GroupA242

Finally some answers!

iDash AFRs
I was at least able to make two logs with the current tune, over about 40 minutes of driving total with VCM Scanner. They both revealed what I was suspecting recently: the iDash for some reason is displaying the AFR backward (or at least incorrectly) from the actual value. With WOT I am showing nearly solid 0.82 - 0.83 lambda all through the RPMs.

14.7 x 0.82 = 12.05 AFR.
14.7 - 12.05 = 2.646. If you add that difference back to 14.7 = 17.346 which is around what was showing on the iDash at WOT. So it really looks like iDash was showing the inverse of what was happening. Then when coasting in DFCO range the lambda shows 1.99. So again, the iDash would show 7.3:1 in this scenario, which looks like it was just "pegging the needle" on the rich stop instead of the lean stop. I have reached out to Banks about this and will update when there is something to share.

Timing around 9-12* BTDC (increasing with RPM), and almost no KR at all. It only showed up with part throttle at low rpms in 1st and 2nd. I thought that was a strange place for it but it was barely more than a full % point. I'm sure that can be smoothed out easily. Of course there is lots of other data but those where the high points I was looking for.

Writing over the Trifecta Tune
ZZP sent me a file to use, I went through the steps but when attempting to read the ECM again I got the same Reader upload request :x7F negative response code error
So I am waiting for what they want to do next. The car did still start though, so it does not appear that anything was "bricked."

fst100

hopefully iDash fizes this issue and just simply need to just download an update to it. regarding the pcm issue, sounds like it needs to be reflashed back to stock to overwrite the trifecta tune. i recall that requires a tech2 or something similar and might be costly from the dealership. i dont know if zzp offers something like that or not.

edit-12.1AFR and 9-12* of timing is rather on the rich side even on pump gas for a DI engine.

GroupA242

iDash- I hope so too.

PCM- turns out I missed the critical step of setting the command to “Write Entire.” Once I did that it worked. I am currently sitting here watching it read the PCM now (no more x7 response code)

Current tune- yeah that is what I understand. And that makes sense considering the old list of mods I had for this car. Since all of them are gone but the exhasut and the upgraded ZZP intake elbow, it was definitely not optimized. With any luck ZZP will send me at least one revision today after I get them this base file.

fst100

ok sounds good. if you end up buying the hptuners and laptop, which might be a good idea, then feel free to ask myself or anyone else in this forum on tuning questions.

GroupA242

So far so good. What are some things you can do to really optimize the highway cruising portion of the tune? I can easily spend 3/4 or more of a trip at 80 mph in 5th gear.

fst100

log and scan MAF freq/lb gs, %load, throttle %, spark advance timing, RPM, MPH, AFR demand, KR to name a few. then look over the scans on where you can either lean the fueling or add (gradually and slowly) more timing where you're cruising to max mpg. check out the hptuners forum and under the 4 cyl section for LNF related threads alot of helpful material on there.

GroupA242

So, after my initial post here and then an email to Banks on the 23rd of March, then a phone call, and two follow-up emails they responded yesterday (4/18): Menu Button > Settings > Units and Density > Air Fuel Ratio > AFR Gas > AIR:FUEL. For some reason, out of the box it was set to FUEL:AIR so it was effectively reversed of what would be expected when you read an AFR gauge....... This detail is not found in the Settings section of the iDash user manual, so I feel a little better having looked but not found anything before. So, now we know.

As far as the tuning, I guess I am glad I got that done. Though, knowing it was just an indication problem I would have been happy leaving it alone. Surely it runs a little better now after being optimized for the current setup. But now I have a bad idle surge on cold start that was not there before. I kept the interface but sent the laptop back so have no way to log it . I definitely called it out on the last few scans but they only changed other stuff or said "looks good."

fst100

if you already have a laptop just download the latest version and install it on there or get a new/used laptop. that way you can scan and record new logs and make edits and ask zzp to send you the before and after tune files.

GroupA242

I only have a Macbook, and it is from work. I already asked about using boot camp to run Windows and they said it would have to be work-related, so that is not an option.

I did save all of the logs I took, and the tune files made during the tuning process onto a USB drive, so I can reference them later. I'll just need to keep an eye out for a cheap windows machine to grab for tuning only. However, I also have the car for sale now, due to us inheriting another vehicle from family. So the Cobalt will be leaving us I'm afraid....