quick timing question

[mountaingoatgruff]

84 hatch with spfi ea81, spfi parts off 92 loyale with 5speed.

 

should i set it to 8* btdc for the ea81 spec or 20* for what i've read is the spfi spec?

 

also, all i need to do to fiddle with the timing is plug the test mode connectors into each other after warmup, correct?

 

i don't have an fsm that covers spfi cars and i just don't trust the fragmented info in my haynes.

 

thanks

[torxxx]

Timing is supposed to be 20 degrees BTC for SPFI, I'm not sure what ur timing is gonna be for a EA81 cuz of the compression difference. I'd say turn the timing up til u get detonation and then back it down a little bit.

[mountaingoatgruff]

so it is 20 deg for spfi then.

 

well, i just played with it a bit and because of the way that i adapted the ea82 dist and fabbed up a new mounting plate, i had the dist cranked all the way over and was running at about 18 deg with no ill effects. i'm making a new hold down plate that will allow me to rotate the dist throughout the whole 0-20 deg range and i guess i'll experiment from there to see where i get the best mileage.

 

edit:

i just pulled the timing back to 8 degrees thinking i'd run the ea81 at it's own spec and that little beast was not happy! it idled well, pulled okay at first but then it was bogging and seemed like it was missing real bad while accelerating. i've got to go to work soon but i'm going to try it at 20 degrees tomorrow, hopefully my beast isn't pissed off at me now.

[torxxx]

The reasons why SPFI has higher timing is due the lack of vacumn advance on it. The ecu controls the timing to a point as far as at an idle and under heavy acceleration. Where as ur stock EA81 would vac advance the timing up to 20 degrees under accelration, the spfi distributor wasnt.

 

 

 

so it is 20 deg for spfi then.

 

well, i just played with it a bit and because of the way that i adapted the ea82 dist and fabbed up a new mounting plate, i had the dist cranked all the way over and was running at about 18 deg with no ill effects. i'm making a new hold down plate that will allow me to rotate the dist throughout the whole 0-20 deg range and i guess i'll experiment from there to see where i get the best mileage.

 

edit:

i just pulled the timing back to 8 degrees thinking i'd run the ea81 at it's own spec and that little beast was not happy! it idled well, pulled okay at first but then it was bogging and seemed like it was missing real bad while accelerating. i've got to go to work soon but i'm going to try it at 20 degrees tomorrow, hopefully my beast isn't pissed off at me now.

[GeneralDisorder]

Timing need to be at 20. The SPFI computer expects to receive the CAS sensor signals on a 20 degree base. The ECU will fire the coil based on it's internal timing maps - which are very well suited to the EA81 being it's nearly identical to the EA82 except for slightly less compression. You might be able to turn the timing up to 22 degrees or so without pinging, but it won't be much over spec. You would certainly never want to run less than 20.

 

GD

[daeron]

http://www.ch601.org/engines.htm

 

find the chunks of the EA82 FSM. Golden.