I was really hoping that my fist post wouldn't be a "newbie needs help" post, but here we are. My 14 year-old son races a 1991 Camaro Z28 in the IHRA teen series at our local strip. He bought it on his own, and has upgraded it with (mostly) his own money as well. The class is limited to 9 sec 1/8 mile, so it's a street car class. We pulled the 305 TPI out of it in November and started our swap. Most of it went well, with a few items that we had to figure out along the way. The engine is a 5.3 from a 2003 Tahoe. Due to hood clearance issues, we swapped the truck intake for an LS1 intake, with rebuilt LS1 (I believe they are the 28 lb/hr version) injectors from South Bay Injector. We are running generic return-style Summit fuel rails, with a Gen 4 Camaro tank and pump. The only other mods from the stock 5.3 are a "Frankentake", consisting of a 6" Spectre filter element, 4" tubing, with a Vortec 5-wire truck MAF in the middle of the straight section of tubing. The car has Speed Engineering long tube headers (1 7/8 primaries and 3" collectors with a merge spike), and Speed Engineering 3" exhaust. There is an X pipe, and bullet-style mufflers that dump just ahead of the rear axle (no cats). Transmission is a rebuilt 4L60E, with a couple of minor upgrades.
I did the wiring (lots of automotive wiring experience, so I was up for the challenge). I thinned out the stock 2003 harness, using pinouts from LT1Swap.com, and also integrated the harness into the Third Gen Camaro harness. It was a pain, but I am very confident in the quality of the connections, and in the accuracy of the pinouts.
Now for the tuning portion... I may have screwed up with this approach, but I just read the stock PCM, and created a tune file based on that reading. I deleted VATS, Evap stuff, EGR, COT protection, etc. The car fired up on the first try - well, technically I had to replace a bad starter first, but that doesn't count, right? It fired immediately and idled well with the base tune. We took it down the road, and it had some major hesitation and stumble, and smelled really rich. I've been there with a carb'd SBC before, so I recognize a lot of the symptoms. After doing a bunch of research, I changed the injector info from the stock tune to injector values from an LS1 tune. It was just a stock tune out of a Firebird. I didn't like the slope of the VE table in the Tahoe tune, so I also changed over to the VE table from the LS1 tune. The car runs reasonably well just after starting, but shortly after becomes really sluggish and stinks like raw fuel. I'm guessing that it's still way too rich. I haven't been able to get decent log data yet, just up and down the driveway. I don't want to take it back on the road until I can get it to quit bogging and lugging in gear. I noticed earlier today that my O2 sensor readings are doing some really odd stuff. In the attached log files, the sensors are reading similar voltage, then they suddenly diverge. The Bank 1 sensor goes really lean, and the Bank 2 sensor goes really rich. I'm thinking that there may be an issue with the Bank 1 sensor, which is causing the PCM to think the car is lean, and dump a ton of extra fuel. That's just an educated guess on my part. I need to swap the sensors to see if it is a sensor problem, or if something else is going on.
I'm not new to cars, and I'm not new to computers or software (I've worked in IT and for software companies for over 20 years), I'm just new to tuning and HP Tuners. If one of you tuning wizards has a few extra minutes, I'd really appreciate a second set of eyes on this. The plan was to get the car to the strip for test and tune this weekend, and I'm behind schedule. I need to try and get it straightened out by April 1st, which is opening weekend. I'm pretty confident that most of the issues are in the tune, as it seems good mechanically. Thank you in advance to those of you who are willing to share your knowledge!
-Chris
9 - Camaro F body MAF Table 2.hpt
Poss Bad O2 Sensor.hpl
Camaro.Channels.xml