Need help

**30thSSclone** · 07-07-2015, 10:26 PM

I don't come on here often. But here's what's going on... Get the build done, drove like crap. Cutting out and hesitating...plug a tech2 in at work (before my wideband was wired up) and saw the o2's were stuck. No big deal...go to parts get o2's throw them in runs great. Kinda... Doesn't hesitate or sputter like it did before but its not making the power it should be making...when I say that I got irritated and put it on a dyno because I knew it wasn't making power and wanted to see exactly how much. It made 300... Which is pathetic. I know the stall is pretty loose...its supposed to be a 3600 but is flashing at 4500.

Here is what's done
355 LT
Stock rods and crank
Flat top pistons
New bearings and rings in bottom end
High pressure oil pump
LE2 heads and intake
235/243 .579 .597 110LSA cam
1.6 roller rockers
Hardened pushrods
LS7 lifters
52mm throttle body
36lb injectors
255 fuel pump
Nitrous outlet plate kit (bottle not hooked up yet)

Transmission
Brad Kimbler built transmission
Vigilante stall

I know I just have a mail order tune on it right now so it may not be spot on...but something just isn't right.

AFR at wide open is about 12.7

Also when cruising along at highway speeds when you let off the throttle and just coast it feels like its backfiring. Hear and feel under you popping

So I guess I'm looking for 2 things.

What is a good dataloggig program for OBD2 cars

Any input on what I've got going on

**MoeHorsePower** · 07-08-2015, 09:37 AM

is it backfiring out the tailpipe or at the intake?

**30thSSclone** · 07-08-2015, 09:58 AM

Originally Posted by MoeHorsePower

is it backfiring out the tailpipe or at the intake?

Exhaust

**30thSSclone** · 07-09-2015, 11:26 PM

*update*

Friend was following me tonight. A cruising in the highway, foot off the gas pedal just coasting....it pops out the exhaust. As said above....but with him following me he said its shooting flames out the exhaust when it does that

**Dan** · 07-09-2015, 11:47 PM

My gramps corvette shot flames out the carb. It was the plugs that were fouled out. Did you replace plugs? Opti?

**firebird_1995** · 07-10-2015, 01:16 AM

Spark plug wires on correctly? What plugs are you running? What gap? How old is the gas in the tank? How much preload on the lifters?
Backfire out of exhaust can be due to spark plugs lighting off too late (whether the timing itself is too retarded, which is usually the case on high vacuum decel, or because the routing is wrong or bleeding through to another wire and lighting off a cylinder when the exhaust valve is open.)
It can also backfire if the valves are adjusted too tight, again leaving the valves open during combustion.

**MoeHorsePower** · 07-10-2015, 01:25 PM

Id check for the simple things first like spark plugs..

**30thSSclone** · 07-11-2015, 04:35 PM

Using TR55 plugs, moroso 8mm plug wires... Already changed the plugs once when I changed o2's.

**30thSSclone** · 07-24-2015, 06:08 PM

Car leaves pretty good for a stock suspension full weight car. But as you can see it just falls on its face. I'm gaining rpm but no wheel speed. Time to save for a new converter and see how it reacts.

**dawdaw** · 07-24-2015, 06:48 PM

I wouldn't even touch the converter until you figure out what you have going on. .. until you can get some solid data at the track and figure out slippage rates and stall speed.

Does the car miss under all areas like idle part throttle and wot? Or just Letting off coasting,?

Any blue or white smoke?

Have you done a leak down test or checked cylinder pressure?

Have you pulled plugs to see what they look like?