Hello,

i have GSR260 VIII(99270000ecu - no map sensor, stock rom), car has catback exhaust and hradpipe intake with mushroom filter(aka HKS). After cleaning throttle body+AFM and resseting ecu car starts to stall on crossroads and after neutral revving.

I read something about AFM scalling due open hardpipe intake, but im idling nice already on 31.25hz. And i made idle callibration(idling around 20 ISC steps, was over 40), this helps, engine doesnt stall, but revs drops around 400-500rpm in this situation.

I tried to rise or lower a little first two column of AFM scalling. Also adding some 82c desired ISCV steps position (from 7 to 13). No better.

Can you help me?
Enclosing two short datalogs of this situation.

 

have you adjusted the BISS (base idle set screw) on the throttle body small adjustment makes big difference try turning it 1/4-1/2 a turn and see if that helps.

 

Yes, that is what i meaned as idle calibration. It help, but not fix.

 

Did you clean off the grey gunk around the throttle plate?

 

Of course.

I read a ISCV dissassembly thread. Maybe my problem is connected with powersteering(pressure sensing), becouse i have f.ked rack(leaking, pump squeezing), will be replaced during next 2 weeks. Hope it helps a bit too.

 

How did you clean the MAF sensor?
I'd suggest trying a different MAF.

 

check front o2 sensor is working correctly and check for air/vacuum leaks

 

Maf cleaned by brake cleaner(o know...).

You can see the logs, MAF and O2 working right, inst?

Im pretty sure about no leaks.

 

have you changed anything recently like dump valve etc , have you tested the idle stepper motor resistances.

 

^this x2.. the problem sounds more related to a vacuum issue, causing poor idle stability.. You can confirm your front 02 easily if you have a wide-band and your tune is still utilizing the "closed loop" functions. You should be hovering the 14.7 area at idle & cruise. If you only have a logger available, check the voltage readings at the primary 02. If the readings are bouncing all over the place, you most likely have a bad sensor.

Also if you have a mechanical boost gauge it should read vacuum, whats your vacuum readings?

 

Just looked at the logs.. Your 02 sensor seems to be working properly..

I am still convinced this is vacuum related. And I would raise your target idle rpm ~50rpm.

 

I have boost gauge mounted only for a while, to check boost pressure. On idle was -0.6/-0.7bar i think. Car idling a runs smooth.
Oh and i forgot, have no bov. Outlets on pipes are just plugged.

 

Installed bigger tanabe downpipe(original have small cat and was rusty), main cat is deleted, othervise catback is still stock.
Switched to E85 fuel. On stock injectors(lowered boost, O2 trim +-2%).

Still the same problem.

May i try to tune some ISCV maps or MAF calibration-smoothing or any other suggestion?

 

Make sure your tps sensor reads below 15% when the throttle is closed. If not then adjust tps sensor to around 13%.

 

According enclosed datalogs, its 14%