Hi, as the title suggests this is my first time doing real tuning. I purchased HPTuners with the MPVI2 about a year ago or longer, to do some tuning for an idle issue I had. I had a friend who knew more than me help me, and we got that issue resolved. I don't know how spot on the tuning really is, but the car idles and runs pretty good. It is a 2006 CTS-V LS2 with a TSP 402 stroker, TF as cast heads, BTR4 cam, Fast 92 intake, headers, other supporting items, etc. I've been watching various videos on the tuning subject, and certainly have a long way to go. The good news is I am knowledgeable and have a very good understanding of how everything works at a high level. I'm hoping to get a few quick answers to help me keep on keepin on. It was a big leap for me today actually making adjustments and writing to the ECM, etc. I'm excited that it seems to be going well (haven't blown it up yet...).
I actually started doing some MAF tuning today and it has been going fairly well. I've mainly been following goat rope garage videos. I purchased an AEM X Series 30-0333 (with the OBD2 pass through) and it pulled up in the scanner just fine. When I went to do the maths to create the MAF error ratio I was not able to locate that wideband. I found some other signals that seem to work (generic WB) and they appear to be giving the correct data. I was wondering if anyone could confirm I have this setup correctly, or if there's some other way to pull in that WB for the math? Here is what I'm using:
100 * ([50127.238] - [50118.238]) / [50118.238]
50127 is EQ Ratio #1 [Sensor]
50118 is EQ Ratio Commanded [Sensor]
I found a few other threads where people had similar issues with this particular OBD2 pass through WB but couldn't really find a concrete answer. This seems to be reading correctly, just would like it verified.
When I first started tuning the MAF, I may have made a mistake... I started data logging with a cold engine. It didn't occur to me until later that the ecm will adjust fueling based on ECT, so this may not be accurate data. I'm not 100% sure I'm thinking correctly about this though. Should I only log with fully warm engine?
What was strange, though, is that when I fired it up, it was not running rich, it was about 17% lean at those couple idle airflow cells it was hitting on the MAF. I stopped there and multiplied the entire MAF table by 1.17 trying to get it to 0. Then it was rich, maybe 8 or 10%. I drove and logged from here on and did about 10 iterations of this (multiplying MAF table by % half) and repeating. It seemed to get better and better every time, and the car drives fine (can't tell a difference really). The only issue I had driveability wise was that first time when it was super rich it didn't like low rpms, it was wanting to stall a couple times.
So, I had let the car sit and cool off, then drove home doing another log. It was again very lean at startup. I let it fully warm up then restarted my log. It was still a little lean in most areas but only a few percent. It just seems odd that it was rich all day then after sitting it went lean. Is there something I may be overlooking being that I'm new to this?
I should also note I have decel fuel cutoff disabled, clutch in fuel cutoff disabled, I removed 5 deg base timing from entire table, and apparently my car was tuned MAF only (dynamic airflow disable rpm set to 400), so I didn't have to force it out of speed density. I also turned off closed loop by raising O2 Readiness ECT higher than actual operating temp.
The only real issue I've noticed through all the tuning today was that after making the changes and writing the tune to the car, the car was very hard to start almost every time (a couple times I really thought it wasn't gonna start). It cranked like it was under a lot of stress. I'm not sure if it has something to do with the tuning or what. The car always was slightly harder when it was hot, but not this bad.
Any help appreciated. I'm sure this is all covered somewhere, and I've been watching videos. It'll just take time/practice/experience. I have a pretty good grasp of the MAF that's why I started with it. I plan to eventually learn how to reenable SD on my car and tune VVE tables but right now I'm just not there.