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View Full Version : Camshaft position problems and questions...



Arsigi
2010.03.22, 06:27 AM
Greetings,

So, recently my GTI (ABA, OBD2, bone stock) began having an intermittent issue. It would run fine for some time, and then die... not to restart again for many, many tries. Then it would run fine again for some time, and the cycle would repeat.

The code being thrown was the somewhat infamous P1340 code - "camshaft position sensor, incorrect correlation". I did my research on here and found the most likely culprit to be the timing being a bit off, possibly due to a deteriorating belt. Since it had been ages since the last belt change on this car, I changed the timing belt. The timing on the old one appeared just fine, though - and I how have a nice new belt on there that is also timed just fine.

My problem, however, has not gone away. The symptoms remain the same - it will run fine for a while and then die with the P1340 code - eventually to start again. One time only I also received the accompanying P0341 "camshaft implausible signal" code.

So, I am thinking the next logical step would be to target the camshaft position sensor itself. As I understand it from searching on here, the CPS is not actually connected to the camshaft at all, but is rather the 'hall' sensor within the distributor. I am thinking that, given the fact that this is a 14-year-old car with 175K miles on it, I might as well replace the entire distributor at this time rather than try to work a new sensor into the existing one.

Does all that sound reasonable? Is the distributor as straightforward a swap as the Bentley seems to indicate? It is one of the few things I have not yet replaced on this car! I'd appreciate any input or insight. :weird:

Edit - some people are chiming in here... food for thought: http://forums.vwvortex.com/zerothread?id=4814337

Rabbit 16v
2010.03.22, 10:47 AM
The distributor is not the problem. those cars can run with the distributor unplugged. you are correct that the CPS is in the distributor. When it is not starting are you losing spark?

Rabbit 16v
2010.03.22, 10:49 AM
oh and with relation to the note about the water pump, the plastic impeller problem is inherent to MKIVs not MKIIIs.

Arsigi
2010.03.22, 12:54 PM
I have not verified the spark issue - will check, next time it acts up!

Rabbit 16v
2010.03.22, 13:06 PM
I suspect ignition coil. If you have an extra, try packing it around with you in the event that the problem duplicates itself. That way you are not stuck.

Arsigi
2010.03.22, 14:01 PM
I don't have an extra... but like most things on this car, that too is the original, 14-year-old unit that is in there. Is it not uncommon to have them act up sporadically?

Rabbit 16v
2010.03.22, 17:00 PM
well, they usually will act up when they are hot. then after they have cooled off, they will work again.

Arsigi
2010.03.24, 18:29 PM
Finally had the opportunity to check into this... sure enough, once things get good and hot, the car dies, and then there is no spark. Coil it is! Thanks for pointing me in the right direction! :D

Rabbit 16v
2010.03.24, 19:03 PM
No prob man. Glad to help. although, not very likely, there is a slight possibility that it could be something else. But most of the time its the coil. Let us know when you confirm so that others might benefit ;)

Arsigi
2010.03.27, 12:02 PM
Well, got a new coil and swapped it in, but unfortunately the symptoms remain. D'oh! (now I have a spare! ;) )

Have you ever heard of spark plug wires behaving in a similar way to what we were thinking the coil was doing? Working fine when cold yet losing continuity when they get hot? I was testing for spark by putting a timing light on the wire between the distributor and the coil, so, having eliminated the coil, I was thinking perhaps that wire might be the culprit. Can't think of a practical way to test that theory, though (other than just replacing that as well).

Rabbit 16v
2010.03.30, 11:09 AM
not likely unless the coil wire or the distributor rotor are bad. usually though it will do wierd things and not just plain crank over and not fire at all. the next culprit is the crank position sensor located in the block to the right of the oil filter. if you have vag com, ou can check measuring blocks for rpm and if rpm is not present during cranking then it would point toward the crank position sensor. the crank position sensor is not to be confused with the cam position sensor which is in the distributor.

Arsigi
2010.03.30, 12:24 PM
Interesting... in at least one of the many threads I have dug up in which someone had a similar issue, it did in fact turn out to be the crank position sensor. So, does the crank sensor tell the coil to turn on, essentially?

Edit: some research has turned up that it can affect the coil, and fuel pump as well possibly. You wouldn't happen to be able to look up a part number, would you? The only one coming up on 1stvwparts is called out as being for the VR, which I suppose could theoretically be the same part but doesn't seem likely!

Edit #2 - found it. Spendy little bugger!

Rabbit 16v
2010.04.03, 14:15 PM
essentially, yes. the crank pos sensor gets input from the trigger wheel on the crank. this tells the ECU that the engine is rotating. The ECU then sees this signal and says, ok, lets send a ground out to the fuel pump relay to get the fuel going and lets send a trigger signal out to the ignition coil to get spark. Thats kinda how it works. If you have VAG COM then you can test this easily. HTH!

Arsigi
2010.04.05, 07:35 AM
Well, got the new CPS installed this weekend... man, such an easy thing to replace, but what a pain to get to! And the good news is, that does (for now) appear to have been the root of the problem. I ran it for 30 minutes, letting things get good and hot, with no issues. I'll get it back on the ground this evening and start using it as my daily this week to ensure that this pesky gremlin is banished for good.

Thanks for all the help!

Rabbit 16v
2010.04.05, 15:03 PM
Fingers crossed. Hallo auf DEUtschland!

Rabbit 16v
2010.04.29, 19:20 PM
update?

Arsigi
2010.04.30, 13:19 PM
Everything seems to be A-OK - it was indeed the crank position sensor that was the issue. I've kept the old one, out of curiosity, just to see if I can actually verify with a multimeter that it fails when it gets hot, but I haven't had time to play with that idea yet! But I daily-ed the car for a week with no issues. :thumbup:

Rabbit 16v
2010.05.07, 09:46 AM
good to hear! :thumbup: