MFJ

iTrader: (4)

Just like the title states. My engine tuner has put a few hours into it already and that's after Vengence sent me a base tune to get it running. So far, I'd like to burn it to the ground.

Engine specs
LS6 forged internals, balanced rotating assembly
-4cc valve reliefs in the pistons
prc 225cc heads milled .060
fast 102 intake , PTM 102mm TB, 85mm maf (I'm making a 100 mm maf)
Longtubes, 2" primaries 3" collector dual exhaust stopped at the door jamb
Cam 232/239 .595/.605 113 lsa (I'm gonna spray it if it'll ever run right)
42lb LS3 injectors, racetronix pump

I'm getting my tuner to email me the tune today.
Getting a MAF performance code/tps performance code/ intake code as well

But my question for now is....Is this too much air in and out for a 346?

eaglegoat

No. It's perfectly "tunable".

2xLS1

iTrader: (25)

Looking at data logs would be more helpful. I see a lot of tunable combinations that have a mechanical or electrical problem that make them untunable. How experienced is your tuner? Many times a tuners ability to troubleshoot and recognize a problem is just as important as their ability to tune.

MontecarloDrag

iTrader: (3)

What are the problems? Idle, WOT, Mileage, all of them?

MFJ

iTrader: (4)

Idle is fine. Sometimes it'll flood when you try to crank it, you'll literally have to hold the pedal to the floor to get it to clear itself out, but most of the time it starts fine.
Lots of bucking under light throttle no matter the rpm. WOT is sometimes like a frieght train but other times goes no where (bogs) I literally floored it at 40 mph and it stayed at 3 k rpms for 3-4 seconds then just all of a sudden took off like a shot of nitrous kicked in.

Gas mileage isn't a problem.
Sometimes it drops idle when coming to a quick stop but others it idles perfect. I'm waiting on the tune file.
I checked voltage readings , etc... on the tps sensor and maf sensor today and they're fine. Low end sucks (up to 4k rpm) 5k to 6800 is dead on though.

Sorry, it's a 4L80E tranny.

Darth_V8r

iTrader: (4)

Well said! First time I had my car tuned, the NicD was able to figure out that the cam was off.

MFJ

iTrader: (4)

Well, they have the fastest LS street car around here running 5.00's in the 1/8th .They've been tuning on them for years. And I know the mechanicals are good. I built the motor.

Now with that being said it's an aftermarket MAF sensor. It's not an OEM. It's not the corvette MAF it's the one for the trucks. I don't know if that'll make a difference or not.

MontecarloDrag

iTrader: (3)

Ask the tuner to tune it in Speed Density to rule out the MAF

2xLS1

iTrader: (25)

Sounds like you have the situation well under control then.

MFJ

iTrader: (4)

I took the car back to them yesterday along with an OEM 85 mm maf sensor. About 6:30 last night I hadn't heard anything so I sent him a text and asked how it was going.
Not a confidence inspiring response.
"No real progress. Fuel is all over the place between lean and rich."

Looks like I'm gonna pick it up and carry it to Vengeance.

MontecarloDrag

iTrader: (3)

MAF turbulence or noise can cause that. Speed density allows to isolate the problem and troubleshoot.
If the fueling issue persists after the PCM is tuned in SD, I suggest going Open Loop. If this doesn't solve it then you have a mechanical issue.

After doing this without success, you need to go back to the basics: Check vacuum and exhaust leaks, check spark plugs and wires, coils, etc.
Random misfires cause that. A good spark plug reading will tell you a lot.

murphinator

iTrader: (2)

this ^ is all very logical diagnostics 101 , isolate and eliminate... you would be hard pressed to get better advice for free

Old Geezer

iTrader: (3)

"Looks like I'm gonna pick it up and carry it to Vengeance."

Good move. Mike can find it.....And, w/ a dyno at hand, he could put the finishing "touches" on it.

Slowhawk

iTrader: (12)

Sometimes combo's can be over some tuners head. Easiest way to figure out your car is to just tune it olsd, that can bring out bad sensors then add in closed loop if you wish.

Pulse_GTO

iTrader: (2)

Those 4" MAFs need about 6" of straight tubing before the sensor in order to eliminate turbulence. Have the tuner try SD or the GM 85mm MAF. I bet it clears up. Also, silly question, is the MAF installed in the correct orientation?

2xLS1

iTrader: (25)

Wouldn't guys that have the fastest LS street cars around know all of that?

MFJ

iTrader: (4)

Just for the record, they've been tuning LS motors for years and were taught by one of the best around here. I do have the GM 85mm MAF on it now, I didn't before. Yes, it's in the correct orientation.
I've found the problem. I hooked the smoke machine to it and the Fast 102 pos intake is leaking for almost half way down the left side. I took the intake off and took the top shell off and it's warped. Won't seal up. Bought a new seal for it and still won't seal up. That explains it. Been chasing our tails over an intake leak. talked to Fast and all I got was excuses. So I'll have to buy another shell and hope it seals up.

At this point I'd rather go with a Victor Jr. intake but I don't think my cam would work as well with it from what I've read.