I understand that if the injectors are oversized for the application, its possible for the ecm to switch to async mode at idle.
How do you tell when this has happened, and why is it undesirable?

 

Myself, I don't like async mode on the TBI setups. The amount of fuel changes when the ECM switches between the two modes (async & sync).

As for using it at idle some of the newer masks ($0D, $31) look to have some RPM & MAP qualifiers that will allow the ECM to use async mode during idle. This mask also has better injector compensation tables for voltage changes. So all in all async mode may work out better using this mask.

As for being able to tell when in async mode there is a status bit that gets changed. If not already can output this to the ALDL stream.

RBob.

 

Thanks RBob.
I am using $E6, very similar to $0D, it uses the MAP and rpm qualifiers. I will experiment with both modes and see which gives best results.
Thanks for your help once again.

 

In the $0D mask, there is a flag to select Synch mode at idle, even if the MAP and RPM qualifiers are not met. The flag forces Synch mode at idle. Some of the $0D (V-6 S-10) cals run synch at idle and Asynch off idle. All of the V-8 cals I have seen switch to Asynch at part throttle and the transition is smooth as long as the transition pulsewidth constants are good. With enough injector, the Asynch mode can be delayed some or even eliminated if you run a VAFPR. The status bit is already in the datastream. HTH

 

yes digging up a old post...but say in the 7747 ecm i have 2 tabels for asynch bpw...one min ..one max.....if i want to get rid of asynch all togeter do i jsut move both to a very very high bpw or lower them out to zero oe move one to zero one to max...what exactly do i do?

 

edit

 

asynch transition high set to 0
same low 0

 

Ben,

I can back up what RBob said. Using EBL, I can tell you I used Synch only with very good results. Never noticed any diff.

 

well so far so good.....i did notice afr at wot lot more stable.... still have a lean spike you don't feel it but theres a pretty big spike on my wide-band as soon as i crack the throttle full open i go from 13.8 to 16 then just like a needle straight down to 12.1 afr..i have added tps and map ae with no luck

 

I believe the initial lean spike is maybe unavoidable. As long as engine does not fall on its face should be OK to disregard. There is an AE table (filter)that will bring in the AE sooner. If not sooner then it will provide more up front as far as time frame of event I believe. I increased MAP 30% and TPS 25% to achieve a lessening of that spike. Also another AE table is RPM multiplier. Not sure if this is good for you but I witnessed a need for more AE 2200-2800 rpms. It was evident at tip in (manual trans) when I was attempting to enter Xway from a standing stop. 0-60 mph in a hurry. Stock bin had 0 in those fields. I added considerable %. In my AE logs I see two enrichment spikes. First I assume is TPS and second MAP. Then PE if I stay on it.

 

ok and does the rpm multply exist in the 7747 non ebl?..... if so how much did you rais yours

 

Not sure if the 7747.xdf will show. Question for Magnus. Anyway i stopped adding to AE in both TPS and MAP and added in 5% at a time in RPM 2200-2800 until lean bog went away.. I ended up with adding 2% more at 1600 22% more at 1800 28% more at 2000 36% at 2200 67% more at 2400 and 45% more at 2800. stock had 0 2000 on up. Cant say this is correct but it removed bog as befor mentioned