help with passenger pre-cat o2 sensor
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351cleveland
- Posts: 48
- Joined: Wed Sep 29, 2010 7:39 pm
- Car: 2003 Infiniti QX4 4x4
1993 Acura Legend coupe 3.5/typeII 6spd swap build
help with passenger pre-cat o2 sensor
Well as the title reads, i need help trying to remove my passenger pre-cat o2 sensor. I have no codes or anything, but shortly after doing my spark plugs a while back, i just cant seem to regain my once good/fair gas mileage and good power. I went from 17-18.6 mpg to 14.5-15.5 mpgs. I know the pre-cat o2 snesors have to do with air fuel mixture readings, and bad or warn-out sensors can cause increased fuel consumption, and relatively poor performance. I have both. My car still feels as it sputters, or struggles especially going up any kind of incline. I also did already replace the drivers o2 sensor pre-cat with no difficulties. It just seems impossible to get to the passenger side one as too much stuff is in the way to turn the ratchet once i finally got it on there. I had to remove three coolant tubes that are just to the left and behind the valve cover and i.m. on that side. I know i probably need a special socket adapter or something that can reach it at an angle and turn it. Anyone that has had success doing this, please let me know what your solution was. Also i have already replaced my MAF sensor, air filter with k/n drop in, and did the power valve screws. Also cleaned the throttle body and power valves. Car has 130k miles. And should i just take it to the dealer to have the ecu re-flashed? Seems to be a must when changing o2 and MAF sensors.
Re: help with passenger pre-cat o2 sensor
Stuttering at load, may be a lack of vacuum. Vacuum leaks??? The O2 sensors get blamed for a lot but if no codes I would seek out other problems.
Try a raw propane feed from a small propane torch, at warmed, idle, turn torch on and pass over and under the many vacuum lines and around the throttle intake. Listen for the engine to speed up even a little, if it does you have a leak.
Also test your EGR, it may be plugged or plugging.
Your idle should be 700-750 RPM, if not IAC MAY be plugged.
How is timing, right on, what about advanced timing, see if it advances when revved.
Your plugs were changed, what is gap and what was condition of plugs changed out.
Bad injectors , bad spray pattern, bad noid effect with them can also be your problem.
A new MAF sensor may be off, do you still have the old unit, also air filter volume within the MAF may change what the MAF reads and so you blame the O2.
If you have an OBDII scanner, reader, put it on and see if there are codes deep within and current, because if the O2 sensors are slow, lazy, dirty the relationship will cause a rich when indicating a lean and a bad O2 sensor cannot keep pace. Is your exhaust black at any time?
As you can see there are a whole lot of possibilities to your problem. It will need a code reader to start the quest otherwise your going to be second guessing yourself and plug and play is too expensive.
Try a raw propane feed from a small propane torch, at warmed, idle, turn torch on and pass over and under the many vacuum lines and around the throttle intake. Listen for the engine to speed up even a little, if it does you have a leak.
Also test your EGR, it may be plugged or plugging.
Your idle should be 700-750 RPM, if not IAC MAY be plugged.
How is timing, right on, what about advanced timing, see if it advances when revved.
Your plugs were changed, what is gap and what was condition of plugs changed out.
Bad injectors , bad spray pattern, bad noid effect with them can also be your problem.
A new MAF sensor may be off, do you still have the old unit, also air filter volume within the MAF may change what the MAF reads and so you blame the O2.
If you have an OBDII scanner, reader, put it on and see if there are codes deep within and current, because if the O2 sensors are slow, lazy, dirty the relationship will cause a rich when indicating a lean and a bad O2 sensor cannot keep pace. Is your exhaust black at any time?
As you can see there are a whole lot of possibilities to your problem. It will need a code reader to start the quest otherwise your going to be second guessing yourself and plug and play is too expensive.
-
351cleveland
- Posts: 48
- Joined: Wed Sep 29, 2010 7:39 pm
- Car: 2003 Infiniti QX4 4x4
1993 Acura Legend coupe 3.5/typeII 6spd swap build
Re: help with passenger pre-cat o2 sensor
Yes i agree it could be a number of things. I thought about the vaccum leak because of all the hoses and intake tube that you have to move out of the way,not to mention the removal of the throttle body to get to the number 5 spark plug. I changed the spark plugs at roughly 116k as i had no verification of service records upon purchase of the vehicle. So yeah i'd say the plugs were the originals, and definately looked worn out and burnt up a bit(ie. rustic discoloration on the white ceramic part) around the electrode. Also re-used the gasket to the throttle body.
I did take it to autozone or advance auto parts(i dont remeber which) to see if i could have them scan it for free to see if there where any stored or pending codes. The woman told me she couldnt scan it unless the CEL was on. So back to the drawing board and fix or replace relatively cheap or maintenance type items to see if i could fix the problem. The next on my list of things to check or replace would be the throttle position sensor, as it makes a clicking or solenoid acuator type click noise after i shut off the engine. Though maybe it got damaged or tweaked when i took off the throttle body when removing it.
I did however replace the two upper i.m. gaskets as well as the throttle body gasket when i did the power-valve screws around 128k(they were all tight btw!).
Next would be the ignition coils, or atleast the number 2 coil as i tore the boot into three peices when trying to pull it out. Please note that this was only after the second time changing my spark plugs at roughly 122k miles, since i replaced them originally with the pulstar platinum plugs(116k) and the lack of performance/sputtering still existed prior to tearing the boot. I decided to not risk it and replace the pulstars with the oem ngk platinums. I super glued it all back together and it seems to be fine though. Note i do have an 03' so i highly doubt they are bad since i only have 130k miles and no CEL.
