Chevy 350 TBI stumble

AuroraGirl said:

also no offense but you sweapped from a v6 to a v8 and "did some magic" and deleted cats and EGR at the same time.. were you expecting it to run like a champ lol?

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FrankieD61 said:

Lol Bobr did over at DynamicEFI. He installed a flash able prom chip on the PCM. He also has software called What's Up Display which is really nice.

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AuroraGirl said:

Your truck either has the best operating conditions that meant it never had much to handle Or you never noticed the truck pulling timing but the factory knock system possibly kept it in safe range( a good thing)

To note, not all EGR systems these years were the same behavior and not all situations would ultimately need it.

Also, EGR is supposed to be off-idle cruising almost exclusively.

I dont know how gm small blocks with TBI dealt with EGR and what if it didnt have EGR , but depending on the vehicle no EGR when its expecting it could cause a AFR mixup and code, once code fault for those systems, vehicle wouldnt continue to calculate as if it had EGR, thus it would run normal. Some vehicles simply cannot tell and may just correct itself with more fuel and air, and some may be pretty noisy about it.


Being that its exclusive purpose here is to reduce temperatures in the combustion chamber, the mileage difference is hard to gauge. Most new vehicles dont even do EGR anymore at least gasoline wise.

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Id be curious if you ever had a loaded trailer, a hot hot day, a factory 195(I think?) thermostat, and a hill you ever had to climb?

Not bagging on you just wondering. some climates, some uses may see conditions that wouldnt need EGR lol.
EGR is one thing on an old carbureted small block, but when using a PCM and TBI, youre basically wanting to allow the PCM to use as much advance and as lean (well, the stoichiometric) mixture as possible, and to do that you give it the best gasoline, the cleanest, coolest, least restricted air, the proper, sealed exhaust (with cat), and you give it good, non poisoned O2 sensors, no vacuum leaks, functional EGR, proper calibrated idle(mechanically and electronically), a learned computer with driving values under various operating conditions, and clean functional TBI with clean, mechanically sound engine with the cleanest and properly grounded/wired electrical system.

If you give it everything it needs, it can give you the most power and very reliably. I didnt list every factor above, but you get the idea

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Dropped88 said:

I'm interested in what it's doing now. So when I get the interior back in the truck. I will hook up a trailer, cruise and climb hills with the scan tool running and see what happens.

I'll make it a little science project lol

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AuroraGirl said:

Science. I like science.
on a 95 tbi I believe the knock sensor live data was meaningless to view(been a while) but the timing advance live data will show what its doing nonetheless, so if you see some serious KR youd know

and remember, Knock control was only "big" for GM engineers here because specifically speaking, knock is VERY bad for converters. So controlling and keeping ahead of knock keeps auto maker in emissions green zone and also able to state higher horsepower to consumers.

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Dropped88 said:

I have an older verus so I'll try to record it and maybe try to upload it.

And depending on the results and let's say IF Its not pulling anything may advance timing and see how far I can take the ol 454 on pump gas. It's a slug either way haha

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