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By Schnell Gelb
Please refer to this thread on Rennlist :
Then the details are:
This applies to the Porsche M96 with Variocam. Later Variocam Plus is not quite the same.
This is a WIP that I hope others will improve. The info is gleaned from dozens of posts which I have used to put the basics in one place. Now it is your turn to improve it, add photos , links and most important – corrections .
Here is my related Thread:
Check the engine diagram to get the correct terminology.Confusing a Variocam actuator with a Chain Tensioner is a common mistake. When in doubt use Porsche part numbers only.
Without Durametric or PIWIS you will not be diagnosing.You will be guessing.
Beware of cheap Fleabay knock-off cables. They run very old ,often corrupted versions of the software. This causes misdiagnosis or failure to actuate components. They have no Tech Support.A very expensive mistake to make.Pelican sell the genuine Durametric cable.
Make sure you don't have other faults caused by old O2 sensors ,old plugs, vacuum leaks. Check Coil ground for 1.2.3 on the 6mm stud near the AOS is good.
Clear all codes.
Durametric at idle produces no codes. Increase idle speed to 2000 rpm and the 1341 reappears. This is the target identified.But the big diagnostic problem that I never solved is how to distinguish between a failed solenoid and a failed actuator without taking the cam cover off and more.
Using the Durametric cable, “ACTUAL ANGLE” for Bank 1 shows no advance - a flat line or lots of small oscillations but never reaches a # near 25 degrees. Bank 2 shows 25 degrees and deviation is rock steady and within limits(6 degrees). This is the general target confirmed.
Without Durametric at this stage ,you were lost !
You clear the codes and at idle activate (with Durametric) the solenoid for Bank 2 .Hear the change in engine sound? Yes. Try same on Bank 1 – no change - double confirmation.
Seems like the Variocam solenoid is not functioning or the actuator ,or both ? Or the wiring or the DME. Some expensive components here so let’s do some tests.
You will need to make some test cables to use in each of the tests below.AS noted below you can hack some male & female Bosch EV1 connectors to fit.I made dedicated test cables for each test to avoid the risk of arcing between probes or alligator clips.
The man problem is access. On a Boxster, Bank 1 is the worst.
1. Disconnect the plug for the variocam solenoid. Test the solenoid - you are looking for approx..13.5 ohms across the 2 contacts (not to chassis ground!).
2. At the mating part of the solenoid wiring connector use a MultiMeter on the 20V scale.
Connect ONLY between the 2 contacts. Do NOT connect to chassis ground. You are looking for around 10.5 volts (assuming a fully charged battery) . Yes one of the contacts is battery voltage and the other is a switched (3v)ground via the DME – but that is needlessly complicated to get into at this stage.Just look for 10.5 volts. If you get no reading - is the engine up to full operating temperature?
3. With the engine warm & idling , connect the solenoid contacts via a 12v battery (from a cordless power tool?) The engine note should change because you are advancing the valve timing on only this Bank by 20 degrees. Remove the 12v battery connection. Engine reverts to normal idle.
You can make the connector and leads from an EV1 connector if you cut back the shroud/casing.A word of caution about the polarity of the test connection directly to the solenoid. First -use a fuse in the test cable . Check Bentley for the wiring diagram and be very careful to follow the same polarity. In theory it should not matter but Porsche used polarized connectors ,so we should also?
A related test without Durametric is to use the same 12v source to activate the solenoid with the engine OFF, in a very quiet workshop. If the solenoid is working you should hear a 'click' every time you press the MOM switch on the test harness.This is significant because you need to understand what makes the click sound . Is it the solenoid or is it the sound of the actuator moving the timing chain or both ? I ask this question because the solenoid on the suspect Bank passed the resistance tst with 13 ohms- identical to the perfect bank(2). But the external 12v source only producced a click on the perfect bank2). The same test on Bank 1 was silent.
4. Next connect an extender cable to the supply-side connector for the Variocam solenoid.This is the wiring loom that runs above Bank 1 and connects to the DME. The terminals are roughly EV1 size but the standard EV1 shroud is too large. I used the pins/connectors from an EV1 Bosch 1 287 013 003(female) and the corresponding male pins to make an extension. The male pins could be 'hacked' by removing one leg of a 'red' fork crimp connector. Run it to the driver’s seat area. Put a Noid bulb in it. Start the engine and run to 2000 rpm. Does the light illuminate? Instead of the noid light you could use a multimeter on the 20v DC scale - to see if it flashes 10+v?
This might work ?
Pelican Parts - European Automotive Parts and Accessories - Porsche • BMW • Mercedes • Volkswagen • Audi • Saab • Volvo • MINI
Ahsai mentioned using a 12v 6w ‘peanut’ bulb instead.I used a Noid light because I had already made test harnesses thet acceted a Bosch Noid.
By now you should know if the solenoid is defective or if there is a wiring / DME fault. One of the links below shows the culprit as a burnt transistor in the DME. But let’s say the wiring/ DME test O.K.
Note: I fabricated custom test leads for the MM to check supply voltage I also fabricated custom power jumper leads for the solenoid. These included a 10A fuse and an MOM switch.
