Understanding Camshaft Flank Angle - Enlightenment in Progress ECM 644A Topic is solved

Post by **abscate** » 29 Apr 2020, 07:26

I have been fighting this code for a week now, and found this reference (the most annoying ad laden website I have ever seen , by the way) on how cam flank angle works and is reported

The ECM 644A Code is misleading - it has a "Cam overadvanced text' but in fact is reported for any flank angle larger than +-10 degrees, so its basically a cam in bad place message.

Here are some pictures and text of how this works.

There are some logical inconsistencies in this document I am still working through.

Note the two sentences where the same error gives rise to two different cam offset values - I suspect the second sentence was supposed to read" 2 teeth error"

I just got my cam flanks to read below the -20 crank degree limit, for the first time, so Im hoping I can figure out which way they are off and get it right today.

An error of more than 10 crank degrees trips the ECM code (about one tooth) and two teeth will max out the cam flank at +_20 and also trip the code. the ECM code disables the cam solenoid.

The code will not trip the CEL until the car is restarted but it will pend and disable ECM

Post by **abscate** » 29 Apr 2020, 09:35

More good stuff to bookmark

There is a procedure to check adaptation angles after service

Ignition off.
Reinstall the connectors, components etc.
Ignition on.
Start the engine. Let it idle for at least 30 seconds .
Neutralize the idling conditions. Carefully depress the accelerator pedal (AP) for 5 seconds , keeping the engine speed (RPM) below 1,200 rpm .
Then release the accelerator pedal (AP) so that the engine returns to idling.
Read the adaptation values for the camshaft. Check that all values are below 7 degrees .
Are all adaptation values below 7 degrees?
Yes - Testing Complete.
No - Continue below.

Post by **abscate** » 05 May 2020, 14:07

The official abscate DIRECTORY to how to fix your VVT cam based on FLANK ANGLE

(1) First the definition

FLank angle is the number of CRANK degrees the CRANKSHAFT is off from the timing mark when the cam is in its reference position

(2) The Math - cam sprockets have 42 teeth, so 8.6 degrees per teeth. The CRANK rotates at 2x CAM speed, so 8.6 cam degrees is 17.2 CRANK degrees per cam tooth.

IF the Flank Angle is positive, the Crankshaft reaches the mark before CAM reference mark, so the cam sprocket needs to be moved clockwise to retard the CAM

If the Flank Angle is negative, the Crankshaft reaches he mark after the CAM reference mark, so the cam sprocket needs to be moved counterclockwise to advance the CAM

Example - I recently timed my 1999 T5 with exhaust VVT to the marks, set after advancing past and return to the marks.

I then got Cam flanks of about -16 degrees. I removed the timing belt and set the exhaust belt one tooth ccw from mark.

I then meaured flanks angles of 1-2 degrees.

The range of adjustment is +- 20 degrees total

The ECM 644A (P0014) error code is set if the flank angle exceeds +- 10 degrees.

Post by **abscate** » 06 May 2020, 19:05

The ECM 644A error code is set immediately in starting if the ecm detects More than 10 degrees of flank angle required

The check engine light comes on in the next start cycle.

If the cam reset or solenoid is not responsive the flank angle is set to the full range of -20 or + 20 degrees. The solenoid is then turned off and is inoperative until the code is cleared.

Post by **abscate** » 07 May 2020, 04:39

End notes

If you put your car back together and get a sound like the worlds largest mouse squeaking on the back of the camshaft, it’s because you didn’t seat the cam inductor wheel correctly and it’s hitting the cam sensor.

I scratched mine up badly but it’s still working fine

Post by **abscate** » 09 Apr 2022, 02:59

IF the Flank Angle is positive, the Crankshaft reaches the mark before CAM reference mark, so the cam sprocket needs to be moved clockwise to retard the CAM

If the Flank Angle is negative, the Crankshaft reaches he mark after the CAM reference mark, so the cam sprocket needs to be moved counterclockwise to advance the CAM

Did I get this backwardsabove?

I think retard and advance need to be swapped

deano1 · Post by **deano1** » 09 Apr 2022, 06:35

Good Morning
So you did timing belt and now your T5 is throwing a 644A code If I understand correctly?
Maybe I don't truly understand what this post is about but it seems all this could be corrected by using cam locking tool on opposite end from sprocket then lining up crank and sprockets with factory marks,
WaaaLaa! Error 644A Code goes away?
Sorry if I just posted useless information but that's how I understand this post.
Cheers

Post by **abscate** » 09 Apr 2022, 08:15

It’s an old post but I struggled with the the procedure on VVT cars

From 1999 on, it isn’t as simple as locking and aligning marks as one or more of the cam hubs moves relative to the camshaft

The VIDA procedure actually says you align it one mark retarded on my exhaust VVT, so aligning the marks is wrong on my model

Last year I spent hours on this before I understood it. This year , I spent 5 minutes after reading my thread

crlande · Post by **crlande** » 09 Apr 2022, 08:42

I hate having to write stuff down so I can remember even little things as we get older, but it sure feels good when needed!!

Post by **abscate** » 10 Jun 2022, 12:16

Update on this

We did a 1999 XC70 with Exhaust VVT LPT and the B5243T2 engine - the car coded 644A with the exhaust hub set one notch before the mark per the VIDA procedure, when ccw indexed. Idle was lumpy

With the Exhaust hub on the mark, the idle was silky and no codes.

LPT and HPT might be different.