Issues with popping or back firing through my intake manifold. Need some help. Only occurs when engine is under load (going up a hill) and at half throttle right when boost is coming on (2.5k-3k) I can feel my DBC throttle body on my right foot at every pop. Sounds like a distant AR-15 doing a mag dump.

Truck is a fresh build about 4 months old. The truck is tuned. Started happening shortly after my tune it could have happened the day it was tuned but I was babying it trying to see what my best MPG I could get was for a while. Last week I got brand new NGK spark plugs and Firecore50 wires trying to solve the issue. It seemed like it went away but I had some big exhaust leaks from hitting my cross over on a curb and I don't think I was building hardly any boost at the time. Once I fixed the leaks it started popping again with the new plugs and wires mentioned earlier. And to me seems to be getting worse and easier to reproduce on hills. Any ideas? On the forums I saw a similar issue and it was a bad coil pack. Before I drop 100's on coil packs I wanted to see what you guys think. Only happens on part throttle around 3k rpms.

PFA Link to my Build thread for better details https://www.performancetrucks.net/…/lq4-out-5-3-turbo-tria…/

 

got a wideband on it? It's probably running lean. Most likely fuel pressure or tune related. What are your plugs gaped at?

 

I don't have a wideband on it and my fuel pressure gauge is inside the engine bay. Wanted a sleeper look inside the cab. I trust the tuner and he told me truck was 100% when he dyno'd it. I have a walbro 450 with a hotwire kit and Deka 80's. And a Aeromotive FPR. Fuel is 54ish at idle and it's fine under WOT only at part throttle I get popping I either have to get out of it or get on it harder to get it to stop.

 

Going to get a video today on my lunch of the popping. It will probably help alot

 

Video of the popping. Best hill I could get at my work location. I will try for a better one if this isn't enough

 

Were any of your old wires burned? Are you sure none of the new plugs are cracked/bad? What were they gapped to?

 

They were not burnt but the #3 cylinder closest to the turbo had a torn boot when I took it off to replace them. The new plugs I don't think are cracked I inspected them before install. The plugs are the stock NGK gap. I will gap them to .025 when I get home if I have time and see if things get better. Plugs are NGK BR7EF/3346

 

Right now here is my list in order of what to check.

1.Spark Plugs gapped to .025
2. Header Temperature 1" from heads on each pipe
3.Inspect Rockers
4.Inspect Springs
5. Test Coils (how would I go about that)

 

You answered your own question...

It's like a Lean spot in the tune.

A broken plug typically breaks up under any load

A coil, What I have seen is they typically they just die.

You typically get a misfire code on a specific cylinder.

Wouldn't hurt to check the gaps but if it did it with the old plugs That's not it. Sometimes the fill from gas station to station is not consistent either.

 

Sounds like a lean spot in the tune