Dual Camshaft Position Sensor Errors Need Help!
01-30-2011, 04:37 PM
#17
Race Director
Mystery solved....And a new one started..
I spent today looking and finally dropped the engine. What I found is really strange. Both cam banks were off by about 15 degrees. When I put it together I double checked the timing according to the service manual. It ran so it had to be correct then. When I first started it I checked the oil pressure and coolant. Coolant was low so I went through a few stop start cycles and burping. Got that filled and shutdown to check all fluids. The oil barely touched the dipstick and my son asked if "10" was OK for the Oil pressure. After a minute or two of sheer panic, we added oil and called it a night. That was the last time it ran. Here are my thoughts.... For both cam banks to be off the same amount it had to be a slip of the crank to IMS chain. The only way that I can see that happening is if the oil pressure was not enough to keep the tensioner pumped up or the tensioner is bad. If it were, I think that I would have heard the noise. No tension in the chain and the slack goes to the bottom. Skip a tooth or two and bam
I am lucky that there was no valve contact. If you have any thoughts on this I would like to hear them.
I spent today looking and finally dropped the engine. What I found is really strange. Both cam banks were off by about 15 degrees. When I put it together I double checked the timing according to the service manual. It ran so it had to be correct then. When I first started it I checked the oil pressure and coolant. Coolant was low so I went through a few stop start cycles and burping. Got that filled and shutdown to check all fluids. The oil barely touched the dipstick and my son asked if "10" was OK for the Oil pressure. After a minute or two of sheer panic, we added oil and called it a night. That was the last time it ran. Here are my thoughts.... For both cam banks to be off the same amount it had to be a slip of the crank to IMS chain. The only way that I can see that happening is if the oil pressure was not enough to keep the tensioner pumped up or the tensioner is bad. If it were, I think that I would have heard the noise. No tension in the chain and the slack goes to the bottom. Skip a tooth or two and bam
I am lucky that there was no valve contact. If you have any thoughts on this I would like to hear them.Oh my head...
Sincerely,
Macster.
01-30-2011, 05:29 PM
#18
My WAG is you made a mistake in setting the timing or a chain slipped. I've dealt with SOHC engines with just one chain and even one chain is tricky. The job take 3 hands and 2 sets of eyes. God only knows what the Porsche engine with the chain drive from the crank to the IMS and then two separate chain drives one each from the IMS to each exhaust cam and each exhaust cam in turn has a chain drive to its intake cam.
Oh my head...
Sincerely,
Macster.
Oh my head...
Sincerely,
Macster.
01-30-2011, 06:13 PM
#19
Drifting
It is not necessary to remove the engine to reset the cam timing. I have a method for doing this on both the 3.4 and 3.6 engines even without the Porsche tool. PM me with your email address and I will send you the info.
01-30-2011, 06:33 PM
#20
01-30-2011, 06:46 PM
#21
Drifting
I will be happy to share it with anyone by email. I will also try to put the instructions into a format to post here. My challenge is I am caught up in a problem with upgrading my computer from Windows Vista to Win 7 and so I can't start Work right now and the files are in Doc. format. I can send them as an attachment to an email but can't edit them right now.
01-30-2011, 09:12 PM
#23
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Dharn55: I read your method and that is what I used to do it the first time and again today. I think that I understand more about what happened now that my last post. When I timed the cams the sprockets were bolted down with the bolts about mid way in the elongated slots. When I started retiming today both the 1-3 and 4-6 sprockets were rotated to the end of the slots. I searched the posts and find only a few mentions of the sprockets slipping. Coming from a V8 background, I am not used to seeing slots in gears or sprockets. The 4 small 6MM bolts and very light torque just looks like an invitation for this to happen.
01-31-2011, 09:37 AM
#24
There is something else going on here .There are 250,000 cars runing without cam timing slipping .The sprocket on the end of the ehaust cam drives the cams and the return oil pump .I am betting the pump is the culprit for two reasons -could act as a hydraulic brake and there seems to be a quart of oil missing .I'll bet the oil is in the cam cover .What I don't know is if the return oil pump is simply reversed if that is the cause .
Dave
Dave
01-31-2011, 11:32 AM
#25
Drifting
What torque did you use on the bolts on the sprocket? The spec is 10.5 lbs. With all 4 bolts at 10.5 lbs the sprockets should not slip. As a precaution when setting the timing and torquing the bolts I tighten two down. Then put loctite on the other two and torque them. Then take the first two back out and loctire and torque them.
With regard to reversing the scavenger pumps, I made this mistake during one of the several times I worked on my cams due to blowing out the expansion plugs. A careless error, but not that hard to do. It had no effect on the cam timing, just caused erratic oil pressure readings as the pumps were pumping oil out of the sump into the heads rather than from the heads to the sump. This in turn would cause some "starvation." Actually took me a couple of months of trying to identify the problem. Replaced the primary oil pump, swirl pots and other components. Nothing seemed to help. Then bought a set of new scavenger pumps thinking they might be bad. When I went to install them found the old pumps reversed. Put the old pumps back in properly and the problem was gone. A really dumb mistake, but Oh Well
I don't think this would cause the bolts/sprocket to slip.
By the way I now have over 10,000 miles on my engine since I repaired my intermix/cracked head and it is still running strong.
With regard to reversing the scavenger pumps, I made this mistake during one of the several times I worked on my cams due to blowing out the expansion plugs. A careless error, but not that hard to do. It had no effect on the cam timing, just caused erratic oil pressure readings as the pumps were pumping oil out of the sump into the heads rather than from the heads to the sump. This in turn would cause some "starvation." Actually took me a couple of months of trying to identify the problem. Replaced the primary oil pump, swirl pots and other components. Nothing seemed to help. Then bought a set of new scavenger pumps thinking they might be bad. When I went to install them found the old pumps reversed. Put the old pumps back in properly and the problem was gone. A really dumb mistake, but Oh Well
I don't think this would cause the bolts/sprocket to slip.
By the way I now have over 10,000 miles on my engine since I repaired my intermix/cracked head and it is still running strong.
08-14-2011, 03:05 PM
#26
2nd Gear
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Dharn, do you think you could send me those instructions as well?
I'm getting a P0343 error and wondering if it has anything to do with timing or if the sensor itself is just messed up. Any idea if it's possible to replace the sensor without pulling the engine (3.4L 2000 996)
I'm getting a P0343 error and wondering if it has anything to do with timing or if the sensor itself is just messed up. Any idea if it's possible to replace the sensor without pulling the engine (3.4L 2000 996)
08-14-2011, 04:57 PM
#27
Drifting
halcyon_m
PM me your email address and I will get something off to you. And yes you can replace a cam position sensor with the engine n the car by the one on the drivers side is a real PITA to get at.
PM me your email address and I will get something off to you. And yes you can replace a cam position sensor with the engine n the car by the one on the drivers side is a real PITA to get at.
10-22-2011, 06:54 PM
#28
Racer
Sorry to revive a relatively old thread, but I have to ask, rkellison, did you ever figure out the problem? How coincidental is this... just last week we put my father's 996 motor back in after having the IMS upgraded, clutch replaced, AOS replaced, etc. (preventative maintenance) and the car is having very similiar symptoms -- while driving it will cut out. Attached are the DME codes. His too is a 1999 3.4L. We primed the oil pressure before starting the car. Anybody else have suggestions?
