Hi all.
 
My engine throws a tantrum when I hit 5k revs under around 10psi. Stutters and refuses to go faster. If I ease up gently through 5k under low boost it seems to be ok and I can get to higher revs. Mechanics think it's likely a limp mode of some sort in the ECU, but they seem to not know what to do without an ODBCII to talk to. They checked for boost leaks, checked dizzy, regapped plugs, checked leads, put in new fuel filter and checked fuel pressure. Exhaust is a custom 3" turbo-back.
 
Engine is a mystery GT4 3S-GTE from an unknown donor celica with stock ECU from that engine (not retro'd into my old genIII mr2 3S-GTE ECU or sensors or anything).
 
Is it likely I can get error codes out of the (struggling to remember here) shorting something in the fuse box and looking at dashboard lights? (I'll have to look that up).
 
I know this is all very vague, but if anyone has heard of anything similar and can give me things to try myself or get the mechanic to try I'm all ears.
 
cheers
 

Fault finding via the internet is always full of could be... personally i dont trust "a mechanic said they checked it"... so could be; fuel pump (voltage not stepping up to 12v - check as per bgb voltage n grey plug under ash tray / front of gear lever), could be injectors (remove and get them ultrasonic cleaned and flowed), TVIS (solenoid or line issue - check as per bgb with boost gauge on tvis line at 4,100 rpm), issue with a cylinder (compression and leak down test), could be many fundamental components having a small issue.
 
Could be ecu or sensor issue, get your ecu error code (the time before OBDII and less mechanics).  Links  https://www.mr2australia.com/mr2play/tm.aspx?m=58607 
 
There are a few mr2 guys in Canberra who have good mechanical knowledge, however think they are mostly on facebook.  Best of luck
 

Wait. Could it just be something as simple as it's running too much boost and the fuel cut is kicking in? Stock boost on a gt4 is like 6psi or something low isn't it? Maybe I just need a fuel cut defender?

Which would be a 34 error code? http://www.mad-mechanic.c...d/mr2obd9310gten.shtml