Put in new o2 sensors, new map sensor, still runs poorly!
09-02-2005, 04:14 AM
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Put in new o2 sensors, new map sensor, still runs poorly! So the other day I took my car in to Auto Zone for a code scan because it has been very low on power. It has also been bogging and stumbling quite a bit. The results given to me from the scan were map sensor low voltage, and both primary o2 sensors were not responding and showing low voltage.
So I bought new o2 sensors and a new map sensor. I checked to see if I had power running to the sensors as I said I was going to do in my other thread. All three sensors do have power running to their plugs. Pink wires have power on o2 sensor plugs, white wire has power on MAP sensor plug. I did notice that when I used the circuit tester on the MAP plug the light was not nearly as bright as the light when I tested the o2 sensors for power. I also tested the ground wires for the o2 sensors. They are grounded.
Getting to the point, I replaced all three sensors tonight (morning) and disconnected then reconnected the battery. (it was disconnected about 20-30 minutes)
Included are pictures of all three sensors I removed. The MAP sensor was definitely damaged as can be seen in the picture. I thought the o2 sensors looked a little funny as well.
THE CAR IS STILL DOING THE SAME THING! UGH!!
Someone please help me with some ideas.
So I bought new o2 sensors and a new map sensor. I checked to see if I had power running to the sensors as I said I was going to do in my other thread. All three sensors do have power running to their plugs. Pink wires have power on o2 sensor plugs, white wire has power on MAP sensor plug. I did notice that when I used the circuit tester on the MAP plug the light was not nearly as bright as the light when I tested the o2 sensors for power. I also tested the ground wires for the o2 sensors. They are grounded.
Getting to the point, I replaced all three sensors tonight (morning) and disconnected then reconnected the battery. (it was disconnected about 20-30 minutes)
Included are pictures of all three sensors I removed. The MAP sensor was definitely damaged as can be seen in the picture. I thought the o2 sensors looked a little funny as well.
THE CAR IS STILL DOING THE SAME THING! UGH!!
Someone please help me with some ideas.
09-02-2005, 09:04 AM
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I would ignore the O2 complaint for the time being, it
is likely just the consequence of bad mixture from the
MAP sensor being messed up. MAP low = air calcs low
= lean fueling (low O2 voltage).
MAP sensor receives 5V PCM reference voltage on the
gray wire (per 2002 Helm manual, check your year).
Return is black wire to PCM ground. Its output is on
the green wire with an internal PCM load resistor to
PCM ground. So bad connector or wiring harness
open circuit will cause a low voltage fault as will
loss of the 5V power. A DMM reading on the 5V (gray)
and output (green) against the black ground wire
will indicate the health of the sensor & its support.
PCM C2 pin 32 is the output, C1/54 is a the MAP gnd,
C1/48 is the 5V reference. The reference has current
limiting so excess current draw could depress the 5V.
DTC P0107 (MAP sensor low) sets when the MAP
output is below 0.1V for more than 4 seconds.
This low a MAP voltage is abnormal (duh).
For some reason the Helm book says to check the
oil pressure sensor circuits as well as the MAP
sensor stuff. No explanation of the relationship
there.
is likely just the consequence of bad mixture from the
MAP sensor being messed up. MAP low = air calcs low
= lean fueling (low O2 voltage).
MAP sensor receives 5V PCM reference voltage on the
gray wire (per 2002 Helm manual, check your year).
Return is black wire to PCM ground. Its output is on
the green wire with an internal PCM load resistor to
PCM ground. So bad connector or wiring harness
open circuit will cause a low voltage fault as will
loss of the 5V power. A DMM reading on the 5V (gray)
and output (green) against the black ground wire
will indicate the health of the sensor & its support.
PCM C2 pin 32 is the output, C1/54 is a the MAP gnd,
C1/48 is the 5V reference. The reference has current
limiting so excess current draw could depress the 5V.
DTC P0107 (MAP sensor low) sets when the MAP
output is below 0.1V for more than 4 seconds.
This low a MAP voltage is abnormal (duh).
For some reason the Helm book says to check the
oil pressure sensor circuits as well as the MAP
sensor stuff. No explanation of the relationship
there.
