Hi guys, i'm in the processing for fixing up my friends evo 8. B4 he gave the car to me it was making a huge thud under WOT accelerating at 5.5k in almost every gear. Durning the thud, the engine pauses, and it feels like the car hit a big bump or rock. A better description is kind of like the engine just completely siezes up at 5.5k and that it's casusing a tranny shock. He has on the car 660cc injectors with an unscaled ECU (I know, scale the ECU to the injectors but his ECU is locked), K&N cone filter on a HKS Suction Pipe, TBE, Forge MBC set at 20psi, and a walbro. Now he told me that this thud was happeing even b4 the 660cc injectors or the MBC and the K&N cone. I also just installed 272/272 and a 10.5 hotside on his car and the thud is even more apparent and harder. When we figure out how to unlock his ECU, how should i go about tuning the stupid thud out, i'll be scaling the injectors, setting his timing back by 2 degress across the board and set the fuel trims untill it hits 11AFTR and bump back timing. Nething sepcial i should pay attention to so i can get rid of this thud. It's a very scarry thud, it feels like engine should have broke each time it thuds.

 

sounds like boost cut. although the mbc is set at 20, there might be boost spikes which causes the ecu to go over the boost limit set in the ecu.
how is the ecu locked? ecutek? when you unlock the ecu, you can set the boost limit to 319, which is 30psi+.
if it keeps on hitting this thump, it will trigger the cel.

 

definately boost cut have it flashed

 

CEL has been triggered. ECU is locked because I cannot get into it with EcuFlash...rom gets read, but message pops up with "Undefined ROM" when you try and get into perameters...I made a thread in EcuFlash forum and got some info, havn't had time to fix yet.

 

its doesn't mean the ecu is locked just because it is an undefined rom. search under the ecuflash forum. this issue has been covered a number of times.

 

I'm aware, thanks.

 

Sounds like you need to change the plugs! Get fresh plugs and see if it fixes the problem!

Ken

 

Will do.