Boosted lsx backfiring under boost
TECH Enthusiast
Joined: Apr 2009
Posts: 723
Likes: 4
Well it's a brand new lsx376 B15 engine. Not saying it's not an option just cause it's new don't mean it's good but like it did this before the tune and then after the tube it went away besides every now and then at wot in 2nd gear and then I changed pcv system and it got worst and worst
Then go to a proper catch can/ evac system. Heck, I've ran just open breathers on stuff.
This is important info guys need to remember to post.
If something like this happens when you make a change don't ignore it.
Thread Starter
On The Tree
Joined: Jan 2016
Posts: 100
Likes: 0
From: Colorado
Well I have it set to where all the lines (passenger and driver valve cover and valley cover) are vented to atmosphere till my catch can arrives. There was oil on the turbo and on the throttle body. So could I have affects until oil is flushed out or what?
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9 Second Club
Joined: Nov 2003
Posts: 13,616
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From: Norn Iron
I have MSD multiple spark could with upgraded harness and I'm running 91 octane. And I've had to add grounds to the wiring harness before because I would get misfires at 4500rpm. And all the plugs don't look wet or black. The isolator and electrode look good. The ground strap has a bit of white on it though. The insulator is all white still besides one spark is tad bit darker. I'm using tr6s
What ecu are you using, what coils are you using, what plug gap ?
And when you said mixtures are lean when the problem is occurring...as others have said that information is erroneous because of the misfire.
What are AFR readings like immediately prior to any problems, are they normal ?
TECH Enthusiast
Joined: Apr 2009
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A log would definitely help.
Thinking about this. OP did you have any breather system when it was tuned?
If not then there's a chance it just might be a good enough change to VE to throw the tables off. How much blow-by you have is going to determine by how much.
Thinking about this. OP did you have any breather system when it was tuned?
If not then there's a chance it just might be a good enough change to VE to throw the tables off. How much blow-by you have is going to determine by how much.
TECH Enthusiast
Joined: Apr 2009
Posts: 723
Likes: 4
In these test hits that's what you read for boost, 22?
!5.22 wouldn't be close.
You can swap it or break out the Air-reg & test the output voltage with key on/engine off. Step up pressure on the reg to see where it maps to. If it hits 105 in the log & stops there's the problem...
If voltage doesn't go up past that point then it's the sensor. If it does then you have to check it at the PCM. It would be odd that it would be a wiring issue if it works to a point & then stops, but who knows.
!5.22 wouldn't be close.
You can swap it or break out the Air-reg & test the output voltage with key on/engine off. Step up pressure on the reg to see where it maps to. If it hits 105 in the log & stops there's the problem...
If voltage doesn't go up past that point then it's the sensor. If it does then you have to check it at the PCM. It would be odd that it would be a wiring issue if it works to a point & then stops, but who knows.
Last edited by gtfoxy; Jan 8, 2016 at 07:50 PM.