I have a p72 running my ls/vtec with a gsr head/manifold. I had it running fine, and it hit vtec at 4400. It was a noticible change in sound. I just tried to put in an ecu i was told was a p72 (stamp missing) and it didnt hit till 5700. What is goin on? Also, the knock sensor code did not go off like it used to with the old ecu. Any help? Can pics of the internals help?

 

vtec is now different, then you have a different ecu... can't really tell you what it is from internal shots... bump for you

 

This is confusing me. I though vtec on a p28 is at 4800 anyways? What other obd1 ecu could it be? B16?

 

Well with no sticker you can't tell from the outside, pop it open to see if it's stock or reprogrammed (look for 28 pin eprom to see if it's reprogrammed which it likely is with the lack of ks cel). To me just from how you described it, it sounds like it's probably a chipped p28 (could be a chipped p72 or p30 as well, but p28 is the most common).