E84 Chevy Spark, General Guidance

[[email protected]]

Hey guys, Been trying to learn how to tune this car, Maybe you guys can help me out a bit.

Right now i have multiple problems; Mainly possible false knock, VVE table needs more work, Idle negative advance, and strange rpm surging and falling under moderate to heavy throttle.
I'm pretty sure the knock is false, i put the stock low octane table on it and it still told me to pull timing three times before i quit lowering it. Tried making knock sensors less sensitive. I'm
concerned to desensitize them more.

No idea why idle is getting negative advance. throttle issue might be virtual torque issue or driver demand. Any info helps thanks!

Mods: Cold air intake, custom setup. MAF is sitting in a 3" pipe instead of a 2ish inch one. Throttle Body is still a bottleneck.
Muffler gone, CATs gone, Rear o2 replaced with wideband.

[Sith]

Ok, when I try to look at the tune it says validate checksum failed. BUT, Convert it back to stock and tune the MAF not the VVE. The MAF is only seeing the 6 lb/min which is insanely low.

[[email protected]]

Ok, when I try to look at the tune it says validate checksum failed. BUT, Convert it back to stock and tune the MAF not the VVE. The MAF is only seeing the 6 lb/min which is insanely low.

I believe you need to have the most recent beta to read my os. I just noticed that, according to the maf calibration the units need to be changed to lb/h not lb/min. Those numbers look more correct. I just changed that in my scanner. Heres a more recent short run I did today. Messed with fueling and definitely have some lean spikes i have to iron out on the way home from work. Fueling is annoying on this thing lmao
short run.hpl

[Sith]

Ok, I downloaded the Beta and had a look at your tune. I first compared the stock tune and modified tunes you provided. Is the stock tune actually stock to your car and did you make all these changes yourself? There are alot of tables that do not need to be changed at all for you current mods. I would start over with a stock tune and start by tuning the MAF. There are plenty of guides out there to start MAF tuning on a basic level.

[[email protected]]

Yeah the one that is stock was read right off the ECU. some of the stuff I have changed just for drive ability and better performance. I can try putting the stock tune back on and see what happens. It wont even crank with the stock tune because how far off the afr is so ill have to do some guess work. I have verified I have no vacuum leaks so that is a plus

[Sith]

It should crank with the stock tune but I assume you mean it wont run. This is due to the MAF being so far off with the much larger diameter tubing it is in. If it is actually a 2 inch tube stock and it is now a 3 inch tube now, I would start by multiplying the entire MAF table by 2.25 IF the measurements are correct. That is just to get it running. Someone can correct me if I am wrong there.

[sprinto7]

[QUOTE=

Mods: Cold air intake, custom setup. MAF is sitting in a 3" pipe instead of a 2ish inch one. Throttle Body is still a bottleneck.
Muffler gone, CATs gone, Rear o2 replaced with wideband.[/QUOTE]

******From my limited experience I think you can get close to resetting your MAF table by comparing the size (area) of the original MAF tube to the New area 2"-3" and multiplying the old table by the increased percentage. if new tube is 1.25 times larger multiply the entire table by 1.25. it may not be perfect but it should start and run.

Del I'm not a tuner Long ******