420A Car runs rich when warmed up

[DumbtruckDSM]

Hey guys, I have a 97 RS turbo and I’ve got my first problem since I went turbo. It ran fine and pulled good but one day when I was going to work, it was running fine and when it fully warmed up the AFR read 9 and gets to 8 sometimes! Runs stupid rich when warmed up and I don’t know why.

My fuel setup is a Walbro 255, FMU 12:1, and stock injectors. Not the best I know but I’m not runnin nothing crazy, just around 7psi. I changed the spark plugs and checked for any vacuum leaks.

And sometimes the car will magically run fine some days with the AFR reading 14 at idle and 11-13 when driving.

 

[DumbtruckDSM]

So I I kind of fixed the issue, I still had the very old air sensor on my car and I changed it. I also thought while I was working on my car why not install a new part, I installed a new tial F38 waste gate and I took it for a spin and it rides fine, no more stuttering issues and my afr reads 12 -14 when driving. But I can’t hit boost no more i think I did something wrong on the waste gate but idk I’ll install the old one back on and see what happens. I’m still new to turbo setups so idk if the waste gate is the problem.

 

[DumbtruckDSM]

Okay now I believe I have fixed the problem I put new spark plugs in, new oil, replaced the very old skinny o2 sensor, and put a new beefy one from orielly. I put my old waste gate back on which was a rev 9 eBay one and I noticed I also had a blown waste gate gasket. Replaced that and I noticed my aem air filter was ripped and hanging by a thread. I put on a new one but this time I added like about a 6 inch tube from my turbo to the air filter and it sound way cooler and my car runs fine now!

 

[jesse12345]

When I had mine turbo I ran very rich at idle from my fuel pump pushing to much fuel. I didn't have a fpr just an fmu. You also have to take into account when it's cooler or warmer out, your afr will change. I remember having to adjust my stuff constantly to get that right afr on certain days. Just firing off a couple of ideas if you seem to have more issues. Otherwise hopefully you are good to go.