carlos8

Hi, Recently my Ls/vtec start to breaking on boost. I perform the routine test and maintenance for this type of fail. OEM, cap and rotor, plugs and spare ngk blue wires (used but good) but this wont help. then perform compression test to find 185 in three cyl. and about 177 psi. in cyl. 3. Made a little pull till break and remove the plug on cyl.3 and detonation is present. Switched injector and issue persist on cyl. 3

What can cause this type of event? Injector driver on ECU, bad ground or power on harness for this injector?

ls/vtec 9.0:1 piston/rod
850cc saturated inj.
neptune tuned.

Thanks, any question to help understand my bad English, Let me know.

boosted94gsr

It's not uncommon for #3 to run lean a b-series engines. Add a few percent to #3 in the individual cylinder fuel trims also just to be safe pull a couple degrees of timing under boost until you get your fueling evened out.

carlos8

Thanks for the reply, I already tried the individual fuel trim and the car still failing in high boost. It drives great at normal speed, but now sometimes start to cancel injector 3 on idle until i wiggle the harness next to ECU plug. Maybe is time for a new harness?

boosted94gsr

Yeah that definitely sounds like a wiring issue. Check the #3 injector wire where it pins into the ecu (A5). Maybe it's just a loose connection...

.:FFS TechNet : OBD1 ECU Pin out Schematics :.