05VIII

iTrader: (17)

so i have been reading about p0505 alot and have found instruction to get rid of the code. from what i understand, you clean it out first. if that doesnt work you use evo scan and under actuators you choose SAS mode. then turn the biss screw on the tb until the car will idle around 900 rpms.

the iac steps should be under 25 at idle correct? i cant seem to lower mine below 35 so i still get the code to pop up very often.

i even ordered a new iac and installed it and cant seem to get below 35 steps at idle.

anyone have suggestions i could try to get rid of this annoying P0505 code?

Some background.

i use to get this code every month or 2 before my recent cam upgrade. took the iac out and cleaned it so i was code free for a few months. i use to run hks 272's and swapped in some gsc s2's a few days ago and ever since then i get the code to pop up very frequently.

am i doing the evoscan process wrong? or am i missing a step?

anyone deal with this before?

Kakihara

My car since I bought it (2nd hand) never had the ISC steps go lower than 40, it never gave me problems, car had a regular idle and nothing weird....until I had a greenhta installed and the ecu re-tuned, after that I had awful throttle hang, 1100rpm minimum idle etc....

In 6 months everything mechanical has been checked, IAC changed etc... no leaks no problem nowhere, my car just has a higher ISCV demand at idle than others for no reason that evo specialists can tell so after spending a LOT of money with no solutions, I fixed it myself in the ECU thanks to evom forums and all the great people here.

First thing you need to do is add the line in your evoscan .xml and log this parameter ISCV % DEMAND.
This is what tells the ECU how many ISC steps it must use.
Sadly this percentage seems to be quite complicated and almost impossible to "debug" since it is influenced by way too many things including power steering
This is the (real) left parameter on the idle stepper lookup table, it's not load or whatever.

Do a log with ISCV % demand and ISC steps you'll see they are directly related and it will match the cell values in the idle stepper lookup table.

Either you can try to lower the cells in the idle stepper lookup tables like replacing 40steps with 30 or so (never tried it myself)

Or you can like I did lower or zero the values in the two tables that where known as "decel fuel cut" but are actually the "ISCv demand TPS adder AC off" and "ISC demand TPS adder AC on".
https://www.evolutionm.net/forums/ec...sassembly.html

Since I had tons of throttle hang I ended up zeroing everything in both tables after trying different values and this not only lowered my idle to the ecu programmed "target idle" of 797rpm (GSC s1,greenhta and 1000cc injectors) but it got rid of my throttle hang, in fact the engine braking may be too good now, I don't know what I'm doing lafter all lol
it does seem to make dramatic jumps in ISC steps like 80 steps to 30 instantly, and deccelerations aren't smooth at all, you definitely feel it when you lift off the throttle but that's what I like, hope it's not bad for the car !

05VIII

iTrader: (17)

hmm. sorry for the noob question but where exactly do i add it?

05VIII

iTrader: (17)

ok never mind. i figured it out. i am going to go log it real quick. what should i look for?

05VIII

iTrader: (17)

ok well once warmed up at idle hovering around 1k rpm

ISCVDEMAND is at 16.4705882352941

ISC steps are at 42

sorry for my ignorance but what does that mean? any suggestions on what to do?

my bad, didnt know you added to your initial post. ill see if i can figure all that out and see what i come up with.

Kakihara

I should tell you that I'm not a tuner so I don't really know what I'm doing.

But you should simply drive enough for your coolant temp to reach 80°C (176°F) then park and let your car have a stable idle, it's going to tell you how much ISCV % demand you have at idle.
With 35 steps you should have something between 11.8 and 15.7% ISCV demand (look for that in the idle stepper lookup table)
This won't fix anything but at least you'll know if your ISC steps are at what the ECU want them to be.

You could try lowering the 40 and 30 steps cells in the idle stepper lookup table to 30 and 20 and see if that fixes your idle without messing up the driveability.

I'm just guessing, I read my first ecu a few months ago and am learning everyday.

05VIII

iTrader: (17)

LOL that makes me feel good

but good info.

for some reason my isc steps are now at 42 with 16.47% iscvdemand.

ill read that link you posted and see if i can figure anything out.

if anyone else has info, please chime in

oh and my idle is fine when i get the code. before i swapped in the new iac it use to jump up to 2k but now it just sits around 1k how it should.

05VIII

iTrader: (17)

OMG im even more confused now. i added the tables posted by l2r99gst for the 96530006 rom which im using and it added sooo many more options under the new ISCV Control tab

any guidance? step by step possibly?

05VIII

iTrader: (17)

bump..anyone??

05VIII

iTrader: (17)

???

Kakihara

Silly question but you say your idle is at 1k like it should, is it set at 1000rpm in the ecu under :
Idle
Target minimum idle
77-80°C cells ?

If it's still set at 797rpm and you are idling at 1000 that may explain the code.

One solution often mentionned about P0505 is to clean the throttle body/butterfly itself, you can try that if you haven't already.
But be aware that by dismounting it and cleaning it you may end up creating air leaks and make your idle rise, happened to me, it's not something I would do again ><
And it was completely useless for me I fixed my idle-throttle hang problems in the ECU in the end.

05VIII

iTrader: (17)

its set at 898 in the 77-80 cells.

the throttle body is fairly new. had it ported not to long ago so its clean. new gasket and upgraded shaft seals.