08 Boxster Misfires

[vza]

Hi All, Have some misfire CELs  show up. CEL blinks then stops blinking and on some occasions it disappears. Changed plugs and coil packs a year or so ago, not much driving mostly being restored. Was fine and this came up after painting. With using my Durametric I  assume camshaft adj. would  mean activating the variocam solenoids. There was no change in engine note when activated on either bank. There is a change in engine note when valve lift is activated. Cam deviation is nearly 0 both banks. I know with a 99 box I was able to attach a light bulb to the solenoid connecter  to insure voltage was getting through from the DME. Can I do the same w the 08 and I believe it kicks in around 4000 rpms. Thanks V

[JFP in PA]

Yes.

[vza]

Yes, cam adjustment activates the solenoids? So both are bad cause I don't hear engine change or ...Yes I can test w a light. 

Or both. Thanks 

[JFP in PA]

Yes, you can test with a light.

[vza]

Does the 'Cam adjustment' on Durametric activate the solenoids? V

[JFP in PA]

Yes, if everything is functional and connected.

[vza]

OK, so if I get a light it would mean my solenoids are gonzo. Correct? V

[JFP in PA]

1 hour ago, vza said:

OK, so if I get a light it would mean my solenoids are gonzo. Correct? V

 

No, it means you have power on the circuit, but it doesn't mean the solenoids are functional.

[vza]

If the light lights up it means I have power in the circuit therefore the solenoids are bad cause there's no engine note change when activated

with the durametric. (of course when everything is plugged in after the light test) Correct? V

PS By gonzo I meant bad. Wasn't a typo.

Edited December 29, 2023 by vza

[JFP in PA]

If the engine isn't changing when the solenoids are activated, nothing is changing because the cam angle is not moving; the solenoids are not assuming an active position when energized. 

[vza]

Right... so then the solenoids are bad. Just looking for a definitive way for testing them. If there's energy in the circuit from the light test and when the 

solenoids are activated by the Durametric using the 'Camshaft Adjustment' command and the solenoids don't make a change in the engine the solenoids are bad. 

Only good thing is you dont need to remove the covers and cams to replace them. Is there a way to bench test the solenoids?  V 

[JFP in PA]

There have been some video clips posted where the person uses a 9V battery as power source to test them out of the engine, but I have no experience with this type of test; if the unit does not assume an active position when energized in the engine, it has a problem.

[vza]

Ok...I'll do the tests and report back. 

[vza]

Did the light test. Very dim light at idle. Not sure if there's supposed to be current at idle, when rpms were increased the bulb grew brighter I guess voltage was increased along w RPM's.  I removed the solenoid and cleaned and tested it w 9v battery. Seemed to move freely and clicked. Not sure how much the plunger supposed to move. It didn't protrude from the end of the solenoid. Reinstalled with same misfire on 4 and 6. Going to reseat 4 and 6 wires to coil pack see if that does anything. Any ideas? V

Edited January 1 by vza

[vza]

Reread JFP's post. 'if the unit does not assume an active position when energized in the engine, it has a problem.' I'm assuming any bench test w a 9v battery wouldn't matter the solenoid can still be malfunctioning.  Should I replace the solenoid? Thanks V

[JFP in PA]

If attempting to activate it with the Durametric system does nothing, and the electrical connections to the unit are sound, the solenoid has to be bad.

[vza]

Ok, I would definitely hear the engine note change right? OR I would see the cam angle change when activated...(if it's possible to view cam angle and activate the solenoid together with the Durametric.) Never tried that. How likely that both are bad. Don't hear a change on either banks when activated. There are 2 solenoids on each bank, the others located between 2 coil packs are the valve lift solenoids, correct. V

Edited January 3 by vza

[JFP in PA]

You should be able to activate the solenoids one at a time with the Durametric, which should alter the engine's running characteristics. You should also be able to check the real time data section before and after activation and see the cam position changes.  The second solenoid on each bank is for the valve lift controls.

 

And, if you are so concerned about confirming the solenoid activations, you can by-pass the car's control system and use a 9V battery and a couple of pieces of scrap wire in place of the harness connection to try and force the activation while the car is running, or better yet, use a tool like a Power Probe to do the same thing.

 

It would also be very unusual for both banks' soleniods to fail at the same time.  As they share a common trigger signal, that could be a sign of a wiring issue like a voltage drop (weak signal), short to ground in the harness, or high resistance on the trigger wire.

[vza]

Oh boy. Ok I'll do some more troubleshooting. The car I believe sat around for a long time before I purchased. I'll check as follows:

Check coil pack connectors.

Activate solenoids and check realtime cam angle w Durametric.

Try to activate w 9v battery. 

Check oil strainer (maybe it's clogged...forgot to check it when I had it out)

Any info on what the voltages should be at different RPM's? Maybe I can check the voltages as well. As fore mentioned the bulb had a dim glow at idle then grew brighter as I increased RPM's. Thanks for your input John greatly appreciated. V

[vza]

Ok, activated bank 2 solenoid with 9v battery and there definitely was change in the engine note(almost stalling). Opened my DME and no evidence of burnt components.Any thoughts to do next. Voltages at the connector? V

Edited January 7 by vza

[JFP in PA]

The way the system works is that the DME supplies a ground to the  always hot solenoid at the appropriate RPM level, allowing the solenoid to assume the active position; so it is beginning to sound like you have either (1) a harness fault between the solenoid and the DME (high resistance causing a voltage drop), (2) a breach in the harness itself, or (3)an internal failure in the DME.

 

I would disconnect the solenoid harness at the cam cover, and using a wiring diagram, check the harness from the cam cover connector to the appropriate DME harness pin for resistance, which would cause a voltage drop and stall the solenoids.  If the harness is fine, you have a DME issue.

[JFP in PA]

An additional thought: Have you back probed the solenoid harness connector B+ with the car running to see if there is actually supply voltage?

[vza]

I only connected a light to the solenoid harness. Was dim at idle then grew brighter w increased RPM's. Ok..so check for resistance between solenoid connecter to appropriate pin going into DME. Only 2 pins. Then back probe solenoid connector with engine running to see voltage. What voltage should I see.? 

[JFP in PA]

Should battery voltage, or very close to it.  Are you sure your battery and alternator are behaving?

[vza]

New batt and alt. So 12v at solenoid connector?