I removed the airpump a few months ago and the car runs great, but the idle seems slightly more "rough" than before... I'm thinking I may be running a little rich. I drive the car a lot (hence I idle a lot ) and I do not want to be idling too rich (fouled plugs, gas in oil, etc...).

I've read that you can lower the PIM volts to below 100% (for 1k rpm), to lean it out, but I do not want to lower it too much and possibly cause a problem. For those of you who have done this, approximatly what did you set your PIM to for 1k rpms?

Thanks

-Matt

 

I tried lowering pim at 1k on my fd, and if i go any lower then 7% it starts runing rough. Also. If i leave it like that, for some reason it needs more cranking to start next time.

 

Do you mean that you lowered it to 7% or down by 7% (i.e. 93%)?

 

Hit the map trace and see what cells you're idling in. Pull fuel out of those. Leave the PIMs alone.

 

I'm a total newbe to tuning... so if I were to do that, approx how much do I pull out? I don't have a wideband, so I don't want to overdo anything.

Why should I leave the PIMs alone? Thanks.

 

hey i wanna know about that too... i wanna remove my airpump and am REALLY wondering how to cure the idle. so we ARE running rich? that's what causes the idle to be rough? how-to fix!

 

Have you sent the ECU back through the idle learn process? That might help.

Without a wide band 02 it is a shot in the dark. Everybody’s amounts will vary.

But I would start by pulling 1% to 2% of fuel out of the idle cells and see how the car acts. Give it a moment to adjust it's self and then look/smell the exhaust. If it is not eye bleeding rich then you might be in the area you want.

The PIM will pull fuel out (or add, depending on setting) of that RPM range. It is a more broad range of an adjustment.

The 20x20 grid for fuel can be fine tuned (so to say) more then the PIM voltages.

Adjusting the idle cells is pretty safe because it is under vacuum and very low in the RPM range. Just do things slowly and by 1 or 2 %.

Just as an FYI: I was running 10.8:1 for an idle mixture. That was very rich and I could see people choking behind me in traffic. Plus it would blacken my bumper. I ended up pulling 15% fuel out of the two cells that I idle (one was for no load and the other was higher in RPM due to EL load). I now am idling at 12.5:1 which is much more clean and smooth. But I started by pulling out 3% each time and seeing how that worked.

 

Thank you . I will give this a try.

 

No where have I seen anyone mentioning if they turned of the O2 idle control which is the second step aftre removing the air pump.

 

I turned mine off. If i try and lean out cell that i'm idling at, it stars to idle really rough. and I didn't take off maybe like from 110 that was set to like 105 or 100.

 

Interesting, I've had rough idle on the car and had to raise the idle to about 950RPM to 1000RPM (by the idle screw since I haven't figure out how to do that with the Commander yet) in order to keep the engine running. I finally hooked up a new wideband O2 for the first time last night to monitor and play with the FC settings (it was at first 121 (1.214) for the correction setting and read around 10.4AFR or 10.5AFR), when I leaned out a few cells in the correction map to about 100 (1.000), the engine idled smoothly and the stinky rich mixture smell was gone, and O2 reading went up about 11AFR or 11.1AFR. What's everyone's setting for idle?

 

My idle is about 13.8AFR.

 

What does your mapping settings around 400 to 1200 RPM in the first 4 rows look like? below 1.000 even? supposely that calculates to over 15.0AFR... unless if my new wideband O2 is malfunctioning...

 

My car idles at 5th row down, 4th row to the left. and I set it to 100 because if go any lower it idles rough. And yet, with midpipe it still smells rich and o2 reading is .80

 

Just messed around with mine, now it idles at 2nd from left and 5th from top on the injector map, with everything else to the left and above set at .925, idle is fairly smooth with 12.2AFR to 12.5AFR...but exhaust is getting louder. I wonder if my O2 sensor is faulty cuz I can't seem to get it anywhere close to 13AFR, not to mention 13.5AFR reading...I'm afraid it's going to run lean if my O2 is bad..

 

Did that already .


So I screwed around with this yesterday. My car idles in the (2,5) slot (2 to the right, 5 down). the number was originaly set to 121 and I lowered it 115. It seemed to clear things up. but not fully - I will let it settle for a day and lower it some more.

On my warm-up (1600 - 1900 rpms with AWS removed) the car is in slot (4,4) and it was set to 1.06. I get a lot of little "pops" durring the warmup, so I lowered this slot to 1.03 and it did't help out too much. I'll lower today and see what happens.

Since I such a newbe to this, I'm assuming such small changes are alright. Is there some point where I shouldn't go any lower (like 100 or something)?