Supercharged LAP tuning thread

[Dsteinhorst]

Now that there's a solid handful of supercharged LAP Goblins, I'd like to start a thread for their specific tuning. I'm having an issue right now and would like to see how others have handled it.

My donor was a 2009 G5. Has an M62 supercharger with 2.9 pulley, dual pass and 42lb injectors.

I originally took my car to a tuner, and it ran okay, but was in PE all the time on the highway (XFE tall ratios.) Also had vac leaks and I was running on the factory MAP. It was running a MAF only tune.

Fast forward. I'm running an LSJ TMAP and have done MAF and VE tuning a few different times. It runs and drives pretty well, but skews lean in boost when MAF and VE are on. If I'm running MAF only or VE only, no lean condition; runs great.

I had to build/re-zone the VVE table by hand after swapping to the TMAP because the factory table ended at 105KPA. I suspect there's something wrong with a coefficient or calculation somewhere, but I can't find it. My tune and a quick log are attached. This is a work in progress, so feel free to critique.

Other supercharged LAP guys and gals, feel free to post tunes/logs if you feel appropriate. At this point, mine is completely my own. Everything in there, I learned on Goat Rope Garage for free and I'd share my learnings in a heartbeat.

 

[Ross]

Now that...

I originally took my car to a tuner, and it ran okay, but was in PE all the time on the highway (XFE tall ratios.) Also had vac leaks and I was running on the factory MAP. It was running a MAF only tune.

Fast forward.
...

What does "in PE all the time" mean?

 

[Dsteinhorst]

What does "in PE all the time" mean?

It was set to be in Power Enrichment above 75 kpa. With my tall ratios, I was above that at 60 MPH in 5th virtually all the time.

 

[jirwin]

Here's my latest tune. Idle needs work still, along with letting the revs fall to idle after accelerating.

2010 LAP 2.2l
M62 supercharger 3.1 pulley
DF Heat Exchanger, no NACA, only fan
ZZP upgraded intercooler pump
Dual pass and Phenolic Intake Spacer
80# injectors
LSJ TB
3" intake
2" DF exhaust with eBay Chinesium header
Tuned for 93

Hope that helps

 

[Dsteinhorst]

jirwin, thanks for posting. Looks like you're running a MAF only tune (above 1200 RPM.) Did you do the tune or did you have it done? Did you ask your tuner about the VE table?

A good VE tune helped my rev fall a lot. Would probably help your idle too if it hasn't been done since your MAP sensor upgrade. 80s are big injectors though. I see your ETC area scalar is set around 2670. The stock LSJ is 2950, and having it there seems to keep the rev hang down for me.

Your PE mode is interesting that min MAP is 55kpa and the TPS is stepped.
You can turn off COT since you don't have a CAT.

Check your Chinesium header for cracked welds. I found one today on mine.

 

[jirwin]

I am in the process of ZZP remote tuning. I will have to ask about VE.

Most of the rest of that is gibberish to me, but I'm keen to learn. I will check all that out. Thanks

 

[jirwin]

If it interests you I have the first 3 revisions too

 

[Ross]

Checking your header for leaks is important. Any exhaust leaks will ruin your tuning data, and make your custom tune a waste of money, potentially making your engine run worse.

Hang a cotton ball (or feather) on a string, and dangle it around your exhaust, when the engine is running. Check if any exhaust air moves the cotton ball around. Check for soot exhaust marks near any gaskets. My cheap header caused me to waste 6 months of tuning, and the stock cast exhaust header mades the engine run much better.

 

[Dsteinhorst]

jirwin, please do ask ZZP about a VE tune. I'd be curious to see what they say. They clearly have it set up for idle quality, but there's a reason they don't use it above there.

I haven't found much other information regarding the issue I'm having. I think i'm going to sign up to get assistance from Goat Rope Garage. Until then, I'm making sure my exhaust is sealed and will try VE tuning the crap out of it.

