Assuming I use a piggyback system (Apexi VAFC) is it necessary to purchase a PR3 for my LS/VTEC 
I don’t see why a chipped PR4 would not work…Any insight would be greatly appreciated.
TIA
There are programs that turn your LS ECU into a VTEC one given the correct EPROM, but I’m not sure if yours qualifies - there are certian restrictions (might be limited to OBD-I LS ECUs). You do however need to run a VTEC program for your LS/VTEC setup, regardless of ECU, so if there aren’t any conversion chips for your non-OBD PR4, you’ll have to get the PR3.
Thanks Ive. You were my next contact. I vaguely remember someone mentioning at 2 in the morning at a particular meet that they knew how to chip ECUs…Hmmm If I could only remember…
As for chips, where should I look? And what is the differences between vtec and non vtec programs?
Originally posted by Louis
I vaguely remember someone mentioning at 2 in the morning at a particular meet that they knew how to chip ECUs…Hmmm If I could only remember…
LOL - good times… I think someone still has Mike’s sweater from that meet tucked away.
I and several other members have gotten our chips from Adrian at HyperDuckTuning. Haven’t seen anybody beat his prices - and he I received the chips 5 days after I emailed and sent in my MO. I’m giving Marc my P61 for testing the 4 programs I received from Adrian very shortly (it’s taking longer than expected to finish my project motor :().
The difference between VTEC and non-VTEC programs is that the VTEC programs have different seperate fuel curves for the 2 different high and low RPM ranges of the VTEC head, where as the non-VTEC programs are set up only for the more single band nature of the LS head. A VAFC is more of a fine tuning device, and I haven’t yet seen it used on an LS ECU to grossly adjust for the the fuel curve differences between the low and high RPM lobes of the VTEC head.
Louis,
You can use your PR4 and then use your VAFC to activate the VTEC with no problems. My only opinion on that setup (which was used when LSVTEC was first introduced for a cheap ECU setup) is that the fuel and ignition maps of the PR4 aren’t that optimal for any VTEC setup. I did use a PR4 ECU for my first LSVTEC break-in with no problems but the motor was detonating/pinging a lot at part-throttle. After switching to a P61 soon thereafter, the motor ran a lot stronger and smoother and somewhat remedied my detonation problems (considering I was running close to 13:1 C/R on that previous setup).
Well, looks like I will be buying a pr3:( I really wanted to be cheap and get the Zydne later on, but doesn’t look like that will happen. Thanks guys for the help 
if your car is a 90-91 pr3 92-95 pr4 p73-p75 gsr chipped for a single stage intake manifold.