Fast 92, 92mm TB, and new Injectors. Car dies after reving

[ryanater]

First of all, I'm just learning HPtuners, so this might be a simple fix. However, I have been reading on this board and can't seem to find anything similar to my situation.

I have an LS1 with a G5X3 cam and PRC heads. Up until recently I had an LS6 intake with a stock throttle body. At that point I had no problems with the tune. Everything ran great.

Recently I have upgraded to a Fast 92mm Intake and Throttle Body along with 42lb Bosch Injectors (from a 3.8L supercharged GTP). Now I'm having a problem with the engine dying after reving. Both in Neutral or when coming to a stop.

I have the correct values for the new injectors, and I adjusted my RAF table by using the Desired Idle Airflow. The car idles fine with an IAC position of about 40 and a throttle voltage of ~.25V. The only problem I have is that is tries to die when coming back down to an idle after reving. I have to blip the throttle to keep it from dying.

The only way I was able to correct the problem was to set the idle set screw so that the engine would idle with the IAC positioned at 0. At the point, the engine runs normal and doesn't try to die when coming down from a rev. I'm completely baffled. The only other thing that changed when setting the throttle stop was the idle timing was retarded from 22? to 17? in order to keep the idle down. But I don't see how that would keep it from dying.

Are there any tables I should adjust with the larger throttle body? I have read the IAC effective area can be changed, but it's not a big deal.

[5FDP]

You have to completey re-tune the whole primary VE and MAF curve with the intake/throttle body and injector change.

I would start there before you jump to things.

[ryanater]

Ok thanks. I'll try that. I was trying to get my idle right before moving on to the VE tables.

Quick question: Why does the MAF curve need to be recalibrated? I'm using the same MAF, so shouldn't the existing table still be accurate?

[5FDP]

The intake is larger and holds a different amount of air compared to the stock intake and the injector size is different so there will be a different amount of air needed to obtain the same driveability as stock.

If you can make it idle without dying and run just fine without pedaling it, then you should be pretty close. If you rev the motor and it wants to die when it comes back down then you still need to make the VE/MAF better and then fine the idle area's.

[ryanater]

Ok I'll try it and let you know if I have any success. Hopefully I will get to it this weekend. Thanks!

[ryanater]

I retuned the MAF and VE tables over the weekend, and it fixed the problem when the car is stopped for a long period of time. However, when I'm driving and push in the clutch the engine will die. Or when I first come to a stop, I will have to use the throttle to keep it running.

I will keep trying to dial in the MAF and VE tables. Admittedly I don't have a wideband, so that isn't helping. But I should still be able to tune for non WOT conditions.

[5FDP]

You will only be able to ball park it with no wideband, it's still likely pretty far off with the mods you have done. It's so much easier to use an AFR error with both the VE and MAF tuning to get things spot on.

Post the tune aswell, we can tell you how far things are off.

[ryanater]

Attached is the tune I am working on.

I was able to find a tune from an engine with the same cam, intake, throttle body, and injectors. I compared my tables, and everything looked similar except the MAF calibration. But who knows what MAF the other engine was running.RyanCamaro-7-4-16M.hpt