Dharn55

Still trying to figure out if there is really anything wrong with the setting/timing of my cams after fixing my intermix problems. When I first checked the cam timing with my Durametric it was showing the following readings:

Camshaft position 1 deviation -10.86
Camshaft position 2 deviation -02.14

So I have been assuming that the bank 1 cam might be pretty far off. I ran the Durametric on my buddies car and the readings for these are about -1 to -2.

I had borrowed a cam position tool from another member and went to check/reset the cam timing today. But visually, there is no way it appears to be off by -10+ degrees.

Based on this I did not reset the timing but decided to run the Durametric again and now get the following readings:

Camshaft position 1 deviation -12.15
Camshaft position 2 deviation -02.45


Actual angle for camshaft bank 1 .1 (at idle) 25.94 (at 2,000 RPM)
Actual angle for camshaft bank 2 .3 (at idle) 24.74 (at 2,000 RPM)

The actual angles vary a little bit with the engine running, but you can see the advance kick in between 1,500-2,000 RPM.

So here is my question. Do the camshaft position deviation numbers mean that the bank 1 camshaft is starting at -12.15, and then advancing 25 degrees so that it is at 13 degrees advance? Not really sure how to interpret these readings. But it sure dons not look like the bank 1 cam is off by 12+ degrees with the engine off.

Any help would be appreciated.

Pac996

Since you have the special tool to do the cam timing I think its best to time the cams and see what happens. Nice thing about cell phones is long distance to places like suncoast or who ever is cooperative with info from their shops would just cost minutes of usage for the month. I think its best to get a dealer or long time race engine worker thats walked down that path all the time between races.

Maybe throw a call towards the durametric guys.

Page 1-13 of the service manual I believe is saying the range is 0-40 degrees kW. This is kind of a relief since your range isn't way up there.
Page 2-8 shows external locations of sensors and such concerning the cams. The Hall sensor and camshaft rotor operates both banks.
Some voltage readings for checking operation are mentioned.

Yah plenty of things to wonder about. Would be nice to have it sorted with a pro.

redridge

if the engine feels strong and pulls hard then maybe its the sensor.... possible to swap a sensor and see if the deviation follows.

springgeyser

I swapped the sensor on 1 bank...it is still -9.xx. The other side is -2.xx if I remember correctly.

dcdrechsel

This is my first post and don't have your answer but do have a question/observation .
I acquired a 99 Cab in March and have been sorting it out .This Forum is the best tool available -just tremendous !
The question :when you timed it-did you use the auxillary chain tensioner tools ?( I think it's part # 9559
If not that could explain the deviation from spec when running .In a static test-it could look good and under load changes .Also -somewhere in the shop manual is a chart on specs and acceptable deviations -I rember reading 6 degrees -looked this am and couldn't find the chart .Will continue to look .
I have a vested interest in resolving this -I have exactly the same issue
Dave

redridge

just throwing this out.... Im sure you are aware of all this. But, just in case...

http://www.youtube.com/profile?user=.../9/7C5E-yAlZwI

Dharn55

Redridge - Thanks for your responses. The advance mechanisms are working, you can see the advance kick in, and I changed out the pads as part of the work.

dcdreschel -I know of the pretensioner tools, and thought of getting them, but a set is over $400. In talking with Baum Tools, which sells them, they said very few mechanics buy them at the real tensioners will due the trick unless they are collapsed. The difference between the pretensioners and the real tensioners would not give a 12 degree change. I also spoke to Jake Raby about this and he said the tensioners should work.

I think I may have figured out why I am getting a deviation/reading. On the following pictures you can see that each exhaust cam has a pressed on ring with a flange that passes by the sensor. This is what gives the signal of the cam position. When I was doing to many ins and outs of my cams due to the expansion caps blowing out I did bend one of these flanges as you can see in one picture. I did straighten it out, but it might not be perfectly straight so that when it passes the sensor it is showing a slight deviation.

redridge

so are you going back in? is it a big deal? no errors?

