MSefi.com read only forum (Jan.15,2018)

I've been running a standard Rover p5b with a 3.5 V8 engine. I fitted fuel injection from a 1992 4ltr disco and did minor improvements to the ignition system. It ran OK but wasn't much better than the previous carby version. I have changed the old motor for a recon 3.9ltr from a 1998 disco containing a new performance road cam. As the original ecu cooked due to a short in the loom I am going to fit an MS2.
Theres a whole lot of info available on this site but I can't find out how I might try and account for the different camshaft in the settings. Is this likely to be a trial and error thing or are there some basic dos and donts I could observe when mapping fuel and ign?

Cheers
John

The VE table is what takes care of the cam difference, so you need to retune this table. The cam controls how much air gets into the cylinders and how much residual gas gets back in due to intake/ exhaust valve overlap. Since the performance cam is optimized on the side of letting more air in at high rpm/ high load, it is more efficient (higher VE) there, and less efficient at low rpm/ low load (lower VE) due to the longer overlap time.

John,

The process is not so much "trial and error" as "tuning". The difference is that tuning is skill in which you use the results of your last trial to significantly reduce the possible directions you will attempt for the next trial. It isn't that hard, if you proceed methodically and with care, and pay attention to the results you get. There is lots on this process in the manual:

http://www.megamanual.com/begintuning.htm

http://www.megamanual.com/ms2/tune.htm#howto

http://www.megamanual.com/ms2/tune.htm#spark

etc.

Lance.

Thanks for that. I've started reading some of the info and found the bit about auto tuning - and its limitations. Obviously a lot to learn, understand and apply - thanks to you both for the pointers.
John