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MG MGF Technical - Diagnostic Tools for MGF

I have been thinking of purchasing a Diagostic tool for my 1996 MGF 1.8 VVC, to aid solving the little niggles that have been occuring over that last couple of years... (you know the ones.... the type that you take to the dealer who hook up their computer and find nothing wrong...charge you a fortune for the priviledge, and then the fault either goes away by itself or something drastic happens!!!)

Does anyone have information on good and reliable tools.. preferably ones that you can use a laptop with.

thanks
Allan Inness

Allan, if you had a 2001 or later MGF, then the answer to your question would be easy: any OBD port reader would give you the functionality you require.

However, MGs built before 2001 use a different version of MEMS that is not OBD compliant. To cut a long story short, the only code reader that can read all the codes from MEMS1.9 or MEMS2J is Rover's own 'TestBook'

These do, occasionally, come up for sale when garages close down - but this is rare, and probably quite expensive...
Rob Bell

The best diagnostic tool is an oscilloscope.
You can buy add-ons for a laptop that can show several traces, or custom units. The laptop based units have the advantage of data-logging.
If you want to be really clever, then you could hook up to a PDA for an in-car display.

The 'scope will diagnose anything from battery faults, through all the sensor data (eg crank sensor, lamda sensor) to coil/HT problems.
In some cases - eg for coil problems - the 'scope is probably the only tool to give reliable diagnostic information.
Using this, you'll diagnose from 1st principles rather than relying on diagnostic codes in MEMS - which are rarely useful.
Steve

>The best diagnostic tool is an oscilloscope.>
Interesting!. What kind of oscilloscope and how would you manage to get the information? Mike
JM Vega-P.

Many years ago in the late 60s, we were a group of Expats living in Belgrade. We would have a social evening at our friends houses listening to there latest Hi-Fi System when Stereo was in its infancy.
One night a friends party was in full swing, but without any music. He had a record player and a Frequency calibrated record which did not have music, but a frequency signal which showed perfectly on his oscilloscope.
Geoff F.
G. Farthing

>>What kind of oscilloscope and how would you manage to get the information?<<
Just about any 'scope will do - everything on a car is low frequency, and modern 'scopes are auto-ranging.

Accessing *most* of the signals is easy - just use connectors which pierce the cable insulator with a needle-like probe, and clip onto the cable.
* this doesn't work with those signals that use a screened cable (such as the crank sensor).

Attaching to the HT leads is very simple - just use croc-clips over the insulation - there is no direct electrical connection, but the signal is so big that the clips pick it up via a capacitor-type effect.
Great for diagnosing HT / coil problems.

If you're looking for car-specific 'scopes, then I'd go for a PC based unit.

It's in this area that I find the workshop manuals very disappointing. My Suzuki manual lists every sensor and gives details on the signal and levels expected. The MG manual just lists the sensors and gives some data, but by no means all.
Steve

Thank you Steve. Excuse for being such an ignorant about, but could you perhaps be a bit more specific about the signals that you can detect in the oscilloscope and how you establish correspondence between what you detect and a failure? Thanks again. Mike
JM Vega-P.

Mike

Take a look at
http://www.picotech.com/auto/index.html

There are several other sites; I first saw these techniques in about 1970 courtesy of Electronics Today International (anyone else remember that mag?)

Deciding what's failed can be difficult - but the scope does allow very detailed data collection.
Steve

This thread was discussed between 08/12/2004 and 14/12/2004

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