09-02-2005, 11:45 AM
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ok i am trying to follow what you are saying the best i can but i dont totally understand.
the plug has three wires gray, green, and orange with a black stripe
i just tested the voltage of the gray one with the key on but the engine not running. i used a battery tester and used the orange wire as the ground and the gray wire as the positive. it showed 5 volts.
the plug has three wires gray, green, and orange with a black stripe
i just tested the voltage of the gray one with the key on but the engine not running. i used a battery tester and used the orange wire as the ground and the gray wire as the positive. it showed 5 volts.
09-02-2005, 12:14 PM
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i am going to take it back in and have it rescanned.
could it be spark plugs? it has what look like crappy stock delcos in it. not the irridiums i dont think.
could it be spark plugs? it has what look like crappy stock delcos in it. not the irridiums i dont think.
09-02-2005, 04:04 PM
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Sounds like you have different wiring than I do,
but still worth basic electrical checks on the
sensor. I guess the green is still signal, you want
to see something between 0.1 and 5V there. I
don't know the MAP output characteristic, just
the fault limits. Check it at the PCM connector
if you can find the pinout, just to rule out wire
harness / connector opens & shorts.
I doubt plugs will have any way to give you a
MAP code, but it may be time for them anyway.
but still worth basic electrical checks on the
sensor. I guess the green is still signal, you want
to see something between 0.1 and 5V there. I
don't know the MAP output characteristic, just
the fault limits. Check it at the PCM connector
if you can find the pinout, just to rule out wire
harness / connector opens & shorts.
I doubt plugs will have any way to give you a
MAP code, but it may be time for them anyway.
09-02-2005, 04:11 PM
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I took the car back to auto zone today and it was still showing the same codes. i had them clear all the codes and then i drove the car a couple miles and came back. no codes came back on.
how long does it take to show a code? you would think if the sensors were still basically dead like the old ones were it would show codes right away right?
i got denso iridium plugs that i plan to put in as soon as the engine cools.
how long does it take to show a code? you would think if the sensors were still basically dead like the old ones were it would show codes right away right?
i got denso iridium plugs that i plan to put in as soon as the engine cools.
09-02-2005, 08:46 PM
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went back for another code scan. o2 sensor low voltage and o2 sensor no response on both sides.
car is drinking gas and exhaust smells rich. soot on tips.
what wires on the o2 sensors should have power? should more than 1 of the 4 wires have power?
car is drinking gas and exhaust smells rich. soot on tips.
what wires on the o2 sensors should have power? should more than 1 of the 4 wires have power?
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09-02-2005, 09:25 PM
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What mods have you done to the car.The maf could cause your car to bog and stumble. The heating elements might be dirty,sometimes it won't throw a maf code and could cause other sensors to fail.
09-03-2005, 12:20 PM
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I just cleaned the maf like 2 days ago... it was a little dirty but it didnt seem to make a difference
the engine is all stock with a ported throttle body and ported 02 manifolds.
the engine is all stock with a ported throttle body and ported 02 manifolds.
09-03-2005, 01:30 PM
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ok so i just pulled my fuel pump and there is crap all over the sock. i looked down into the tank and there is sediment all over the bottom. i am now getting ready to drain and remove the tank.
do you think maybe my corvette fuel filter/regulator is clogged up as well or maybe the sock would have stopped most of it?
do you think maybe my corvette fuel filter/regulator is clogged up as well or maybe the sock would have stopped most of it?
09-03-2005, 11:10 PM
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TTT
gonna try to get a new fuel filter tomorrow. the tank was full of rusty crap. i suspect that a good bit of it got in the filter and could have plugged it up.
gonna try to get a new fuel filter tomorrow. the tank was full of rusty crap. i suspect that a good bit of it got in the filter and could have plugged it up.
09-05-2005, 05:37 AM
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One thing I noticed that's not helping your power situation is how oily the pic of the MAP sensor is. You should consider running a catch can and doing a top end cleaner.
09-05-2005, 10:08 AM
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Originally Posted by theantirotor
i shouldnt need a catch can on an NA engine should i???
It's worth taking a look behind your TB blade to see how much, if any, oil you have in your intake manifold. You shouldn't have any. If you do, it could be causing your sensors to foul up.
