help with airflow and timing map...

[yangtech]

on my 1991 GSX, i'm running a keydiver chip with the extended map but i'm having problem getting it into the low timing map or even the right map. at 18psi with a BR580 turbo my timing is only dropping to 23 degrees which is giving me knock issues. tuning with maft (blow-thru), safc and wideband... meanly trying to deal with my knock right now.

i know that if the ecu is seeing low airflow value it'll keep it on a higher timing map but i'm running 18psi. anyone know what can be causing this problem? i already checked base timing, boost leak, exhaust leak before turbo. anything else i can check?

 

[CanadianTSi]

The maft is known to throw off airflow readings.

 

[dnhieu]

yes the maft is known for this type of thing. try manually retarding the timing a degree or two and see if that helps.

 

[yangtech]

i'm not sure if its the gm maf... i tried running it at 430cc and the timing is still the same... lower the fuel pressure and the timing is still the same... kind of running out of ideas to tune this thing...

 

[1SloColt]

What is your base ignition timing? Run fuel around 43psi or so, zero out the MAF, which means set it for 450s, and only use the SAFC for tuning. What datalogger ar you running BTW?