LSx 454 Crate Motor Tune

Hey guys,

The short version of the story is I did some work for a buddy's shop over the winter because he was short staffed and overloaded with work. A customer brought in a LS 454 "turn key" motor built and sold by a reputable national speed shop and he wanted the us to swap it into his late model pickup. I have done plenty of engine swaps including 3 LS style and the shop owner has done countless.

Motor and trans went in fine, the only issue we really had was the harness supplied did not match the LS7 map sensor. We called the harness manufacture and they sent us a new pig tail, said it was a direct fit.
The ECU came with a basic tune so we had an email tuner build us a performance map. We have used this tuner multiple times with no issues are they are recommended by the motor builder.

It took 5 tunes, but the truck now starts and idles, however we are still getting a random missfire under any sort of load and when it does pull to past 3k it does not feel like like a 700hp big block, not slow, but not impressive. The tuner has basically thrown up his hands and says its not the tune, the speed shop says its not their hardware and I have checked and rechecked the install and found no issues.

Checked or replaced

Fuel pressure, rock solid at 58-60, volume is good
resistance on all plug wires-good
swapped in new coils (no change)
smoke tested intake track (no leaks)
new race fuel
grounds\powers\wires no obvious issues

Engine specs:

LSx 454
11.45:1 compression
OEM LS7, Map, Intake, TB, rails and injectors
06+ Z06 OEM MAF
LS7R Cam 248/260, .657/.655 with 1.8 ratio rockers, 111 LSA
Bowler 4l80e (not sure of the TC stall but its feels low...noting super aggressive)

Customer has ALOT of money in this and we want to make it right for him but have run out of options.

Can you please look over the tune and log and see if there is anything we are missing.

thanks

Shea

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Cylinder volume is saying its a 6.2

Injector data is wrong for 58psi. I've updated it with stuff from a 2010 LS7, which is a closer match to the ECM.OS than pre-'09 files.

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Also updated the manifold volume - no LS7 file I could find used the 14,000cm setting, they're all 11,340. If you have some other reason why you think 14k should be right, change that back.

I don't see cylinder airmass in the log - add that, it is as important as RPM.

Cam is way too big to try to use a MAF sensor. It's too big for OL too IMHO. The stock o2's are going to drive that thing into a bad place fueling wise. Really need a wideband on it.


When you say misfires? do you mean like popping if you get on it at low RPM like less than 2500 RPM? If so it might be the cam. When the cam is this big it.. that does happen. It will kinda cough back though the intake etc if you floor it at say 1500 RPM.

I really appreciate the feed back.

speaking with the engine builder they mentioned to the customer that cam was not a good choice for a street\strip trucks but that's the specs that were ordered. I wouldn't call them true misfires, more like hesitations. The stored codes are random missfires. In park (no load) the thing cracks right over.

Thanks Blindsquirrel . The shop will do more logs today after they load your corrections.

So the consensus is a speed density tune is the way to go? The truck will not even start with the MAF unplugged.

If it will not even start that is a indication that the VVE wasn't tuned at all. It should be at the very least.. But in reality there is just no way a MAF is going to give a good result.

Also, with a cam that big.. the misfire timers need to be maxed out.. There is zero chance the ECM will be able to sense a miss among the cam lope.

I noticed there was a crank learn code so I asked the shop to do the relearn, they loaded the tune provided by blindsquirrel and this was their reply.

"did the csp relearn and the code went away. seemed better but still having some similar issues. i added cyl mass to the logs and tried the updated tune. it ran worse, smelled like fuel and was pulling alot of fuel out according to ST fuel trims. attached log. put the previous tune in and attached a log of that as well. it breaks up when you start rolling into it and should downshift. it also did the same thing to us that it did for you where it just sat there at rev limit and wouldn't shift. Runs better if you select gears and dont let it try to downshift itself. trans tuning issue?"


I attached the two logs. Is it really worth continuing to try and tune this on a MAF or really a VVE tune is the absolutely only way possible to get this thing to run correctly?


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