Anyone want to look over a 5.3 tune for my son's drag car?

[1991_z28_5.3]

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

[1991_z28_5.3]

I figured I would add a couple pics of the car and the engine, because why not?
123_1.jpg

IMG_3855.jpg

IMG_3856.jpg

IMG_3857.jpg

[2xLS1]

I can't look at your posted files but just a few things. A 03 Tahoe would not have had EGR but you said you deleted it. A 5.7L LS1 Firebird (Trand Am) would have had a returnless fuel system and you are using a return you said so it's unclear what your fuel rail is. Where is the regulator? Injector tables are set up different for return and retuenless fuel rails. Have you verified fuel pressure at the rail? And from 98-02 F-bodies used 3 different injectors so unclear which ones you have. What are the numbers on the injectors. And it is still a 5.3, not a 5.7 so using the 5.7 VE to start with was probably not the best thing to do.

[1991_z28_5.3]

My bad on the EGR statement. I must have been thinking about the block off plate that we installed in the LS1 intake. The injectors are 24 lb/hr Bosch. South Bay Injector lists them at 26.2Lb @ 43.5 Psi / 3 Bar GM Base Pressure(gas). The 4th Gen tank came from a 2000 Z28 (LS1 car) and has the stock GM fuel pump and regulator. The tank setup indicates that it was a return style fuel rail from the factory. There?s a feed line and a return line from the tank. I haven?t measured fuel pressure at the rail, mainly because I don?t have a pressure gauge with a -6 AN adapter. Fuel lines are -6 back to front. I technically used a 5.3 VE table to start, but decided to try the LS1 table because the map looks more linear.

[2xLS1]

Kind of pointless to go any further until you verify fuel pressure at the rail and the actual injectors you are using. 98-02 F-bodies used a quasi return fuel system but the return was from the fuel filter that was mounted about a foot in front of the tank. It did not return from the rail. It was a standard fuel filter unlike the Vette fuel filter with the built in regulator many use on swaps. The 99-02 fbodie's regulator was part of the fuel pump assembly. That injector description does not sound correct for any LS1 injector. 98's were 28.6, 99-00 were 26.4, 01-02 were 28.8 all @ 4 bar or 58 psi. Which is the fuel pressure you should have at the rail with the regulator in the tank. A 26.2 @ 3 bar becomes a 30.25 @ 4 bar.

[1991_z28_5.3]

By way of a small update, I heard back from South Bay Injector today. I'm not sure that it's what I wanted to hear. The injectors that I purchased, listed as LS1/LS6 injectors are actually OEM Ford. They are Bosch DIII Injectors, part number 0280 155 715
Supposedly rated at
24LB at 39.15Psi (apparently that's Ford pressure?)
26.8LB at 43.5Psi

Pretty much everywhere that I can find them listed, shows them as 24 lb/hr. I don't know what to think.

They also sent a data sheet, Bosch Injector Data.pdf. There appears to be some good information in there, but it's all listed at 39.15 Psi, not at a standard 2 or 3 bar pressure. I'm not sure how to correlate that to the 4 bar GM pressures, or if that data is even relevant to my engine. I'm starting to think that this was not the smartest use of the budget on this swap. I've found some cursory references to guys successfully using these injectors on an LS, but what I found is pretty light on details.

On the fuel pressure front, My -6AN gauge adapter arrived today. The fuel pressure gauge should be delivered tomorrow, so hopefully I'll know whether I have 58 psi at the rail on Friday. I have to fly to NY for work for a couple of days, so I won't have a chance to install it until then. I'll post back as soon as I know more.

Thanks for reading!

-Chris

[04silverado6.0]

Here is your correct injector data.

[1991_z28_5.3]

Thanks 04silverado. I’ll get that injector data added to my tune today. Out of curiosity, was that a tune that you already had, or did I miss a resource on the forums/HP Tuners site? I searched the tune repository and it didn’t seem to have anything applicable. I’m still finding my way around the site and forum, and want to make sure that I’m taking advantage of the available resources without bugging the membership too much. I really appreciate the injector data!

[TheMechanic]

24 pound injector will not cut it on anything that isn't bone stock from fan to tailpipe.
Without re-posting a TON just do a search on 12613412 and 12609749

[1991_z28_5.3]

TheMechanic - thanks for the input and for the search terms. I’ll take a look at the search results. Just curious here - are they still considered 24lb injectors when they flow more than 24 lbs at the regulated fuel pressure?

[kevin87turbot]

TheMechanic - thanks for the input and for the search terms. I’ll take a look at the search results. Just curious here - are they still considered 24lb injectors when they flow more than 24 lbs at the regulated fuel pressure?

Those injectors should flow 29.2 lbs/hr at 58 psi. They should work for your application.

[1991_z28_5.3]

Thanks Kevin. I was starting to dread the “we need another part” conversation with my wife. LS swaps are supposed to be cheap and easy. Every magazine, website and show on Motor Trend on demand says so!!

