LS1 turbo problem

[rubaduckee]

Hi guys, I have a bit of an issue with my LS1 at the moment.

we put a turbo on it (TO4Z) and use the intank pump to feed an 044 Bosch Pump through a 2litre surge tank, with 60lb injectors, it is also intercooled.

problem is that it has a miss in it under load, and apparently drops back to 7cyl (intermitantly and not on the same cyl ?) and leans out, we have changed spark leads, checked plugs, they are gapped at .6mm, and have changed the coils over, and tried a different computer - still misses.

it has all been checked on the dyno of a reputable shop.

has anyone else had this or have any idea what is causing it, we are running out of ideas????

thanks in advance

[SirNemesis]

Not much detail there to troubleshoot from... so I'm going to do some guessing.

Does it miss under full throttle or any load?
Can you confirm you are using a 2Bar MAP sensor?
Are you still using a MAF?
Are you still using closed loop fueling?
What plugs are you using?
Is your fuel system deadhead or return?
Is your fuel pressure regulator boost referenced?

[rubaduckee]

thanks for the reply, I will try and answer your questions:

happens under any load
yes it has a 2 bar
no maf
not sure what you mean by closed loop fueling
ngk r spark plugs bpr6efs - I think they are
sorry not sure what you mean by dead head or return
yes it is running a malory ruel regulator

thanks again

[soop]

He means does the fuel system run a line back to the tank, or does it finish at the rail?

[SirNemesis]

You aren't running the right plug for the job, but it shouldn't hurt at all load. You should use a BR6EFS or a BR7EFS if running over about 12psi. The projected tip doesn't do any good with boost.

Other than that, I couldn't tell you without having a closer look.

[rubaduckee]

what difference does it make if the line goes back to the tank?

[soop]

Does it, or does it not?

[rubaduckee]

no i dont believe it does go back to the tank

[soop]

Righto :P.
Nemisis has his reasons for asking. Does it have the standard fuel rail in place?

[rubaduckee]

yes it does

[Kingston_99]

changes the injectors to bigger then stock?
just thought i'd ask

[SirNemesis]

Try the plugs I suggested and let me know how it goes. I don't think it is leaning out. What you are probably seeing is just plain misfire as you describe, which reads as lean on a wideband sensor.

[rubaduckee]

i tend to agree, tho they tell me that when it is on the dyno, they can see it is dropping a cyl, but I will def try the plugs and see how they go

[GMMAD]

try a plain copper plug as SN says and gapped to .8
is your 044 running off a relay?

[rubaduckee]

yes the pump is running off a relay

[thebestsv8]

has anyone else had this or have any idea what is causing it, we are running out of ideas????

Just buy a vtec