I also notice a smell of gas or exhaust when i would do a cold start in the morning. I thought it was an exhaust leak somewhere, but got it checked out and couldnt find any. This is when i leaned more towards a running rich condition, causing the increased fuel consumption and poor performance.
I think i will try the propane trick. Thanks!
I did take it to autozone or advance auto parts(i dont remeber which) to see if i could have them scan it for free to see if there where any stored or pending codes. The woman told me she couldnt scan it unless the CEL was on. So back to the drawing board and fix or replace relatively cheap or maintenance type items to see if i could fix the problem. The next on my list of things to check or replace would be the throttle position sensor, as it makes a clicking or solenoid acuator type click noise after i shut off the engine. Though maybe it got damaged or tweaked when i took off the throttle body when removing it.
I did however replace the two upper i.m. gaskets as well as the throttle body gasket when i did the power-valve screws around 128k(they were all tight btw!).
Next would be the ignition coils, or atleast the number 2 coil as i tore the boot into three peices when trying to pull it out. Please note that this was only after the second time changing my spark plugs at roughly 122k miles, since i replaced them originally with the pulstar platinum plugs(116k) and the lack of performance/sputtering still existed prior to tearing the boot. I decided to not risk it and replace the pulstars with the oem ngk platinums. I super glued it all back together and it seems to be fine though. Note i do have an 03' so i highly doubt they are bad since i only have 130k miles and no CEL.
I also notice a smell of gas or exhaust when i would do a cold start in the morning. I thought it was an exhaust leak somewhere, but got it checked out and couldnt find any. This is when i leaned more towards a running rich condition, causing the increased fuel consumption and poor performance.
I think i will try the propane trick. Thanks!
Re: help with passenger pre-cat o2 sensor
You have a lot on your plate, may I suggest the following and then post your results.
Put on a vacuum gauge and read it at cold start, as it warms and at warm idle then as you rev to 3000 RPM.
At warm, install a timing light on # 1 after you mark the position with a chalk line then watch the light vs. the position and visually see if advance moves and how far.
Since you have new plugs you could use the timing light at various plug positions to see if the light flickers out of the norm as you rev each time and test. This is similar to a noid light on each injector which you should also check.
It is advisable for you to read your own codes and not rely upon a sales clerk. The cost is the cost of owning a car with OBD II.
Do not chase your tail trying to find something, do it in order. Remember that the engine needs: fuel, air, spark at the correct time and compression.
Stuttering in a loaded engine can mean:
not enough fuel--fuel pressure, fuel filter, fuel leaks
not enough air, oxygen which is about 20% of the air---air filer, MAF, changing the air conduits
Spark at the right time and large enough to create a fast burn---ignition, wires, main transistor, bad ignition towers primary and secondary
Timing must be correct statically at idle and must advance when you speed up---a timing light is needed to simplify this look see.
Compression, no or low compression can and does wreak all the above. A compression test is not a final answer but it will give you an idea of the motor shape---A compression tool with the correct adapter to plug into deep down those plug holes is a needed tool and necessary to save you time, money and second guessing.
There is a lot here, but your symptoms are going to take a lot, eliminate what you can by checking the simple and easier and less costly items and progress from there.
It is very hard to tell you exactly what is wrong with your engine, but if you have done the typical PM things, the problem is probably close at hand because when cared for these 3.3 and 3.5 engines can and do last.
Do the things that need a vacuum gauge, a timing light and use the vacuum gauge to measure pressure for your fuel---these acts will eliminate a whole bunch of guesses.
Put on a vacuum gauge and read it at cold start, as it warms and at warm idle then as you rev to 3000 RPM.
At warm, install a timing light on # 1 after you mark the position with a chalk line then watch the light vs. the position and visually see if advance moves and how far.
Since you have new plugs you could use the timing light at various plug positions to see if the light flickers out of the norm as you rev each time and test. This is similar to a noid light on each injector which you should also check.
It is advisable for you to read your own codes and not rely upon a sales clerk. The cost is the cost of owning a car with OBD II.
Do not chase your tail trying to find something, do it in order. Remember that the engine needs: fuel, air, spark at the correct time and compression.
Stuttering in a loaded engine can mean:
not enough fuel--fuel pressure, fuel filter, fuel leaks
not enough air, oxygen which is about 20% of the air---air filer, MAF, changing the air conduits
Spark at the right time and large enough to create a fast burn---ignition, wires, main transistor, bad ignition towers primary and secondary
Timing must be correct statically at idle and must advance when you speed up---a timing light is needed to simplify this look see.
Compression, no or low compression can and does wreak all the above. A compression test is not a final answer but it will give you an idea of the motor shape---A compression tool with the correct adapter to plug into deep down those plug holes is a needed tool and necessary to save you time, money and second guessing.
There is a lot here, but your symptoms are going to take a lot, eliminate what you can by checking the simple and easier and less costly items and progress from there.
It is very hard to tell you exactly what is wrong with your engine, but if you have done the typical PM things, the problem is probably close at hand because when cared for these 3.3 and 3.5 engines can and do last.
Do the things that need a vacuum gauge, a timing light and use the vacuum gauge to measure pressure for your fuel---these acts will eliminate a whole bunch of guesses.