What should the LTRIMS be at idle for a properly tune cam car?
03-14-2005, 03:48 PM
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What should the LTRIMS be at idle for a properly tune cam car? What should the LTRIMS be at idle for a properly tune cam car?
My car starts and runs good, but the L-trims are around +14.
Is this normal?
My car starts and runs good, but the L-trims are around +14.
Is this normal?
03-15-2005, 01:19 AM
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+14 isn't normal. -5 to +5 is acceptible since you don't race from idle. I tune all of mine as close to 0 (or slightly negative) as possible within the allotted timeframe.
03-15-2005, 04:45 AM
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Originally Posted by Billiumss
If you have 0 to positive valve over lap, you gonna have a hard time keeping your Ltrims negative at idle...
It's all about the overlap........
It's all about the overlap........
@ seat, I have 59* of overlap on my cam and my ltft's consistantly run between -8 & +0.8 at idle depending on weather. Point being, overlap doesn't necessarily mean you will have + LTFT's.
Slick Vert, +14 does seem high. You may consider raising you VE values at idle to help bring this number down.
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03-15-2005, 02:21 PM
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If the o2 sensors are cooling off in the header collectors/tubes during extended idle periods, that will also cause high fueling trims in those areas even though the engine has no real demand for such trimming... I've been there and and am still fighting those battles. 
-franklin
-franklin
03-16-2005, 07:46 PM
#12
Originally Posted by TAQuickness
@ seat, I have 59* of overlap on my cam and my ltft's consistantly run between -8 & +0.8 at idle depending on weather. Point being, overlap doesn't necessarily mean you will have + LTFT's.
I tuned 2 408 cars, one with a 240 244 114lsa cam, the other 240 244 112lsa cam, almost impossible to get them get close to negative. One blip on the throttle and they stablize really quick, especially when going down the road.
03-16-2005, 08:11 PM
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Originally Posted by Billiumss
I beg to differ, having more "+" overlap, your IDLE Ltrims will be harder to get negative. I have seen this on many cars, it has to due with reversion.
I tuned 2 408 cars, one with a 240 244 114lsa cam, the other 240 244 112lsa cam, almost impossible to get them get close to negative. One blip on the throttle and they stablize really quick, especially when going down the road.
I tuned 2 408 cars, one with a 240 244 114lsa cam, the other 240 244 112lsa cam, almost impossible to get them get close to negative. One blip on the throttle and they stablize really quick, especially when going down the road.
03-17-2005, 07:38 PM
#14
Originally Posted by Another_User
:shrug: Mine are pretty stable (and negative).
You have the LS1 Hot Cam Right? If so, then your cam only has -.5 degrees of overlap @ 0.050", easy cam to tune.
http://www.sdpc2000.com/catalog/1981...mshaft-Kit.htm
The 240 244 112 lsa cam I was talking about has +18 degrees of overlap, huge difference from your cam.
My first cam was a TR 224 114lsa and then went to a 230 230 114 lsa. Tuning for -ltrims at idle was done but harder to maintain with the bigger cam.
Like I said, the more POSITIVE overlap you have the harder it is to get your Ltrims in line at idle due to reversion.
A lot people have a hard time understanding this. I've tuned alot of cars the past 2 years, some mild some wild!
