2005 Larson 5.7 Volvo Gxi. Efi no idle Poor idle quality

[Warauto]

Boat was an original 5.0 GXI. Installed a new 5.7L Gxi Had PCM flashed from Volvo.
Engine will idle normal for about 30 seconds, then iac open up and stalls, will restart and stall after 2 seconds of running. No trouble codes, all sensors working in normal parameters, ect ok,tps ok,no knock sensor sensed, checked for vacuum leaks none, It still says 5.0l on engine size on parameters. When you get the engine past the idle stage it runs perfect, great power, no ping, no codes etc. Has anyone ever ran into this problem?

 

[BlueLightSpecial]

Re: 2005 Larson 5.7 Volvo Gxi. Efi no idle Poor idle quality

Keep in mind, I am speaking from automotive knowledge... Does it have a MAP sensor? I remember GM's having issues stemming from a bad MAP sensor. Next, is it possible that the base or target idle is too low, or is the IAC plugged up with carbon. I would first start with a wiggle test, then verify good grounds, and good connections. Did a dealer do the reflash? I would ask them why it says 5.0l on the data and inputs monitor. I would imagine that the fuel injector pulse width would have to be increased, due to the increase in engine displacement. How did you check for vacuum leaks? I personally use throttle body cleaner, and spray around the intake manifold to head and any other possible vacuum leak source, to see if the rpms change. Obviously you'd have to do his off idle, maybe a high idle, if possible. I am just shooting from the hip, I am sure the more marine experienced on the forum will have a better idea, and be able to help you better. Good luck!

 

[Tail_Gunner]

Re: 2005 Larson 5.7 Volvo Gxi. Efi no idle Poor idle quality

When you say Volvo flashed your ecu,did you mean Volvo or a marine repair shop. How much may i ask and as to the 5.0 id... i take it that's in print on the ecu cover and not being displayed by some diagnostic tool on a screen