Sync Loss Fault Check Bug?

[shaodome]

This has been happening on the late version 1.4 beta codes and it is still there in the 1.5a8 variant. It is my understanding that once the cam/crank signals sync and the engine runs, there technically could be sync loss still on the CAM, but not affect the running of the engine. This obviously would not apply to multi-tooth cam triggers (aka vvti). In my case I'm talking about the 2jz/1jz engines with a single cam tooth and 12 tooth crank (nippon denso).

The cam sensors on these engines are VERY problematic with the MSpro input circuit and continue to be problematic on the 2jz PnP ecus as well when the amount of teeth is low (in this case, 1) and the speed is low (say 800 rpm on the crank), but that is not the point of this thread.

On the sensor checking/CEL settings you can specify the amount of sync loss events before triggering a CEL. That is where the bug is. Even if it is disabled, it will still throw a CEL for sync loss even when the engine is in a sync'd running state.

Here is the scenario:

-Engine start
-idle speed, everything working, no missfire, etc.
-Noise on the cam input as seen in the composite logger, so it triggers the lost sync counter (hence the cel)
-Engine runs with no timing drift/miss because the crank signal is solid, no noise

Again, the point of this thread wasn't to discuss hardware/trigger input issues. It was to point out that even if you disable the sync loss check in the CEL options, it will still throw a code/CEL.

[jsmcortina]

The non-checking of the cam only applies to missing-tooth crank wheels. On your install a cam fault is still a problem.

James

[Reverant]

What shaodome is saying is that if you enable the Check Engine Light (for example for CLT, IAT, TPS and EGO) but disable the Sync Loss check, you will STILL get a check for a sync loss, even if it disabled.

[jsmcortina]

This should be resolved for the next pre-1.5 beta.

James

[dillusion13]

shaodome, did you ever fix the sync loss issue or did you just turn it off so it doesn't trigger CEL? I ask because I'm having the same exact issue. I lose sync on cam signal between 900-1100 rpms. Revs clean, etc.