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

[1991_z28_5.3]

Nice diagram, Alvin! I hope that will help someone who comes along later.

[2xLS1]

Ground = Earth !

I'm well aware what earth means. It just reads so odd when I see people use that term when it's not used here.

[GHuggins]

According to the last logs you posted it's controlling fuel on the correct banks now, so I would say either a misfire on bank1 which it appears too lean for, an injector not firing - which is possible, but again should show as a misfire or just a large vacuum leak, but one that big should again show as a misfire or effect both banks and not just one. It may even have the wrong injector connectors going to the wrong injectors causing them to fire at the wrong times. That wouldn't necessarily show as a misfire, but would greatly effect fueling. There was a tsb at one time for plugging the injectors into the wrong connectors causing weird problems like this.

You mentioned doing the harness yourself - did you alter the injector harnesses any?

[1991_z28_5.3]

According to the last logs you posted it's controlling fuel on the correct banks now, so I would say either a misfire on bank1 which it appears too lean for, an injector not firing - which is possible, but again should show as a misfire or just a large vacuum leak, but one that big should again show as a misfire or effect both banks and not just one. It may even have the wrong injector connectors going to the wrong injectors causing them to fire at the wrong times. That wouldn't necessarily show as a misfire, but would greatly effect fueling. There was a tsb at one time for plugging the injectors into the wrong connectors causing weird problems like this.

You mentioned doing the harness yourself - did you alter the injector harnesses any?

GHuggins - You might be onto something with the injectors. All of the injector plugs were replaced with EV1 connectors to match the injectors. I didn't want any splices in those wires, so I cut right at the original plugs and crimped new (correct) connectors for the EV1 plugs. I checked resistance on all of the wires when I did it. The harness was rerouted from the stock Tahoe configuration, to come up more cleanly behind the engine. When we tried connecting Bank 1, I came up about an inch short on cylinder 1 and had a ton of extra wire on 7. Based on that, I repinned at the PCM (I was out of EV1 pins and PCM pins) by carefully swapping wires around, to get the lengths that I needed. I swapped 1 & 7, 3 & 5. basically wired it backwards, with regard to wire colors. I documented it on my PCM pinout chart so I can reference it in 5 years when I forget. I don't get back home until Wednesday, but my first stop will be to unplug the PCM and tone out each of the wires from the injector plugs. It's entirely possible that I didn't pin them out correctly, but I'm wondering if I didn't simply switch some plugs when they were reconnected to the injectors. If the injector plugs are switched around, the injector is obviously firing at the wrong time in the cycle, but would there potentially be enough unburnt fuel in a cylinder to light off when the spark plug fires? I've not experienced an engine with injector plugs swapped around, so I don't know if it would seem to idle smooth, even when the injector is firing at the wrong time. Based on where the changes to the harness were made, I'm thinking this might be a strong possibility. Thanks for that!

[GHuggins]

I've seen engines with completely dead cylinders run smoother than engines with all 8 firing. I would most likely bet on connectors to the wrong injectors from the sounds of it. Kind of sounds like 1 and 7 are backwards. You might want to verify all 8 while you have it apart.

[1991_z28_5.3]

I've seen engines with completely dead cylinders run smoother than engines with all 8 firing. I would most likely bet on connectors to the wrong injectors from the sounds of it. Kind of sounds like 1 and 7 are backwards. You might want to verify all 8 while you have it apart.

I'll definitely verify all 8 when I get back, but I just got a call from my son and he may have located the issue (one of the issues?). Apparently the headers were loose. I mentioned exhaust leaks earlier today, and he decided to check the exhaust system. He said that both headers seemed like they were only hand tight. He got them tightened up, but unfortunately didn't get to start it up because he had somewhere he needed to be. Based on that, I'd put money on our lean condition being resolved. If it isn't, I'll absolutely check the wires, and my go ahead and do it anyway just to be sure. It seems like we might be making a little progress, thanks to all of you who are willing to provide your input. I greatly appreciate all of this! Side note, I ordered an AEM UEGO wideband, some sensor bungs and the HP Tuners Pro cable yesterday, so I'll be able to see what's going on with a wideband. I'm planning to put bungs in both banks, and use plugs to block the unused ones. Seemed like a good way to verify AFR on both sides without having to invest in 2 sensor setups.

