Is this even Possable?? Turbo 5.3 at 700 ftlbs+ torque , Not shure this is correct

Hello need some help Please, I attached log and tune, I installed a T76 twin ball bearing turbo on my 5.3 silverado 80 # deka injectors and sheet metal intake, turbo straight threw exhaust. the rest of motor is stock.

I'm trying to improve my tune. I tuned VVE then MAF now tweaking VVE. under 2k runs perfect. but as the log shows if I get on it, the torque went way up but the truck really isn't that fast seems like. maybe it's me but I think I'm missing something.

how can i have so much torque and not really going that fast, it also looked like spark died at 4k whats up with that.

help is greatly appreciated.

Torque is just a calculation, it's not going to be 100% accurate.

I can say this for sure and excuse my french, your airflow model is completely fucked. Look at the 3D graph of your VVE and the MAF curve. The VVE has so many valleys and spikes it's insane. The MAF curve isn't the smoothest yet either.

How have you been trying to tune this thing when you don't even have a 2 or 3 bar MAP sensor to tune for boost?

You say you are trying to tune the VVE but you never turn the MAF sensor off. VVE tuning has to be done with the MAF sensor failed, otherwise any data you gather will be skewed.

Use your wideband to tune the fueling, this mean disabling closed loop and all fuel trims.

Thanks for the reply, I maxed MAF to force it to VVE. weird enough the truck drives nice wide band is fairly steady. I started 3-4 times with a smooth table and it brings me back to this, it must be me, put the truck fires up and runs around town pretty nice and responsive. What am I doing wrong?? Thanx

I agree with 5f, the MAF and VVE tables need some work. It also looks like you have quite a bit of timing advance for tuning. Not sure if that is real knock or if there is another aspect of the tune pulling timing. While tuning I might pull 5 degrees out across the table just to be safe, no point in blowing something up while tuning. Also, you will be surprised at just how much tuning will affect the way the engine behaves with boost. Even dialing in the MAF vs the VE tables will feel like 2 different powerbands till they are closer to dialed in. Like 5f said, to tune the VVE, you will need the fuel trims and MAF failed. To tune the MAF you will need the VVE and fuel trims failed. that way you are only seeing those parameters influence the fueling and can dial them in. Assuming you have a wideband you will need to create some maths to identify the percent you are off from commanded AFR and adjust in small increments till they are within a percent or so. Then you will be closer. And be sure to start rich and lean out the tune, not the other way around. I would be careful with the MAF table you have, it looks very low at the start

I'm not sure what you mean by maxing the MAF table.

To fail the MAF is to set the MAF fail high freq to something like 2hz and 1hz, then set the timers and also set the 3 MAF dtc's to MIL on first error. Log the MAF sensor status and make sure the MAF says failed. If it doesn't, you can not tune the VVE for speed density.

Disabled closed loop and fuel trims and use your wideband to create an error graph with the commanded AFR against the actual AFR.

I'm sure the truck starts and drives because you didn't do these things yet and the fact that you have the fuel trims correcting the fueling for you. Look at how your short term trims are pulling massive amounts of fuel and or adding in fuel to make it run.

How do I disable fuel trims, I thought you use those in the log to adjust the VVE table. can I disable MAF by going into dynamic airflow and making both high and re enable set to 8000.

I have LTFT disabled, will retry VVE tonight

Thanks for the input.

Did you skim over the part about using your wideband?

You can't trust or use your fuel trims when it's so far off right now and besides fuel trims do no work in power enrichment so a wideband is the only choice. Fuel trim tuning can be done later to fine tune the table under cruising conditions.

Set the closed loop enable temp to 284 degrees. Set the o2 sensor readiness temp to max as well. The current tune already has LTFT disabled so that is good.


No, you can't just set the dynamic airflow settings to 8,000/7,999. The MAF still must be failed with the settings listed above. The MAF fail status MUST SAY FAILED otherwise you are not in speed density.

Don't forget about your MAP sensor. The current tune says you only have the stock MAP sensor installed. That sensor can not read above ~120kpa, so you can not tune fueling under boost when the computer and you don't know how much boost pressure there is. Purchase a 2 or 3 bar MAP sensor so you can continue tuning.

Ok will do, I'll purchase a 3 bar MAP sensor tonight, I do have a wide band installed, and I finally figured out where to shut off the MAF at.

Thanks for all your help.

Hello 5FDP can you check out my tune to see if I have MAF disabled, I seem to be making headway but I would like to be shure.
Thanks again.

Yes, that is right. Change two more setting for the MAF and you are done with that part. Set the Test ERT min run time from 1.0 to 0 seconds and the Enable test delay to 0 seconds.

Great, thanks, I'll run a few adjustments threw this week end and re-post results for a once over, make shure i'm going in the right direction.
Thanks Again

Hello 5FDP, I received my 2.5 Map sensor 2 days ago, extended VVE table, now in the process of tweaking and smoothing the table, I'll post log and tune results mid next week.

have to say it's running nice, I want to get into the 2% zone then I'll be happy, and tune for MAF.

Since the last post, I created 3 separate tunes, 1 VVE only, tuned till happy, then I transferred the VVE table over to a MAF only tune and tuned MAF till happy. then I transferred both the VVE table and the MAF table to my street tune which has all the sensors and down stream o2's ...

I did this up to about 3500 rpm. and the truck runs very good, steady, responsive and relatively fast for a 4 door silverado.

I would like to tune the rest of the rpm range on a dyno. steady and safe.

Thanks

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Originally Posted by CGHARING

Hello need some help Please, I attached log and tune, I installed a T76 twin ball bearing turbo on my 5.3 silverado 80 # deka injectors and sheet metal intake, turbo straight threw exhaust. the rest of motor is stock.

I'm trying to improve my tune. I tuned VVE then MAF now tweaking VVE. under 2k runs perfect. but as the log shows if I get on it, the torque went way up but the truck really isn't that fast seems like. maybe it's me but I think I'm missing something.

how can i have so much torque and not really going that fast, it also looked like spark died at 4k whats up with that.

help is greatly appreciated.

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By combining boost from efficient turbos with modern fuel injection and electronic boost control, a street car can drive around like every other mild-mannered Clark Kent, and then, just as easily, transform into a boosted man of steel. stock 5.3L short block now factory fresh (sort of), we set in on increasing the power output. By now, you should be aware that the power output of any boosted (turbocharged) motor is a function of the power output of the normally aspirated motor multiplied by the boost pressure