My chinesium header also has a banana for a mating surface. I'm going to see if I can chuck it in a mill and fatten it.

 

[jirwin]

Will do, let me know if you have any other questions. I'll email back this weekend after I get a couple more logs.

 

[jirwin]

Are you running the Chinesium gasket too? Mine was this thick (for a gasket anyway) shiny material with evenly placed small circular indentations in them. I think I'm running that but I can't remember why.

 

[Dsteinhorst]

Yes, it was pretty much the only option I had because my donor had SAI so there's a bunch of extra ports in the head. The other manifold and gasket options didn't cover the ports.

 

[Dsteinhorst]

Someone on the HP Tuners forum turned me onto a timer setting for the MAF fail frequency. This is from jirwin's tune, but mine had the same value.

This timer is set for just over three hours stock, which is longer than any of my runs.
The way I was running VE tuning, I would set the fail high frequency to 100, so it would fail "immediately."
My theory is the timer prevents the test from running, so the car is still calculating airflow using the MAF. It would explain inconsistencies in my VE tuning results.

I set the timer to 20 seconds (matches my wideband timer) and will give it a test when I get the exhaust back together. Hoping to have good data by Wednesday.

 

[jirwin]

Haha... well... slight leak

I ordered new studs since mine are pretty old and rusty. I also found out that the nuts for the studs are oval-ed like the axle nuts to help keep them on, so I figured they would be worth replacing. I figured right. Half of them were finger tight (I know I tightened them before), and one had even fallen off. So I looked around and found these online: https://www.dormanproducts.com/p-132535-03422cd.aspx

2010 Cobalt 2.2L was specified as compatible...

They are the right thread and all that but the issue is the position of the... what do you even call it? The break in the stud? The part where there's no thread. Here is a comparison of the old stud and the new one:

The new ones are a bit shorter before they hit the non-threaded part. I don't think this is a concern - they will just not go in as far, but will function the same otherwise. Do you guys agree?

 

[Gtstorey]

Might be a slight concern since they go into an aluminum head and fewer threads mean not as strong, assuming the original studs came close to using all of the threads. Check the depth of the hole and see how much depth is available. You can always switch to bolts.

 

[jirwin]

Upon closer inspection, on the head side the thread length is the same. The old stud just has a taper after the threads. So I should be ok

 

[Dsteinhorst]

I had that exact thing happen. Must be the pressed metal gasket. I had to take .035" off my manifold flange to make it flat too. I'm picking up new studs tomorrow.

 

[jirwin]

I used a 2 piece Felpro just now. Seems to have worked better. I used to have a tick on startup, which I now know was just an exhaust leak. After it warmed up it probably closed. It started up nice and quiet now. Even idles a bit better. Thanks for making me check guys

 

[Dsteinhorst]

Well, I tried to run in just VE mode by unplugging the MAF sensor and it wouldn't idle. Would run if I held the RPMs higher. Was running pretty lean so I scrapped that idea. This does tell me the MAF was still working into the airflow calculation previously as I suspected.

ZZP indicated to jirwin they don't trust the VVE tool to make the necessary changes to run under boost. I disagree, since LS guys do it regularly, but I have more work to do on my end to get it to work.

One upside. The car felt truly gutless at low-moderate throttle in the 75-100 KPA range. I took out a whole bunch of intake cam timing in that area, and it was like a flipped a switch. My car was an XFE model, so it had a lot of overlap in to reduce the volumetric efficiency and save gas. Getting rid of the overlap really helped. May have to dial back the ignition timing a bit to make up for the higher cylinder charge. That sea of 10s below was high teens and mostly 24 degrees.

I put the 2" exhaust back on, and the reduction in noise was really nice. I did end up pulling 10%+ of fuel at higher MAF readings, though showing that it had a pretty big effect on airflow. I'm still planning my long-term exhaust solution, but I know the 3" is too loud.

As always, more work to do, but it's running pretty good with a MAF only tune right now.