5. There is one other very creative test kindly suggested by Jake Raby. Connect with a jumper between the 'good' bank and the suspect one.Be careful to follow the same polarity !! Consider using a fuse and MOM switch in the test cable you fabricate. Needless to say - check all your test cables for continuity before use and avoid crimp connectors - solder them !
It is a final, positive elimination of variables.This is a good test to indicate problems with the transistors in the DME(thank you Ahsai !). This would have been indicated in the prior test that measured for 10.5 volts at the Variocam connector from the DME.
Note on the 5.2 DME - transistor and/or solenoid failures were more common for reasons unknown.
There is so much work involved in getting to the defective unit that people often replace both the actuator and solenoid ,when only the solenoid was positively identified as defective.
Conclusion: the solenoid &/or Variocam actuator are defective.
This video on re-timing gives an idea of the access problems:
Now this gets expensive and time consuming.
2001 Porsche Boxster S Convertible - Camshafts & Timing Chains - Page 2
The solenoid needs to be replaced, or the actuator repaired or both.
You need the special tool # 9624 /P253 to hold the cams in a safe position while you do this. Read the details elsewhere . Ignoring it may break a camshaft !
The link in French below(google translate) has the dimensions for the tool. I had already bought the complete Baum engine tool kit in a case.
variocam - Tuto changement solénoid variocam
On Bank 1 for the Boxster the access is so restricted some mechanics cut an access hole in the firewall of the trunk ! Certainly remove the wheel ,header, plates and anything that gets in the way !
Check elsewhere for the special sealant and gaskets required and the ‘while you are in there’ jobs like spark plug tubes/seals.
Read Wayne's write up project again! This is the best write up/photo of timing the M96 by Insite,
DIY: Setting Cam Timing on M96
Lock the engine with the 8mm bolt in the c/s pulley and lock the cam with the special tool 9624 or ‘French’ equivalent. Place all bolts carefully in a cardboard template (see French link again !) Some of the bolts are different lengths and if you muddle them you will be helicoiling! Remove cam cover. Note no gasket ! But a lot of sealant to remove with a PLASTIC scraper. Find the instructions on how to lay a bead no more than 2mm wide when replacing the cover. Use the correct sealant ! See Wayne’s article for more. Porsche Boxster Camshaft Upgrade / Chain Tensioner Replacement - 986 / 987 (1997-08) - Pelican Parts Technical Article
2001 Porsche Boxster S Convertible - Camshafts & Timing Chains - Page 4
Replacing the $200+ solenoid is now simple. Careful not to crimp the wires during reassembly.
Now you can do a visual check of the actuator. Connect 12v to the solenoid contacts. Does the actuator jump about 1/8 “ ? Can you feel the click in the solenoid. So is the solenoid defective or the actuator?
If you need to remove the actuator it gets more complicated. The actuator needs to be compressed a little to remove. In theory you can use 5mm x 0.8mm (verify !) threaded rod and deep nuts on the older Boxsters. The newer (post 2000?) changed to LEFT hand threads ! I found the necessary L.H. parts- Brass rod, L.H. die nut, L.H. nuts on EBay but waited for months for them to arrive from China ! In theory you can use high quality zip ties but access is so difficult that you may struggle to achieve enough compression of the actuator. Much easier with the engine on a stand !
On the bench you can repeat the test for the actuator and confirm with a new solenoid.
If the actuator seems weak or can be easily compressed or is locked rock solid -it perhaps can be dismantled and cleaned- but I could find no info on this. If it has high miles it may be better to replace it ? If you are curious about repairing an actuator,no,it can't be done -see here:
http://forums.quattroworld.com/a8/msgs/83599.phtml This is interesting because it hints at a diagnosis - an oscillating part that would produce an oscillating readout on the Durametric graph.
It is a pity Audi actuators do not fit. They are $200 or less !
The part # for the complete assembly for Bank 1 is : 996-105-051-58 Bank 2 (4.5.6) is 996-105-053-58. Do not confuse - just 1 digit difference.Note - these numbers supersede prior lower numbers.Be careful to confirm if the actuator you buy does/does NOT include the solenoid. Some sloppy vendors list the part number for the combo actuator+solenoid but do NOT include a solenoid - if you study the very fine print in the parts diagram alongside their ad.Be sure you order correctly - these $1000+ parts are often not returnable !
Tests with the camshaft cover off
Before you just replace parts here are a few tests to do. First watch a video to see what it should look like- start at 5minutes in this one:
Check for slack chains. It may be that the chain tensioner(not the Variocam actuator) has failed. If the engine has just been rebuilt, perhaps the new chain tensioner was not installed correctly.
Use the solenoid test lead to make the actuator 'jump'. The actuator should jump in the direction of the crankshaft when you hit the Mom button on the test lead.At rest it moves the opposite direction.See video cited above.
Suppose the Solenoid Passed the 13 ohms test, failed the click test and the actuator fails the visual test with the MOM switch. Which part has failed - the Actuator ,the Solenoid or both? Suggesting that you substitute a known good solenoid is probably impractical. You may have to just use probability and buy a new one and try it. If the actuator still fails to jump, even with a new solenoid, you are going to have to remove the actuator and test it on the bench. In theory you can try to purge the oil out of it and look for debris or blockage. But realistically ,after all this work it is probably better to just buy a new one.BTW the pin on the Solenoid should jump about1/16".