The truck will literally fall on its face around 4 to 5lbs boost. I have changed plugs, plug wires, and swapped coils. The last thing i can think to do is check fuel pressure. Fuel system is stock with an aeromotive 340lph pump and 65lb injectors. Any help is appreciated

 

And of course all this started after i sent my wideband back to autometer. So i cant tell what the afr is doing.

 

with out that you are shooting blind

 

Yeah i was trying the simple stuff first. My experience with fuel pumps is they either work or they dont. This pump was already in the truck when i got it, so im not sure what fuel hose was used on the install.

 

I had something like that happen when I had exhaust leaks on my crossover flanges. As soon as it would start to boost it would run like crap(4-5psi). It farted and would bog out until the turbo was at full boost(10psi).

I fixed the exhaust leaks and all was good. No more cutting out. Hope this helps you out.

 

You need three gauges (wideband, fuel pressure and boost) to be able to diagnose the problem. I have the three in A-pillar triple gauge pod.

You need to find out if your fuel pressure regulator is maintaining fuel pressure.

Your title says "cutting out under boost " but the way you described it tells that it does not boost past 4-5 psig. So, check your exhaust manifolds and cross over pipe for leaks. Also check your WG to make sure it is not leaking past 4-5 psi.

Also, check your plugs gap to make sure it is not blowing the spark although stock gap should work upto 9-10psi on some vehicles.

 

It will build 10psi boost if i make it. It starts to misfire at 4-5. Plugs are br7ef gapped at .028. Exhaust has no leaks and wastegate is functioning properly.

 

Im gathering fittings to hook up a fuel pressure gauge as i type this. And im waiting on autometer to send my wideband back to me. Im trying to get in touch with my tuner so we can get some logs as well.

 

Get a fuel pressure gauge ASAP. 340s are known to overheat and shutoff. The breaking up could be the pump switching on/off quickly when its overheated

 

I'm having the same situation I'm taking my injectors in to get serviced and tested