Cold Idle is Improving
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TECH Senior Member
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Joined: Nov 2001
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From: Bethesda, MD
Cold Idle is Improving I've had my warm idle tuned great for a while, but couldn't get my cold idle (below about 100*F) to stop surging. I'd try messing with the VE (60/80/90 and variations thereof), adding timing and raising the IAC, but nothing worked short of opening the TB so much that I had massive cruise control issues when coasting. I recently saw a NoGo post (or reply to his post) about adjusting the Open Loop Fuel Air Multiplier and tried it.
First, I put my TB blade back to a more normal amount. On the OLFAM table, I multiplied the 20*C and below by 90% as recommended in the post. At first it didn't seem like it did anything, but my cold idle surge dropped a lot once I did the idle relearn. There's a little surge left, so I'm going to try another 3% reduction for 30*C and below. I also am taking another 1% off from the VE table since I may still be a bit rich there.
If you get totally stuck with cold idle surge, I'd give the OLFAM table (Fuel Air Multiplier in LS1Edit) a try.
First, I put my TB blade back to a more normal amount. On the OLFAM table, I multiplied the 20*C and below by 90% as recommended in the post. At first it didn't seem like it did anything, but my cold idle surge dropped a lot once I did the idle relearn. There's a little surge left, so I'm going to try another 3% reduction for 30*C and below. I also am taking another 1% off from the VE table since I may still be a bit rich there.
If you get totally stuck with cold idle surge, I'd give the OLFAM table (Fuel Air Multiplier in LS1Edit) a try.
Yes, I found this table was a big part of the
problem in a "tune by mail" I worked on. The high
idle MAP on cammed cars puts you up into like
1.3 fuel air multiplier range, cold.
In fact I think really it wants reducing until you
find some reason, to stop reducing it (like cold
ping).
problem in a "tune by mail" I worked on. The high
idle MAP on cammed cars puts you up into like
1.3 fuel air multiplier range, cold.
In fact I think really it wants reducing until you
find some reason, to stop reducing it (like cold
ping).
