hi guys I need help!!!
i replaced the short block and after starting the car the AEM wide band goes super lean reading 3 bars at idle but goes back to normal with some throttle. I replaced the upper O2 sensor as the jack got damaged during removal also replaced the O2 housing with a Megan higher flow unit.
but the car still sound weird and running lean.
i checked for any hoses that could have come off or broken or installed wrong but all look correct/good.
plugs looked ok like they always looked nothing off but changed them out and regapped them to .24 like always.
timing is still spot on but will go all the way down to the timing belt/balance shaft marks and double check
it worked fine before the Shortblock install it just seams to be something small I'm overlooking.
Any ideas will be greatly appreciated

 

Btw there is no check engine light and I checked and recheck all my hoses and clamps but still no bueno

 

Was the Evo previously tuned? Was a break in tune done?

 

do a boost leak check, it will help you locate any potential vacuum leaks. What do your fuel trims look like? If you don't have a way to check those, pull the negative battery cable to clear out all the learned trims and see if that makes a difference.

 

Thank man I will try that.
I have a AEM ECU so will that work to clear the lean codes???

 

Trims not codes
sorry!!!!

 

Oh NM then on clearing the trims. I don't even know if the AEM does fuel trims. Since its an aftermarket ECU it might just need a little touch up on the tune to get it back in line. Definitely do the leak test though to eliminate that as a potential issue.

 

Thanks bro.
My job takes me outta state but I can't wait to try out ur tips when I get back home Sunday.
I will post an update if it worked or not. Either way

 

Since you say it sounds funny maybe an exhaust leak that sucks in air at idle and leaks making noise on the road. This could confuse the O2 sensor.

 

The thing is I have a greedy complete system and the only part that got touched was were I replaced the O2 sensor and Megan housing and that got buttoned up back with a new gasket and hardware. But it was making that sound with the sold OEM O2 housing.
thats y I ordered and changed it but it still sounds lawn mowerish
i guess u could call it "missing"!!!!!!

 

Sorry id33 I completely missed ur post
but since I replaced the Shortblock i haven't gotten the chance to break in the engine, drive it or take it to get a tune as it's been doing the extreme lean and missing thing.
If that's what ur asking????
but I'm sure the past owner did some tuning as there were cables attached to the AEM ECM that could be connected to a laptop for tuning!!!!!!
once again very sorry to overlook ur post
it was not intensional nor did I mean any disrespect.

 

No worries dude! Hope you find the solution.

 

You should be asking yourself why it blew up in the first place or why you had to replace the shortblock.

Murphy's law says it'll happen again.

 

Good question. But 1 I don't have the answer to.
See I just pickup this car and the past owner however he was put on a lot of nice bolt on but never seam to take the time to install/ do me right. This also applied to the tuning which I think he was doing himself as with the cables I found in the car still attached to the ECM.
Having said that I think he fried a piston and then sold it.
Now it ran fine even with the messed up pistion. No lean/rich or missing. It had symptoms of a blown head gasket. Oil in the coolant type stuff so I knew I had to remove the head but that's when I saw the #4 piston was missing a chunk. That how the replacement short block came about. But before that a built block was put in and it ran fine but that block smoked so that lead me back to the Shortblock that in it now.
Look it ran fine up to this point it just seam I forgot to or damaged a hose a line a fitting or something when I was putting it back together I think.
But at this Point it's all just theoretical

 

So it had the usual problem with detonation and broken ring lands on no 4.
That's what always happens when you get the tune wrong.