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when sitting at red light with foot pressing on brakes car will jump up in rpms and jump forward. once in a while upon trying to start car has issue starting. i am thinking it is an o2 censor going bad. but there is no check engine light on. how do i tell which o2 censor is bad. and anyone have any other suggestions
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any engine light? have a scan tool pugged in and see if there are any codes too help narrow down your problems.
also check this out.
http://www.ericthecarguy.com/faq/solving-automotive-performance-issues
there are no check engine lights on at all. i just got done doing an obd check and it says o2 censor but not which one. how do i find out which one is faulty. also coolant temp censor but that could be coming from the o2 censor correct.
i found out it is bank 1 sensor 1 now i need to find out where that is located at i nknow it is before the cat but rad side or firewall side
B1S1 bank one sensor one, the upstream typically i think on the exhaust manifold,
B1S2 Bank one sensor two, the downstream 02 sensor located after the catalitic converter
KEEP IN MIND
a code thrown for a 02 sensor may also be hinting at a rich or lean condition because the responsibility of the 02 sensor too sniff out how lean or rich your engine is running, what is the exact code?
if you have a scan tool that can read live data
the upstream 02 sensor typically the upstream O2 sensor B1S1 should read readings bouncing between 0.3V-0.8V and if this one is bad it can cause major drivability issues because it is responsible for telling the PCM how rich or lean the engine is running so the PCM can adjust fuel trim too adjust for ideal air fuel mixture
the downstream 02 is mostly for monitoring the catalytic converter and its operation, it doesn’t effect the performance of the vehicle so much but can some what… it should maintain a somewhat steady voltage near .5V give or take .1V at times, but if you start heading towards .3V or as high as .7 it may be bad or the cat may not be doing its job as well
the higher the voltage number the richer the condition, the lower the leaner…
lets not condem the O2 sensor just yet, lets do some diagnosis..
[video]http://https://www.youtube.com/watch?v=NIzcztO-CCs[/video]
ooh, so its B1S1, okay that will cause serious drive ability issues if its really bad. id almost be willing too say just replace it but just in case i say do a fuel pressure test, because low fuel pressure can cause you too run lean, and if it checks out there and there are no other codes and data looks good for everything ells like MAP, MAF then go ahead and replace the 02 sensor
I actually cover how to determine bank 1 and bank 2 in this video.
As for the idle issue, perhaps the O2 will help based on your description. If not, then you might find useful information here.
http://www.ericthecarguy.com/faq/solving-automotive-performance-issues
Good luck and keep us posted.
low compression can cause drivability issues and idle issues too, a compression test may be wise especually if your car has VERY high miles, and they can throw O2 sensor codes because it can leave more un burned fuel in the system, certainly something too not over look.
[quote=”stravo71″ post=99719]there are no check engine lights on at all. i just got done doing an obd check and it says o2 censor but not which one. how do i find out which one is faulty. also coolant temp censor but that could be coming from the o2 censor correct.[/quote]
The O2 sensor is not going to throw a code for coolant temperature. This is a separate issue. If the coolant sensor is completely out of range then the code is set. But if the computer decides to believe what the sensor is telling it and that value is 190 degrees while it is actually a winter day and the engine is cold, well, you car will crank but not start. So, this could be the cause of your hard start problem. The engine computer uses the coolant sensor to determine how rich to make the starting mixture.
BTW, the O2 sensor doesn’t even start working until after the engine is up and running a short while.
I agree with barneyb, looking into the coolant temp sensor is likely a better option than looking at the O2 at this time. If the coolant temp sensor is having an issue it may never go into closed loop and never even look at the O2 readings as a result.
Keep us posted.
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