Y12 hesitation / coil pack issues

nareshseep · Postby **nareshseep** » November 12th, 2024, 7:23 am

I have a y12 that has hesitation issues, whenever I changed spark plugs or coil packs or both, it will start out fine and then the hesitation returns and it will blow coils. Last weekend changed engine and transmission, since the previous transmission was going. So I thought since everything new. I in the clear, got a new ecu but used back the old harness which was in good condition, start back and sounded nice and fine until about a half hour later when the hesitation returns. My ecu is 9P and it is a wingroad non cvt. Pretty sure if I get a 9P harness in good condition it may cure this problem. However I'm not sure if I can get one that is in good condition. Anyone else ever got issue like this before?

nareshseep · Postby **nareshseep** » November 12th, 2024, 7:24 am

Also I did an idle relearn, but it didn't seem to help

Postby **Dave** » November 12th, 2024, 8:37 am

Check your intank fuel filter

hover11 · Postby **hover11** » November 12th, 2024, 9:36 am

Service the throttle body

nareshseep · Postby **nareshseep** » November 14th, 2024, 1:46 am

Alot of folks recommended changing the harness but what I ended up doing was changing the fuse box and the idling improved but still was not quite stable, I removed the egr and saw it stuck slightly open which was responsible for the bad idle, also the intake gasket was changed since the old one was brittle, the throttle body was cleaned. After this idle was steady. So hr15 folks if you keep blowing coils, it could be a vacuum leak that foul the plugs, if this is corrected and problem persists then the issue could be the square fuse box in the engine bay and ecu.

Make sure the replacement ecu and fuse box is the same as the one in the car, the harness is specific to the ecu and fusebox