Help diagnosing misfire problem

ToySup88

New Member
Apr 8, 2005
33
0
0
Twin Cities
My 88 turbo started misfiring this summer and i seek feedback on possible causes. I was running 10-11 psi for a several years with no problems so something recently went failed.

Under WOT, I get check engine light - fuel cut (error code 34).
Under partial throttle and 4000+ RPM it misfires with a more of a fluttering feel and no check engine light.
I see black smoke out the exhaust when this occurs.
I have turned the boost down to 7-8 psi and the misfiring still occurs.
Always runs fine at low rpm (normal driving) and idle

It hard for me to tell if its fuel or spark. Ideas please only if you have experienced similar behavior.
 

Mk3runner

Supramania Contributor
Nov 19, 2006
2,033
0
0
37
Nor Cal
I had this happen tonight on my way to the shop.. I got on the freeway and theres goes the CEL.. I just put new ngk wires on so I'm with MDC on this one.. boost leak.