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Iron Duke 2.5 has now migrated to Mercruiser 3.0! Yep ... Mercruiser 3.0L boat motor which shares same bell housing as small block chev. Lost of design changes ... but same old 12P!

I'm struggling a bit on the tune and am asking for some guidance. Same fuel injectors, just more diplacement. For now, I am running same bin as before ... but due to the cam change, the vacuum is different. All normal tuning ... I got it starting and idling just fine. Tip in AE is a problem ... but working on it.

Here is the challenge ... in open loop it says ... and all of a sudden the BLM cell changes from 20, to 2. Fueling goes LEAN even though VE is the same. Engine stumbles and tries to recover, cell goes back to 20 and smooths out. Does this on and off it seems ... but I'm sure there is a reason. Also when you blip the throttle, the cell will change and the fueling.

Now ... the ECM was disconnected from power ,so aren't all cell references basically nil until close loop adjusts them? For some reason, my cell reference have a bad value.

If i force it open loop, will it just ignore the cell values and let me tune?

Mark.

Unable to answer your questions Mark but have you made sure the fuel supply is working as it should? Sounds like it's not keeping up to demand.

Charlescrown wrote:Unable to answer your questions Mark but have you made sure the fuel supply is working as it should? Sounds like it's not keeping up to demand.

There is lots of fuel. Dealing with a too rich condition most of the time due to the vacuum of the cam. But getting that dialed in. So far ... forced open loop is all I can work with. If I leave it in closed loop, it jumps to BLM cells and the fueling goes wacky. Its like there is a stored value in the cell ... and it should be whatever it is a battery ON. Maybe I'll swap ECM just to be sure. I wish I could see what is in the CELL as a value to know for sure. It's not in the data list ... but I suppose if I knew the location I could send that in the tunerpro stream.



The other issue for me is AE ... can't seem to tune it down ... big blip when you touch the throttle ... I tried all the AE tables, but it does not seem to reduce the fuel tip in. Need more testing.


Might also be a vacuum leak somewhere to find. Something funny ...

For anyone interested in details on the Iron Duke Turbo ... to a Mercruiser 3.0L turbo ... you can watch my Son's youtube videos on it. Lots of details for those that like building. Here is the one were it was first started up https://youtu.be/ZBkzmVFx4JA (kinda funny how well it ran that day ... )

Mark.

I did make some comments but after starting out looking at the video it's in a car not a boat. I'll watch the full video.
Without going thru all the posts what type of ignition are you using inductive or hall effect?

Charlescrown wrote:I did make some comments but after starting out looking at the video it's in a car not a boat. I'll watch the full video.
Without going thru all the posts what type of ignition are you using inductive or hall effect?

Inductive pickup. GM HEI.
TBI Throttle body for fuel.

It ran well for the last 2 years with the 2.5L motor. Now with a 3.0L motor and different cam. Starts well. Runs well when cold. Cold Loop doesn't work well when it changes cell values.

Latest challenge is a high idle when it gets warm. No changes in data, but idle creeps up. So looking for vacuum leak now.

Mark.

I picked up in the second video your using 90 deg for spark reference. I may be wrong but from my notes spark reference angle should be 10 degrees for a inductive pickup. Thats what I have on 2 four cylinder cars and they both run fine. Don't ask me just what it is and does but it may pay to check your angle in the bin file.

Im well late to this but if you can post a bin and a log I think that'll help with diagnosis.

Charlescrown wrote:I picked up in the second video your using 90 deg for spark reference. I may be wrong but from my notes spark reference angle should be 10 degrees for a inductive pickup. Thats what I have on 2 four cylinder cars and they both run fine. Don't ask me just what it is and does but it may pay to check your angle in the bin file.

With the Iron Duke ... it had a weird Dizzy with both a hall effects and mag pickup ... it needed 90 degrees to work. With the Mercruiser ... it uses a typical inductive pickup and yes base timing is 8 with that setup.

Good eye!

It's not the base timing it's the spark reference angle. From my collection of notes Hall Effect are different for 4,6 and 8 cylinders but Inductive use 10 degress for them all. I have no idea what it is and how it changes the running of the engine. maybe someone a bit smarter can elaborate.