2006 Carver 36MY VP 8.1L stumble/die from quick throttle change to neutral

[Cliffm]

The captain and I recently took her 2006 Carver 36MY out for a 5 day cruise in PNW. We experienced a couple of occasions where some low speed maneuvering (in the wind) requiring some throttle "blips", but coming back to neutral, killed starboard engine, and it didn't immediately want to restart/idle. I could bump throttle, restart, then bump throttle back down?

Some earlier docking lessons had similar scenario, that hadn't repeated before now?

After getting docked in Port Orchard for the night, and since no one was near us, I tried bumping throttles up then, immediately pulling to neutral, managing to now stall both port and starboard engines. Neither V/P 8.1L Gi-FF motor has more than 250hrs, but it is a 2006 with OEM parts. From reading numerous forum posts it would appear the IAC's are either sticky/dirty or failing?

My question, is has anyone recently tried the $35 units on amazon as they are listed as replacements for V/P 3843751 IAC, if so... are they junk? NAPA has #320177 IAC for $50, which would be my next step before paying $195 at Marine PArts Warehouse.

whats steps do i need to do without a scan tool? are there codes to clear on the V/P ECM, or just plug & play, codes clear on their own?

as always, thanks in advance for the insights and knowledge share!

Cliff & Beth Mathison
Renton Wa.

[bud37]

You can try the napa ones, I have used their stuff and has worked fine.......but heh before you go there, clean the throttle blades in the throttle body throat and make sure the flame arresters are clean also......any dirt in there will restrict idle air flow......also check the IAC passage for gunk.

What is probably happening when you close the throttle after the blip..... the engine cant get enough air and shuts off.....IAC not reacting fast enough as it has closed down on rev increase or passages carboned up.....have a good look first.

Let us know how it looks....if this continues it may be a good idea to get a laptop on there and see what the IAC counts are at idle....that will tell a lot.

I think if there was a trouble code you would experience some extra beep sequence when you turn the key to on.

Let me add there are other things that can create this kind of scenario, but check that first since you have already looked into it a bit.

[Cliffm]

Source of the post Let us know how it looks....if this continues it may be a good idea to get a laptop on there and see what the IAC counts are at idle....that will tell a lot.

How do you "get a laptop" in there? is there a coupler that goes to the harness? or a coupler directly to the IAC plug? more info on this would be greatly appreciated.

[Viper]

Just like an automobile, there is a plug on the engine for diagnostic equipment to read ECM data. Only Volvo dealers will have the Volvo software but there are aftermarket options as well.

Pretty common symptom for a failing IAC however you can't really tell what's going on without a diagnostic tool. One could usually swap the part from one motor to the other and see if the symptom follows the part but if both engines are doing it now, that may not be an option.

Aftermarket parts are okay for some hardware but you have to ensure that the OEM spec doesn't simply fall within a window of the aftermarket's parameters, especially if it's something the ECM is relying on it reacting a specific way. While there are good aftermarket replacements out there, beware of cheap imitations that will cost you more in the long run. How you ask? Consider the possibility that you buy a cheap aftermarket unit, install it, and yo have the same problem. Now you start suspecting other components because the IAC is new, so you spend more money on parts and possibly a mechanic whom you tell the IAC is new so he also starts suspecting/replacing other components. Be careful.

If your application utilizes an IAC muffler (foam filter), ensure that it's actually there and replace it if dirty. You should also ensure your ignition components are in good working order; coils, plugs, plug wires, and that your supply voltage and charging system are within spec.

[Cliffm]

Source of the post Just like an automobile, there is a plug on the engine for diagnostic equipment to read ECM data. Only Volvo dealers will have the Volvo software but there are aftermarket options as well.

I'd like to know more about these aftermarket options? I've used the Dynojet Power vision to flash ECM on my harley and do other diagnostic adjustments, speedo calibration, Big bore kit, altered timing and AFR maps, etc...

who makes a volvo compatible scan tool for this year of Carvers?

[bud37]

Source of the post

Source of the post Let us know how it looks....if this continues it may be a good idea to get a laptop on there and see what the IAC counts are at idle....that will tell a lot.

How do you "get a laptop" in there? is there a coupler that goes to the harness? or a coupler directly to the IAC plug? more info on this would be greatly appreciated.

Check out Rinda technologies.......there will be a program to load onto a windows based laptop, and an adaptor plug that interfaces with your data port. Really all this stuff is just based on older GM injection ecm. I have heard that Rinda wrote the programs for gm delphi originally.

I got the program for the mercruisers and it helped a lot to see and understand what is going on, as I had much the same problem as you and it is very frustrating to say the least.

[Cliffm]

Source of the post Check out Rinda technologies.......there will be a program to load onto a windows based laptop, and an adaptor plug that interfaces with your data port. Really all this stuff is just based on older GM injection ecm. I have heard that Rinda wrote the programs for gm delphi originally.

I got the program for the mercruisers and it helped a lot to see and understand what is going on, as I had much the same problem as you and it is very frustrating to say the least.

yes... thanks!

Will check out Rinda

[Cliffm]

FYI: update, installed (2) IAC from Amazon $35 ea based on VP part numbers.
No more idle issues, old ones didn't look terrible? just a little sooty, but did have corrosion spots on the solenoid shafts ?

[Cliffm]

I had read a post relating to the "stumble at idle" that suggested checking that the throttle cables where closing the throttle bodies against the stops.

I checked the starboard engine first (easier to get to) disconnected the cable, then had the Captain (aka wife) move the helm controls to verify cable movement, and verified the "closed/idle" position was pressing the throttle body against the stop (it was).

Then we went to the port engine, which had the initial stumble issue. Visually, the cable was adjusted exactly the same as starboard, however there was more slack that meant the throttle body was "not" pushed closed against the stop. I loosened the jam nut, un-threaded the adjuster to achieve the same closed tension as the starboard engine, then re-attached to throttle body.

No stumble issues encountered now, but the IAC's were replaced earlier. Hindsight, I probably should have checked this first?
I have the OEM starboard IAC as backup now. We'll see if this eliminates all issues.