Lean at cruise bucking, what to do?
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Joined: Oct 2002
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From: NJ
Lean at cruise bucking, what to do? Haven't gone through all the tricks yet to try and remedy the issue, but something new for my head/intake combo just installed vs my old set up. The VE table in HPT is slightly on the rich side in the cruising cells 2krpm and below, spark is at 29*. If I lean this out to stoich, then I get some pretty bad bucking, but obviously more power and response.
So okay great, richen it up, loose some power, but KILL my gas mileage. So with this in mind, any ideas what to try in order to increase gas mileage (such as leaning out) and reduce the bucking and get some power back?
Thanks!
So okay great, richen it up, loose some power, but KILL my gas mileage. So with this in mind, any ideas what to try in order to increase gas mileage (such as leaning out) and reduce the bucking and get some power back?
Thanks!
How long has it been running with the new setup? Maybe the PCM is just 'learning' from the new readings and adapting. I read in the tuning 'sticky' that it takes the LS1 some quantity of hot/cold cycles for the car to relearn how to administer fuel after a battery disconnect.
Open this and look at item 2D to see that to which I'm referring.
http://ls1sounds.com/temp/ls1tuninginfo.doc
Open this and look at item 2D to see that to which I'm referring.
http://ls1sounds.com/temp/ls1tuninginfo.doc
Thread Starter
TECH Enthusiast
Joined: Oct 2002
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From: NJ
No nothing to do with that. Running in OLSD so most of the fueling variables have been leveled. Plus car has been running for while with new tune/heads/intake so anything that would adjust would have done so already.
either way I'm worried about the relashionship of bucking vs afr richness, and leaning the mixture out and still reducing bucking.
either way I'm worried about the relashionship of bucking vs afr richness, and leaning the mixture out and still reducing bucking.
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From: Lexington, KY
If you have your IAC counts in the ballpark at idle, and idle airflow correct, then it's probably in the cracker and follower tables or in the learning tables. And keep the rpm's up a little more than you did before...
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From: NJ
You think there may be too much air in the cracker table? Right now it seems to keep the rpms from nose diving and stalling. Just bounces once and back to normal idle after a hot or cold cruise.
How rich is it to stop the bucking? Have you tried to keep adding timing (while keeping it safe) as a test to rid the bucking? To me there needs to be a smooth transition between timing and fueling cells to remove any bucking, especially in OLSD tuned modes.
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From: Lexington, KY
Hard to say but it may need more or less. I don't know of any way to know for sure other than to experiment with it. I set mine up to log TC and TF and watch it while I'm driving to see if it's adding air where it's bucking or surging. But it's not really supposed to be a stall saver I don't think. That's more in the learning tables. Just be sure to adjust the right one, cracker is for when you let off, follower is for when your on the gas. And I agree with the timing comments above. That could be it as well. Finding the right combination of fuel, spark and air has been a real challenge for me.
