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Thanks for the input guys. I found some time this weekend to make it over to the shop and make some changes. I feel like I should mention my goals here. I'm a complete tuning n00b, and my intention...

I'm running a return system, and all of the data is what came with the injectors from Fuel Injector Connection. It's possible that I misinterpreted some of their data, but I don't think so.


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The quick and dirty:

2003 LQ9 that I had running in another swap truck almost 5 years ago now. Been in the process of swapping it into another vehicle for going on 3 years.

Since it last ran I...

Alright, so I've figured out that my 52lb @ 43psi Five-O Motorsport injectors are just stock 8.1L injectors that they've modified. They're 30lbs/hr at 43psi stock, and now they're 52 at 43.

With...

I really appreciate your help. At least, now, I've got some some hard issues to resolve. That's a lot more than I could have said a couple of weeks ago.

I'm going to ease up on the engine issue...

Still getting the same stuff after making the above changes. It looks like while cranking I'm commanding as low as 2.9afr which appears to result in pulsewidths as high as 46.8 or higher.

Also, I...

2003 Silverado SS. I originally purchased the engine, harness, and PCM from the same salvage yard, and I've used this powertrain in another swap vehicle before, if any of that matters.

Also a...

Made all of the prescribed changes, and I'm still seeing min. 8 max 56 pulsewidth while cranking. It's still pig-rich too. I've fouled another few plugs. I changed my spark tables to fit a vehicle...

Thanks for putting the time into that. I went through and made all of the changes to my SD tune, but the engine will barely start, and if it does, it runs for just a few seconds. It's also very rich....

Another day, another set of spark plugs! My bike left me stranded at work last night, so I didn't have much time this morning to tinker with the truck. I switched back to my 1bar MAF tune since it's...

This might be adding to too many variables into this discussion, but just for shits and giggles I threw in a 2bar MAP sensor and tried to run my SD tune. It started and ran for longer than the...

Yeah, I'm a moron. I forgot that I can change the units of measurement for that table. My injectors are rated at 53lbs at 43.5psi and 62lbs at 50psi. I've set my fuel rail pressure to 43psi and...

This is good stuff. I've done what you said, and I'll give it a shot in morning and see what happens. Going through your tune made me look at a few things that I think were probably leading to my...

Might be making some progress.

After doing some reading yesterday, I realized I might be entering my injector flow rate improperly. I'm using a return-style fuel rail with a boost/vacuum...

Made an attempt to log commanded AFR. Unfortunately, the injectors are dumping fuel so I foul plugs every time I try to start it. I'll pull out the fouled plugs, replace or clean them, and drop...

Just checked, stoich AFR was set to 14.17. I'm only running one set of oxygen sensors, and the harness only has provisions for pre-cat O2s, so they're plugged in correctly. I just set up the scanner...

Well, no progress...only more questions.

I returned most tune values back to stock, and the engine still runs like crap. It sounded like it was firing on 3 cylinders. I was just about to start...

Yeah, sorry, I just found that illustration while checking my work. Mine is hard wired to a fused and ignition-switched 12v source and is grounded to the vehicle's accessory ground block. I'm sure...

Yep, and like I've tried configuring the sensor manually using PLXs data. Got the same results for each. It's also hooked up like this -...

Thanks for the data. I've been doing exactly what you recommended today. I've been blending my mail-order tune with the stock tune to create a new "square 1." I've been studying the MAF/SD debate,...

Yeah, I've never seen short term fuel trims that high before. +50% seems very strange. What's at work here?

Found a stock LQ9 tune just in case the 5.3 was different. Set dynamic airflow back to stock and saw no change. I downloaded RussK's idle airflow configuration, but it's useless unless the engine...

Meant to get on that this morning, but I don't have the stock file, and I don't have internet at the shop. I'll track one down in the repository and see what comes up.

Forgot the log - here it is

Good news: fixed the IAT and MAF sensors. My high idle is gone and my MAF appears to be reading correctly (approximately 5lbs/min @2000rpm).

Bad news: Engine now won't idle. It surges pretty...