Can wrong offsets for map cause erratic idle
Can wrong offsets for map cause erratic idle I'm running the holley dominator with the gm 3.3 bar duramax sensor. I had to play with the values for a while to get it up and running at the start of the season and it runs pretty good except for a surging idle that I've never been able to get rid of. Could it be the map or something else? I've been playing with the IAC all summer and haven't gotten anywhere.
Ditch the damx sensor and get something that reads into vacuum well. traditional 3bar brick style or 3.3 bar ZR1 would be good. Good vacuum reading was not a design intent on a diesel sensor.
I just pick one from Holley's drop down window, makes life easier.
It doesn't take much to throw off the fuel map when you change something, I have blackened a couple sets of plugs.
If the orange ball is moving thru a few squares, try lighting up the surrounding squares, use the arrow keys +/- and see if you can force it into just a couple squares by adding/sub. fuel-I started the CL comp. over 500 RPM's, let it work on the idle and help stab. it, then I man tune below 1600
It doesn't take much to throw off the fuel map when you change something, I have blackened a couple sets of plugs.
If the orange ball is moving thru a few squares, try lighting up the surrounding squares, use the arrow keys +/- and see if you can force it into just a couple squares by adding/sub. fuel-I started the CL comp. over 500 RPM's, let it work on the idle and help stab. it, then I man tune below 1600
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From: Norn Iron
The MAP sensor reading is either right or wrong.
Simple...get a Mityvac or similar device and test it.
Although as long as it is a linear output/reading.......it doesnt really matter as you'd be tuning accordingly. But it would be silly to tune with the wrong values when it's much easier to do it with the right values.
Simple...get a Mityvac or similar device and test it.
Although as long as it is a linear output/reading.......it doesnt really matter as you'd be tuning accordingly. But it would be silly to tune with the wrong values when it's much easier to do it with the right values.
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Verdad Gallardo 9 Second Club
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From: Norn Iron
9 Second Club
Joined: Nov 2003
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From: Norn Iron
What's difficult to understand ?
You could have a faulty pressure gauge that reads fine at atmospheric.....but wrong everywhere else.
You could have a clock that reads fine at 12 oclock....but the mech is wonky everywhere else.
Likewise just because a map sensor readout on an ecu ( after the voltage has been converted into units you wish to see ) gives a sensible reading at atmospheric...doesnt mean it will be correct everywhere else.
As said before, if in any doubt, test it. And IMO even if you arent in any doubt....test it anyway. Always ensure critical sensors are reading correctly as you would expect before using them.
What's difficult to understand ?
You could have a faulty pressure gauge that reads fine at atmospheric.....but wrong everywhere else.
You could have a clock that reads fine at 12 oclock....but the mech is wonky everywhere else.
Likewise just because a map sensor readout on an ecu ( after the voltage has been converted into units you wish to see ) gives a sensible reading at atmospheric...doesnt mean it will be correct everywhere else.
As said before, if in any doubt, test it. And IMO even if you arent in any doubt....test it anyway. Always ensure critical sensors are reading correctly as you would expect before using them.
You could have a faulty pressure gauge that reads fine at atmospheric.....but wrong everywhere else.
You could have a clock that reads fine at 12 oclock....but the mech is wonky everywhere else.
Likewise just because a map sensor readout on an ecu ( after the voltage has been converted into units you wish to see ) gives a sensible reading at atmospheric...doesnt mean it will be correct everywhere else.
As said before, if in any doubt, test it. And IMO even if you arent in any doubt....test it anyway. Always ensure critical sensors are reading correctly as you would expect before using them.
You get those two as close as possible and make up the rest in VE like everyone else.
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From: Norn Iron
So as said before...test the thing and adjust whatever you need to adjust so it does read correctly.
If you cannot get it to give correct readings, then use an ecu that can as that's just ****. Not the end of the world as I've already said....but there really is no reason for any ecu not to be displaying the correct values.
Either way, it's mental to run an engine on a setup where you are not 100% sure that all sensors are reading as you would expect. That's just basic basic first steps
Well all such sensors are linear....so produce a straight line pressure vs voltage only 2 check points should be needed.
So as said before...test the thing and adjust whatever you need to adjust so it does read correctly.
If you cannot get it to give correct readings, then use an ecu that can as that's just ****. Not the end of the world as I've already said....but there really is no reason for any ecu not to be displaying the correct values.
Either way, it's mental to run an engine on a setup where you are not 100% sure that all sensors are reading as you would expect. That's just basic basic first steps
So as said before...test the thing and adjust whatever you need to adjust so it does read correctly.
If you cannot get it to give correct readings, then use an ecu that can as that's just ****. Not the end of the world as I've already said....but there really is no reason for any ecu not to be displaying the correct values.
Either way, it's mental to run an engine on a setup where you are not 100% sure that all sensors are reading as you would expect. That's just basic basic first steps
I thought you were hinting at a way to adjust the calibration of individual map sensors.
I just went through this same thing, it's totaly different order than the standard gm 3 bar, if I remmber the pins on the zr1 plug, 1 -power, 2-ground, 3-signal