I have a 1998 A4 Quattro 1.8T AEB 5 speed that I bought for a decent AWD winter beater.

I got code P1338 which is a Camshaft position sensor code. I found the timing belt was old and I decided to change it just out of preventative maintenance.
Upon changing the cam seals I found the dowel on the Cam pulley was about to fail (pulley has spun a bit relative to the cam) so I changed that, the belt, the tensioner and water pump. Cleared the code.

Car ran great for about 10K miles with no codes.

I now have the same code P1338 up again. The car runs like crap when the engine gets warmed up. Upon a cold start up the ECT and IAT temps are within a couple degrees of one another and appear to be accurate. ECT also increases with run time as it should to thermostat temp. It is down on power, runs rough and is in limp mode by limiting boost due to the code.

From reading code P1338 will be set for a couple different reasons:

1. Cam and crank sensors are out of sync (cam timing)
2. Cam sensor signal to the ECU is messed up

I have back-probed the ECU to check with an oscilloscope.....it has the expected square wave signal.

I have checks for shorts between the wires, shorts to ground, and shorts across the sensor.

I have performed continuity checks on the wiring. I have verified the correct 5V across the power and ground wires at the sensor.

I have verified the timing belt timing marks.

I have verified the timing pulley dowel is still intact.

I have verified the timing chain links (between exhaust and intake cams) and cam marks vs. cam bearing caps.

I have verified the cam sensor shutter wheel is clocked correctly and not damaged.

I have even thrown a new bosch cam sensor at it.

The engine has 140-145 lbs of compression in each cylinder. So im reasonably confident that the valve/cam timing is correct.

I am at a loss on where to go from here. The only things i can think of from here are.

1. The PCM is bad
2. The crank sensor or crank trigger wheel is loose causing a PCM perceived out of sync issue.

Anybody have some light to shed on this thing or have experience? I am using a generic OBDII scanner. I do not have VAG-COM or the enhanced program for audi on my AutoEngiuity software.

Thanks

 

Cam vs. crank sync was my go to for this as well.......but I think I have that covered/ruled out

Ive been considering the PCM as well.........but that is usually the last thing I go to. Anyone know if PCM's can be swapped in these cars without reprogramming the VIN?

Sensor is tight, no oil on it. I was also considering if the crank sensor/wheel was acting goofy that it would cause an out of sync.

Ive also considered that it might be throwing the code since it runs rough that the cam/crank get out of sync momentarily....but then I would think it would throw a misfire code.

Fuel trims are within 5% and there is spark at all 4 coils.....O2 sensor seems to be functioning properly as well.

Im usually the go to guy for drive-ability diagnostics....but I dont generally work on too many European cars and this one is having its way with me. I was wondering if there was another condition that Im not aware of that throws this code. The Bentley manual is vague/incomplete at best and didnt even indicate that cam/crank sync issues can throw the code...so I am somewhat flying blind.

 

whats vacuum at idle

 

Vacuum at idle is about 14 "hg........normal is around 18"

This is a chicken/egg scenrio.......because it is throwing this code......it locks/retards the spark timing and limits boost.

So is it running like crap....thus throwing the code....thus making it worse? Or is the (unfound) code set condition causing it to run like crap?

 

My experience with this is. If the vacuum is low then the mechanical timing is off. 14 " is definitely low. should be 18-20 on stock camshaft timing.
But it seems you have verified the cam/crank timing.

In this case I think I would try and investigate mechanical a bit more to see if something weird is going on with tensioners or something.

PT cruisers got this thing where you have to setup the exhaust cam to the point it looks retarded almost a tooth or that cam will be off and have low vacuum , exhaust cam error, and put the ecu in limp mode.

I realize it ran good this way already. Im just throwing it out there.

keep us up to date

 

One thing that did occur to me is.....

The timing chain (that goes between the intake cam and exhaust cam) tensioner could be failing....thus allowing too much slack and the intake cam's timing/phase to jump around a bit......the cam sensor is on the intake cam.....this would also explain why all the timing marks line up during a static check.

Kind of a loopy cam drive system......crank to exhaust cam via belt.....exhaust cam to intake cam via chain on the back of the cams......cam position sensor on the front of the intake cam..........lots of opportunity for phasing stack up error

 

crank timing belt pulley keyway/crank keyway is toast....thus altering cam timing and setting the light

what a POS.

Thanks for the help guys.

 

What a POS is an understatement lol. I work on German cars all day the worse they are.

 

I had a chance to get a 2008 mini s . Cousins coworker had it. Mint car. Just over 100k. Went to start it one day and it just chugged.
He stopped right there. Had it towed to auto shop. They said the timing chain broke or jumped and said they scoped it and piston got hit.
Looked into worst case and repair details. Apparently because was in such good shape and parts yard was gonna give him 850 for it.
I decided no after finding out that the tensioners break and fall into the oil pan and not sure of valve damage. And the crank cam timing setup is all retarded. It looks like you have to have the tools to time it because nothing is referenced to TDC.

 

Its gonna get fixed with a new pulley and a dowel kit........then sold.....sux....when it runs I like it for a daily/winter beater

thankfully I caught it before it banged valves.....AGAIN

 

English cars are pretty terrible too. That mini engine is a BMW / Dodge hermaphrodite lol . I seen a classic mini with a civic engine swap. Probably the only way to have a reliable Mini

 

Sad to say that 1.8T was one of their better engines. I got a friend that works in another shop that has a 9 sec vr6 turbo gti it took 5 engines to get there but it's there a ton of money later but it's figured out now