I have a problem I have the ej25 I have done plugs and wires fuel treatment and still have a real bad hesitation on acceleration any tips would be helpful thanks in advance by the way the engine only has 131k and 31k on a rebuild with a 20thousands bore

Plugs and wires, used NGK plugs with Subaru or NGK wires?
Check the timing belt and see if it skipped a tooth

Bad MAP/MAF/02?
Getting any codes?

Edited November 25, 201411 yr by TKFlight

The plugs are NGK the wires are Subaru timing is all less the 50k and not one code or pending code I'm at a loss

knock sensor

 

IACV

knock sensor even without a code?

yeah, you're right, most people get a P0325 I think. I'd still Inspect it for cracks and make sure it's bolt isn't loose. cheap sensor too. Most folks report the inexpensive Ebay units work fine.

 

here's a video - some voltage drop measurements are possible - start around the 5 minute mark I think.

 

Engine Temp Sensor sometimes won't set a code. But usually folks have easy cold start with bad running when warm or, hard cold start with good running while warm.

 

gummy IACV might also cause poor running at, and just off,-idle. kinda depends on the actual symptoms you experience.

 

If the problem is at a certain throttle setting regardless of gear/speed - could be an intermittent spot on the TPS.

Edited November 25, 201411 yr by 1 Lucky Texan

I can't believe I didn't even think about the temp sensor I'm going to check that one out knock sensor seems fine and I cant get the video on my phone but thank you I'll post what I find