So I've read through the BISS adjustment threads and can't seem to get mine set correctly. Just want to verify I'm doing it right.

Get the engine to operating temp.
Disable the IACV in evoscan by activating the Speed Adj. Screw mode ACTUATOR.

Then set the idle with the BISS close to desired idle.

Then reactivate the Acuator in evoscan. and idle should be good.

Correct?

Problem is if I disable the iacv in evoscan and set the idle with the biss, once I deactivate it the idle surges up to 2,000 rpms and back down constantly.
The only way I can get it to idle correctly is to adjust the BISS screw almost all the way in.

So am I missing something or do I have a problem somewhere?

 

What was it doing that caused you to have to adjust the BISS?

 

when you activate the actuator it will drop the rpms, when you adjust the the biss screw you need to keep in mind the ecu will adjust the idle higher when you deactivate it.

 

Sounds like you adjusted it right but that's not the only thing that affects idle.

 

It idles fine, I am just getting a weird random misfire at idle. I don't think the BISS is causing it but I just want everything to be right before I move on.

The thing is, If I adjust the BISS so that it idles correctly normally, When I activate the SAS in evoscan, the car almost shuts off it idles so low.
I have no problems changing the idle in the Rom so I think my iacv is working correctly.

Ive checked multiple times for vacuum/boost leaks as well.

 

if the iscv trims were way off, idle will be messed up for quite a while because it takes several hours of stop-and-go driving for the trims to find their new values to produce the target idle. when i swapped an ecu into my evo that came from a 2.4L, 2150 cc/min, sd evo, my idle was all over the place for the first hour or more of driving. and a battery disconnect or flash do not zero out the iscv trims. seems like its a good chance that this is what you are experiencing.

idle misfire - plugs or injectors? comp check?

 

Ok, So maybe since my BISS was so far out that it will take some driving to get the idle to set itself. I will try this out.

As far as my misfire problem, It started a while back and seems to have gotten worse.

I've tried 3 sets of injectors, new plugs tried diff gaps .19-.24, injector resistor all ohm correctly, switched to Spoolin COP from stock coils, fuel pressure is close to 45psi at idle with vacuum line disconnected, swapped fuel pump, compression test all close to 150, leak down test less than 6% on all.
Checked cam timing, boost leak tested like 4 times.

Weird thing is it runs fantastic off idle, even when the a/c compressor kicks on and puts a little bit of load on the engine it smooths the misfire out. I can also run it open loop at idle and run very rich like 12:1 and it will smooth out as well.

 

UPDATE:

Like everyone already knew, MRFRED is the man and was correct,

The idle trims do take a long time to reset, and since my Biss was adjust so far wrong, the idle went crazy when I set it correctly.

And just for the record you have to run it with the a/c off and a/c on as the trims must be different for each load, for the ecu to get the idle set right.

 

And indeed, there are trims for A/C on and A/C off. I should have mentioned that since its summer. BTW, the trims are loggable if anyone wants to have a look. I may have already posted the MUT addresses somewhere in the ECUFlash forum.

What about your idle misfire?

 

Misfire is unfortunately still there. I think I'm gonna get another set of plugs, I doubt thats the problem but maybe I messed up the iridium when I gapped them. Unless anyone else has some ideas?

 

Stock flywheel?

 

Ps idle trims don't reset every flash?

 

Have you tried a different fp regulator, how does it idle with the vacuum line disconnected? You said you changed the fuel pump, is did you change the sock?

On the ignition side of it, cam or crank sensor check out ok?.

Does it do it at any no load idle speed say if you bump the idle up does the mis follow?

Are you sd or maf?

 

Nope. And they do not reset with a battery disconnect.

 

211Ratsbud- yea stock flywheel, the trims don't reset at all, you must idle at least 30 minutes with a/c on and 30 minutes with a/c off for them to learn all the way.

Wheatley- Havn't tried another fpr, but fuel pressure is ~45psi with vaccum line off, it idles the same with line off.
Did replace the pump with old oem pump and have switched socks.
As for cam and crank sensor Im not getting any codes for them but havn't really checked into them either as I figured if they were bad it wouldn't be just at idle.
I am on MAF still, Currently having Tom from Tscomp do a tune to see if it's tuning related but I don't think it will be.

And yea it does it at any no load speed, even when barely creeping in 1st gear it does it, but as soon as it sees some load it clears up, even when the a/c compressor kicks on it smooths out.