Really he has not necessarily adjusted it wrong.
The problem is that the only way to know if the maximum fuel rate is too high/low, is to put the
maximum load on the engine.
This can be done with a dyno, but if you don't have a dyno, then you have to suck it and see. You need to put a load on the vehicle on the steepest hill you can find.
That hill in the mountains for example. Ideally adjust it at the bottom of the hill, then drive up it and measure the exhaust gas temp.
Then if EGT is below acceptable max. increase fuel some more and repeat test. If EGT is too high, reduce fuel.
This adjustment is simple and only requires a flat blade screwdriver and EGT gauge. Will take 1 or 2 minutes max. each time to make the adjustment (not including time for testing).
Your mechanic would probably have limited ability to put the maximum load on your engine (I'm assuming he doesn't have a dyno).
Once the maximum fuel is set correctly, so egt does not go too high, then carry out the other adjustments.
I can tell you how to do this yourself - or read Ian's instructions.
Quote:
Since it is only a problem when you climb that hill, there is no need to do it now. Wait until the EGT gauge is installed
.