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Lose connection between ECU and PC link Software

Sherif Nabil

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Communication Dropouts and Freezes


Feedback has shown that under certain conditions (usually full power) communications problems can cause the following symptoms:

· ECU disconnects completely from PCLink.
· PCLink freezes momentarily.
· USB communication breaks and won't reconnect until the cable is disconnected or PC is restarted.


The cause of these problems can almost always be traced back to electrical interference.  Electrical interference is generated by ignition systems and switching on and off of solenoids/relays.  Under most circumstances USB communications is robust in an automotive environment.  Unfortunately, excessive electrical interference can compromise the integrity of the high speed signals.


PCLink V4.x.x.738 and later have improved communications.  Ensure you are running the latest version of PCLink before trying to diagnose communication dropout problems.


If communication problems are still encountered, the following items MUST be checked (NEVER assume they are correct):

· Fit Standard Resistive Spark Plugs - Nearly all ECU communications problems encountered by the Link technical support department are caused by the use of non resistive plugs or HT leads.  Even race plugs that state to be resistive type may not suitable.  Remove these plugs and refit after tuning is complete.
· Fit Resistive HT Leads - Non resistive leads are a source of ignition noise and are not suitable for use with most modern ignition systems.
· Check All Grounds - Check all ECU and engine grounds are clean and well connected.  Perform measurements if necessary.  One installer reported communication problems that were a result of poor ECU grounding through a main engine loom connector that had been added to allow easy removal of the engine!  Another tuner reported issues where the ECU was grounded to the intake manifold but there was rubber intake manifold insulators!
· Check Wiring and Install of Igniter and Coils - This is particularly important where after market igniters or coils are used.  Consider the following points:
1. The igniter must be grounded with an appropriate rated wire to the engine block (and to nowhere else!).
2. Power supply to coils must be fitted with a suppressor.
3. Coils should be positioned to minimise HT lead length.
4. Igniters should be positioned to minimise wiring length to the coils.
5. Igniters designed to ground through their mounting bolts must be mounted to the engine block.
6. If fitting coils from another engine, ensure the mounting frame provides grounding for the metal coil body.
7. Some coils require a ground wire connection from their main connector to the engine block.
· If using a rolling road dyno, grounding the vehicle to the dyno chassis may improve the situation.  This can be done using jump starting leads.  Also make sure the dyno is properly grounded (consult an electrician).  Several tuners have reported this as a solution to interference issues.


In some instances the problem is not related to electrical interference but rather to the laptop, windows or driver installation.  The following solutions have been found to improve communications problems:

· Check FIFO settings.
· If you have a problem where communications fails every minute or so even without the engine running there may be an incompatible USB driver version.  Driver version V5.4.29 was known to cause issues on some Windows installations.  To resolve this issue:  To check the USB Driver version.  In the Device Manager, under Ports (COM & LPT) select Link USB ECU.  Right click and select Properties.  In the Drivers tab, select Uninstall.  Download and install a previous version of PCLink (eg V4.4.3).  When asked to install the USB drivers, check the version and select OK.  contact your Link dealer for further assistance on downgrading your drivers if required.
· Check USB Power settings (Windows 7 and Vista).  Go to Control Panel, Hardware and Sound, Power Options.  To the right of your selected power plan select Change Plan Settings.  Select Changed Advanced Power Settings.  Scroll down to USB Settings expand it and select USB selective Suspend Setting.  Change this to disabled.


If USB communication can not be made stable, all Link ECUs are equipped with RS232 (serial) communication port.  This allows direct connection of the ECU to a PCs serial port eliminating USB communications completely.  A lot of modern laptops have no serial port fitted.  A USB-Serial converter can be used, but it is likely that communications will fail as USB communication is still being used between the PC and the adapter.


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  • 2 weeks later...

If you can post you MAP we can try it on the bench.

This will check if it is a firmware related issue.

The other option is to roll back the firmware and see if you still have an issue.

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