MoTeC Global Forum

I am installing an M800 on an LS engine. Its gen 4 for its 60-2 on reluctor and can sensor on timing sprocket. Its a built engine but the sensors were new GM with LS2 part nos but as far as I am aware any LS2 (60 tooth), LS3 LS7 cam or Crank sensor should interchange but from reading some previous posts there seems to be some suggestion an LS7 might run other than mode 17

Here is the trigger capture below and the Ref Sync Setup.

Problem is whilst cranking we tried a number of times we could only twice it it to sync but for only very short times. We did also try the CRIP at 440 and just either side of it as well as both sides of around 80.

This vehicle was running a Link ECU previuosly and all worked fine and we have just repinned the loom at the ECU so the loom and sensors should have no issues as was operating fine a few days ago. We have an issue that if we span the TPS it operates in a narrow voltage window (around 1 to 2v) and once spanned to say 95% starts making an injector pulse. Normally 7 but has been 5. Also when we switch the ignition off but with battery power still on injector 7 starts clicking away for no reason that I can yet determine. I have checked for any conflicting Pin assignments and internal voltages and sensor values all look good. Ignition and injector test all seemed good. We are running it wasted spark. There appears to be some conflicts going on and that may be interfering with the Sync process.

If anyone could chime in with any thoughts would be much appreciated.

Additionally the RPM trace looks to erratic at this stage so that may be pointing to something wrong

I just checked a file from running ls7 , ref sync setup is the same as yours except tooth ratio is 50 and crip is 78 in this case.

You have the grey crank sensor I trust?

This thread may be helpful to you..... viewtopic.php?f=30&t=584
There's an ecu file on page 2.

I would be revisiting the wiring if you have injectors firing at random.

I have since cranked it again with plugs removed and with that being the case "ref/Sync Synchronised" goes good and the timing light confirms spark. With the plugs back in then its no go so the issue is maybe cranking speed.

Its still has 10.6 volts whilst cranking with plugs in but would appear to only be cranking at around 100 to 160 RPM. This vehicle runs a Tilton reverse mount starter so maybe it cant generate the required speed but I can't imagine this would be an unusual setup. Therefore I wonder if the an adjustment somewhere in the software with regards to a cranking threshold, Have had a look but can't find anything.

You have got a decent earth cable from the gearbox to the chassis? Hall sensors have no trigger levels you can adjust.

Just as an update to this the problem was the Tooth ratio setting. It was originally at 30. In the ecu manager software when sitting on the box for entering tooth ratio it saids "only used for Ref/Sync modes 3 to 9". However after discussion with Motec it does actually alter things. At a tooth ratio of 50 we sync up and all is ok