I modified my 1999 7.4MPI over the winter.
This is what I did:
-Heads were bowl ported, new SS valves, and new double valve springs installed.
-Cam shaft was changed for the stock GM L-29 to a 454/502HO crate engine cam.
-Stock cast exhaust trashed for Stainless Marine aluminum manifolds with stainless risers.
-ECU re-calibrated by AZ Speed and marine.
The biggest change I would say is the cam. When from 206°/211° duration, .480/.480 lift, 115°LSA to 211°/230°, .511/.540, 112°LSA.
Anyway, I got it running a couple of weeks ago and it has been a real struggle to get this thing to run smoothly below 1000rpm...
I have messed with sensors, throttle bodies, and changed the IAC motor.
The engine seemed to perform OK out on the water under load. Acceleration was good and it gained about 150rpm over stock.
Last night I decided to try the original ECU with the stock calibration.

A world of difference!

The engine loped along at a 600rpm idle, had great throttle response and gained even more top end.
Change out a plug with a new one to get a good read.
After a 20-25min hard run the plug looked great. I would have though it would have run lean...
Sorry to be so long winded.
AZ Speed obviously didn't get it right and I will send the re-calibrated ECU back for them to tweak.

Do you fellows think I can run the stock ECU???

My water temp was fine, the engine didn't seem to run hot, the test plug looked good. I don't have oil temp., that would help I guess.

Pat, Merc usually runs the fuel mixture on the rich side, so if the plugs look good you are probably ok with the stock ecu. I would check the plugs at several rpm levels and if all is good, run it. You havn't made any hugh changes. I think AZ has probably messed up the programming.
How many rpm's did you gain with the stock ecu?

My Engine is a Volvo Penta, if that makes a difference?
Last year I tried all kinds of props.
Best overall performance was a 26p Bravo I spinning 4300-4400rpm.
Best speed, a 25p Mirage + at 4400-4500rpm.
Got the Mirage+ on there now with the engine spinning 4650-4700rpm. Up 200rpm and 2.5mph from last year...
Have not tried the 26p Bravo yet.
The stock ECU gives 50-100rpm more on top than the AZSM.

Any other comments?
Thanks...

did you also add an adj. fuel reg and up the pressure ?

No, I did check it though.
40lbs or so...

AZSM.

Try to Find someone else to program

I have talked to Tyler Crockett, and he will give it a shot. I just don't feel like spending another $300...

I may just stay with the Stock ECU. Waiting to here back from the Volvo Penta specialist I bought the engine from last year. Great Guy, knows his ****. Sells engines here on OSO.

The idle speed was to be raised to 700rpm and the rev limit to 5100rpm. Stock settings are 600 and 4800...
No problem with the rev limit as I'm 100 below that. The engine does not idle great at 600, but it does not stall when I shift, so...

I have never heard any bad about Tyler

There are 2 people in La that program also.

Mark at Precision marine

Steve at Total Marine Per. he is a advertiser her

I think Paul Plaff does also . but you better ask to make sure Arizona doesn't do it for him .


Good Luck

Rob

Thanks Rob.