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SVTPerformance's Chain of Restaurants
Tuning À la carte
PRP questions
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<blockquote data-quote="97RioRedSnake" data-source="post: 15264937" data-attributes="member: 73948"><p>I had a similar problem after dialing in my MAF transfer function for the first time. A/F mixture would go lean within the first 30 seconds to a minute after startup, idle rough, accelerate rough and then all of a sudden it would be back to (around) stoich and run perfectly.</p><p></p><p>I have two suggestions for you:</p><p></p><p>1. In the "Open Closed Loop" menu in the advantage software there is a time delay for closed loop and other delays related to triggering closed loop in the scalars. Try increasing these values by a significant amount (I doubled them a few times). </p><p></p><p>In my datalogs I was seeing somewhat erratic O2 sensor activity in these first 30-60 seconds after startup when my car would be running like crap. One O2 would be switching, the other wouldn't be, or both wouldn't be. I theorized that my O2 sensors were not heating up fast enough/staying hot enough after initial startup since I've added longtubes and found out I had an exhaust leak near the PS header collector. </p><p></p><p>I believe that increasing the closed loop delay gave my O2's more time to heat up and start functioning properly before the PCM dumped the responsibility of controlling the A/F mixture on them.</p><p></p><p>2. Check for exhaust leaks. </p><p></p><p>Like I mentioned, I had an exhaust leak near one of my header collectors and I'd have to assume that this made the situation worse since more heat was allowed to escape near the O2 sensor location.</p><p></p><p>Even with the exhaust leak, my car ran 100% better after cold start-up by increasing the closed loop delay.</p><p></p><p>Hope this helps.</p></blockquote><p></p>
[QUOTE="97RioRedSnake, post: 15264937, member: 73948"] I had a similar problem after dialing in my MAF transfer function for the first time. A/F mixture would go lean within the first 30 seconds to a minute after startup, idle rough, accelerate rough and then all of a sudden it would be back to (around) stoich and run perfectly. I have two suggestions for you: 1. In the "Open Closed Loop" menu in the advantage software there is a time delay for closed loop and other delays related to triggering closed loop in the scalars. Try increasing these values by a significant amount (I doubled them a few times). In my datalogs I was seeing somewhat erratic O2 sensor activity in these first 30-60 seconds after startup when my car would be running like crap. One O2 would be switching, the other wouldn't be, or both wouldn't be. I theorized that my O2 sensors were not heating up fast enough/staying hot enough after initial startup since I've added longtubes and found out I had an exhaust leak near the PS header collector. I believe that increasing the closed loop delay gave my O2's more time to heat up and start functioning properly before the PCM dumped the responsibility of controlling the A/F mixture on them. 2. Check for exhaust leaks. Like I mentioned, I had an exhaust leak near one of my header collectors and I'd have to assume that this made the situation worse since more heat was allowed to escape near the O2 sensor location. Even with the exhaust leak, my car ran 100% better after cold start-up by increasing the closed loop delay. Hope this helps. [/QUOTE]
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