Chevy TBI tuning help

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Justa1time
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Re: Chevy TBI tuning help

Post by Justa1time »

dfarr67 wrote: Thu Feb 02, 2023 6:42 pm Modified 7747, factory harness- FTW

http://www.dynamicefi.com/
I have a TBI truck. I have always wanted to go this route but haven't pulled the trigger yet. Also want to add a heated o2 sensor.
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Re: Chevy TBI tuning help

Post by Truckedup »

In Tech, sounds great... Your help is invaluable....This is my first time into any type of electronic injection modifications....Let me inow when you get the parts together and we will go from there...
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mt-engines
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Re: Chevy TBI tuning help

Post by mt-engines »

If you need any EPROM or EEPROMS I still have quite a bit.

If you get creative, you can make a new header and use an EEPROM.

I might even have a few 24-28 adapters still. I used to do a bunch of them in the late 90s early 2000s.

Being from Minnesota, the southern guys don't realize how much better a TBI setup is over a carb for a daily driver when you can have a 80 degree swing in temp in day. -40 to +40 nobody likes pumping the gas and trying to keep an engine running for 3 or 4 minutes in arctic air.
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Re: Chevy TBI tuning help

Post by Schurkey »

Truckedup wrote: Thu Feb 02, 2023 4:41 pm a V8 ECU and prom is required...
I keep looking at the carb , intake and distributer in the corner of the shop.....But I am determined to use this TBI...
rebelrouser wrote: Thu Feb 02, 2023 6:12 pm Just buy a used V-8 computer and prom, check the wire pins on the connector to see if they go to the right places.
Yep. A suitable computer and a PROM with appropriate programming for the application. Manual-trans PROMs are less-common than auto-trans PROMs, but if you're having one custom-tuned, I don't suppose that matters.
rebelrouser wrote: Thu Feb 02, 2023 6:12 pm One issue might be the cam and crank sensors. Cam sensor triggers at TDC the 6 cylinder computer then looks to see 6 pulses of the cranks sensor. It uses this relationship to set timing and fire the injectors. So when the computer sees 8 cylinder pulses before the nest cam pulse it may be confused about what to do.
I will believe that the 6-popper computer/PROM is confused when run on an 8-cylinder engine. However, TBI does not have a crankshaft sensor. The "cam sensor" is the distributor pickup coil, not a dedicated "sensor" in the usual sense. The computer has no idea where the crank is, and only knows when to fire the coil based on pickup coil/ignition module signals. It doesn't know which cylinder is firing, just that "a" cylinder needs to fire and one of the injectors needs to squirt fuel. The injectors alternate squirts.

Again, it would be worth connecting a scan tool so you can verify all the sensors. Loading-up as it idles could be a fault due to incorrect injectors and incorrect computer/PROM. It could also be a faulty TPS or coolant temp sensor, for example.
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Re: Chevy TBI tuning help

Post by Tuner »

I have had good luck on several vehicles with using the Innovate WBO2 devices, such as the MTX-L gauge and LC-2 WBO2 controller, which have an analog voltage output that can be programed to mimic the narrow band O2 signal to the ECU, but set it to do so at between 16 to 17 / 1 AFR. The leaner A/F dramatically improves fuel mileage.

Each engine has its own appetite, but usually something similar to 16.25/1 = .9 V 16.5/1 = .1 V keeps the ECU happy, thinking it is seeing a narrow band O2 sensor output, but the engine is running at the leaner AFR and getting much better mileage.

The NB sensor signal is straddling across stiochiometric (.45 V) bouncing between rich and lean .1 V is near 17/1 and .9 is near 12/1, so with the production feedback setup half the cylinder firings are way richer than is acceptable for minimum fuel consumption.

The Innovate MTX-L gives you a gauge to see the A/F and provides the analog voltage feedback to cheat the original ECU without needing a custom chip.
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Re: Chevy TBI tuning help

Post by Truckedup »

Tuner wrote: Sat Feb 04, 2023 1:43 am I have had good luck on several vehicles with using the Innovate WBO2 devices, such as the MTX-L gauge and LC-2 WBO2 controller, which have an analog voltage output that can be programed to mimic the narrow band O2 signal to the ECU, but set it to do so at between 16 to 17 / 1 AFR. The leaner A/F dramatically improves fuel mileage.

Each engine has its own appetite, but usually something similar to 16.25/1 = .9 V 16.5/1 = .1 V keeps the ECU happy, thinking it is seeing a narrow band O2 sensor output, but the engine is running at the leaner AFR and getting much better mileage.

The NB sensor signal is straddling across stiochiometric (.45 V) bouncing between rich and lean .1 V is near 17/1 and .9 is near 12/1, so with the production feedback setup half the cylinder firings are way richer than is acceptable for minimum fuel consumption.

The Innovate MTX-L gives you a gauge to see the A/F and provides the analog voltage feedback to cheat the original ECU without needing a custom chip.
I really appreciate all the help here and that not all of it applies to me.....However.. :D My fuel delivery tuning background is motorcyle slide venturi ,newer and CV types for high performance.I understand the basics of electronic injection and so on....But this TBI is my first time actually working on a system other than a scanner...I understand wiring but when the talk goes on signals and adjustable tuning values, it's more than I need to know.. :D :wink: :D .
I alway wanted to build a V8 Vega..I missed that bus..So now it's the V8 S10.....it's got a stock 95 truck 350 that rated for about 210 HP...The better exhaust and fuel delivery might add 20 HP....and with a 5 speed in a 3000 pound ass light truck , good enough for an old guy, lol...
But keep on with suggestions because you just never know....
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Re: Chevy TBI tuning help

Post by PackardV8 »

mt-engines wrote: Fri Feb 03, 2023 1:19 pm Being from Minnesota, the southern guys don't realize how much better a TBI setup is over a carb for a daily driver when you can have a 80 degree swing in temp in day. -40 to +40 nobody likes pumping the gas and trying to keep an engine running for 3 or 4 minutes in arctic air.
For true and the immediate starting and stable idle also saves piston rings and cylinder walls when they're not being washed down with cold liquid gasoline.

I've been working with Studebakers and Packards for sixty years and they're always worn out; big ridge at the top of the cylinders and no ring seal left, engine full of sludge. Tear into an EFI engine with twice the miles and often the crosshatch is still on the cylinders and it's clean inside. The later generations of LS with 250,000 miles could be freshened with rings, bearings and valves and run another lifetime without any machining. Part is due to a century of learning how, improved materials and CNC machining, but mostly better EFI and computer ignitions, unleaded gas and oil.
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Re: Chevy TBI tuning help

Post by dfarr67 »

Justa1time wrote: Fri Feb 03, 2023 11:31 am
dfarr67 wrote: Thu Feb 02, 2023 6:42 pm Modified 7747, factory harness- FTW

http://www.dynamicefi.com/
I have a TBI truck. I have always wanted to go this route but haven't pulled the trigger yet. Also want to add a heated o2 sensor.
Easy mod- ignition on to heat the sensor. Helps a little with economoy and if have a non stock exhaust where the oe o2 has cooling off problems.
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