$0D TBI to MPFI conversion, how is your idle quality?

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Originally Posted by 96lt4c4

So at what MPH are you locking and unlocking the converter in 3rd? How does this effect towing in 3rd?

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My truck has 3.73 gears and 265/75-16 tires. I lock the TCC in third at 30 mph at zero tps and increase to 75 mph at 56% tps. It doesn't effect towing since the TCC unlocks with increased throttle. I don't think the GM TCC linings are designed to handle much torque so I wouldn't want to keep it locked with a lot of throttle, particularly with a 383 like yours. I also unchecked the flag that unlocks the TCC during upshift. I found it annoying when the TCC would unlock to shift into 4th and then lock again. The upshift with the TCC locked is not harsh at all.

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Originally Posted by Roadknee

My truck has 3.73 gears and 265/75-16 tires. I lock the TCC in third at 30 mph at zero tps and increase to 75 mph at 56% tps. It doesn't effect towing since the TCC unlocks with increased throttle. I don't think the GM TCC linings are designed to handle much torque so I wouldn't want to keep it locked with a lot of throttle, particularly with a 383 like yours. I also unchecked the flag that unlocks the TCC during upshift. I found it annoying when the TCC would unlock to shift into 4th and then lock again. The upshift with the TCC locked is not harsh at all.

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Cool thanks, I will try this out and see how I like it. Its crazy, I have been messing with this thing for years and still learning stuff. I always wondered why my 1st to 2nd shift was so soft at WOT. It got way better by populating "PE Line Pressure vs. Input Speed". Was all zeros stock. By zeroing out the table you mentioned "Ramping Pressure vs. TPS vs. Shift" I may end up with a really hard shift and have to go back and fine tune. If you noticed in my tune I have raised the line pressure slightly in the "Added Line Pressure vs. TPS vs. 0 - 64 MPH" and " Added Line Pressure vs. TPS vs. 64 - 128 MPH".

So after re tuning my VE, leaned it back out, the truck is starting and dying again. I am going to play around with the Choke and Crank tables to see what I can figure out. Can anyone explain exactly how the choke routines work?

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Originally Posted by 96lt4c4

So after re tuning my VE, leaned it back out, the truck is starting and dying again. I am going to play around with the Choke and Crank tables to see what I can figure out. Can anyone explain exactly how the choke routines work?

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It has been years since I have played with a OD MPFI setup, but from what I remember.

When you crank the engine the crank pulsewidth table is used along with the temperature and DRP multiplier tables.

Once the engine is spinning and fires it is on the choke afr table. The choke afr table uses some multiplier tables to decay the choke air/fuel ratio out. How much and how long are dependent on coolant temperature. Choke afr can last anywhere from ~3 to 60 seconds depending on the calibration and temperature.

I also seem to remember some manifold/air temperature decays on the 2.2 MPFI and 4.3 CPI calibrations.

Once the choke afr table decays out the engine is running on the air/fuel ratio in the open loop vs vac vs rpm table. Might be useful to connect to the PCM then start the engine and see what command air/fuel ratio is doing. It could possibly be decaying out too quickly.

the open loop idle lean limit table in your bin is set to 13.0 across the board. This is the AFR the ecm is targeting after the engine starts and all choke enrichment has decayed out. Your engine started fine with increased fuel pressure before you modified the VE tables. The increased fuel pressure had the same effect as reducing the target AFR. You might need to richen or reduce the target AFR's in the temperatures you're experiencing problems.

Your choke afr vs temp values are also set much lower than a stock bin. My stock TBI bin decreases from 8.0 at -40°C to 2.5 at 68°C. Your highest value is 2.5. If the above change does not work, try increasing the choke AFR values at the temp you're experiencing problems.

If those changes don't work, double the time before choke AFR decay from 2.0 seconds to 4.0 seconds.

If none of that works try increasing the choke AFR decay time.