Idle speed, Mercruiser 2.8 165hp D-tronic

[Aye Cap'n]

Hi All dodge
yes the ECM Ref voltage needs investigated. I've still got the Rinker diagnostic tool - if that can assist in some way?
Eitherway, the 'Low idle set point' is held at 600 rpm and the rev counter confirms that the engine is indeed idling at 600rpm. I feel this is too rough running for the engine.
I'm told this 'set point' is going to need changed.
Not sure if the Diagnostic tool can reprogramme this? I think I've had a guy connect/disconnect the red/orange wires in the 'idle speed setting circuit' to supposedly induce an increase to 700rpm - but when doing so he felt there was no change in the engine speed? - which is puzzling.

I've been told that the Fueltemp sensor (163 f) is a sensor contained within the fuel injector pump and that to remove the injector pump is not easy. To have it repaired is specialised and that a replacement cost of a whole pump is expensive...... Apparantly It subtly amends the fuel injection to take account of ambient climatic conditions etc. Whether it induces an unacceptable rough run at 600rpm?

Our air temp is around 9 degrees C to date as we enter our Irish winter, although we are soon entering a cold spell.

This looks like its going to take real detective work and I think its a job best taken in stages over the coming days/weeks, reflecting on tests and ensuing results. I hope its a simple wire connection somewhere but its just finding it ...

 

[alldodge]

9*C isn't bad, was just wondering if it use close to 0 and if waxing may be happening

The fuel temp sensor will have wires on it, and should not need the pump be removed to change. This shows the location and test

 

[Aye Cap'n]

Many thanks all dodge
Will keep you posted when I get back to the boat and I've more to report - hopefully after this weekend

 

[DDM1]

Many thanks all dodge
Will keep you posted when I get back to the boat and I've more to report - hopefully after this weekend

Check your PM!!

 

[DDM1]

Ps don't worry about the pcm reference voltage. That's about the right range of value to see on your Rinda scanner. Even on my bench testing setup with no loads connected and sweeping through different input voltages. It has to do with how the injection quantity adjuster feedback sensor works. It's not a normal voltage dividing potmeter. It's an AC sensor with some electronics.

 

[DDM1]

Also, there's no need or reason (or diy doable) way to adjust the idle setpoint. Something is wrong that needs fixing and it's not the value. There is however a way to tweak the idle rpm by about 100 by connecting or disconnecting a wire in the electronics box, but leave that alone for now. That's only to improve drivability, idle smoothness and heavy aux equipment load performance (like a belt driven watermaker).

Check your private message please, I sent you my contact details

 

[alldodge]

Check your private message please, I sent you my contact details

Sure hope your an expert, we could use one, but posting answers in PM's and phone calls do nothing to help others in the future.

 

[DDM1]

Sure hope your an expert, we could use one, but posting answers in PM's and phone calls do nothing to help others in the future.

I don't feel comfortable posting my phone number on here, but trouble shooting often requires a more direct form of contact than via a slow chat in a forum topic. I would post the solution if Aye Cap'n wouldn't do it because I highly value forum information. I had to figure out everything myself because of this.

Trouble shooting over text can get very lengthy too, nobody is waiting for 50 posts of try this and do that and maybe it could be this, what about checking that.

Also I've been working on a product specifically for this engine (a gateway) and don't want to advertise that. Both because I'm not a paying seller (don't know what the rules on this forum are) and because there's no commercial intent.

 

[alldodge]

Agree, don't post your phone number here
You can buy and sell thru PM just no posting of such.
So long as the solution is posted it would be good, and no one is under a requirement to do so, it just helps the community.

 

[Aye Cap'n]

Also, there's no need or reason (or diy doable) way to adjust the idle setpoint. Something is wrong that needs fixing and it's not the value. There is however a way to tweak the idle rpm by about 100 by connecting or disconnecting a wire in the electronics box, but leave that alone for now. That's only to improve drivability, idle smoothness and heavy aux equipment load performance (like a belt driven watermaker).

Check your private message please, I sent you my contact details

Hi DDM1
Do I detect a glimmer of hope?
I agree, something is wrong and needs fixing. I've had a guy 'tweak the idle' by 'the wire' but apparently no change in the engine was detected. The boat always did idle at 700rpm - so something has changed?? As a mechanic said to me, she is now not going to idle at 700rpm when the Low Idle Set Point is set at 600rpm - I need to alter that setting, somehow.
DDM1 I am intrigued. Will be in contact.
Standby All Dodge.