1995 Nissan Stalling when coming to a stop

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#1
My daughter has a 1995 Nissan Maxima. She was having trouble with it stalling when coming to a stop. The codes displayed is a P0130 and a P0136 which indicates an upstream and a down stream Oxygen sensor or circuit fault. This vehicle also has a oxygen sensor after the converter. I am thinking about replacing these three sensors myself but I have limited tools and not a real good place to work except out in the yard and in the 90 degree plus heat in the southeastern Pa. I have a 7/8 inch sensor removing socket that I used on my 91 bucik. Hopefully all of the sensors are of the same size...correct me on this if I am wrong. I would like to know if anyone else has done this work before on a Nissan and if so, how hard it is to get to the upstream sensor. They look like they are very close to the firewall. While I am at it I will also check the sensor harness and see if they are clean and tight. By the way, this car has over 90,000 miles on it. I am assuming that the sensors had never been replaced before. I am thinking about buying these Bosch sensors from AutoZone. Is this a good type of sensor?
 

Jim Davis

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#2
Stalling on coming to a stop may be a sticking egr valve, but first before putting new 02 sensors on it and because you want to do the work yourself, why not get an alldata sub and go thru the test and see if they are bad or if you have another problem. be nice to check them first before spending the money on the sensors and then finding out its not the problem. Any other work been done lately? Fuel pressure checked, fuel filter changed?
 
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#3
Jim, you are right, it could be something else causing this problem. I was thinking since this vehicle has 90,000 miles or more on it that the 02 sensor replacement is way past due. It is possible that the egr valve may be malfunctioning. I do have a Haynes Auto Manual that tells how to check the egr componant out. I will have to buy myself a hand vacuum pump to check out the egr valve. They are not cheap. I think they cost around $100.00. My daughter has had new plugs put in the car, had the PVC cleaned and has had a new fuel filter put on. Since you mentioned it, I think I will check the egr valve out first before replacing the 02 sensors. Do you think if the egr valve was bad that it could cause the scanner to read codes P030 and P0136 which indicates the upstream 02 sensor and the downstream 02 sensor as being the cause? I have not had that much experience yet in checking out the newer emissions control components. So far I have bought an OBD 11 scanner and a new digital VOM. Thanks for your imput Jim. I appreciate it. If I can get it fixed I will let you know.
 

Jim Davis

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#4
Since this is the upstream and the downstream sensor, wouldnt hurt to check the exhaust system over good and make sure there are no exhaust leaks, would let air (oxygen) into the exhaust and confuse the sensors. It very vell could be bad sensors but check them out according to your manual if it has the test. The egr could be dirty and sticking, your manual should tell you how to test it too.
 

2POINTautO

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Lets look at your idle only for a moment, does it idle high when started cold, does the idle slow down as it warms up from a cold start. Once fully warmed up and you turn on the AC, does it idle up when the AC is commanded on. Have you cleaned the throttle body. Once clean you can disconnect the battery for awhile the reconnect and restart and allow to fully warm up again from a cold start to relearn the new idle strategy again.

Does your state have emission test stations or better yet emission stations who are allowed to diagnose. As a DIY all you have to prove on the O2 sensors is that you can force it full lean and full rich, IT WORKS, dont change them. A true O2 test is done after other repairs that may be causing it full lean or full rich not allowing them to swing normally. Example, ECT that does not warm up, keeps computer in Open Loop=Rich.

What type of monitor does the EGR valve use, a downstream temp sensor, a pintle position sensor or what. If you monitor these voltages from the sensor, this is where you start on the EGR system. Did the voltage change during slow down to a complete stop, the car dies and the voltage changes even more immedietly, EGR or sensor problem. Cant you pick up a hand vacuum pump kit from Sears for less than $100.

Have you tried to pop it in neutral prior to stopping or stopping with or without the AC on. Does it die at stops while still cold or only after the engine warms up. Have you cleaned the MAF sensor hot wire, the MAF has the highest authority on fuel delivery for a fully warmed up engine and a major Nissan problem. Of course with any sensor you can compare its voltage against the repair manual chart.

You are on the right track, let us know what you found so far. I would not put a lot of faith in the O2 codes just yet. Downstream is after the cat convertor.
 
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2POINTautO, I have a vacuum pump ordered. According to the Haynes Manual I have the egr valve which has a pintle type valve. Our state, Pa. does not have an emissions control requirement. I finally found a vacuum pump from Mityvac for less than $50.00. I have in on order. After reading the manual thoroughly, I realize that there are several things that could cause the 02 sensors to to show up bad. I am just trying to find the most obvious thing first but after reading the manual I notice a lot of things can cause these same symptons. I guess when I get all my tools together and get the time I will just take one thing at a time and check it out. I will probably start with the most obvious solution first, egr valve, IAC valve, the coolant solonoid, and then proceed from there. I am hoping I can get in to those tight spots to do the work as I have arthritis in my right hand. The throttle body has already been cleaned previously according to the Nissan Dealership who tried to fix the problem earlier and quoted my daughter a price of nearly $2000.00. At my request Nissan put in a new fuel filter and cleaned the throttle body and the PVC valve but this did not help. Hopefully I can fix it a lot cheaper than the amount they quoted. Thanks for your imput. If I do find the problem I will post back here.
 

2POINTautO

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Then I recommend that you pull the computer and do your pin testing from there, of course your book will need to show pinout chart and voltage levels. I am glad to help like anyone but I am only scheduled to check back here once a week although I have been checking back more often lately. I do a lot of other work on line too, this is one of my favorites but my freakin DVD is broken in my PC so I cannot check my Mitchell on Demand right now, that is the second player to break, will break out the external big boy from storage and get the drivers loaded. In the interim, can you maybe talk about what your plans are and we will follow along.

Meaning do you have the pinout and voltages right now on hand, lets talk about it and get you in the frame of mind while you are waiting for your pump. Is the computer burried?? Again, how does the car run from cold through full warm up when coming up to stops?? Your motor is the VG30??

When I lived in the US, I loved stories like yours where the dealer wants the big bucks, I was going to be a traveling tech to fix vehicle problems like yours, from state to state, what a dream.