https://www.yotatech.com/forums/ 4th gen pickups and 3rd gen 4Runners en Tue, 09 Jun 2026 01:40:39 GMT vBulletin 60 https://www.yotatech.com/forums/images/misc/rss.jpg https://www.yotatech.com/forums/ https://www.yotatech.com/forums/f2/running-rich-long-post-lots-detail-320670/ Wed, 13 May 2026 15:09:39 GMT I’m at my wits end. Truck runs rich with CEL for P0172, P0300 and P0306. It failed emissions because the CEL was on. Replaced coils, plugs, wires, and upstream air/fuel with Denso or OE Toyota... I’m at my wits end. Truck runs rich with CEL for P0172, P0300 and P0306. It failed emissions because the CEL was on.

Replaced coils, plugs, wires, and upstream air/fuel with Denso or OE Toyota parts.

Checked compression… 150-160 across all cylinders. Not amazing but relatively equal.

On the monitor, it starts out okay and then fuel trims climb to -30 short and long term.

Leaked down held. Fuel pressure was high at 55psi, replaced the fuel pressure regulator and it went down to spec @ 42. (I thought maybe the high fuel pressure was pushing passed the closed injectors)

Clearing the computer and restarting the truck runs smooth until the it loads up and tries to lean out. Leading me to believe this is an electronic issue versus a mechanical one.

I have a used ECU that is currently having the immobilzer codes cleared in hopes that’s it.

any thoughts or things I’m missing?

’99 Limited 225k 3.4L Auto engine and trans are stock. ]]> fierohink https://www.yotatech.com/forums/f2/running-rich-long-post-lots-detail-320670/