try to educate me here. do you see any advantage synch vs asynch mode for those of us that run dual pane manifolds vs single? i periodically see asynch at idle should idle drop under 800 rpms. could you elaborate as far as relationship of distributor pulse vs the individual TBI inj that is firing in synch mode. i am going to assume each TB is using a dedicated plenum/runners and no contribution from sister TB. ie dual plane w/divider(holley projection. sorry if a dumb Q. does this make a diff?

One major difference is that sync alternates injectors with each DRP. Async fires both injectors together at 80 times/second.

When in sync mode and alternating injectors, it can start with either one. There isn't anything to set up which injector fires at which cylinder.

As far as which is better, one thing to do is to try it. Set the inj PW terms so it runs async always and see how it is. I do know that some Astro van bins (4.3L) are set up this way.

I've been meaning to do that on the LG4 TBI vehicle, but still need some round-tuit's. There are also some posts where I have simple time line grpahs of why I don't care for async mode on a hi-po engine. My feeling is that some cylinders are going to run lean while others are rich. All dependent upon when that async pulse fires.

RBob.

I know some 3.1 TBI Lumina Mini-Vans, run in Async all the time as do some Heavy Duty but Low RPM 366, 427, 454 Trucks.

OK. thanks.

in "synch( alternate firing of inj)" mode is it possible that the injector that is firing is not specific for the specific "manifold plane " that feeds the cylinder that is getting the spark.

IOW is there any importance to have the proper inj firing into the proper manifold plane so that the inj firing is in "synch" with the appropriate cylinder spark? i would be more specific but i dont know what inj serves which plane/cylinder bank.

a non issue with single plane manifold as common plenum feeding all cylinders. this is what i was getting at.

thanks again.