Dharn55

I am definitely not going to take off the cam covers, etc. at this time. I had the green plug off of the intake cam yesterday preparing to use the timing tool that I was lent. But the cam seems right on based on the markings/groove so I stopped there. It is kind of tight to get the tool in place and get the scavenger pump off to reset the timing, really need to take off the bumper and the exhaust. Visually the cam is right on the proper setting, no way it is off by 12+ degrees, unless it is the tensioner, so I stopped there and started asking questions here and on the other sites.

I am thinking of replacing the tensioners as a preparation for the IMS bearing upgrade but thought I would see if anyone had specific knowledge on the readouts.

dcdrechsel

Doug -thanks for the feedback .My hang up was that Porsche designed and spent money on a tool for a
reason .I don't know the reason and I guess it doesn't matter if Jake says it should work .
Think I have read almost all your posts and my compliments on taking considerable time to document and share what you learned .........
Dave

Pac996

I wonder if the numbers it is sensing off the sensor are used for running the vario-cam and adjusting other inputs.

That sure was a bend. Cuss words just don't cover every situation.

Paul 996

Dharn,

Curious what do you set your timing to?

rb101

If you do replace the adjusters, make sure you get the older style crank to IMS (996-105-180-54). Last month, I pulled out the new style and replaced it with the last old one in the states (there were 19 in Germany). The new one is a touch shorter and it was fully extended.

Rick
99 996C4
87 944S

george996

doug,

just an fyi, a reading of 10 degrees deviation is at the crankshaft and is half, 5 degrees, at the camshaft. this would make it more difficult to determine visually.

Dharn55

Thanks for everyone comments and thoughts.

Pac996 - On the VarioCam engines the systems is pretty simple for the advance, RPM based, and I don't think it effects much else.

Paul 996 - You set the cam timing by fixing the crank at TDC and them setting the grooves in the non-driven end of the exhaust cam straight up and down with the narrow side toward the outside of the engine.

With the OEM Porsche tools you set the engine at TDC, attach the tool at the non-driven end of the cams, one end fits in the opening of the head/cam cover on the intake cam to lock the tools in place, and the other end actually fits in the grooves on the end of the exhaust cam, and the tools has a lever that allows you to rotate the exhaust cam relative to the crank, this is done after loosening the bolts on the drive sprocket of the exhaust cam. This them puts the cam in the proper position and then you tighten the bolts on the drive sprocket.

With the ZDMax tool I was lent it is a little different process as there is no lever to move the exhaust cam. First you rotate the crank unit the exhaust cam is in the proper position, then you install the tool, which also fits into the opening for the intake cam, but merely slips into the grooves in the exhaust cam to lock it in the correct position. Then you loosen the bolts on the drive sprocket, rotate the crank to TDC, then tighten the bolts on the drive sprocket. Same result.

rb101 - That is interesting on the Crank/IMS tensioner. This is one of the questions I have been trying to figure out. The 1-3 tensioner has not really been changed, and the change to the 4-6 tensioner is really just a change to the head so that instead of using a sprocket you use an allen wrench. However the Cranck/IMS tensioner has been totally redesigned, and now instead of a closed piston it appears to have an exposed spring. This change was made when the engines went from the VarioCam 3.4 series, which are 5 chain engines, to the VarioCamPlus engines, which are three chain engines. And apparently the Porsche Tech bulletins say to used the old style tensioners. However if you look at the LN engineering site for the IMS bearing upgrade, where they recommend that you replace the tensioners, they say to use the new styles all the way around. And I spoke to Charles at LN the other day and he says that they are using the new style Crank/IMS tensioner in their 3.4 engines that they race. Still trying to figure this out but your comments are appreciated. Maybe I will email Jake RAby and see if he has some input.

I also received some input from a member on Renntech.org who had an interesting thought. What if I missed one link on the chain that drives the intake cam off the exhaust cam? This would explain why the cam timing of the exhaust cam appears correct, and yet the sensor, which is on the intake cam, could be off. Unfortunately the only way I can check this is to remove the cam cover on that side, which is doable with the engine in the car, but is a real pain in the XXX.

Probably will give this a try next week.

Thanks, to all!!