1jz black smoke and bad idle
- Thread starter chris_2jz
- Start date
Keep in mind with those codes... you can trigger them if you unplug any sensors while the key is on. So don't chase after a code if you might have triggered it yourself. Clear them and run it again to see what codes come up without you touching anything under the hood.
Like was mentioned earlier, check the wiring near the O2 and crank sensor. If you weren't messing with the plugs for those sensors with the key on, then it sounds like they have wiring issues. Just look for water in the plugs or busted wires. Give the wires a light pull and see if they stay in the connectors, they could have been pulled off of the pins inside and still look ok at a glance. Also do this with the wiring along the harness. I've seen where someone poked pinholes in the wiring to test something and then the wire just corroded into green powder inside the harness where the hole was and it went unnoticed till a problem came up.
Also check the wiring back at the ECU plugs for the same problems.
FWIW... I just unplugged the 02 sensor on my car and it runs pretty decent, plus a little black smoke. The car will ignore the O2 sensor if it knows it's not there and will run on default fuel maps, which are close enough for the car to run and drive, but not good for fuel mileage or hard driving.
Like was mentioned earlier, check the wiring near the O2 and crank sensor. If you weren't messing with the plugs for those sensors with the key on, then it sounds like they have wiring issues. Just look for water in the plugs or busted wires. Give the wires a light pull and see if they stay in the connectors, they could have been pulled off of the pins inside and still look ok at a glance. Also do this with the wiring along the harness. I've seen where someone poked pinholes in the wiring to test something and then the wire just corroded into green powder inside the harness where the hole was and it went unnoticed till a problem came up.
Also check the wiring back at the ECU plugs for the same problems.
FWIW... I just unplugged the 02 sensor on my car and it runs pretty decent, plus a little black smoke. The car will ignore the O2 sensor if it knows it's not there and will run on default fuel maps, which are close enough for the car to run and drive, but not good for fuel mileage or hard driving.
destrux;1769599 said:
Yea im gonna have to do some investigating cause I picked a used working map sensor from a good source induction performance (F&H performance) and a o2 sensor from a friend and im still getting the same codes 21(o2) & 31(map). Still running rich and back fires at 3-4k rpms
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Something else to check would be timing just for shits and giggles.
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Well if ur using the jza70 harness it's the second smallest connector called W it's 2nd to the left or if ecu is properly mounted it should be the 2nd connected closest to the passenger direction once u have the knowledge of that connector look for these three colors - brown -drk blue with blk stripe and - light green with blk stripe check at ur map sensor connector that should be ur colors. If u leave the ecu connector W in the ecu this is the position of those pins pin# 1 vac Blue blk stripe pin# 2 vac light green pin# 9 intake manifold ground Brown that grounds a few sensors so just becareful with it u can use a T pin to back probe for checking ur ohms or volts when the keys in the on position or better check volts at sensor when running with using the t pin to back probe the connector at the sensor to assure that it is a good sensor should be at 5 volts around idle and go up as u raise Rpms
Before anything pull the efi main relay leave it for a good minute than put it back start the car try to get it to come across the back fire after that happens turn it off check codes let us know what u got if still o2 and map than we know where to go from here on
soso714;1769917 said:
The green and black weren't getting power due to the hks fcd so I removed it and now the map sensor is working But other then that the car is running fine except for the o2 sensor. Will not having a o2 sensor make my car sputter a little?
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JZ's don't really trigger a check engine light unless it is something very serious. The O2 sensor really should not make your car sputter. Have you check your coil packs?
Have you checked that the harness for the O2 sensor gets power ad ground when the ignition is on? You will need to connect the two wires that are the same color on the Mustang O2 sensor to those wires of the O2 sensor harness that get power and ground when the ignition is on.
The O2 sensor has not polarity on the heater wires( wires that are the same color), so you can connect them without a problem.
Have you checked that the harness for the O2 sensor gets power ad ground when the ignition is on? You will need to connect the two wires that are the same color on the Mustang O2 sensor to those wires of the O2 sensor harness that get power and ground when the ignition is on.
The O2 sensor has not polarity on the heater wires( wires that are the same color), so you can connect them without a problem.
IBoughtASupra;1770321 said:
What would a bad o2 do? What i've experienced within the last hour is: @5-6k rpms it feels I have no power and it back fires 1-4k feels fine.
Idles fine
Spools fine until 5-6k
Ill check what I'm getting at the harness
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Also I forgot to mention im still using a mk3 o2 sensor found a 89 cut the plug and tied my plug into it. I wanted to use the mustang one but it would occupy my only lambda nut. From the same colored plugs im getting with the key on both have power and the signal has nothing. With the car running one heater wire has power and the other is grounded and signal still has nothing. I cleared the codes ran the car still getting the error code 21(o2)
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IBoughtASupra;1770350 said:
several methods, I have a test light you plug into the cigarette light and it has a little light red (power) green (ground) - reliable test for determining power and I'm using a snap on auto ranging mulitmeter. With the multimeter I have no continuity from the spiced o2 sensor wires and cut harness wires. But the test light is telling I have power and ground just not how much voltage or ohms or resistance.
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Food for thought I never had my o2 plugged in my 1jz. Always threw code 21, never effected it.
When I used my LC-1 I emulated it but still threw 21 for the heater. Never ran bad. Try taking off the FCD and going back to a close to stock setup
When I used my LC-1 I emulated it but still threw 21 for the heater. Never ran bad. Try taking off the FCD and going back to a close to stock setup
Albert;1770373 said:
How do you know it was for the heater? Ill leave it for now im just a little concerned about the backfire at 5-6k never happen before and I gapped my new copper plugs at .28 and it feels slow at high rpms, would the fact I took my FCD off effect my performance? I know my car was tuned with safc2 and the FCD at time of dyno and tune. Any input?
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