How do I cure rich idle?
03-02-2005, 08:40 AM
#1
How do I cure rich idle? I've got a cam & headers with ORP. A baby girl is on the way and the wife is demanding I get rid of the "gas smell."
I know I'm running rich at idle and I've got no cats. What's the best way to fix this - slap on some cats, or is it more of a tuning issue? Car was tuned by MTI.
I know I'm running rich at idle and I've got no cats. What's the best way to fix this - slap on some cats, or is it more of a tuning issue? Car was tuned by MTI.
03-02-2005, 10:41 AM
#3
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^^^He's right. You can lessen the smell though if you're overly rich. Reduce the first three columns of ve table to help. It sure helped the smell on mine a lot. Before, it would burn your eyes at idle, now I can still smell it, but it's nowhere as bad as it was before.
03-02-2005, 10:59 AM
#4
Yeah reduce the first three columns of the VE table to like 50%, 60%, and 70% as a starting point. Then keep reducing them even farther 5% at a time until the engine starts to stumble as you start out from a dead stop, then put the last amount back in. After that, slap some high flow cats on there, but do the VE thing first or you might burn them up. The only other thing you could do would be switch back to the stock cam, but I'm sure you don't want to do that!
03-02-2005, 12:08 PM
#6
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or one of the other options that includes a scanner and tuner (such as HP Tuners ... board sponsor ---->)
easiest solution would be as mentioned... get Cats put on it... will clean the smell up alot
easiest solution would be as mentioned... get Cats put on it... will clean the smell up alot
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03-02-2005, 04:30 PM
#10
Originally Posted by BJM
Does changing the VE table imply he is running O/L in idle? Wouldn't the PCM just trim out the changes?
03-02-2005, 06:39 PM
#11
You need a cam with NEGATIVE overlap.
Having positive overlap messes with your idle tune. At idle, some, but very little of the fresh intake charge goes out the exhaust from the intake side and the O2's pick that up as a lean condition, the computer adds more fuel and thats the main reason why it smells so bad.
I just went from a cam that had +2 degrees of overlap to a cam that has -8 degrees and it made a big difference in the smell...
Having positive overlap messes with your idle tune. At idle, some, but very little of the fresh intake charge goes out the exhaust from the intake side and the O2's pick that up as a lean condition, the computer adds more fuel and thats the main reason why it smells so bad.
I just went from a cam that had +2 degrees of overlap to a cam that has -8 degrees and it made a big difference in the smell...
03-02-2005, 07:18 PM
#12
Originally Posted by Billiumss
You need a cam with NEGATIVE overlap.
Having positive overlap messes with your idle tune. At idle, some, but very little of the fresh intake charge goes out the exhaust from the intake side and the O2's pick that up as a lean condition, the computer adds more fuel and thats the main reason why it smells so bad.
I just went from a cam that had +2 degrees of overlap to a cam that has -8 degrees and it made a big difference in the smell...
Having positive overlap messes with your idle tune. At idle, some, but very little of the fresh intake charge goes out the exhaust from the intake side and the O2's pick that up as a lean condition, the computer adds more fuel and thats the main reason why it smells so bad.
I just went from a cam that had +2 degrees of overlap to a cam that has -8 degrees and it made a big difference in the smell...
Interesting... are you talking about reverse split versus traditional split?
03-03-2005, 10:48 AM
#13
No he's talking about the amount of time both the intake and exhaust are open. Its based on total duration of both intake and exhaust, as well as the lobe separartion angle and even ramp rate of the cam. In short, you need someting like a TR224 on a 114 LSA. Even that one will stink some, but not nearly as bad as what you have now.
03-03-2005, 11:08 AM
#14
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There may be multiple problems with the car. The O2s
may be cool and mislead the trimming process making
for positive trims at idle, closed loop that aren't really
needed. The open loop tune adjustments are a good idea.
Raising idle a bit may also help, it lessens the time of
the overlap dwell, heats up the O2s some, etc.
may be cool and mislead the trimming process making
for positive trims at idle, closed loop that aren't really
needed. The open loop tune adjustments are a good idea.
Raising idle a bit may also help, it lessens the time of
the overlap dwell, heats up the O2s some, etc.
