tough time getting a base tune

[Slowguy]

So the engine has been in the truck for a while now. I started it a couple of times and it will run but you must feather the throttle body to keep it running. It smokes like crazy but doesn't smell like oil, smells more like how a 2 cycle snowmobile would.

The engine has been completely torn down and redone. Stock LQ4 318 heads work to include, pac springs, ls3 lifters, lapped valves, new valve seals.

Engine work, bead hone cylinders, new rings gapped for boost, new main and cam bearings, new elgin e-1839-p cam, block spotless, high pressure oil pump, cam chain tensioner, siemens deka 80lb injectors, cable throttle body, arp head bolts, main bolts, flex plate bolts. Custom log manifold with stock truck intake and 78/75 vs racing turbo. 340 LPH fuel pump in-tank.

I really hope it's not oil. I called local tuning shops and no one wants to mess with it. If I'd had known when I started, I would have opted for a Holley terminator system but I already paid to have the stock wire harness reworked and the base tune put on the pcm.

I just purchased HP tuners so I can do something with this myself or possibly get someone to remote tune it. All my other car builds (all Audi) have been remoted tuned so I'm no unfamiliar with the process; just never used HP tuners or worked with the chevy PCM.

Does anyone have any recommendations whatsoever? I just want to get this thing idling on its own and possible driving normally down the street so I can finish up all the mechanicals stuff. I assumed since I follow a "sloppy mechanics" baseline it would be cake to get a tune since there is so much of it out there.

[MySons68C20]

Have you run a compression test to rule out a bottom end issue?

[aknovaman]

if your tune is whacked, it's likely you have washed down the cylinder walls and that could also explain why you need to peddle it to keep it running. get an inperson boosted tune before going further. just my guess.

[Slowguy]

I will do a compression test next....and I would LOVE to have someone tune it at their shop via dyno in person, but I can't find anyone.

[edgeleycanuck]

This subject is well out of my scope, however.....
I have a return type fuel system, mine ran awful at first, big problem was the fuel pressure regulator was bad. Pressure was low so it pumped even more fuel.
Of course it needed a tune also but the fuel pressure being low was a big problem.

[Slowguy]

Funny you mention that. The guy who did the base tune also asked about fuel pressure. I made assumptions since the fuel pump is brand new, but I have a stock FPR as well. I have a fuel rail gauge I installed but it didn't read because I need to remove the schrader core from the port on the fuel rail - I'll do this as well.

Did yours smoke when it was overfueling?

[MySons68C20]

What color is the smoke? Blue is oil and black is fuel.

[edgeleycanuck]

You know I can't really say if it smoked...but it really smelled of fuel in the shop. Like a choke being partially on , on a carb'd engine, kinda. And it ran awful!!! I'm not very knowledgeable on this necessarily, just thought it may be something to rule out. I was told by the tuner who sorted things out( and did my wiring) that when the computer sees low pressure it dumps more fuel.

[Slowguy]

Originally Posted by MySons68C20

What color is the smoke? Blue is oil and black is fuel.

It's actually kind of gray. I know the smell of coolant - it's unmistakable. This isn't coolant. I also know the smell of oil, it too is unmistakable. fingers crossed for overfueling. I should know soon when I figure out fuel pressure, and learn how to take a log with hp tuners. Tuner recommended to start by verifying fuel pressure, then unplug o2's to force it into a base map and see what happens. I will also pull the plugs, inspect for fouling, and do another compression test (although I swear i did this when I assembled the engine a while back). I put a cap of engine oil in each cylinder as well to recoat the walls.

[LS short box]

Not an expert but the injectors you are running are pretty big. Was the base tune setup to run with those injectors?
With your engine combo you really need to get it tuned on a chassis dyno IMHO.

[Slowguy]

Originally Posted by LS short box

Not an expert but the injectors you are running are pretty big. Was the base tune setup to run with those injectors?
With your engine combo you really need to get it tuned on a chassis dyno IMHO.

I chose those injectors because I followed the LQ4 Turbo Sloppy Mechanics build to the tee. If I have to end up changing them, it's easy to do. I think (if I get the motivation to do it) this weekend I'll compression test all the cylinders, add a few drops of oil to each cylinder, check the fuel pressure, (and maybe, just maybe) figure out how to get a beginning log going with HPtuners.

Oddly enough, my tuner from Russia who always tuned my high performance Audi's said he HATES those injectors. He recommended tuning the base tune FIRST with the stock injectors and only after that's ironed out go with some 100 lb Bosch. So, the consensus seems to be, I need that much fuel for a 6.0 liter running that size of Turbo? Dunno. We'll find out I guess

[Joyridin]

Originally Posted by Slowguy

I chose those injectors because I followed the LQ4 Turbo Sloppy Mechanics build to the tee. If I have to end up changing them, it's easy to do. I think (if I get the motivation to do it) this weekend I'll compression test all the cylinders, add a few drops of oil to each cylinder, check the fuel pressure, (and maybe, just maybe) figure out how to get a beginning log going with HPtuners.

Oddly enough, my tuner from Russia who always tuned my high performance Audi's said he HATES those injectors. He recommended tuning the base tune FIRST with the stock injectors and only after that's ironed out go with some 100 lb Bosch. So, the consensus seems to be, I need that much fuel for a 6.0 liter running that size of Turbo? Dunno. We'll find out I guess

LS Short box sounds like he is on to something. It sounds like your tuner didn't put in the injector data for the new injectors. You said you bought HP Tuners? Go on the injector web site and see if the injector tables match what you have. Also, did you change the MAP sensor to a 3-bar? Maybe that info is incorrect?

There are a few really good videos on how to tune on Youtube. One guy has a whole series. I used these to straighten out my car when the guy I sent the computer to do a bench tune botched it. They state idle guides and chop guides, but they worked well on getting it running. The link to the ls1 forum is a whole series. He uses a Gen3 computer, but most of the info can be used with a Gen4 if you are using that. You never mentioned with computer you were using.

https://www.youtube.com/watch?v=qK1wWh26cbA
https://www.youtube.com/watch?v=pY2phcqg5Tk

https://ls1tech.com/forums/pcm-diagn...eo-guides.html

[LS short box]

The reason I bring up the injectors is because on a different LS swap project I bought "rebuilt" injectors and then sent the ECM off for a mail order tune. Stock LS1 the only mod was headers.
When the tuner asked me about the injectors and he said the injector data was critical for a good tune. He said rebuilt injectors can be problematic flow wise. I switched out the rebuilt injectors for stock brand new. It ran perfect.

[Slowguy]

Thank you! Those are great videos! I already bookmarked them. Decided to get the truckside wiring done so I can actually turn a key to start the engine vs jumping the starter wires together. Would be nice to sit on a seat too!