[1991_z28_5.3]

I got home from my work trip today, and we headed straight to the shop. I verified continuity on all 8 injector power (pink) wires back to the injector fuse. I also toned out all of the control wires to the PCM pins, and according to the PCM pinout diagram that I've been using from LT1swap.com, all 8 are correct. After verifying the injector wiring, we swapped coil packs side to side with no change. It's still dead lean on bank 1 and super rich on bank 2. The big exhaust leak from the headers being loose is corrected, and my son smoke tested the intake again yesterday, just to double-check. I'm starting to be concerned about compression or something of that nature on the bank 1 cylinders. The wideband arrived today, but is not installed yet, and I'm not hopeful that it will show anything different. I didn't post a log because we only ran it for 30 seconds, and shut it off after the O2 sensors did the same rich/lean split on the same banks as the last log. Can anyone think of any items that I haven't checked yet? Thank you!

**edit - We are planning to swap injectors from bank 1 to bank 2, but I'm ordering another AN fitting with a 1/8" NPT port so that I can install a Schraeder valve to take pressure off the rail. It sucks to deal with the fuel spray while it's depressurizing. I'll report back after the injectors are swapped. We are going out of town tomorrow for a couple of days, so the injector swap won't happen until Sunday/Monday timeframe

Chris

[GHuggins]

I've seen a few bad injectors right out of the box as of late. You should be able to ohm them out. Usually a bad one will check far different from the rest. This of course if it's a winding issue and not a mechanical flow issue.

Did you confirm good grounds to each bank - no high resistance or anything there?

[1991_z28_5.3]

I did not directly confirm the quality of the grounds, but as a general description, the engine block is grounded with a 4 AWG wire directly to the negative post on the battery. Every ground in the wiring harness runs to a ground bus bar, which is grounded by a dedicated 4AWG to the battery. I don’t think that I have ground issues, but who knows at this point. I’m heading back out to the shop before I get started on real work for the day. I will ohm the injectors and will swap them side to side.

[DrLoch]

Just to throw something else into your checks. Where is the PCM/ECM grounded? Where are the coils grounded?

PCM should be grounded to G103 location and the coils G102 location. My guess is those grounds may be the head and/or block not directly to the battery or a battery ground bus terminal. I have seen issues with smart coils that were grounded to a bus rather than the head that the coils providing spark. Just a thought....

Grounds are put in different locations for a reason.

[1991_z28_5.3]

DrLoch - Everything wiring harness related is grounded directly to a BUS bar, which is in turn, directly grounded to the negative terminal via 4 AWG wire. Electrically, it shouldn't matter, but I'll keep that in mind as I continue to chase my tail!

I just finished swapping the injectors side to side. I checked resistance on them, and most were at 14.4 ohms. There was one at 14.2, and one at 14.6, but those were my most extreme outliers. I don't think that .2 ohms one way or the other would cause this, but who knows. I was hoping to see the rich/lean condition swapped bank to bank with the injector swap, but I'm not that lucky. I've attached a log file from the idle session after swapping injectors. It's doing something different now, so I might be in the right area. B1S1 is now fluctuating in a manner that I would expect from an O2 sensor, maybe a little wider swing than normal, but I think it is heading the right way. B2S1 is also swinging, but it's variations are much more extreme. If you guys think that I should dump these injectors and go for a real-deal LS1 injector to match my intake, I'll open the checkbook. I'd love to have some part numbers (I think there were 3 LS1 options), or if there is an injector that works well on the LS1 intake for a close to stock application, let me know. I'd rather not drop a grand on a set, but I'm willing to buy more if that might help. Thanks!

[GHuggins]

Just thinking outside of the box on these...

Have you tried moving the maf to the pipe section closer to the filter? Just swap the two putting the maf further from the tb and the 90 bend.
Have you tried swapping the feed and return lines on the rails?
Have you done a crank relearn?
Has it been smoke tested?
Has compression been checked?

[1991_z28_5.3]

Greg,

I have smoke tested the intake manifold with no leaks. I have not tried the other things. I don’t have a compression tester, but I can do the rest quickly. Im really hoping that it isn’t a compression issue on a cylinder. What does a normal O2 sensor swing look like? I know it moves back and forth from rich to lean and back again. Bank 2 is now swinging wildly, Bank 1 seems to be trending towards what I’d think is normal.

