First start running rich
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First start running rich Just started the transplant 57 Belair. 2001 LM7,4L60E, Com cam, long tube headers, cold air, stall convertor, mail order tune (150 Tunes) Car started right up but is running very rich, O2 are in the collectors running open exhaust for now. My question is with the O2 right at the end of the exhaust can they get a good reading, do I need some type of exhaust pipes on the headers? If so how long do they need to be ? I will install a full system later on just want to get some bugs worked out . Their not moving much in closed loop 450-500 and not switching. The only other code is a TPS but the numbers are good on it. Emissions, downstream O2 deleted in tune.
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I don't want to put a full exhaust on it yet so what would you think would be the minimum amount of pipe I would need to get an accurate O2 reading? I have a couple of 48" 3" pipes that I might be able to get on it if that would be enough??
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Planning on installing the pipes over the weekend and will see how things work out. Thanks for the reply. The rich condition should not cause the TPS to set a code which doesn't make much sense but will check that out after I get it back running again.
If the O2's are more than 6" from the end of the header they should be fine at everything but idle. At idle I would want a few more inches of pipe to keep them from seeing outside air that could skew readings. Since you are reading RICH, however, this point is moot. When you say 450-500mv, are they sluggish, or not switching at all? If you are not getting any feedback at all they should stay at 450mv, but may fluctuate due to charging system voltage changes.
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If the O2's are more than 6" from the end of the header they should be fine at everything but idle. At idle I would want a few more inches of pipe to keep them from seeing outside air that could skew readings. Since you are reading RICH, however, this point is moot. When you say 450-500mv, are they sluggish, or not switching at all? If you are not getting any feedback at all they should stay at 450mv, but may fluctuate due to charging system voltage changes.
https://lh3.googleusercontent.com/T8...=w1503-h844-no
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Lager cams require less fuel at in the lower idle area. You need to adjust you VE tables to run leaner.
What ecm tuner are you using.
WHen I put cam heads turbo larger tb on my motor you would think I would of needed more fuel right? Not even close I had to subtract about 20% in my ecm idle to get it to just start.
What ecm tuner are you using.
WHen I put cam heads turbo larger tb on my motor you would think I would of needed more fuel right? Not even close I had to subtract about 20% in my ecm idle to get it to just start.
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Well actually a larger cam does require both more fuel and more air in the idle area, but because the cam overlap acts like a vacuum leak, the idle values in the VE table will need to be lower, as stated.
The values in the "VE" (Volumetric Efficiency) table roughly indicate how close to theoretical efficiency (in %) the engine is at that RPM and Throttle opening. The overlap of a large cam wastes air/fuel at low RPM and the efficiency is therefore very low. However at high RPM the cam allows resonances in the intake and exhaust system to boost efficiency past 100%. (Some people call this the "ram effect", but engineers say that isn't really accurate.) This is all greatly simplified, but hopefully helps conceptualize the meaning of the values in the VE table.
The values in the "VE" (Volumetric Efficiency) table roughly indicate how close to theoretical efficiency (in %) the engine is at that RPM and Throttle opening. The overlap of a large cam wastes air/fuel at low RPM and the efficiency is therefore very low. However at high RPM the cam allows resonances in the intake and exhaust system to boost efficiency past 100%. (Some people call this the "ram effect", but engineers say that isn't really accurate.) This is all greatly simplified, but hopefully helps conceptualize the meaning of the values in the VE table.
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I installed 48" of 3" straight pipe to the headers but something still isn't as it should be, better but not right. I took a picture of the scanner after it went into closed loop, ant suggestions would be helpful.
https://lh3.googleusercontent.com/T8...=w1503-h844-no
https://lh3.googleusercontent.com/T8...=w1503-h844-no
To me this indicates a likely misfire or dead cylinder, either of which allows a lot of unburned oxygen to hit the O2 sensor and show super lean. (Notice I did not say unburned fuel because O2 sensors measure "unburned" oxygen.)
