Rtek Tuning idle on ported motors with a/c
Tuning idle on ported motors with a/c
I've got a street ported s4t2 running the 2.1 and tuning the idle with and without a/c is tough.
This motor has 2 idle rpms. Idle 1 is 850rpms and idle 2 is 1100. If I have no load on the motor and let it idle down, it will only go to 1100. In order for me to get the lower idle, I have to slip the clutch to give it just enough load to idle down to 850. I've looked at the logger and it uses the same airflow and injector PW at both rpms. That is a strange behavior. The difference between the two is the timing. I can emulate it on a couple other 7s as well.
My dilemma is that I cannot get a good idle with ac on and off. I can only get a smooth idle if I tune for one or the other. I can get a smooth idle with ac on, but a super rich idle without or a smooth idle w/o ac and a lean idle with. The only difference with a/c on or off is the timing. It switches from -5,-20 to 14.1.
I can get a smooth idle with a/c at an afr of about 12.9. That results in an idle of 11.2 or less if I click the a/c off. If I do a/c off at 12.6, which is very smooth, I get upper 13s when on.
In the rtek, two different spots can affect the idle AFR. The variable resistor and cell 2,2, which is -8 vac & the 3rd rpm cell. I've tried tried many combos with the map cell and the VR, but I just can't get a happy median.
What can I do to get a good idle besides going back to irons with stock ports? Does anyone else run a/c with a street port and rtek?
This motor has 2 idle rpms. Idle 1 is 850rpms and idle 2 is 1100. If I have no load on the motor and let it idle down, it will only go to 1100. In order for me to get the lower idle, I have to slip the clutch to give it just enough load to idle down to 850. I've looked at the logger and it uses the same airflow and injector PW at both rpms. That is a strange behavior. The difference between the two is the timing. I can emulate it on a couple other 7s as well.
My dilemma is that I cannot get a good idle with ac on and off. I can only get a smooth idle if I tune for one or the other. I can get a smooth idle with ac on, but a super rich idle without or a smooth idle w/o ac and a lean idle with. The only difference with a/c on or off is the timing. It switches from -5,-20 to 14.1.
I can get a smooth idle with a/c at an afr of about 12.9. That results in an idle of 11.2 or less if I click the a/c off. If I do a/c off at 12.6, which is very smooth, I get upper 13s when on.
In the rtek, two different spots can affect the idle AFR. The variable resistor and cell 2,2, which is -8 vac & the 3rd rpm cell. I've tried tried many combos with the map cell and the VR, but I just can't get a happy median.
What can I do to get a good idle besides going back to irons with stock ports? Does anyone else run a/c with a street port and rtek?
Senior Member
Joined: Jan 2005
Posts: 321
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From: Rancho Cucamonga Ca,
Sorry, no AC. I do however have the exact same to speed idle issue w/ the stock timing map. I fudged around the timing and go it to stop but I was more concerned w/ idle quality than afr's.
How is your idle speed change when you turn your ac on and off?
How is your idle speed change when you turn your ac on and off?
The idle speed with a/c on is around 825. When I kick the a/c on, the rpms jump a tad as the timing advances, but drops back to 825 as the compressor builds pressure and increases load.
The idle speed behavior is a strange one to start with. The idle fuel & timing runs on a map cell for a second or two until the timing retard and variable resistor settings are used to control the idle. I can tell this from the timing readout on the PDA and the AFR readout on the wideband.
The idle speed behavior is a strange one to start with. The idle fuel & timing runs on a map cell for a second or two until the timing retard and variable resistor settings are used to control the idle. I can tell this from the timing readout on the PDA and the AFR readout on the wideband.
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