Hi...

Did my 730 ECM swap today. Started it up and scanned the car.....

Ign. was jumping between 15-24 at idle, If I look at the main spark table it should be minimum 20 deg. Where does it get 15 deg from?

Closed loop, 180 deg F, idle 700-750 RPM, MAP 0,47-0,50 kPa.

/thanks.

/N.

 

Its in the code for the ecm :-( Its there basically to maintain an even idle as posible under most circumstances. So u will see the timing vary at idle as the ecm deems necessary to keep the desired idle speed.

I dont know of anyways to disable it. Others here who know more will most likely chime in there 2 cents as well
Later
Jeremy

 

On my 165ECM I changed in the main spark table to 22 deg. at idle and it would never go under that at idle................

Does the 730 has more than one spark table for idle?

/N.

 

Six parameters/quals and 4 tables. Just zero the two SA change vs RPM tables.

RBob.

 

There is some good info here: http://forums.corvetteforum.com/zerothread?id=556467

 

Thanks Doctor J!

I'll try to modify my TC 8D ecu file......................

 

very interesting :-)

So if i zero out the SA vs. rpm(ill go check'em out on TC) i can actually stabilize my idle further?(least keep the timing at a constant degree) hmmmmmmmmmmmm

sound slike something i will be playing wiht shortly
thanks rbob

later
Jeremy

 

It depends. The SA vs idle RPM is there to stabilize the idle. If the engine has been improved upon it can help to reduce the amount of SA timing change.

RBob.

 

I was under the impression that the idle timing change table also insured frequent O2 sensor transitions, for the idle AFR set point. Isn't that where the "slow O2 transitions" table is used? I need to go look at the hack again - can't remember which was which AFR calc...