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Discussion Starter · #1 ·
I think that my car may be running rich.
If I drive it for 30 minutes or more in warmer weather, the idle and engine firing starts to act funny. If you turn the car off and come back to within a short period the car seems as it doesn't want to run in lower gearing and at idle. Also driving at 20MPH in 1st and 2nd the car misfires really badly. Also in 5th at highway speeds the car will misfire slightly if traveling up a hill. The car never has up and down idling. The ideling acts as the car doesn’t want to run, or the engine is not firing as normal.

I have pitch-black exhaust residue on my tailpipe and back bumper.

How does one diagnose a car running rich? What causes the car to run rich?
What needs fixing? Do the above symptoms sound like another problem I should look into?

Thanks
 

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Discussion Starter · #3 ·
bojacks said:
is the car burning oil? also how is the engine temperature, i wounder how your o2 sensor acting, if its clauged or shot.
Engine is burning some oil.
Engine Temp is fine.
If o2 sensor acts up, does it through a code?

Thanks!
 

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it might not, but are you getting a check engine light? so at first when you drive its fine since all cars run a bit rich to start the car properly, but when your car warms up and needs that 14.7 air fuel ratio its not doing it. oxygen sensor seems like the culperate.

quoted from how stuff works
When the oxygen sensor fails, the computer can no longer sense the air/fuel ratio, so it ends up guessing. Your car performs poorly and uses more fuel than it needs to.
 

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Discussion Starter · #5 ·
bojacks said:
it might not, but are you getting a check engine light? so at first when you drive its fine since all cars run a bit rich to start the car properly, but when your car warms up and needs that 14.7 air fuel ratio its not doing it. oxygen sensor seems like the culperate.

quoted from how stuff works
When the oxygen sensor fails, the computer can no longer sense the air/fuel ratio, so it ends up guessing. Your car performs poorly and uses more fuel than it needs to.
Thanks my dad thinks it is the O2 sensor. No check engine light.
 

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Discussion Starter · #9 ·
I'm currently trying to get the O2 sensor off.
Check engine light came on last night during my drive home.
I'm going to try and get the code once I can jump the diagnostic jumper.
 

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ok so I have a question along these lines - I am also running rich as hell. As I am driving the CEL comes on about 5 minutes after warmup or when I just get out of VTEC. Also we checked the code and it came out to be O2. When I did my JDM D15b swap I put in the p08 ecu, but left the USDM o2 sensor. Would swaping a p28 ecu with the existing p08 ecu fix the o2 problem and not damage the engine? Also if it is able to be swapped would I have to rewire the ECU harnesses?
 

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GBR said:
Maybe the idle up and down has to do with the TPS? (Throttle Position Sensor)
or the IACV
 

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Discussion Starter · #14 ·
Update

Ok
I found the ECU is showing code 43
Replaced O2 sensor with a Bosch O2 sensor and still have the problem.

Any other ideas?
How do I go about troubleshooting fuel problems?
Thanks!
 

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you could test the o2 sensor itself if you had a multimeter, this will tell you if the senor is functioning correctly and what condition it is seeing in the exhaust. if you have a meter set it to VDC and connect the leads (one each) to the wires coming out of the sensor. on your car it will either be a GRN and WHT wire b/4 the connector or a WHT and GRN-WHT wire after the connector which is under the distributor. when the engine reaches operating temp the voltage signal from the sensor will fluctuate from 100-900 mV under normal conditions if the voltage stays high then there is a rich condition in the engine which could be caused by a misfire. that would actually cause the ecu to drive the injectors even longer making the situation worse ....oh, yeah to connect to the wires shove a T-pin or a paperclip into the back of the connector beside the wires and test the circuit live...sorry about the long post
 

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Discussion Starter · #16 ·
forcefedhatch said:
you could test the o2 sensor itself if you had a multimeter, this will tell you if the senor is functioning correctly and what condition it is seeing in the exhaust. if you have a meter set it to VDC and connect the leads (one each) to the wires coming out of the sensor. on your car it will either be a GRN and WHT wire b/4 the connector or a WHT and GRN-WHT wire after the connector which is under the distributor. when the engine reaches operating temp the voltage signal from the sensor will fluctuate from 100-900 mV under normal conditions if the voltage stays high then there is a rich condition in the engine which could be caused by a misfire. that would actually cause the ecu to drive the injectors even longer making the situation worse ....oh, yeah to connect to the wires shove a T-pin or a paperclip into the back of the connector beside the wires and test the circuit live...sorry about the long post
Thanks!
The 02 has been replaced so I don't think that is the probelm.
I will update as I find out more.
I am trying to figure if the probem is a fuel system problem.
Not sure where to begin though.
 

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:D okay, running rich won't cause your engine to miss and carry on, but if your engine is mifiring it might cause it to run rich. if you haven't done this already, pull off your distributor cap and look for carbon tracking. it looks like white lines or splotches between the plug terminals. also inspect the rotor to see if there is any track marks on it. this would cause the misfire. here's the crash course on o2 sensors. if you had a cylinder (or more) that was misfiring you would have unburnt fuel AND unused oxygen going out the tailpipe. remember that the O2Sens only reads O2 and it would see the extra oxygen as a lean condition. the ecu, in turn, would see that lean signal from the sensor and drive the injectors rich to compsenate. which actually makes the condition worse (similar to what your problem sounds like.) check the cap, button, and check for spark at each wire. it may not be your fuel system at all if the O2s and ecu are doing their jobs. we'll get it figured out sooner or later :D
 
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