Also had done the test where you pull and block
the vacuum line to the FP regulator at idle and it jumped right up like its supposed to.

Just a guess have you ever tried lifting your engine hatch while running to see if you can gain rpm's - Just asking.

MAP,or IAT or coolant temp sensor out range can / will make your engine run rich. If you do not know your engine serial #, what year do you have or both of that info ?

did you check your throttle cable and throttle plate for WOT. Are you still running rich - 4 sure ? Your spark plug wires in good shape.

If you pulled your header(s) off couldn't you get to the PCM somewhat easier - just asking. Plus it would be another good reason to pressure test them, at least one side anyways.

Well Merc engine scan found nothing. Compared data between the two motors and they look damn near identical.

If you can post your scan results that would be good. Did you test the scan while running WOT ? Next since I see now you have a 2004 year model 525 hp here is the engine serial #s that needed the PCM calibration change.

Engine serial # - 0M950064 and below

I would make sure that this has been completed - triple check because Merc is not always right about it being completed. Another possible thing to try is switch out the 2 coil packs & plug wires from your known good source and see what happens. Weak ignition can make it seem as the motor is running rich when in fact it could be spark / ignition related.

You ran the Buffalo run so maybe you got this fixed - if so what was the problem / fix ? Hopefully it was something simple like prop related. If it could only be that easy & simple everytime out.

SN is OM901186 Did not run scan at WOT just because of the guys available time. He said he would but weather is so so. I had emailed Merc and they said both my motors had all updates. I will scan and post print outs. He scanned cold, at temp. But all on the garden hose.

I did run the BPR (pace boat for 70 group) and if you check out the one video there's only one Cat that could run with me. That said I was still having to lean on starboard throttle more than port and wait for it to play catch up.

Had previously swapped plug wire between 4&6 when I was thinking it was single cyl related. Also put new coil pack on that fed #6 with no change.

Ok had a felling your motor fell under the recalibration. Also I know you were the 70 mph pace boat because at the start we were almost right behind you. I put it together after the fact that your boat and post was this.

On the water hose compared to under load is 2 different stories for these marine engines running. Who is helping you with diagnostics - a repair shop or others. I would look under history from your scan and see if the had any knock sensor faults. At this point I know you said swapping over PCM's was a PITA but maybe is a very good option for testing. .

BUP ur inbox is full Wanted to discuss my 525

you can hit my email

put a title on your email so I know who its from.

I will give U my cell if needed. from one NY er to another

[email protected]

Dave I emailed you back from day one and even Sunday. Seen your email last night if I got yours - I sent another email and sent the original 2 back to you. Did you get them this time out. If not send me your phone # and times to call in a new email and I will get back to you that way. I have no idea why you can not get my emails. Sorry. John