This car has recently had a (second) head gasket replacement. The quality of workmanship is very poor. Silicon sealer in great big globs, rounded off fasteners, complete inability to diagnose failed ignition lead despite big burn mark on the side etc. I did ask the customer if the job was done by a family member or a "professional" and apparently she paid good money for the work, but when she got it back it was misfiring and the engine light was on. We wonder why we get a bad name!
To the problem:-
P0340 returns immediately Which Autodata decodes as "CMP circuit problem". I told customer that I could fit a sensor or spend time diagnosing. The answer was fit a sensor. Problem remained so out comes the scope, trace attached.
It certainly looks to me as if the CMP signal is late in relation to the crank signal. Does anyone have a known good trace for this engine,or information on which edges should sync?
I do find it frustrating that the code is listed as "circuit fault" and not "cam/crank synchronisation error" or a different code given for this fault. Unless of course this trace is correct and the ECM cannot see the cam signal at all. Customer feedback suggests no MIL before headgasket replacement.

wouldn't it be just as easy to remove timing belt cover and physically check valve timing as they aren't to bad to do compared to most other cars.

if the head gasket job wasn't the best then i'd guess they've probably borke the timing belt cover fiings anyway.

That's if its an 8 valve engine though.

Hi Lee,
This is the 16v engine. According to Autodata the procedure is relatively complex and needs tools to hold the pistons and camshafts. Not as simple as removing the covers and checking the marks align. I got the customer to phone the previous "mechanic" who said he marked the belt and retimed it that way, well nearly, anyway. As the head has been off twice recently it is of course also possible that the last guy got it back as it was but the previous work was incorrect.
From the procedure it looks as if it's timed 90 degrees BTDC so I can probably do a basic check without the kit if I probe the piston crowns and look at the cam index marks.
The engine starts and runs fine by the way.
Shaun.

Hi Shaun,
How many channels does your scope have ?
If more than 2, why not scope the ignition event on cylinder 1 and see where that falls on the cam & crank trace, may be able to work out whether timing is incorrect or not from that !!

Regards
Dave

Hi Shaun

Remove cylinder 1 + 2 spark plug and get the pistons level, maybe with a screw driver and a sliding cable tie. Then remove the allen key blanking plugs on the front and back of the cylinder head and with a bit of nifty mirror work (or a camera) you will be able to see if the cut outs in the cam shafts line up with the holes.

hth
James

Hi Shaun

Following on from Dave Harney's post:

If you have only got two channels you may get some idea of the timing if you pull the fuel pump fuse and scope starter cranking amps and an ignition event. With a bit of math you will be able to roughly see where in degrees the ignition event is happening in regards to TDC.
(this is not 100% accurate)

hth
James

A stab in the dark but to time this up or remove the alternator belt you would need to move the crank sensor(if not taking crank pulley off).
Is the air gap correct? Has a phonic wheel relearn been carried out?(full snap throttle 3 times, idle etc)

There is virtually no way on that engine that without the cam locking tools you could get it spot on, especially as you have to loosen the camwheel to carry out tensioning, a la zetec stylee.

Who reuses a cambelt anyhow????

HTH

Liam.

Hi All,
Thanks for the replies.
The belt was a tooth late.
I couldn't find (borrow) a timing kit for this engine but the one for the 1.3 JTD engine has the right cam locating tools.
Set the crank with a rod down the plug'oles and a digital vernier, bit of a faff but got it spot on in the end. It was not an exact tooth so I did it the proper way by unlocking the cam wheel.
The tensioner was on its bottom stop when I got the engine mount off.
I also found one broken bolt in the bottom pulley and five of the six bolts fitting the engine mount to the head were stripped, so I had a merry time drilling them out and fitting Helicoils.
Shaun

Spot on shaun.

The one I have just done needed all the mounting threads helicoiling, what a pain, even with an angle drill!

Liam.