Boost loss/backfire after 15 lbs?

[DaveyX87]

Well the oil and coolant are good. Fuel pressure is good. I don't have any restrictions with the -8 feed and -6 return. I also have a massive fuel filter. It must be spark related as mentioned some of the posts above. I guess I need to open up the wallet yet again and get the TR6, plugs and wires. I hear it makes the car idle much smoother as well.

 

[No disintegrations]

I would hate for you to buy the tr6 and still have this problem. I'm all for you making the purchase, as long as you need it, but maybe we missed something.
Why did it run right at first?
Did it act this way after turning up the boost?
What has changed?

 

[DaveyX87]

It ran good when I first turned up the boost from 13 to 20lbs. I drove it a couple weekends and it was fine. The last couple times I tried getting into it, it would cut out once boost hit about 15. Nothing has changed except maybe topping off the tank with more e85. I got it from the same station but I don't have a content analyzer yet so I don't know if there was a difference. I have no knock or any other issues. It just falls and stutters once boost exceeds 14lbs.

 

[bison]

Id change plugs first


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[robzombie]

At what RPM are you experiencing this ??

Is it a stutter and or pop in the intake when you get to a certain boost under full throttle and upper RPM in second or third gear ???

If so I think I know what it may be if you have ruled out electrical/ignition issues.

 

[No disintegrations]

Figure this out yet?

 

[MDavis]

May have pushed a head gasket.

 

[GNRick]

Mine is sputtering at 15 also, but not backfiring. New ac/delco ignition module from Rock Auto should be here in a few days.

My car runs much better now at 20 psi with the new ac delco module and coil. I'm not on e85 though.

 

[DaveyX87]

I don't think it's head gasket which is a good thing. However, I was told it could be related to worn original valve springs. I plan to change these out soon.

 

[gn_steve]

Did you ever fix this??? What was the problem?


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[TURBOELKY]

These people never post results. It's pretty annoying.

 

[Powertechn2]

I had a backfire issue bad enough it blew out the mufflers... Lol.

My issue turned out to be a ground issue though, luckily.