Tuning for 2... 99 Silverado DBC/ 03 Tahoe DBW

[400Horses]

I have searched and read until my eyes have crossed. I have done everything for a base tune that seems to be in line with the rest of you. The build the Silverado is the stock 5.3, mild ported heads, LT's, 218/227 .525 cam, CAI, and 36lb/hr injectors. Nothing fancy just a freshened topend with a cam. When I got the motor back together I could get it to start with the stock tune, but it was dumping enough fuel that you could see a cloud behind the truck. I start tuning and do all of the basic changes like mentioned. However, when I tried to start the truck it wouldn't fire and flooded the engine with enough fuel that I have to change the oil, and the plugs were black and wet when my son and I pulled them. Attached is my current file to look through and see what I may have missed. I haven't made any adjustments to the throttle body. I don't understand the correlation between the idle file 9which is currently set to 800 rpm) and physically adjusting the throttle blade for the DBC setup. Now for the Tahoe. It currently has a 4.8, but it is getting upgraded to a 5.3 with a TSP 212/218 .560 lift stage 2, LT's and of coarse tuned. That will come after the truck is right. Any help is appreciated.

[RDF1]

What 36# injectors are you using?
Is the 99 still Return fuel system?

[400Horses]

Yes the fuel system is return style, and the injectors are some I found through Amazon.

[blindsquirrel]

So they're fakes then, and none of the data taken from any stock file will apply?

[blindsquirrel]

https://www.youtube.com/watch?v=2h8n2hQWlaA

And what do you know, 12594512 is supposed to be 36lb...

[400Horses]

I used the calculations in HPT to set the rate and I still have the original injectors that I can re-install. The OEM were still good I took a chance on the 36# injectors. The truck is my 1st attempt at the LS and I will do what I have to to get it right. Carbs and Distributors are what I started with so I know the mechanical side its the EFI that I'm figuring out.

[blindsquirrel]

The fake Amazon injectors will have none of the same characteristics of the genuine injectors. They probably don't even flow the same as real ones, and the flow rate is the least important of the 3 main injector tables (flow rate, offset vs volts vs vac, short pulse adder). What you have there are injectors that have copied the external appearance of real ones, with totally unknown mystery innards. Sorry to be the bearer of bad news.

[400Horses]

It's not bad news. It is a learning experience. I have had my issues with electronic devices from Amazon, but this set of injectors were purchased earlier in the summer. I didn't know how they would work, and thought I would give them a shot because they were only part of the system. I would have pulled them already if it wasn't for the fact that the truck would start and run with them installed on the factory tune. I just need to get the truck to start and idle so I can start a log. Then I can see if I need bigger injectors. I know they have a duty cycle and I don't think my mods will push them to hard, but I was trying to think ahead.

[blindsquirrel]

If you stick with them the only thing you'll learn, after much frustration, is that it's a bad idea to try to use injectors with no data with the stock PCM. The issue isn't so much that they're fake, it's that by being fake the data isn't the same anymore as it would be with a genuine version of the same part number.

[400Horses]

I am going to pull them. The 5.3 I am building for the tahoe came with 12580426 injectors. I have checked the data for them and they are 30lb/hr. That should take care of the issue, and I will get another set for the tahoe when I'm ready to put the motor in.

[blindsquirrel]

You can get real-deal no BS AC Delco 12613412s, 51lb, for around $200/set. There's something weird about the supply for that one, and only that one, that makes them really cheap. They can be had for less than that but there are tons of fakes of that number too. They're $21/ea from Rockauto, and only like $35/ea direct from the dealership even after their massive markups. And all the data can be taken and converted from a Gen4 L96 file.

[400Horses]

Thanks for the part# I will look into them. The stockers were showing 21.7 in the base file. So anything higher is going to be better. I'm having to work around this crazy weather so those will probably be a Spring time upgrade. right now the main focus is getting it running and drivable.

[RDF1]

The stock injectors will be fine to put back in there to get it running and driving just know that they wont flow enough fuel above about 4000 rpms.