured in some generic "lifter-cleansing" fluids today (I was going to to change the oil in the engine soon anyway) in the hope of cleaning out the HLAs if there are dirt on them. Also, the adaptation values you refer to, are we talking about O2 sensor readings? Or are they readings related to the camshaft angles/duration etc? Can a generic OBD2 reader access these values?

Edited January 2, 2008 by Jinster

[Loren]

My information comes from the Porsche OBD II manual (5.2.2) which covers your model year car.

Yes, reset the DME.

The adaption values are the TRA, TRA2 and FRA, FRA2. Most generic OBD II readers can not read those values.

[juniinc]

I just got off the phone with a buddy of mine Ron at a local PORSCHE dealer. If you are sure it is the cam actuator solenoid. U might not like what I'm writinng.

That part can only be ordered from PORSCHE dealer & it cost $1040.00 USD. Total quote was $2460.00<- OUCH.

But I bet my $$$ on it 90% it's not the actuator. it's probably just the solenoid u need!

The part number is 99660590100

Degree on this project can be difficult, it is usually a professional recomended job but I think U can do it!

Also u must have a Tool P9624 - plate that goes from one cam plug to the other behind the passenger seat. It has a tab where a bolt fastens it to the cyl-head to hold the cams down while the cam cover is removed

Yes we've done it once back in Spokane with another buddy of mine Jared, he also is a Master dealermechanic. It's supposed to take 6~10 hrs with proper tools ,shop . Unfortunately no detailed pix for this, some online soured pix maybe .

For u hopefully 20hrs? lol This was quoted by busa4 by the way, lift the rear end of the car so you can get under, best to have 2 floor jack stands,,,exaust manifold first, coils,plugs,solenoid seal,any wire or connector in the way and the spark plug tunnels (spark plug tunnels are the plastic sleeves that prevent oil from leaking into the spark plug and coil). you will have to remove each of these plastic tunnels with a hook tool. make one out of a hanger. that hook and allen wrenches is the only speacial tool you really need.

Edited January 3, 2008 by juniinc
made image viewable

[Jinster]

Thanks again guys.

Loren, unplugging the battery overnight didn't do much. Somehow I didn't think this was going to work. Do you think Porsche says stuff like this so that it "eases you in" so that you can come to terms with needing major repairs? :) I don't know if the noise I am getting is HLA or not. But I would have thought if it's the lifters, the noise would be present at idle as well as decelerating RPMs. Currently, the chattering noise is only present if I push the accelerator pedal. To me, it sounded like a broken exhaust, or HLA noise, or variocam being constantly engaged. I don't rev up my car beyond 4-5k rpm often at all so I am not too familiar with variocam noises. But the few times I did, variocam sounded like a chattering kind of noise to me. Is it possible that the bad solenoid (if it is due to that) has caused the variocam to be stuck in a engaged position? I mean, if variocam is not engaged and the solenoid has gone bad, then instead of getting constant chattering on acceleration from low rpm, I should have no variocam noise/lack of power in high rpm, right?

Juniinc, thanks for the helpful pointers and for ringing your friend for me. Between your comments, my reading of the factory manual, and getting under the car, I think I understand what needs to be done now. The steps are:

1. remove the exhaust header

2. remove the spark plugs and oil protection tubes

3. remove the cam cover

4. replace the solenoid

Is this right? The special tool is to hold the cams in place because they are vertically secured in a boxer engine, right? So would I need two such clamps then (at two different spots along the length of the camshaft)? The factory manual seems to use quite a few different ones. Or can we rely on the tool to be block (rather than a plate) and thus its 3D shape would hold the cams temporarily? I was thinking about fabricating my own "special tool", but it would be a plate, not a block....

Anyway, this could just be wishful thinking here. From a previous post by Paul Fraser, (http://www.renntech.org/forums/index.php?showtopic=4190&hl=p0303) he had the variocam solenoid replaced for 322 pounds (including parts?), which, given the UK cost of living, is not a lot of money. This leads me to think it might just be possible to do this without taking apart everything. On close inspection, I can't figure out what No.4 is? It would seem to be where the variocam solenoid housing mounts to the cam cover. If that's the case, when you look at the exploding diagram of the solenoid/actuator assembly, it would seem that the external housing is in fact the actual solenoid. So then, can't I just remove that directly from the cam cover without removing anything else at all? Or have I got the wrong part and the No.4 in the photo is not No.4 in the diagrams at all?

[juniinc]

Any time! Jin.

Edited January 6, 2008 by juniinc

[td873]

I encountered the exact same symptoms: CEL, rough idle, blinking CEL at low RPM, and sometimes a backfire. It was diagnosed by a lay person as a possible spark plug coil pack of some sort. At the shop, it was properly diagnosed as a cam actuator solenoid. The repair is estimated at 10 hours. I am not able to do these things on my own, so I wish you all the luck in the world on your DIY. My car should be ready by Friday...

-td

[dcporsche99]

Good luck there Jinster!

Please let us know about your progress! Hope it worked out well for you!

Would love to see pics of your DIY. :)

-Dana

Edited February 7, 2008 by dcporsche99

[oryanlee]

one thing that I noticed with my car... its doing the exact same thing is that it has a brief but sharp loss of power as it's rising in rpm but im not not feeling the varios th9ing kick in around 5500 rpm like I used to... I changed my air flow meter last week with a used meter would that have anything do to with it? Before I replaced the meter I was driving with the air flow meter unplugged and it felt alot stronger and I could really feel the varios when I should.... would this have anything to do with that rattle? bad airflow meter sending bad info to the comp? also the previous airflow meter that was bad did not set off the check engine dummy light but the car would not run with it connected.... this one also does not set it off but I'm nervous about the sharp loss of power and the rattling.... anyone?