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Old 06-08-2012, 08:57 PM   #4
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Join Date: May 2012
Location: Colorado
Posts: 6
Thanks PaulV for your info ..... I think you have me looking on the right path for my issue.

Here is an update to the things I did and learned and I would like to share with the forum:

* I swapped the fuel injector of #1 with #3 - results no change the only CEL error is 301.

* I then did not quite believe the freeze frame data of the short term being 25% that I previous listed. I did some more real time data collection. I found that BOTH banks on the short term fuel trim would be ramping up during idle. When they hit close to 25% the it would cut back to 0 . That is when the engine cuts out and the CEL would flash and either give a pending error of 301 of eventually over many flashes, a steady CEL error of 301. I'm thinking that it is just throwing a P0301 is because #1 is the first that is in line when the software decides that it hit the 25% limit (being #1 always has its benefits:-)

* attached is a chart of the short term over time where the DME is ramping the mixture until it hits @25% ..... then it drops off to 0. This is cyclical with about every minute or so.

* at RPM above 1000 the mixture is right on the long term of .078 and no CEL codes are thrown. The engine is purring and I have all the power I want :-) When I drive it it's fine until I have to stop and sit at idle.


my conclusions:

it's not just a #1 cylinder issue.
it's how the DME controls the mixture during idle

Might be :
a vacuum leak which is causing the DME to over compensate on the mixture?
a bad senor which is confusing the DME ?


Now I need to fine the thing causing the problem. Any thoughts are appreciated






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