Hi,

I hope you can help.

We are two guys in Denmark, each with a Maserati 430.

We are having some problems adjusting the throttle body.

Unfortunately, on both cars the "DO NOT TAMPER" anti-crawl screws have been tampered with! See attached image.

Can you help by telling us how to calibrate them - or alternatively what the standard position ought to be?? (closed, 1 mm open, 5 mm open??).

Is it correct that the potentiometer value should be 155 mv (+/- 15) when the car is not running?

Currently the cars have problems when starting from cold. They start but do not take the revs - starts with near 1,000 rpm and doesn't run smooth. (I thing normal should be starting with about 1,500 rpm and then fall to 1,050 rpm after a short while).

When hot both cars run okay - but not perfectly smooth during idle (rolling a bit in RPM).

WTS and ATS are okay (new) and the spark plugs are fine, new and burned grey.

Do you know how to check ignition timing on the 430?

Thank you for a great site,

Jørgen and Thomas."

"Hi Enrico,

If the throttle anti-crawl screw has been tampered with, then the best way to reset is as follows:

1 - Set the larger air adjuster screw (the one to the right of the intake body) to about halfway through its travel (in other words, between fully closed and the ‘O’ ring at the top of its bore).

2 - Then adjust the basic idle speed so that once the engine is hot, it will run at around 800rpm with the idle control valve disconnected. To do this, adjust the screw that is originally protected by the tamper proof plug.

3 - Once you have done this, adjust the potentiometer in the way you have described, but with the engine RUNNING. During the adjustment, make sure you open the throttle a number of times and check that when released it returns consistently to between 140mv and 170mv (150 – 160 should be easily achievable).

Other things to be aware of:

1 - If the CO is too weak, the idle will be poor – should be 2.5% on non-cat cars.

2 - If the idle control valve piston is seized, the idle will be erratic – remove, clean with injection cleaner, make sure it moves easily.

3 - The ignition timing is totally controlled by the ECU so checking and/or adjustment are not necessary.

4 - Good strong idle needs good compression. Are your valves seating well?

5 - Finally, in our experience, most of the running problems on these cars stem from poor connections on the negative battery cable, between battery and body and then engine. Make sure all in this area is in very good condition.

Hope this helps.

Cheers,

Andrea."