Help, Very lean startup cold or not!!!
 

Id appreciate some help regarding the weird issue that am facing. Its an Evo 7 with bolt ons and an ECU flash.

The car fires up instantly but idles very lean, as per my AEM, and its takes the car about 2mins to go back to normal AFR levels and stays there. Very lean that it can go up maxing the AEM AFR gauge. This isn't only during cold starts, it does it on warm starts also.

It drives very normally and with good AFRs, sometimes it goes very lean when stopping for a red light and bounce up again.

the car has OEM fuel injectors, OEM spark plugs (less than 500 miles), walbro 255, a DIY COP, and OEM FPR. Those are my ignition/fueling mods.

Again id appreciate any input/solution regarding the matter, thanks.

You should ignore your sensor reading for the first 5 min or so.

Well, i would but i actually could feel the car acting weird during the lean running period indicated by the gauge.

Its like having a very loopy cam setup for a few mins and then its back to normal, normal AFRs.

It does have hks272 cams....

What do you mean by this? If it's lean it should "bounce down". Low numbers imply richness. Startup is always rich.

sorry meant bounce to rich, or ratherly the set 14.5-14.9 AFR....

Its running mostly above 16 AFR at startup, and can go up to 18.

Sounds to me that you have a vacuum leak/boost leak.

Wouldn't the lean behavior continue if that was the case? since it does go back to normal afrs after 2 mins.

Sounds like an injector scaling issue. It's lean on startup but once the car goes into closed loop and the ECU starts compensating the problem goes away.

Boost leaks/high AFRs at startup
 

I am experiencing similar issue. I tested the pressure in my system and 4 of my couplers where leaking and my throttle body leakes where the pin goes in and connects to butterfly valve. Hopefully that makes sense. I also disconnected battery for about an hour to see if my problem could be resolved that way. I was getting fuel cut at barely above wastegate and it was a weird clicking noise coming out the exhaust is the only way I can explain it.

During cruise I get 15 afrs, it will not richen up intil 35+ throttle....cleaned MAF also

Not always, especially if it is a small leak. Once things get heated up and expand it could temporarily seal up.