Synch vs Asynch fueling

[RobertISaar]

MOAR THOUGHTS!

so.... if it's unavoidable with the 60V6 TBI intake, what other engines have the same issue? apparently GM thought the 4.3s would benefit from it since most, if not all, of those calibrations seem to be async.

another thought is how are all of the people running these engines that have fuel distribution problems working around them with other ECMs(like megasquirt, etc)? i HIGHLY doubt those run async injector fueling schemes...

ugh, GM's different engineering groups must have hated each other throughout the 80s and 90s... "OHAI GUYZ, INTAKE MANIFOLD IS DONE, GUD LUK GETTIN THAT TO WORK WITH AN ECM, TROLLOLOLOLOL".

[RobertISaar]

Robert I got confused about intake manofolds the 60v6s I worked on was port injection my 4.3 is a thb lot of differents looking into the way the manifold is made sorry I got confussed, did look at my sys bin going to change a few things an burn some more gas , it went down to 331 a gallon yesterday.

i didn't find anything odd about your 2.8 vs 4.3 stuff, i'm just one of the 60V6 nuts who thinks they know everything about the 60V6, then something like this comes along and blows my mind how it hasn't been discussed before... multiport vs TBI/carb intakes ARE going to be vastly different... it's pretty much a requirement for them to perform at their best.

i'm not really a fan of anything that doesn't have at least 1 injector per cylinder, so something like this going over my head isn't really surprising.

[gregs78cam]

I am pretty sure the Asynch requirement comes not only from the firing order, but from the layout of the intake runners and which bore feeds which cylinders in the firing order.

[RobertISaar]

firing order is perfectly normal in both V6 applications, they alternate which bank gets fired every time.

the runner layout and which bore feeding which cylinders, that's what i can't get any solid info on.

[1project2many]

IIRC the 4.3 dual plane TBI intake feeds alternating cylinders.

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This *should* provide relatively equal fuel distribution with the "long" runner feeding the RH bank and the "short" runner feeding the left. The firing order provides a left - right - left - right scheme so the same injector shouldn't be required to fuel two consecutive cylinders.

[EagleMark]

I had forgot about the other issue with tuning Async bins, INT and BLM do weird things, espiecally the INT.

From another thread where logs from Async and Sync bins are.

I'm glad you posted that! It stirred up another memory from Async bins besides idle. If I'm remembering right... they all do the same thing as this data log. INT and BLM all over the place when ever you accelerate. After you reach a steady speed they finally come together and settle to straight lines. Trying to adjust VE from BLM never seemed to work right? Then when I got away from WinALDL and Datamaster and used TunerPRo I had the tools I needed to see why it never worked!

Can't wait to see a driving log with a Sync bin!

Idle was always a major concern because the majority of vehicles I tuned were off roaders and they all complained of idle issues! Now I remember the BLM issues as well...

[daleulan]

If I remember right, some of the 4.3L TBI engines had different injectors installed in each bore and you had to make sure you put the right one in each spot. To me that implies that there is a fuel delivery issue there of some kind and various patches were done to make it work. Maybe async fuel was the best of the worst they could make run?

[EagleMark]

That's right, 2 differant sizes. Seems like something was wrong and this was a patch for mechanical design? Or was it a patch because of Async fueling?

To be safe anyone running a V6 and doing the Sync should really read all spark plugs. Next time I have my hands on one I'll be doing the same.

[damanx]

I'll pull all my plugs afternoon and check them out. I've been running a modified ASDU bin that Mark has helped me with, but still having some issues.

[damanx]

Pics of the plugs, top pic is 2,4,6 plugs and the bottom is 1,3,5.

Using the ASDU bin.

DSCN2445_zpsb5e46b46.jpg

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[daleulan]

I'm thinking that the injector asymmetry on the injectors and/or the async fuelling mode were both used to cover up (or otherwise compensate for) some air/fuel distribution issue much as the Buick V6 went with SEFI long before any of the others did. Otherwise it does not make that much sense to me.

[damanx]

I'm thinking that the injector asymmetry on the injectors and/or the async fuelling mode were both used to cover up (or otherwise compensate for) some air/fuel distribution issue much as the Buick V6 went with SEFI long before any of the others did. Otherwise it does not make that much sense to me.

I'm betting that their foremost priority was emissions and due to that, they did whatever to meet the guide lines up to and including the using of different injectors in the set to accomplish that. Much cheaper to adjust hardware than rewrite software. But this is nothing more than a guess.

[1project2many]

AFAIK only the Astro vans were equipped with mismatched injectors. Full size vans, trucks, and cars all received a matched set.

[EagleMark]

Pics of the plugs, top pic is 2,4,6 plugs and the bottom is 1,3,5.

Using the ASDU bin.

DSCN2445_zpsb5e46b46.jpg

DSCN2443_zps0308eef2.jpg

The plug color can't get any better!

Now get rid of those plugs and put in AC Delco, standard, Platinum or Irdium, it does not matter they are all the same, the fancy metal ones just last longer.

[RobertISaar]

I'm thinking that the injector asymmetry on the injectors and/or the async fuelling mode were both used to cover up (or otherwise compensate for) some air/fuel distribution issue much as the Buick V6 went with SEFI long before any of the others did. Otherwise it does not make that much sense to me.

knowing what we do about GM, highly possible. there were some rather odd decisions made in that era.

The plug color can't get any better!

Now get rid of those plugs and put in AC Delco, standard, Platinum or Irdium, it does not matter they are all the same, the fancy metal ones just last longer.

yeah, those are some decent looking results. i know of a lot of people who like the NGK plugs, but they do seem to be hit and miss(pun intended). depending on how easy they are to get at to change is what kind of plug i would run.