[ctsv2011]

have a set of 33# injectors out a flex fuel L59 5.3
if you ever step it up with more bolt ons or a cam
$25 bucks buyer pays shipping

[1991_z28_5.3]

have a set of 33# injectors out a flex fuel L59 5.3
if you ever step it up with more bolt ons or a cam
$25 bucks buyer pays shipping

PM sent

[04silverado6.0]

I had the data in excel format I just copied it into the tune you posted. That should be plenty of injector to run your setup currently but probably not with a camshaft and intake swap.

[1991_z28_5.3]

04Silverado - I appreciate it. I made adjustments to the tune and emailed it home. I travel for work all the time, and I’m. In upstate NY right now, but my son was able to load the tune and give it a shot. I was on FaceTime and it sounded like it was idling better, and my son said it smelled leaner. I’ll get the fuel pressure gauge installed on Friday to verify that I have proper pressure. I’m going to check for any I take leaks on Friday as well. Im hoping to get the idle and driving characteristics stable enough to log some data on Saturday. Im shopping wideband sensors, since I know that’s coming. I feel like this is a “baby steps” process, where there are multiple things contributing to the issues. It seems like I’ll just have to identify and fix them one at a time.

[1991_z28_5.3]

We had some time to look at the car. I got a fuel gauge installed, and I'm reading right at 58lbs at the rail, so that's good. We had some concerns about vacuum leaks, so I smoke tested the intake. It wasn't definitive, but we went ahead and replaced the intake gaskets and torqued to spec in the proper sequence. The gasket set that we used came with the paper style gaskets, and I didn't like them, so we did new Fel Pro o-ring gaskets.

After straightening out the gasket situation, we went ahead and tried to fire it up. The idle seems a lot leaner with the new injector settings (thanks again 04 Silverado!). It used to burn my eyes, and made awful black sooty spots under the turndowns. Now, it smells a lot less like fuel, so that is good. The idle had some backfiring, so we checked plug wires and had a couple of loose ones. After fixing those, it idled well... until STFT kicked in. For some reason, the O2 sensors go nuts after a short time. One bank appears to go way lean, the other way rich. I've seen this before. Originally Bank 1 would appear lean, Bank 2 rich. Swapped the O2 sensors side to side with no effect. I was expecting that Bank 2 would appear lean (bad sensor), but it didn't work that way. Now, Bank 1 goes way rich and Bank 2 way lean. It's the outcome that I was expecting last week when we swapped sides. I need a wideband to help confirm some of this, but my working theory is that the super rich condition fouled the sensors. They were new OEM replacement Bosch sensors, installed when we did the swap. I've read mixed things about Bosch sensors in swaps, and I'm thinking about replacing them with new NTK sensors. Any advice there?

I've attached the latest version of the tune, and the 2 most recent log files along with the configs. I'm not comfortable enough with the idle performance to take it for a drive, so the log files are short. I disabled STFT in open loop, which helped the idle a lot. With STFT out of the mix, it seems to idle well. If they are enabled, it starts backfiring and seems rich. Of course it decided to go to closed loop as soon as I got all of this sorted out, and predictably things started going a little haywire so we shut it down.

I could use some advice on the VE table. I have 2 versions of the tune, 1 uses the truck VE table, the other uses a 2000 LS1 VE table. I can't really tell much difference between the two yet, but the decision to use the LS1 VE table was based on some threads here. The idea being that the LS1 intake flows much differently than the truck intake. I know that the 5.7 VE table will be a little rich on a 5.3, but it can be leaned out later. Do you guys have some thoughts on which way to go? Thanks!

Chris

[2xLS1]

The B1 and B2 harnesses are probably swapped. (laid out on the wrong sides.) You can verify this by unplugging the drivers side O2 and see if the log for B1S1 shows 450 mv. If B2S1 shows 450 mv then you know the harness is swapped. I've been using Bosch O2 sensors for years with no issues.

[1991_z28_5.3]

Glad to hear the Bosch sensors are working for you. I’m pretty positive the wiring for the O2 sensors is correct, but the wiring harness was not moved around when we swapped sensors side to side. The way the harness is laid in, it’s not even possible to mix up the plugs. There are headers and a transmission in the way from that happening. The (O2 sensor reported) lean condition from bank 1 is now happening on bank 2. I think the only right answer here is either replace the narrowband O2 sensors and see what the new ones read, and/or get a wideband in there.

[kevin87turbot]

Glad to hear the Bosch sensors are working for you. I’m pretty positive the wiring for the O2 sensors is correct, but the wiring harness was not moved around when we swapped sensors side to side. The way the harness is laid in, it’s not even possible to mix up the plugs. There are headers and a transmission in the way from that happening. The (O2 sensor reported) lean condition from bank 1 is now happening on bank 2. I think the only right answer here is either replace the narrowband O2 sensors and see what the new ones read, and/or get a wideband in there.

2xLS1 is correct. The sensor harnesses are switched side to side. If they were fouled, they would typically not work at all. Yours are working.

Here's a quick test to prove it. Just disconnect the DS sensor. Then start the car. If they are switched side to side, there will be a DTC for the passenger side sensor.