PLEASE HELP! 99 Cobra Throwing Lean Codes and Stalling During Cold Starts

SVT_Aidan

New Member
Nov 22, 2021
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Troy, Il
I bought a 99 cobra and it ran great and had no problems. I thought that the engine bay was a little boring though so i decided to get the valve covers powder coated. I went through hell and back to get them off and back on but i ended up finishing it. It looked great and I liked the result but when i went to start it, it would idle really low. I just adjusted the idle screw and went about my day even though the exhaust smelled kinda rich and didn't want to always stay going during a cold start. Later on I took it in the get inspected and it wouldn't pass due to what they called "cat system not ready", couldn't fix it for the life of me so i took it in and my mechanic said he thought it might be the ecu, so i got a new stock ecu with the stock tune. It didn't fix the emissions problem but i just ended up moving my address so i wouldn't have to pass emissions. Then I decided to replace the O2 sensors and when i went to start it up after that it started throwing 2 codes (P0171 and P0174) "System Too Lean Bank 1 and System Too Lean Bank 2". I then noticed the my IAC valve was consistently open so i replaced it, then I found out that I had put the throttle body gasket on wrong during the valve cover job, fixing that solved the IAC problem. But it was still had a lean code and i though i might be caused by an exhaust leak so i completely examined the exhaust system and there was what i thought might be a slight exhaust leak so i fixed it and cleared all my codes, i didnt throw a code for a awhile but still had the cold start problem but i didnt mind it. But about 2-3 weeks later my engine light come back on and it is still have the cold start problem. if you have any clue what this could be PLEASE HELP ME.
 
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COramprat

...I can take it. I think.
Mod Dude
Mar 2, 2003
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Sea of Tranquility
If it was fine before you took the valve covers off, go back and make sure everything is back where it should be. Kind of sounds like a vacuum leak.