Toyota Previa

The correct tire size for a 92 Prev is 215-65R15

My 94 Prev wheel size is 215/65/R15 but with this size of wheel. my prev actually running lesser mileage compare with my GPS device. shall i reduce the 65 to 60 in order to get a correct mileage reading? My prev mileage is 250kilometer but what shows in gps is 300kilometer. a difference of 50 kilometer.

The exhaust gas oxygen sensor (EGO or O2), or lambda sensor, is the key sensor in the engine fuel control feedback loop. The computer uses the O2 sensor's input to balance the fuel mixture, leaning the mixture when the sensor reads rich and richening the mixture when the sensor reads lean. Lambda sensors produces a voltage signal that recognises the amount of unburned oxygen in the exhaust. An oxygen sensor is essentially a battery that generates its own voltage. When hot (at least 250 degrees c.), the zirconium dioxide element in the sensor's tip produces a voltage that varies according to the amount of oxygen in the exhaust compared to the ambient oxygen level in the outside air. The greater the difference, the higher the sensor's output voltage. Sensor output ranges from 0.2 Volts (lean) to 0.8 Volts (rich). A perfectly balanced or "stoichiometric" fuel mixture of 14.7 parts of air to 1 part of fuel gives an average reading of around 0.45 Volts. The lambda sensor's output voltage doesn't remain constant, however. It flip-flops back and forth from rich to lean. Every time the voltage reverses itself and goes from high to low or vice versa, it's called a "cross count." A good O2 sensor on a injection system should fluctuate from rich to lean about 1 per second. If the number of cross counts is lower than this, it tells you the O2 sensor is getting sluggish and needs to be replaced. Most lambda sensors will cycle from rich to lean in about 50 to 100 milliseconds, and from lean to rich in 75 to 150 milliseconds. This is referred to as the "transition" time. If the O2 sensor is taking significantly longer to reverse readings, this too is an indication that it is getting sluggish and may need to be replaced. Observing the sensor's waveform on a scope is a good way to see whether or not it is slowing down with age. If the sensor becomes sluggish, it can create hesitation problems during sudden acceleration. Heated Oxygen Sensors To reduce the warm-up time of the Lambda sensor, an internal heating element may be used. Heated O2 sensors can reach an operating temperature of as high as 500 degrees C in as little as eight seconds! Shorter warm-up time means the system can go into closed loop fuel control sooner, which reduces emissions and improves fuel economy. Heating the sensor also means it can be located further downstream from the exhaust manifold. A lambda sensor's normal life span is 30,000 to 50,000 miles. But the sensor may fail prematurely if it becomes clogged with carbon, or is contaminated by lead from leaded petrol or silicone from an antifreeze leak or from silicone sealer. As the sensor ages, it becomes sluggish. Eventually it produces an unchanging signal or no signal at all. When this happens, the Check Engine Light may come on, and the engine may experience drivability problems caused by an overly rich fuel condition. Poor fuel economy, elevated CO and HC emissions, poor idle, and/or hesitation during acceleration are typical complaints. If the average voltage from the lambda sensor is running high (more than 0.50V), it indicates a rich condition, possibly due to a bad MAP, MAF or Air Flow sensor or leaky injector. If the average voltage reading is running low (less than 0.45V), the mixture is running lean possibly due to a vacuum leak or because the sensor itself is bad. If the lambda sensor continually reads high (rich), it will cause the engine computer to lean out the fuel mixture in an attempt to compensate for the rich reading. This can cause lean misfire, hesitation, stumbling, poor idle and high hydrocarbon emissions (from misfiring). If the lambda sensor continually reads low (lean), it will cause the engine computer to richen the fuel mixture. Injector pulse width will increase causing fuel consumption and carbon monoxide emissions to go up. Constant rich fuel mixture can also cause the catalytic converter to overheat and it may be damaged. If the lambda sensor's output is sluggish and does not change (low cross counts & long transition times), the engine computer will not be able to maintain a properly balanced fuel mixture. The engine may run too rich or too lean, depending on the operating conditions. This, in turn, may cause drivability problems such as misfiring, surging, poor idle, and high emissions. If a heated sensor has a faulty heating circuit or element, the sensor can cool off at idle causing the system to go into open loop. This usually results in a fixed, rich fuel mixture that will increase emissions. Sometimes an apparent lambda sensor problem is not really a faulty sensor. An air leak in the intake or exhaust manifold or even a fouled spark plug, for example, will cause the lambda sensor to give a false lean indication. The sensor reacts only to the presence or absence of oxygen in the exhaust. It has no way of knowing where the extra oxygen came from. So keep that in mind when diagnosing oxygen sensor problems. The lambda sensor is also grounded through the exhaust manifold. If rust and corrosion of the manifold gaskets and bolts is creating resistance, it may affect the sensor's output. To rule out a bad ground, use a digital volt meter to check for a voltage drop between the sensor shell and the engine block. More than 0.1v can cause a problem. Lambda Sensor Checks A good lambda sensor should produce a fluctuating signal that changes quickly in response to changes