[2xLS1]

O2 sensor signals should ideally look like this depending on how much you zoom in or out on the graph display. Here both banks are oscillating between about 50mv and 900mv.

[1991_z28_5.3]

O2 sensor signals should ideally look like this depending on how much you zoom in or out on the graph display. Here both banks are oscillating between about 50mv and 900mv.

Based on that, bank 2 appears to be acting normally. Bank 1 should be fluctuating more, but it still looks closer to normal than my earlier logs were looking. Given that just swapping the injectors side to side made that much impact on my O2 sensor readings, would you guys keep going in that direction?

[1991_z28_5.3]

Just as a small update... I've been fighting this thing for part of the weekend. Today I decided to pull the plugs and look at them. They were completely black and fouled. Good bad or indifferent, we originally put a set of E3 plugs in it. After pulling the plugs, I decided to throw in a set of new NGK platinums, which are a replacement for the 2003 Tahoe that the engine came out of. On startup, it idled better immediately. The O2 sensors are not in sync like the graph that 2xLS1 posted, but once they settle down they are swinging up and down pretty well. I talked to the injector shop today and they swear that stock LS1 injector settings should be good for those injectors. I grabbed the tune that had previously idled the best, and added the LS1 injector settings to that tune. I have posted both tunes, and idle logs for both. The tune with 04Silverado's injector data is tune 15, 15A is the same tune with LS1 injector data. The log files are named to indicate which tune was in it at the time. It still smells rich, but it seems like my data is heading in the right direction. Any thoughts here? To GHuggins' suggestion, I have not yet tested compression, and I'm not comfortable enough with how it's running to do the crank relearn, but both are on the list.

Nasty E3 plugs:

IMG_6625.jpg

[GHuggins]

So misfiring the whole time then. Don't ever use E3's. They're semi good in small engines, but that's it... From the looks of it, you need to tune in fueling now.

Did you make sure to move the MAF further from the TB too? I really thought that air flowing around that curve right at the MAF was the lean driver's bank issue or at least part of it as I have seen that before - the air getting around the MAF on the short radius will usually go more to one bank vs the other and since it's unmetered at that point - well. Make sure to move it if you haven't yet... Should be good to start tuning it in after that as long as injector data is right.

[jsf55]

Better off with copper plugs than platinum if it's a drag only car, i'm sure someone else will have an input too this ?

[1991_z28_5.3]

So misfiring the whole time then. Don't ever use E3's. They're semi good in small engines, but that's it... From the looks of it, you need to tune in fueling now.

Did you make sure to move the MAF further from the TB too? I really thought that air flowing around that curve right at the MAF was the lean driver's bank issue or at least part of it as I have seen that before - the air getting around the MAF on the short radius will usually go more to one bank vs the other and since it's unmetered at that point - well. Make sure to move it if you haven't yet... Should be good to start tuning it in after that as long as injector data is right.

I’ll move it today before I mess with anything. I placed it in that location because GM recommends the MAF be at least 4” from the throttle body and 11” from any bends. I’m going off the top of my head on the numbers, but I had them in front of me when we were making the intake. As it sits, it’s 3.75” from the centerline of the throttle body and 10” from the 45 degree elbow that’s right after the filter. That felt like a good compromise. Being a truck MAF with the honeycomb, I didn’t think that air would get around the sensor, but I’m the newbie to this. Still learning! I’ll move the MAF and see how that looks. I don’t know that the injector data is right, but I can get started with this setup. For what it’s worth, I also have an LY6 (2010 6.0) sitting in the engine bay of a 1964 C10 project. Those injectors were rebuilt and flow tested last year. Would it be worth my time to get a set of injector hats and put those in the Camaro? I would have factory data from a tune file for that engine, so I would know that my injectors are right.

[gtstorey]

You need to consider the bend that is just down stream of the MAF also. At least try and swap it for the piece of pipe in front of it.
If it was mine, I would get an aluminum MAF mount tube and weld up a single tube that runs from elbow to elbow with the maf centered or slightly toward the 45. Even the transitions from adapter to pipe can cause some turbulence. You can probably get one of the MAF bracket only pieces and epoxy it on a tube temporarily to see if it helps.