TXjeepTJ

iTrader: (8)

Swapped a LS2 24x into a 1970 Chevelle, having an issue where when you take off a little hard the engine almost dies (the harder you take off the more the engine wants to die). Scanning it with HPTuners, I can see that the timing drops to zero the same time this issue occurs.

Anyone know what this could be?

Scan file and tune attached

JoeNova

Look into abuse mode.

TXjeepTJ

iTrader: (8)

As a last resort, I disabled it to see if it would prevent it - it still had the timing drop the same way (I don't have a scan of the drop after I disabled it)

ddnspider

iTrader: (26)

is burst knock turned off? what about torque reduction/torque management in both the engine and trans section?

TXjeepTJ

iTrader: (8)

Yup, I was getting burst knock, tuned it out - it helped a little, but it's still bad since it drops down to pretty much 0 advance. I also believe I removed torque reduction in both areas

ddnspider

iTrader: (26)

hmmmm....and I assume its not picking up knock?

TXjeepTJ

iTrader: (8)

Not knocking at all, it doesn't even have a chance to knock - right when you hit the gas and go past 50% throttle, timing immediately drops to zero (or around there)

dw456post

Is there a reason that you have rolling idle disabled? Also, your MAF table looks high? Your Primary VE table needs some work.

ddnspider

iTrader: (26)

rolling idle has been disabled in most factory tunes i've looked at.

TXjeepTJ

iTrader: (8)

I wasn't aware that rolling idle was disabled, the tune was originally for a 6 speed manual, then did an 80E segment swap. Maybe on manual transmission rolling idle is disabled? Would that affect timing though?

This is an SD car only, so it doesn't have a MAF

How do you know the VE table needs work? We've been trying to get it dialed in, but after doing paste special - 1/2 percentage, the car goes super lean, and I know the numbers are right (only taking out about 2% from VE results in a 15% lean..) not sure what is going on. That is a whole different issue though..

JoeNova

This. Its usually disabled, even in 6 speed tunes. I always have to enable it when tuning really big cam stick cars that start to choke out when coming to a stop.

dw456post

If this is an SD Tune, you need to go to DTC's and make P0101, 102,103 MIL on 1st error and uncheck the boxes if you don't want the dtc light on the dash.

dw456post

Your IAT's are stuck around 180 degrees. Where is your sensor? Is it part of the MAF that you removed?

dw456post

And go to Airflow--Dynamic and make the disable 8,000rpm and reenable to 7,900rpm

TXjeepTJ

iTrader: (8)

That was done in the tune

The air filter is right off the throttle body, I cut the MAF plug, and hard wired a stand alone IAT sensor to the two wires for IAT from the original MAF wiring. The IAT is located right in between the air filter and throttle body.

IATs are high, probably due to it pulling in all/or some of the heat from the radiator, but it was also 110 degrees outside that day..

I didn't know this was needed in order to go into SD mode, I thought I just needed a failed MAF. I will make this change. Thanks!

TXjeepTJ

iTrader: (8)

I think we didn't run into this problem until I did a 4L80E segment swap on the PCM. I need to really dig into the transmission settings and see what can be pulling timing. I think that is where it will be


Does anyone know if Timing can be affected if AFR is way off? If engine starts to die, could the PCM be telling it to pull timing via an idle parameter or something?

dw456post

Go to your first post and open the tune, go to Engine diagnostics--DTC's and look at P0101,102,103 and tell me what it says

TXjeepTJ

iTrader: (8)

Oops!! But still, with no MAF present at all, it would still go into SD mode, right? I'm going to change it to on first error still though. Thanks for catching that!!

dw456post

Nope, gotta have them set to fail the maf

Russ K

iTrader: (1)

Coolant temp & Intake temp tables are retarding the spark timing. And your fueling is lean everywhere.

Russ Kemp