in the oxygen level in the exhaust. The best way to check the sensor is to observe the sensor's output on a waveform scope or oscilloscope. A scope will display not only the sensor's minimum and maximum voltage readings, and average voltage reading, but also its back and forth voltage oscillations from rich to lean. Sensor output can also be read directly with a 10K ohm impedance digital voltmeter, or some code readers. CAUTION! Never use an ohmmeter on a zirconium O2 sensor in an attempt to check the sensor because doing so can damage it. And never jump or ground the sensor's leads. The lambda sensor's voltage reading should have a minimum reading of 200 millivolts (0.20 V) and a maximum reading of 800 millivolts (0.80 V). If the sensor reading is averaging low (under 400 millivolts) or high (over 500 millivolts), the engine may be running rich or lean because of some other problem. If the sensor's output voltage never gets higher than .60v and never drops to less than 0.30 V, it needs to be replaced. The same is true if the sensor's output is sluggish or doesn't change. To check the sensor's response to changing oxygen levels in the exhaust, first create an artificially lean condition by pulling a large vacuum line. When extra air is introduced into the engine, the sensor's voltage output should drop to 0.2 V. To check the sensor's rich response artificially richen the mixture by, if possible, clamping the return fuel line momentarily. This will force more fuel through the injectors and should cause the O2 sensor's voltage to increase to 0.8 V. If the sensor's output fails to respond to the changes you've created in the oxygen level in the exhaust, it's time for a new sensor. Zirconium sensors can also be bench tested by heating the tip with a propane torch while monitoring the sensor's voltage output with a digital voltmeter. Connect the positive voltmeter lead to the signal wire (normally black) coming out of the O2 sensor and the negative voltmeter lead to the sensor's outer shell. Then heat the tip of the sensor with the propane torch. The tip should be hot enough to turn cherry red, and the flame must enter the opening into the sensor tip. If you get a voltmeter reading above 600 millivolts (0.6 Volts), and the reading quickly changes as you move the flame back and forth over the tip, the sensor is okay. A low reading or one that is slow to change means the sensor needs to be replaced. Removing Lambda Sensors Removing the sensor when the engine is cold will lessen the odds of stripping the threads in the exhaust manifold. Penetrating oil may be needed to loosen rusted threads. Once the sensor has been removed, the threads in the manifold should be cleaned before the new sensor is installed. Apply graphite grease to the sensor threads unless the threads are precoated. Replacing Lambda Sensors Everybody knows that spark plugs have to be replaced periodically to maintain peak engine performance, but many people don't realise the same goes for oxygen sensors. As long the lambda sensor is working properly, there's no reason to replace it. But after 30,000 to 50,000 miles of being constantly bathed in hot exhaust gas, a build up of deposits on the sensor tip can make it sluggish. If there's enough clinker on the sensor tip, the sensor may produce little or no voltage at all. This produces a false "lean" signal that makes the computer think the engine needs more fuel, which it doesn't but gets anyway. This creates a rich fuel condition that kills fuel economy and sends carbon monoxide and hydrocarbon emissions soaring. The engine may also experience additional drivability problems such as surging or hesitation. The same kind of thing can happen if the lambda sensor is contaminated by deposits from sources other than normal combustion. It only takes a couple of tankfull's of leaded petrol to ruin an lambda sensor (and catalytic converter). A lead contaminated oxygen sensor will typically have light rust coloured deposits on the tip. Another source of sensor contamination can come from silicone poisoning. If somebody used the wrong kind of silicon sealer to seal up a leaky rocker box cover or manifold gasket, silicone can find its way into the engine and foul the sensor. Silicates, which are used as corrosion inhibitors in antifreeze, can also cause the same kind of poisoning. Sources here might include a leaky head gasket or racks in the combustion chamber. Silicone deposits on the sensor tip will have a shiny white to grainy light gray appearance. If the engine has an oil consumption problem due to worn valve stem seals, piston rings and/or cylinders, a build up of heavy black to dark brown oily deposits on the sensor tip can make it sluggish. If the deposits have a black powdery consistency, the fuel mixture is running rich. This may be due to the sensor already having failed, or it might be due to something else such as a leaky injector or a computer problem, or constant short journeys where the cold start system doesn't have time to come off (open loop) known as housewives car. When ever you suspect a lambda sensor problem, the first thing you should do is scan for any codes that would implicate the sensor circuit. A code by itself doesn't necessarily mean the sensor is bad, however. It might be a wiring problem or something else. So always follow through with the diagnostic check to diagnose what's wrong before you replace anything. If you don't find any codes, that doesn't necessarily mean the lambda sensor is okay. In many instances, a sluggish sensor may not be bad enough to record a fault code but will still be causing an emissions or drivability problem.

it is under the drivers seat, yellow lever to pop the seat back, under the panel. same area as the oil fill.

