My truck has been running like crap lately. Under load it coughs and backfires. When this happens the vacuum gauge will jump up 1-2psi. The plugs look fine, besides number 7 which is dark and sooty. I did a compression test on #7 and a few others and it checked out fine. It also sounds like I have a second wastegate on the driver's side.

Changed fuel filter, plugs, swapped coil packs around, checked fuel pressure.

I'm going to drop my crossover and take a look at the flex pipe. I was just wondering if anyone else came across a similar problem.

 

Could be a bad injector maybe?
Driverside sounding like another gate.
If its all the time. Probably a blown gasket.

 

Not all the time, just when I stay into boost.

I'm going to either move the #7 injector or swap in some stock injectors.

 

Get an automotive stethoscope and put the "rod" on the body of the injector and you will be able to hear if it's firing

 

Hmmm , any codes ? Misfire DTC flash ?

Do you need a set of stock injectors. ? If you don't have any I will give you a set .

 

I wish it would give me a DTC, haha.

I'll try the stethoscope. Also going to double check pressure while driving, even though my wideband tells me it's getting enough fuel.

Thanks for the offer Tim, but i'm running FIC 1000's with EV6 connectors. I have a set of TBSS injectors I can put in it.

 

Right when my turbo would start to boost my truck would start to misfire and bog a bit until I was at full boost (8-9psi). I Changed the plugs and wires and still had the same problem.

Found out bolts on crossover came loose. Had a exhaust leak before the turbo. Tighten them up and all is good again. Hope this helps.

 

Weak valve spring is my theory.

 

I agree.

 

Would that explain the boost gauge showing little spikes?

The springs are Patriot 650's, about 5 years old with less than 5k miles.