An infrared thermometer is very useful here if you have headers. Read each header pipe right at the cylinder head and you will likely figure out which has the misfire. I once had a dead injector and that cylinder read 90F at idle.
A bad injector, bad plug or bad coil is the likely culprit.
Harbor Freight and other discounter often sell infrared thermometers for under $30 and they are very useful for automotive diagnostic work, And also in the kitchen; meaning your wife will approve it and then steal it.
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If I am reading that right, Bank 1 is working well but Bank 2 is running extremely lean and the PCM is adding 25%+ fuel to it.
To me this indicates a likely misfire or dead cylinder, either of which allows a lot of unburned oxygen to hit the O2 sensor and show super lean. (Notice I did not say unburned fuel because O2 sensors measure "unburned" oxygen.)
An infrared thermometer is very useful here if you have headers. Read each header pipe right at the cylinder head and you will likely figure out which has the misfire. I once had a dead injector and that cylinder read 90F at idle.
A bad injector, bad plug or bad coil is the likely culprit.
Harbor Freight and other discounter often sell infrared thermometers for under $30 and they are very useful for automotive diagnostic work, And also in the kitchen; meaning your wife will approve it and then steal it.
To me this indicates a likely misfire or dead cylinder, either of which allows a lot of unburned oxygen to hit the O2 sensor and show super lean. (Notice I did not say unburned fuel because O2 sensors measure "unburned" oxygen.)
An infrared thermometer is very useful here if you have headers. Read each header pipe right at the cylinder head and you will likely figure out which has the misfire. I once had a dead injector and that cylinder read 90F at idle.
A bad injector, bad plug or bad coil is the likely culprit.
Harbor Freight and other discounter often sell infrared thermometers for under $30 and they are very useful for automotive diagnostic work, And also in the kitchen; meaning your wife will approve it and then steal it.
Thread Starter
Teching In
Joined: Jul 2014
Posts: 6
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Lager cams require less fuel at in the lower idle area. You need to adjust you VE tables to run leaner.
What ecm tuner are you using.
WHen I put cam heads turbo larger tb on my motor you would think I would of needed more fuel right? Not even close I had to subtract about 20% in my ecm idle to get it to just start.
What ecm tuner are you using.
WHen I put cam heads turbo larger tb on my motor you would think I would of needed more fuel right? Not even close I had to subtract about 20% in my ecm idle to get it to just start.
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Joined: Dec 2014
Posts: 48
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More than just a camshaft will come into play when tuning your motor. Dont get me wrong mail order tunes are good for slight upgrades but you need to bring it to someone local with a wideband.
There are some guys that make you / send you their data log , scan tools then ship them back and do a tune thats acceptable but some guy just guessing will never be spot on.
HP tuners is like 400$ after a few tunes it pays for its self. Best tool you could ever buy.
Well actually a larger cam does require both more fuel and more air in the idle area, but because the cam overlap acts like a vacuum leak, the idle values in the VE table will need to be lower, as stated.
The values in the "VE" (Volumetric Efficiency) table roughly indicate how close to theoretical efficiency (in %) the engine is at that RPM and Throttle opening. The overlap of a large cam wastes air/fuel at low RPM and the efficiency is therefore very low. However at high RPM the cam allows resonances in the intake and exhaust system to boost efficiency past 100%. (Some people call this the "ram effect", but engineers say that isn't really accurate.) This is all greatly simplified, but hopefully helps conceptualize the meaning of the values in the VE table.
The values in the "VE" (Volumetric Efficiency) table roughly indicate how close to theoretical efficiency (in %) the engine is at that RPM and Throttle opening. The overlap of a large cam wastes air/fuel at low RPM and the efficiency is therefore very low. However at high RPM the cam allows resonances in the intake and exhaust system to boost efficiency past 100%. (Some people call this the "ram effect", but engineers say that isn't really accurate.) This is all greatly simplified, but hopefully helps conceptualize the meaning of the values in the VE table.
Last edited by mrich0908; Nov 13, 2016 at 10:22 PM.