CEL diagnostic

[BlancoEDurty]

Hey all,
I've been having a check engine light come on for about a month now.

Before you go bashing me for not searching before I post this, I've done and tried everything so far and I still have the same code flashing after the stomp test.

I've cleaned my MAF sensor, ICV, Throttle Body and Airbox. Fuel filter, upgraded my injectors and installed a performance chip. Changed my Valve cover gasket, upgraded the headers, cat, and muffler w/ 02 sensor. And finally flushed the fuel rail. I changed the 02 sensor lastly after finally saying eff it and I'm still getting 1221 stomp test flash.

I had a rough idle but that was due to an exhaust leak that I finally caught and welded up. I stomped tested it and it read back 1444 which means no issues. I took it out and the CEL came back on under the same conditions before. I thought the leak made me run more rich which would build carbon on the O2 sensor so that's what finally made me change it.

The CEL doesn't come on until the car is at operating temp and under acceleration after that at about 2800-3000k, then stays on until I take my foot off of the throttle.

I'm stumped. I can't find anything else. I'm probably going to take it to someone with a code reader but I don't see the point.

What do you guys think?

[BlancoEDurty]

Oh, there's no hesitation and I don't feel any misfiring. When I pulled the injectors they were pretty filthy so maybe I was running rich/lean for a long time and it's taken its toll? Idk. Seems like everyone has had the opposite symptoms.

[BlancoEDurty]

Please help.

[dnguyen1963]

The most critical diagnostic test that you have not mentioned is to do a smoke test to find any vacuum leaks. Rough idle almost equates to vacuum leaks.

[BlancoEDurty]

The most critical diagnostic test that you have not mentioned is to do a smoke test to find any vacuum leaks. Rough idle almost equates to vacuum leaks.

I eliminated the rough idle when I got the exhaust leak welded and O2 sensor switched out. Like I said, it idles strong and there's no hesitation when the gas is pressed. No jerking or anything. I checked the hoses under the intake manifold and didn't see anything but please explain the smoke test so I can be sure.

[dnguyen1963]

What happened when you take your foot off the gas at 3k rpm? Smoke test is a procedure where you pump smoke into your engine from the intake (with the exhaust plugged) at 2 - 4 psi constant pressure. The smoke will come out where there is/are breaks in the system. This is the only definitive way to find all of your vacuum leaks. The procedure would have to be repeated multiple times to find all the leaks. It is best to have a shop do this test for you.

[BlancoEDurty]

What happened when you take your foot off the gas at 3k rpm? Smoke test is a procedure where you pump smoke into your engine from the intake (with the exhaust plugged) at 2 - 4 psi constant pressure. The smoke will come out where there is/are breaks in the system. This is the only definitive way to find all of your vacuum leaks. The procedure would have to be repeated multiple times to find all the leaks. It is best to have a shop do this test for you.

Okay. This has to be it. Otherwise Idk what else to do.
At 3k the light stays on for a little under 2secs and then turns off. I can press the pedal and it won't come back on until its on a good accelerated pull. Its friggin weird lol.

[mazzo]

Smoke Test is your best friend.
Also, did you change fuel filter by any chances? Is the fuel pump working fine?
How is your FPR? You may want to hook up a gauge and check (3.0 bar)
Finally, your TPS and Crank sensor may also be the cause of 1221, if all else failed.
Good luck and keep us posted :)

[BlancoEDurty]

Smoke Test is your best friend.
Also, did you change fuel filter by any chances? Is the fuel pump working fine?
How is your FPR? You may want to hook up a gauge and check (3.0 bar)
Finally, your TPS and Crank sensor may also be the cause of 1221, if all else failed.
Good luck and keep us posted :)

So, I changed the fuel filter almsalmost 3 months ago. It was filthy and looked like it hadn't been changed in a while. Before I swapped the old one I noticed my fuel pump was louder than normal, but after the new one went in the noise went down but didn't go away.

I took my car to a shop to get my fenders rolled and they also did a minor diagnostic. He pulled off the FPR breather hose and the engine stopped the low idle and sounded like it came to life.

I've also been getting a sweet/sour smell in the cabin and the exhaust spits fluid. I'm pretty sure these are telltale symptoms of running rich which may be what's causing my O2 sensor to send the CEL code 1221. I have a new FPR and will see if that does the trick.

[dnguyen1963]

Stop throwing money at your car...do a smoke test.

[Dave1987]

make sure you don't have a leak, spray some carb cleaner around the manifolds port gaskets & the throttle body base. If rpm changes you still have a leak.... If no leak there is always the possibility of a crack in manifold or faulty o2...