AE ? issue

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my friend is having 350 gm goodwrench with tbi in his trial rig, we have adjusted blm:s and sa from it and those are pretty good now but theres one really bad i think ae related issue that i cannot handle.

engine "bogs" or something like that when rapidly floorig from idle/near idle, dont know correct name for it but flame goes trought intake to air filter and engine almost dies, also acceleration could be better...


egine is gm goodwrench 12499529, stock tbi intake and tb 14.5 psi fuel pressure, open round filter and long headers...


12499529

You have a bad timing issue. 30* in the main table, 11* PE adder, high RPM adder is adding 3.4*. Then finally the ignition control module could either be adding 2* or removing up to 6* depending on which part number is in use. You could have as much as 46* total at 4,200 rpm!!!!

pe adder is not in use anymore, i just dont have latest bin in my home computer...

we diding get enought advance for some strange reason at higer rpm and i tested several ways why it was so so there might be still some things wrong in SA

intrial, this engine rarely seen rpm over 3000, mostly all driving is done from idle to 2000 rpm


btw, 42 deg advance with fuel we have is ok

now we have set base timing to 10 degrees and it works that way, but i dont thing any of those will cause or bog/stall/hesitation from of idle, its something like lean bog, like in cabbed engines where is some acceleration pump broken etc. but not sure what to do with it anymore.

Quote:

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Originally Posted by rytari

pe adder is not in use anymore, i just dont have latest bin in my home computer...

we diding get enought advance for some strange reason at higer rpm and i tested several ways why it was so so there might be still some things wrong in SA

intrial, this engine rarely seen rpm over 3000, mostly all driving is done from idle to 2000 rpm


btw, 42 deg advance with fuel we have is ok

now we have set base timing to 10 degrees and it works that way, but i dont thing any of those will cause or bog/stall/hesitation from of idle, its something like lean bog, like in cabbed engines where is some acceleration pump broken etc. but not sure what to do with it anymore.

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Its not so much the fuel as it is the mechanical of the engine. I would expect to see the engine like 36-38* at most. Our 93 octane is very close to your 98 and 40*+ is just does not add power over 38 even in old smog chambers with low dynamic compression ratio. You have the wrong cam for a 2,000-3,000 rpm grunt engine. That crate engine only has 7.8-8:1 static compression ratio when the real math is done and the cam has 224/224 @ .050, very long 290 duration @ .004 and a wide 114* LSA, talk about lack of cylinder pressure.

You can add AE fairly easily. Just my past experience has taught me, do not touch the lowest value on the MAP AE table. For a vortec head engine with a carb engine, I usually end up with 50-60% more AE than stock.

i have kept 36 maximum for that engine, just that timing issue made us change some things...

i have change ae value without any luck, we have tried almost s much as double the AE tps values and still it makes the same... not sure what map value should i change so that it would make more fuel go as quickly as possible and then just add some more when asking more... we tried firts with air gap intake but bogging was too bad wiht it...

car was previously with 4.3 tbi, enought power for trial but lack of sound... any cam in that 350 is enought grunt compared to that, this season goes with that setup, my friend is not able to tear down and change parts during summer...

Quote:

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Originally Posted by rytari

i have kept 36 maximum for that engine, just that timing issue made us change some things...

i have change ae value without any luck, we have tried almost s much as double the AE tps values and still it makes the same... not sure what map value should i change so that it would make more fuel go as quickly as possible and then just add some more when asking more... we tried firts with air gap intake but bogging was too bad wiht it...

car was previously with 4.3 tbi, enought power for trial but lack of sound... any cam in that 350 is enought grunt compared to that, this season goes with that setup, my friend is not able to tear down and change parts during summer...

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Are you still using the 4.3 injectors?

Also the TPS AE does not contribute much AE as it only last a very brief period. The MAP AE is what adds ~75% of your AE fuel. Try multiplying by 1.5 in every value above the lowest. Leave the lowest entry alone as it can mess with the idle.

Are you running EGR??

no, at beginning we had 454 tb and injectors but didind work so well so we changed 350 tb and we dont have egr on it.