sounds like you have an exhaust leak. my truck had a little leak from the headers and when i would lift i would have a pop pop pop coming out the duals because air is getting into the exhaust from the leak and causing the unburnt fuel to ignite inside the pipes. check to see if you got some carbon leaking out where there are welds or connectors.
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解体屋 Just a gearhead in paradise...
I know what caused the light to come on
The air density or temp sensor got messed up, it was too short and me and some friends tried to lengthen wire on it and the light kicked on after that.
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-1994 Toyota Corolla-Ksport Coilovers, custom exhaust, Weapon R intake with Ram Air Kit
Have you figured out where your exhaust leak was that was causing the backfires/popping noise? Or even if that's what was causing it? Hopefully there were no weld issues.
I'm getting 35 mpg as it runs now, and as for power, I have no problems keeping up with my friends on the highway and from a dead stop at lights.
That's all fine and dandy, but for the ECU to calculate the amount of air coming into the engine using Speed Density (as yours does...or should I say used to do), it does NEED to know the air temperature. It's two wires, how can you not extend that correctly? Two wires.
Quote:
Speed density operation starts with the basic ideal gas law, which states the following relationship between gas (air) pressure, temperature and volume.
pV = nRT
Where:
p = absolute pressure of the gas (air in this case)
V = volume of the gas
n = amount of gas
R = gas constant
T = absolute temperature of the gas
So, you NEED the following sensors working:
Barometric pressure sensor (atmospheric air pressure)
Manifold Absolute Pressure sensor (engine vacuum)
Intake Air Temperature sensor (air temperature)
Crank or Camshaft position sensor (engine speed)
Now the magic happens, the ECM takes those inputs, with some math and the known displacement of the engine, the speed at which it's running, the difference between manifold pressure and atmospheric pressure, and the temperature of the air that's entering the engine, and voila knows pretty closely how much air is coming in. It needs to know the temperature to get one of the calculations, hell it's right in the name. Density! The density of air changes with its temperature. As of right now the ECM cannot tell the amount of air entering the engine, it's running off of assumed safe values which are often too rich or too lean for the actual operating conditions. It does get oxygen sensor feedback but may be ignoring it due to it missing that vital sensor input. Fix it. It's just two wires!
That's all fine and dandy, but for the ECU to calculate the amount of air coming into the engine using Speed Density (as yours does...or should I say used to do), it does NEED to know the air temperature. It's two wires, how can you not extend that correctly? Two wires.
So, you NEED the following sensors working:
Barometric pressure sensor (atmospheric air pressure)
Manifold Absolute Pressure sensor (engine vacuum)
Intake Air Temperature sensor (air temperature)
Crank or Camshaft position sensor (engine speed)
Now the magic happens, the ECM takes those inputs, with some math and the known displacement of the engine, the speed at which it's running, the difference between manifold pressure and atmospheric pressure, and the temperature of the air that's entering the engine, and voila knows pretty closely how much air is coming in. It needs to know the temperature to get one of the calculations, hell it's right in the name. Density! The density of air changes with its temperature. As of right now the ECM cannot tell the amount of air entering the engine, it's running off of assumed safe values which are often too rich or too lean for the actual operating conditions. It does get oxygen sensor feedback but may be ignoring it due to it missing that vital sensor input. Fix it. It's just two wires!
I'm gonna fix it when I get a chance, and being colour blind and kinda twitchy its hard for me to do little things like wiring.
Quote:
Originally Posted by Corolla Sound
Have you figured out where your exhaust leak was that was causing the backfires/popping noise? Or even if that's what was causing it? Hopefully there were no weld issues.
If it is a leak, I have access to a welder, and know people who can teach me or do it for me.
Quote:
Originally Posted by Piloter
Could it be that the PCM's not cutting fuel on closed throttle? This is the classic fuel-burned-in-exhaust crackle.
I'm starting to guess its my exhaust setup, its 2 glass packs a 4-2-1 header, high flow cat and 2.5" piping.
If I can't find a leak, and I can get the CEL to go out and it still does it I'm gonna assume its the exhaust setup.
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-1994 Toyota Corolla-Ksport Coilovers, custom exhaust, Weapon R intake with Ram Air Kit
I can get it to do it at 2k rpm in any gear except first and second.
I let of then tap it and it does it, but if I let off then hop on it does the same, that's how it happened the first time.
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-1994 Toyota Corolla-Ksport Coilovers, custom exhaust, Weapon R intake with Ram Air Kit
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1997 Corolla
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