IAC problem/damaged (?)

[WASyL]

Hello,

setup: MSII 2.89 code, hot start problem mod(don't remember how was it called), TPI adaptor board

i'm not quite sure if this can be a reason so i need to ask, when i drive my car to about 2500RPM my car idles normally but the more hard pull i take the faster my car dies when pressing clutch, id does fight a bit to keeep idle speed and dies in a second or so. was checking different ignition and fuel settings but with no luck. then on warmed up engine i set Idle control algoritm to: none and problem disappeared. thought i can leave it as is but in the morning driving a car is a nightmare without working IAC until it worms-up. and suggestions is it my settings or damaged IAC who cause all the problem with idle on hot engine with higher RPM pulls.

Best regards

[Matt Cramer]

Usually a damaged IAC circuit will just keep the IAC from moving. You may have turned the IAC off and left it in a position where it's far enough open to avoid stalling.

[WASyL]

ok, then what other thing may cause such behaviour ??

best regards

[Matt Cramer]

If you could post a data log of the stalling behavior along with a copy of your MSQ, I'll have a look and see what it could be.

[WASyL]

ok, should be here latest monday morning

best regards

[WASyL]

ok, here they are, problem starts at the end of this file when engine starts loosineg RPM and dies (a this moment my laptop also losses power as it has no battery ) as You can see untill i drive normally it heeps it idle quite good (not perfect as should be also do not know why and cannot findsolution yet, but after hard pulls (only on warmed-up) i dies and i tried diffrent confings but it always ends u same like in log, will be gratefull if You cold take look thru whole log and see if there is something wrong
right-click "Save as" files:
http://www.fbody.home.pl/pub/2010-10-06_20.28.05.msl
http://www.fbody.home.pl/pub/2010-10-06_21.33.msq

best regards

[Matt Cramer]

Looks like at the end of the log, things went crazy for a while, the RPM started see-sawing - and then it dropped below the cranking RPM. At that point, the ECU tried to move the IAC valve to its cranking position, and the engine didn't seem to like that.

It looks like the most important thing to do is tune out the oscillation that eventually put you there. There's a couple lean spots in the fueling towards the end of the log, and I suspect it could use more timing at low MAP and low RPM.

[WASyL]

that would mean it's getting to few of fuel to air is given by more oppened IAC
so i should advance idnition to 25 deg. to fix it and make whole table more reach, then AFR table at that area should go atleast 14.1 to keep it alive
do You see any thing more tha can be set wrong, my engine has aggresive cam (and samll heads) so getting smooth idle is quite hard, any idea how to fix it
problem for me is that until MS is in warm-up mode it idles good but when it is after warm-up it and i'll pull a bit harder it starts to loose these RPM and battery charging and dies

best regards

[WASyL]

extension to prev post. why when it is tuned to proper values on idle (RPM/MAP) with WUE off works but after these hard pulls it does not idle in same area of RPM/MAP and goes very different

best regards

[grippo]

What I would do to determine if IAC has anything to do with the problem is to start the car and get it warm. Then turn off the engine and unplug the IAC. Then restart and adjust throttle so it idles properly. Then run the car and make hard pulls. If it works fine, then the problem is in the IAC or IAC control. Some IACs need holding current, so need to set IAC always on instead of on for 15 min. If you still have the same problem, then it is likely a tuning problem.

[WASyL]

grippo i did thios tes before this thread and it stopped dieing this is why i thought it was IAC fault
IAC replaced but problem has not dissapeared. then i advanced timing on idle up to 25 and made whole area more rich. until now no problems but car idles at about 1100 and osccilation of RPM is lower. will make some more test to find if this helped

thanks for all suggestions and help

best regards

[grippo]

OK, but if you haven't already tried it, try setting the Idle Control to "Always On" instead of the "15-Minute IAC" setting that is in your msq.

[WASyL]

will do. wether in poland is already to bad to drive my car and haveing no traction even on 6th gear is a bit risky

best regards