![]() The 02 sensor is designed to function once the vehicle has warmed up which is about after 10 minutes where the thermostat begins to open at 190 or 195 degrees Ferenheit depending on thermostat then the vehicles ECU system enters what they call a "closed loop system" then the exhaust manifold's temperature reaches 400 degree Ferenheit (I think)that's where the sensor starts to do it's job which is usually when the thermostat first opens up then the oxygen sensor senses the ratio of air to fuel and sends a signal back to the ECU then ECU compensates by increasing or decrease the open time for the fuel injectors to pump fuel.So usually the problem of stalling shows up after about 10 minutes of driving or so.Many folks think that the o2 sensor is bad but an exhaust leak can cause excess oxygen to enter the exhaust system thereby fooling the sensor into thinking there is too much oxygen,there are other problems that could cause it to give false reading such as a vaccuum leak. Symptoms of a bad o2 sensor are poor gas mileage,hesistation in acceleration,worse emmissions,and in severe cases after the stat opens the engine can no longer maintain stable 750 rpm (with manual 5 spd tranny) idle and the engine begins to stall. On average the oxygen sensors should be replaced every 6 years or 100 000 miles or so which ever comes first as stated in the owner's manual,warranty booklet and factory service manual. The oxygen sensor is replaced for free in the USA only when the vehicle reaches it's first 80 000 miles regardless of the age & number of owners as stated in the factory owner's manual in the maintenance section,some Toyota dealerships are reluctant to replace it for free if that happens contact the Toyota regional head office for your region where they will give your local dealership 48 hours to comply. Pulling the ECU codes is the first thing I do to diagnosis a problem thereafter I reset the ECU to see if the same problems show up and if so I then take voltage measurements both with the engine running and not and compare with the factory service manual,I also close the ignition switch after a cold engine and also after a warm engine and compare them with the factory service manual.This technique will completely isolate your problem without having to do trial and error and it is the technique I use when repairing tv's,vcr's,home/car audio.Ĭheck the oxygen sensor wire harness at the exhaust manifold,front exhaust pipe and front drive shaft.The best oxygen sensors for Toyotas are:ġ)Toyota OEM (NipponDenso, now called Denso)Ģ)Denso aftermarket (Same as OEM but sold outside of Toyota Corp)ģ)NTK (oxgen sensor division of NGK spark plugs Corp) Pull the ECU code to see if it's o2 sensor:Ībout half of the ECU codes stored on the first & second generation EFI Toyotas don't show a constant blinking check engine light therefore you must pull the ECU codes to see if a fault is registered.Īll 1980-1995 and including 1995 EFI equipped vehicle allow you to find engine and related faults by pulling the ECU (computer) codes without the need for a handheld OBDII diagnosis scanner,the sites listed below have the fault codes needed to pull the codes and the instructions on how to do it: Does anyone know how to hook one of those smoke machines up to the manifold so I can check for leaks? I've seen it done thru the tail pipe for exaust leaks, but I think it can be done thru the manifold for other leaks (vacuum) as well. This is why I think it is a vacuum issue now. It only stalled as I was coming to a stop. Originally, that's where my problem began. I noticed this morning that the idle started to act up when I applied the brake to put it in gear. Sometimes it's real bad and other times it idels down low (like it going to stall) and back up again. I cant seem to find the damm notches on the crank pully. ![]() The only thing I haven't done is check the timing. Since the new TPS, it actually runs smoother now, but still stalls occasionaly. The throttle body was cleaned out last week when I installed the new TPS. I check all the connections and everything is good. Click to expand.All the usuall things (cap, wires, rotor, (air filter one month ago)) were all replaced mid last year.
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