Quote:
Originally Posted by Slade
Im wondering if the headers were loosely installed as well. My first thought was the 02 sensor but I was told earlier in this thread that the 02 sensors wouldn't cause that problem.
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The sensor may be fine, but if there's a leak anywhere from the valve to the last O2 sensor in a given exhaust set up, the ECU will compensate incorrectly, see other conditions change unexpectedly (like low RPMs from the now incorrect A/F ratio) and compensate for those, then cycle like that in a rough idle until the point where it can't recover and dies.
Along with the other guys, I'd go back to a stock tune and stock headers if possible. If you don't have the headers, definitely flash back to stock and make sure you're only throwing a P0420 Catalyst Efficiency code.
Maybe pick up a set of gaskets and start there too. I've seen many builds where the headers leak because of cheap or re-used gaskets. I'd also check that the flanges aren't warped if you have a good straight edge or a machinist friend.
Lastly, since it sounds like you're OFT so here's their article for logging:
https://support.openflashtablet.com/...e-datalogging-
Some of the key channels to log are Air Fuel Ratio (AFR), Commanded AFR, Short Term Fuel Trim (STFT), Long Term Fuel Trim (LTFT), Ignition Advance, and Advance Multiplier (IAM). A normal log for a good tune at idle will have trims that are close to 0%, an AFR that's tracking the Commanded AFR almost perfectly, and an Advance Multiplier that's trending from 0.7 towards 1.
If you grab a log datazap.me is a pretty widely used site to chart and share them.