Hey guys, i have an evo 8 on sd. Has evo 9 turbo, cams, all bolts ons. When the ac is on and i come to a stop i can see the afr gauge to 16s or so and the idle gets pretty lumpy. Then it will go back to its regular idling afr around low 14's then back again. Im thinking that its happening when the condenser turns on or the fans. Is there any table i can adjust to help with this? Theres one thing i wanted to check but havent had the chance. Wanted to check my timing map just in case its interpolating to a cell that has lower timing causing it to lean out. But either way, wanted to check with you guys to get some thoughts.

* note - Ok, timing is not an issue. Its the same at the load when ac is on. Now, im logging and listening in the driveway and i can see it happens when the condenser and fan turns on. When it cycles off it will go back to normal idle afr. I thought when the ac is on the condenser fan should be on at all times? It is cycling on and off. Also noticed the battery level on evoscan drops to 13.4 - 13.6 when condenser and fans come on. Then it will go to 14.

 

Try fiddling with the injector latency.

 

Crazy thing. I richened up ve tables and it stopped doing it. Car idles rich though 13.4. Can you answer something for me? I thought with stock injectors you weren’t supposed to touch latencies?

 

I always play with latency no matter what. You need to get the desired results.
There are many ways to do the same thing.

 

I see. Interesting. **** it I’ll give it a try.

 

Mine kind've does the same thing but is not entirely consistent. Sometimes it dips into 15s, sometimes 16s and sometimes the RPM raises correctly whereas sometimes it kind of bogs a little bit. At 1000rpm idle, I am closed loop; but at 1500rpm I am open loop due to lean spikes (I saw you have/had the same issue). I don't have too much useful info to odd other than I feel it is somewhere in the tune (despite my previous tuner kept telling me the electrical system was "bad") and that I feel your pain. I have searched both of these issues in the recent past but haven't had too much luck. I am currently working with a new tuner for help and will eventually get a full tune from then upon my next sizeable mod that requires a full retune (probably a Red spec sized turbo).


Sidenote somewhat related: when your AC kicks on, do you hear a slight whine that resembles that of a Vortech supercharger? Mine has that and matches the tone and pitch match engine RPM. When I rev to take off from a stop, the whine matches. I do not believe it is my fuel pump, as it sounds like it's coming from the dash area. I haven't had much luck searching this issue.

 

If you are getting mid 16's and your target is 14.7:1, then you need to reduce either of the below tables at the coolant temp you are experiencing the problem by -11.5%, as a start.

ISCV Demand CTS Adder#1a***/ AC On-Drive (sub_1F2C6, 1F596) [sub_1EFC0]
ISCV Demand CTS Adder#1b***/ AC On - Neutral (sub_1F2C6) [sub_1EFC0]

You may have to also amend the below table to get your idle rpm dead on with your "desired RPM idle with A/C on"

Desired ISCV intial step position with AC on-Neutral.

Of course your injector scaling & latencies have to be dialled in correctly with the a/c off. Ensure your "Idle Stability Timing Control" and "Idle Error - A/C On" are also set up correctly.

There is a post in this forum about ISCV control by @mrfred look it up and u will be fine.

Steve.

 

Well, when I was having this issue I richened it a little bit at idle and also messed with the Iscv initial step position table ac on. Let me tell you something though. I’ve been having electrical issues. I just fixed everything and it is a different car. Check out my other thread on battery relocation. Look through the thread and check out what I found. Now with good voltage the car is silky smooth.