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SVTPerformance's Chain of Restaurants
Tuning À la carte
help with a rough idle on a 98 cobra
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<blockquote data-quote="encasedmetal" data-source="post: 11943719" data-attributes="member: 80137"><p>they have dick to do with idle. I have noticed lately alot of BAMA cars doing this. OP- you need to datalog using livelink and a laptop. </p><p>IDLE problems:</p><p>To work on fixing this you need to datalog “Spark Source” and see if it returns a value of 8, this means that it is on the minimum spark clip and not controlling idle. A returned value of 9 means it is in control. If it is not 9, you need to lower idle spark. If still having problems with idle, -with the engine running unplug the IAC valve, if it stalls the engine restart with IAC unplugged. Adjust using the throttle stop screw to find desired idle speed. Turn engine off and disconnect the negative battery cable, press the brake pedal 3-4 times. Reconnect the battery cable, plug in the IAC valve and the car should idle better. Try to make sure that TP absolute is close to 200. Vacuum at idle on a stock cammed car should be 18-22. ISC duty cycle at idle needs to be 35-50%, and if using a EEC V, the idle speed integrator should be close to zero. If you get anything below 15% duty cycle the ISC valve is closed and not controlling anything. </p><p>here is what to choose once getting livelink set up:</p><p> </p><p>Datalog these PIDs for idle values:</p><p>Fuel source- when in closed loop, this will read 0.00</p><p> </p><p>Idle air integrator-should be fairly close to zero. If it’s negative then you need to take air out of the ISC tables, if it’s positive then you need to add air into the tables. It’ll never be exactly zero. Allow the car to be at operating temp and idling for a few minutes before making a decision on this.</p><p></p><p></p><p>Idle speed valve duty cycle- aka-ISC duty cycle- log this at idle, it should read between 35-45%.</p><p></p><p>Desired idle rpm- desired idle is what you have it set for, being in drive or any adders such as AC will affect this. </p><p> </p><p>Rpm- actual rpm at idle, in comparison to desired idle rpm, these should be extremely close.</p><p></p><p>Battery voltage- Another issue in getting the A/F may be the “Injector comp battery volt”, try adding 0.2 or 0.4 to the voltage area where you are idling (if that doesn’t work, try subtracting that much). You may be overcompensating for pulsewidth based on battery voltage. </p><p></p><p>Spark source- if it returns a value of 8, this means that it is on the minimum spark clip and not controlling idle. A returned value of 9 means it is in control. If it is not 9, you need to lower idle spark. </p><p> </p><p>Spark- * timing at idle.</p><p></p><p>TP absolute- should be close to 200, and can be adjusted to desired by adjusting TPS sensor location</p></blockquote><p></p>
[QUOTE="encasedmetal, post: 11943719, member: 80137"] they have dick to do with idle. I have noticed lately alot of BAMA cars doing this. OP- you need to datalog using livelink and a laptop. IDLE problems: To work on fixing this you need to datalog “Spark Source” and see if it returns a value of 8, this means that it is on the minimum spark clip and not controlling idle. A returned value of 9 means it is in control. If it is not 9, you need to lower idle spark. If still having problems with idle, -with the engine running unplug the IAC valve, if it stalls the engine restart with IAC unplugged. Adjust using the throttle stop screw to find desired idle speed. Turn engine off and disconnect the negative battery cable, press the brake pedal 3-4 times. Reconnect the battery cable, plug in the IAC valve and the car should idle better. Try to make sure that TP absolute is close to 200. Vacuum at idle on a stock cammed car should be 18-22. ISC duty cycle at idle needs to be 35-50%, and if using a EEC V, the idle speed integrator should be close to zero. If you get anything below 15% duty cycle the ISC valve is closed and not controlling anything. here is what to choose once getting livelink set up: Datalog these PIDs for idle values: Fuel source- when in closed loop, this will read 0.00 Idle air integrator-should be fairly close to zero. If it’s negative then you need to take air out of the ISC tables, if it’s positive then you need to add air into the tables. It’ll never be exactly zero. Allow the car to be at operating temp and idling for a few minutes before making a decision on this. Idle speed valve duty cycle- aka-ISC duty cycle- log this at idle, it should read between 35-45%. Desired idle rpm- desired idle is what you have it set for, being in drive or any adders such as AC will affect this. Rpm- actual rpm at idle, in comparison to desired idle rpm, these should be extremely close. Battery voltage- Another issue in getting the A/F may be the “Injector comp battery volt”, try adding 0.2 or 0.4 to the voltage area where you are idling (if that doesn’t work, try subtracting that much). You may be overcompensating for pulsewidth based on battery voltage. Spark source- if it returns a value of 8, this means that it is on the minimum spark clip and not controlling idle. A returned value of 9 means it is in control. If it is not 9, you need to lower idle spark. Spark- * timing at idle. TP absolute- should be close to 200, and can be adjusted to desired by adjusting TPS sensor location [/QUOTE]
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Tuning À la carte
help with a rough idle on a 98 cobra
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