Mikes Extended, Full Frame Goblin - 2009 Cobalt LS with 135k donor

M

mike_sno

Goblin Guru
I am at the end of my tuning knowledge. I made lots of lots of runs to tune my car, but still not able to get it to idle correct.

Here is in short what I did:
1. Calibrated MAF with Wideband
2. Calibrated MAF with Fuel Trims
3. Calibrated VE Table with Wideband
4. Calibrated VE Table with Fuel Trims
+ Some other smaller adjustments.
So far all runs well, besides the idle.

Followed up with idle only today.
1. MAF dialed in with Fuel Trims (Error <1%)
2. VE dialed in with Fuel Trims (Error <1%)

The result is attached. If I run VE only and disable MAF the engine idles just fine.
If I run MAF only the car does not idle well, but ok.
If I run VE + MAF see attached. Every now and then it goes in this weird low rpm, followed by a strong overshoot....

I wish the ECU had more parameters for idle unlocked. It feels like there is to much happen at the same time! Throttle body, Sparc advance,...

Now, I am wondering:
1. Is my MAF bad?
2. Do I have after market cams?

Any help is appreciated.
 

Attachments

Ross

Ross

Goblin Guru
Lots of heavily modified engines are tuned on VE only, and they leave MAF disabled.
Your engine runs well at idle on VE, does it run well in mid range, and top end too?
Do you care about getting the very best gas mileage you can, or it more about the smiles per gallon?
 
M

mike_sno

Goblin Guru
Yes, the rest of the tune seems to be ok. I will go to a tuner to see where the best performance is, but I kind of want to keep the MAF enabled.
 
Ross

Ross

Goblin Guru
For the LSJ, there is a setting in VCM editor that is used to set what RPM the engine uses when switching between VE and a blend of MAF/VE.
Been too long for me to remember exactly where that setting is, but remember some youtuber talking about it.
Maybe playing with that can help you get it to idle, while still keeping a blend of MAF/VE for the rest of the RPMs.
 
M

mike_sno

Goblin Guru
Yes, I saw that setting. But its from 0-3500 rpm you have VE + MAF and above that only filtered MAF (According to goar ropes video). So it's essential the opposite. Low RPMs have VE, high rpm MAF.

But I could be wrong. the VE table has a lot more fields... maybe in case the MAF fails. Not sure.
 
Ross

Ross

Goblin Guru
From what I remember of the Goat Rope Garage videos, MAF is used when the engine is at steady state, like going down a highway. VE is used when quickly changing RPM. The ECM calculates both formulas, and often a blend of the two are used.
I think you are right, low RPM, like idle, are VE only. Strange that disconnecting the MAF makes your engine idle better, as I thought it was VE only at that point.
 
Anks329

Anks329

Well-Known Member
Ross said:
Lots of heavily modified engines are tuned on VE only, and they leave MAF disabled.
Your engine runs well at idle on VE, does it run well in mid range, and top end too?
Do you care about getting the very best gas mileage you can, or it more about the smiles per gallon?
Click to expand...
For the most “smiles per gallon” should we disable the MAF and run in VE only?
 
Ross

Ross

Goblin Guru
Only if MAF is causing you problems. Otherwise leaving it stock can give you the best of both worlds. MAF for steady state, VE for quick transistions.
 
M

mike_sno

Goblin Guru
Not sure what this is, but I read at the ETC Area Scalar has something to do with the idle. Played around with it, turned out that if I increase the number the idle up and down gets worse, if i lower it, it gets better. Stock was 2950 I am at 2300 currently.

49240

Changed the idle base spark advance from around 9deg to 1deg and reduced the over and under rpm spark a bit. Idle is better, but still not ideal. It was to late and mosquitos came out, hopefully tomorrow I can get it to idle perfect.
 
M

mike_sno

Goblin Guru
Received the LS4 TB today with the Adapter from ZZP. Now I am looking for a new intake pipe and a 90deg. Seems like it's 3.5in diameter. I read somewhere that the MAF should be located after a few inch of straight pipe, but can't find the exact value anymore. Anyone knows that by chance?
 
M

mike_sno

Goblin Guru
And another question will those Silicon 90 deg elbows with ID 3.5" fit on the LS4B? I measured the diameter at 3.38".
 
Robinjo

Robinjo

Goblin Guru
Probably since it’s less than 1/5 of an inch, but can’t you just remove the arm and test fit it? My intake comes off with 1 band clamp and unplugging the MAF.
 
M

mike_sno

Goblin Guru
Robinjo said:
Probably since it’s less than 1/5 of an inch, but can’t you just remove the arm and test fit it? My intake comes off with 1 band clamp and unplugging the MAF.
Click to expand...
I can once I ordered them. Currently I have only the TB and ZZP adapter.
 
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