2011 134k miles. Recent plugs and valve adjustment.

replaced 4 original coils (was fine no issues) with Astemo (original Hitachi after mergers and name change) and engine seems to run better? Real or placebo? Anyone else with experience?

 

Definitely not placebo. New coils = Stronger spark, less misfires, smoother idle, better MPG. Healthy ignition happy engine!

 

Cool, might have to try this on other cars under my care haha. But might get costly (150k 2011 Prius, 215k 08 RX350, 96k 17 Audi A4)

 

mine def. seems to be running better, especially with the ac on

 

Update on all ovserved improvements

• Idle smoother
• Engine runs smoother
• Seems to have remapped the throttle response? Prior to coil change engine/transmission has a sudden rush right when get off the line from a stop. Now is much more linear, can gradually and gently accelerate from a stop. Fit is not my car but I've been driving it in the last couple of days. Owner is slow driving grandma. Wondering if the much more linear off the line throttle response is result of the coil change or adaptation to my driving style (slow and steady)
• More sewing machine than it was before haha

 

Yeah, definitely not placebo. While coils typically either work or don't work, an older coil will just be weaker than a newer coil. That's probably not a large enough difference to warrant a CEL and the ECU can likely adjust for the weaker/slower spark as a coil ages. But it's still an older coil that's worn out and tired when compared to a new coil.