Catamount90

Hello gents.

My 2005 A6 3.2 (120k) has developed some mis-fires and I'm trying to figure out what might be going on here.

First, I am getting the dreaded Camshaft Position Sensor B Bank 1 (G300): Implausible Signal (Short to Plus) DTC. Sensor B Bank 1 is the passenger side exhaust sensor.

If I monitor the mis-fire count on cylinders 1, 2 and 3 they steadily tick up as the car runs.

Okay, I thought maybe it's the sensor. I switched the intake & exhaust sensors on that side and the DTC didn't move to the intake sensor so I will assume for now that the sensor is okay.

When that didn't change anything (the DTC didn't move to the intake side), I started logging measuring block 090, which is the exhaust cam adjustment specified & actual for this bank.

The "actual" adjustment is pretty much pegged while the engine specifies no adjustment.

Specified: 0.00
Actual: 10.1 - 10.5

So my question is, what could be causing this? Is the adjuster "stuck out"? Would it be worth replacing the solenoid valve for this adjuster (and if so, is that a DIY job)?

I do not have the resources to drop the engine so I am at the mercy of my local indy here. I want to collect as much information as possible before turning it over to him.


==========

UPDATE: This issue was resolved via "electroshock therapy". See below for details.

hrc4u

what does meas block 093 say?
/H

Catamount90

I don't have the log handy but all of the other three "phase positions" were in spec. The Exhaust Bank 1 was some crazy high number, caused by the cam adjustment no doubt.

I'm wondering what would cause the cam adjuster to provide 10 degrees of adjustment while the computer is calling for no adjustment. Are these solenoid valves easy enough to replace?

Catamount90

UPDATE:

I found a TSB that seems very relevant here.

http://audi.workshop-manuals.com/a4_...ex.php?id=6627

CN: "The condition can be caused by one or more jammed Camshaft Adjustment Solenoid Valve(s) (N205 / N208 / N318 / N319). This may be due to
contamination (e.g. debris) of the Hydraulic Mechanism of the Solenoid Valve(s)."

Maybe I'll try swapping solenoids to see if the problem goes to the other bank.

hrc4u

your 091 block says 10.5 Kw degres adjusted?
(just to make shure..... since the "duty cycle box under 091 shows 10.5% on mine..and i have no issues....)
/H

Catamount90

Well, my group is actually 090 (091 is the intake) but yes I'm at around 10.5 "actual".

However, it says 0.0 "specified". In other words, it sounds like the computer wants no advance but the VVT actuator is advancing... which makes me think the solenoid is perhaps stuck.

If you are reading 10.5% actual, what is the specified number? I would think the specified is close to the actual, or you'd be throwing MILs too?

hrc4u

is no specified on duty cycle..guess it's just info.. =)
put up screen shot on 90-93 blocks....
or write all values here..
/H

ProtoFly

WIth respect to 'stuck' solenoid valves: I've read on some of the VW W8's that the similar valves get stuck, and that by 'over voltaging' them, they can be unstuck:

http://www.w8forum.dk/forum_posts.as...t-adjuster-fix

Perhaps this will be useful to your problem as well.

Catamount90

That is amazing!!! Even if that doesn't work for me, it was a great read regardless. I will absolutely be trying this out though.

Thank you for cross-posting!

Catamount90

ProtoFly, gave me a ray of hope earlier today with his electroshock link. Based on his link, I took a two phased approach tonight.

First I tried to exercise the solenoid via the output tests of VAG-COM. I ran through them several times but could not really hear the exhaust solenoid firing on Bank 1. However, VAG only exercises the solenoid with the typical 5-volts that the ECU sends.

Time for the big guns, er, big voltage. Based on ProtoFly's link I made up some test leads with alligator clips on either end. I pulled the air box for better access on the passenger side. After connecting to the solenoid, I clamped one clip to the positive terminal in the engine bay. Then I tapped the negative post with the other lead to "exercise" / shock-with-12-volts the solenoid.

After 20 or so clicks, I'd reverse the leads and run through again in the other direction. I did this several times.

Here is a video of someone performing the same "job" on a W8.


After firing up the car and monitoring block 090 again... the solenoid is at 0.00%!!! No more misfires, and the car runs great!

Unreal. I'm sure if I had dropped the car off at my local German repair shop they'd be suggesting dropping the engine for a timing chain right about now. I hope this thread helps someone in the future. If anyone sees a "Camshaft Position Sensor Implausible Signal" DTC and upon monitoring the measuring blocks notice that the ACTUAL cam adjuster position is different than the SPECIFIED position... try this fix. It takes all of 30 minutes.

This may or may not be a permanent fix, but it's clearly made a difference in the short term. I may end up having to replace the solenoid eventually... who knows. Either way, GREAT technique!

ProtoFly, I owe you a beer... or a case of beer!