Misfires Under boost

Hey, Im having a serious problem. I have a 90 GSX. It runs fine until the boost starts to kick in. Then it misfires and sputters like crazy, it actually loses power under boost. Plugs are fine, injectors are fine, seems to be a timing problem or something. Could it be a bad ECU, or maybe the MAS? Anyone had any similar experience?

Running 12 lbs on a 16g at 5000 ft, everything else stock.

yea that happened to me when i put new 8mm wires in. it like misfired under boost only.when i put the stock wires, my car ran fine.
i put the same 8mm on another GST and it ran fine, even under boost

so the conclusion is that I had bad spark plugs, you may want to check those

This defintely sounds like an ignition problem, though there is the chance it could be a bad boost leak (see the vfaq for how to build the tester and check it out). Try to use only NGK plugs, like the stock ones, gapped to 28 to 30. BE wary of what wire you decide to run. They almost all give DSMs problems. The ones that work 99.9% of the time right out of the box are NGKs. Some people swear by Magnecores, but I've had 3 sets go bad on me. I still run stock wires, a couple years old, to 11 second passes and 400 whp on pump. Works for me.

though there is the chance it could be a bad boost leak (see the vfaq for how to build the tester and check it out).


I vote for boost leak, I tested so many things, only to find out the turbo inlet was incorrectly installed and had a 1/4" gap around the inlet pipe. New piece put on, all boost problems were fixed.

Rob

Thx, Ill try changing the plugs and wires first, if not that then Ill check for the leak. Hopefully I can figure it out.

Check for a boost leak first then change plugs & wires.