Final tune, Need help |
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Final tune, Need help |
Morph914 |
Mar 23 2022, 12:34 PM
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#1
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Member Group: Members Posts: 435 Joined: 22-August 16 From: St Augustine, FL Member No.: 20,326 Region Association: South East States |
Ok , so I have the engine running but it needs tuning. A little background, rebuilt stock 2.0 with D Jet, running a 123 dizzy. It fires right up and idles a little rough at first then smooths out. It revs fairly well and sounds good. The problem starts under load, it starts to stutter a bit.
I have not messed with the adjustment screw on the ECU or tried adjusting the throttle position sensor, or been able to check my fuel pressure. I’m hoping to rally any troops in the north Florida area to help me get these final details ironed out. Thanks in advance, John |
Morph914 |
Apr 28 2022, 05:31 AM
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#2
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Member Group: Members Posts: 435 Joined: 22-August 16 From: St Augustine, FL Member No.: 20,326 Region Association: South East States |
I switched the hose from the retard side of the throttle body to the advance side and reconnected to the dizzy, plugged the retard port and it brought the idle down to about 1000. Now need to test drive again and see if this worked.
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JamesM |
Apr 28 2022, 10:34 AM
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#3
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Senior Member Group: Members Posts: 1,915 Joined: 6-April 06 From: Kearns, UT Member No.: 5,834 Region Association: Intermountain Region |
I switched the hose from the retard side of the throttle body to the advance side and reconnected to the dizzy, plugged the retard port and it brought the idle down to about 1000. Now need to test drive again and see if this worked. If you can only get idle down to 1000 rpm with the TB bypass screw all the way in, something is wrong. Turning the screw all the way in should stall the engine, or at least bring it very close to it. It sounds like what you did by moving the vac hose for the 123 is just stop it from ADDING extra advance at idle that the "1" curve supplies when vacuum is applied. Less advance at idle is a step in the right direction, but you are still running to much advance at idle. it sounds like you had the hose in the right place before you moved it, you are just running the wrong curve. You gain nothing from running the wrong curve but the inability to fully control/set your idle properly. If you want to try to pick up low end throttle response by futzing with the advance curve then get the fully programable 123 or go aftermarket injection to do it properly otherwise you compromise your idle by running to much advance. D-jet is a fixed system, designed to be set one way so that all components interact properly with each other. So again... Set the 123 to Curve "B" Dizzy vacuum line to the port that sees vacuum at idle. |
DRPHIL914 |
Apr 28 2022, 11:26 AM
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#4
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Dr. Phil Group: Members Posts: 5,768 Joined: 9-December 09 From: Bluffton, SC Member No.: 11,106 Region Association: South East States |
I switched the hose from the retard side of the throttle body to the advance side and reconnected to the dizzy, plugged the retard port and it brought the idle down to about 1000. Now need to test drive again and see if this worked. If you can only get idle down to 1000 rpm with the TB bypass screw all the way in, something is wrong. Turning the screw all the way in should stall the engine, or at least bring it very close to it. It sounds like what you did by moving the vac hose for the 123 is just stop it from ADDING extra advance at idle that the "1" curve supplies when vacuum is applied. Less advance at idle is a step in the right direction, but you are still running to much advance at idle. it sounds like you had the hose in the right place before you moved it, you are just running the wrong curve. You gain nothing from running the wrong curve but the inability to fully control/set your idle properly. If you want to try to pick up low end throttle response by futzing with the advance curve then get the fully programable 123 or go aftermarket injection to do it properly otherwise you compromise your idle by running to much advance. D-jet is a fixed system, designed to be set one way so that all components interact properly with each other. So again... Set the 123 to Curve "B" Dizzy vacuum line to the port that sees vacuum at idle. i am running either B or C on my current 2056 motor with d-jet and123, this is different than my stock motor due to the increased displacement, compression, etc. and different cam, so i think i found for this motor the C was working better than B, which is what is recommended on the 2.0 75 according to the distributor numbers listed on 123 website and in the manual, and the stock motor was perfect smooth idle at 900rpm, no issues at all once timing was set. 75 throttle body does not have both vac ports only one, the retard. Some guys run it without that hooked up but i think most do. Phil |
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