2.0TS timing goes off, won't rev above 3,000rpm - Alfa Romeo Forum
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(Post Link) post #1 of 15 Old 05-09-16 Thread Starter
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2.0TS timing goes off, won't rev above 3,000rpm

This problem has now occured for the third time (accompanied by the MOTOR CONTROL SYSTEM FAILURE warning in the dashboard). After the first time installed new camshaft position sensor and checked the crankshaft position sensor (which was alright). All was OK for 300-500 miles then the problem reappeared. As far as I can see there is nothing mechanical that could affect the camshaft position sensor that has not been checked/changed (timing belt, all pulleys and waterpump changed). Now again after 300miles or so and the problem is back. My suspicion now is an electric spike upsetting the system, and if so where to look. Has anybody had a similar problem? Any help or pointers to a possible cause welcome. Thanks.
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Diode failure in your rectifier pack is possible, look at the charging output on a scope if you can. Also failure of the throttle body is not unknown.
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Failed woodruff key on the crankshaft pulley (its happened before!)

Did you use cam locks etc when the belt was changed?
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Have you put it on a diagnostic to find out what the ACTUAL issue is? MCSF covers a multitude of problems ..
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(Post Link) post #5 of 15 Old 08-09-16 Thread Starter
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Thanks addo, Rockhopper and gazza82 for the replies. Re the diagnostics, the error codes were (and still are):
P340 - "PCM sensor A bank 1 circuit malfunction": this was why the camshaft position sensor was changed and the wiring checked as OK. But its still there, so thinking the ECM is somehow being upset after the engine is started.
P481 - "engine coolant blower motor 2 circuit malfunction": fan is working fine and triggers at 92 degrees as it should. So again thinking the ECM is somehow being upset after the engine is started.
Havn't had chance to check rectifier diode/charger output. Any ideas why the motor won't rev over 3000? Certainly seems a pre-programmed value, but seems a bit high for a limp mode. Any other thoughts/suggestions welcome Thanks
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sometimes pins of connectors on top of ECU get bent on plug/unplug operations and cease to make contact.
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1/ If its a Manual, then yes, the 3000 RPM IS LIMP HOME MODE! one the fault has been rectified you can clear the errors using MultiEcuScan or AlfaOBD and it will run fine again.

2/ P0340 is Camshaft Position Sensor Failure, and seeing you have replaced the sensor once already the most likely culprit is damage or a ding in the "Sensor Pickup Ring" running around the back of the exhaust camshaft pulley that runs through the "Hall Gate" of the sensor. If there is any deformation in the ring whatsoever it can make the slightest contact with the "gate" causing it to eventually fail.

It is usually caused during Cam Belt Changes and the incorrect tools are used to hold the pulley when the locking bolt is loosened for the Belt change.

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Patty - 2004 Alfa 156 2.0JTS Sportwagon

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Did you use cam locks when the belt was changed?
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(Post Link) post #9 of 15 Old 17-09-16 Thread Starter
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I've not driven the car much since I started this thread but when I did today it was practicably undriveable. When the timing was re-set around a month ago the engine ran sweetly for about 400 miles. Then suddenly MCSF lit up but even then engine continued to run smoothly for about 30 miles and then it gradually became rougher and rougher finally refusing to rev above 3000 rpm. I've talked to 2 professional mechanics (and run the diagnostic with them) but they both had no answer. If I am right about an electric spike initially upsetting the ECM, why doesn't the engine go off tune immediately instead of gradually as I'm observing? Anyone experienced anything similar? Thanks
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Have you checked the woodruff key and pickup ring on the exhaust cam pulley yet - they were both suggested a while back ?
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(Post Link) post #11 of 15 Old 17-09-16 Thread Starter
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No not yet. Trying to get some clear targets before taking things apart which planning next weekend. cheers
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Quote:
Originally Posted by dandy View Post
I've talked to 2 professional mechanics (and run the diagnostic with them) but they both had no answer.
These mechanics, are they Alfa Romeo Specialists using DEDICATED Alfa Romeo Diagnostics or the usual All purpose diagnostic systems that most garages use?

If it's the former it's pretty much a waste of time.

Just one thing, what gave you this idea about a voltage spike upsetting things?????

"Car gets re-timed, ran sweetly for about 400 miles. Then suddenly MCSF lit up but even then engine continued to run smoothly for about 30 miles and then it gradually became rougher and rougher finally refusing to rev above 3000 rpm."

In your own words you are describing a gradual failure of something, a component, a sensor (most likely) And again, your car is in "Limp Home Mode" thus why it wont go above 3000 rpm. This can ONLY be activated by something triggering or damaging a sensor.

This weekend you need to check the "Hall Effect" ring on the back of the exhaust cam for the slightest imperfection, and check the face of the Cam sensor.

You can remove the cam sensor for inspection/replacement without touching the cam belts pullys, here's the procedure, and it's nothing too complicated.

http://www.alfaowner.com/Forum/engin...ys-solved.html (Twinspark cam sensor change without the need to remove belts or pulleys solved !)

Baz
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(Post Link) post #13 of 15 Old 18-09-16 Thread Starter
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Thanks Baz. Mechanics are mates who build/prepare their own rally car but not Alfa specialists. So will check cam sensor and thanks for removal info. Cheers
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do your mates have the proper timing tools to check/replace the timing belt?
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That's the fourth time we've asked if the correct timing tools were used :-)
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