It is at the dash board bottom just at the middle. You can see a plastic rectangle were the heater core is and at the right side are the pipes that goes to the coolant valve at the engine

It's happening to mine at the moment. I'm going to tighten the fan belt.

hi mate i have same model and year remove screw at rear of remote then remove bty before replacing with new one hold remote and press both open and close buttond at same time this resets it then replace bty and screw back on this should work

On top of the rear axle. This is from pictures I've seen from guy that replaced their own sensors.

Hi everyone after much research on the net and very little results, i went to the wreckers and finally worked out how to remove the rear bumper from the Toyota tarago/previa

This is how you remove a rear bumper from 1990-2000 Toyota tarago or previas and maybe even the 2001-2013 models.

There are two upper 10mm corner bolts under the mud guards or wheel arches that secure the ends of the upper corner bumper onto the body, remove the left and right one and store bolts in a container to reattach.

Next there are two 10mm bolts on the lower corner of the bumper connected to a rail that is secured to the bottom of the floor pan of the van, remove the left and right one and store in your container (please note sometimes the 10mm rail bolts are difficult to remove, so remove the 12mm bolts that are connected from the rail to the floor pan instead.

Some taragos/previas have a bull bar with a tow bar attached and some models may not, the bull bar is attached to brackets by 6 X 18 mm bolts 3 x 18 on the left and 3 X 18mm bolts on the right and the brackets are secured to the floor pan by 6 X 14mm bolts 2 X 14mm bolts on the left and 2 x 14mm bolts on the right are secured to the floor pan and 2 x 14mm bolts are secured to the reinforcement bar which the plastic bumper is attached too.

If you have a bull bar attached to the brackets, it is recommended that you remove these 6 X 18mm bolts securing your bull bar to the brackets first, because if you remove the 6 X 14mm bracket bolts with the bull bar still attached you may injure your self when the bull bar drops down with the brackets.

These are the last 6 X 14mm bolts that have to be removed, 4 x 14mm bolts secure the 2 brackets to the floor pan, 2 X 14mm bolts are on the left and 2 X 14mm bolts are on the right, the last 2 X 14mm bolts are secured to the reinforcement bar, they are the last 2 bolts to be removed, and then the plastic bumper which is attached to the reinforcement bar will simply slide out towards you as you pull on it, then you can remove the plastic bumper from the reinforcement bar.

Dont forget the trailer plug is also attached to the bull bar or tow bar and will have to be removed or cut and reattached.

Once the reinforcement bar with the plastic bumper is out, you will be able to access the lower bumpers 2 X 10mm center bolts and 2 X 12mm corner lower bumper bolts and then the 6 x 10mm upper bumper bolts, two of the bolts you couldn't see or access when you were desperately trying to find them and keep wondering why the bumper wouldn't come off.

Finally store the foam between the bumper and reinforcement bar in a secure place and try not to forget them once your ready to reassemble everything like i did.

Enjoy, another mystery solved.

Under the van on driver's side, difficult removal. You must drop driveshaft first. No fun.

WRONG UNSWER,,,,, its under the car behind the pass remove the hot wires, and the ground, then remove two bolts that holds the starter ,,,that "s all..lift up passenger seat ,unplug 1 plug and a 12 mm bolt then undo the two holding bolts and is out

The EGR Valve is located under the Drives Seat. Flip back the seat and open the access hatch. You will see where the oil cap and to the right you will see a round 3 inch dimerter top with hard lines coming out of it. That is your EGR. on the EGR valve body is a a small 12 or 14 mm hex head plug with two wires protruding from it. this is the EGR temp. sensor. James V bestmr2.com (added to by Toyota tech guy)

Tools: Philips screwdriver; small flat blade screwdriver. 2 feet of wire - bell wire or twist-tie or craft wire; a hook-ended tool or large paperclip straightened with about a quarter-inch hook on the end. Flashlight.

Disassembly:

The first two steps are fairly well described in the Chilton manual for this vehicle, the rest are not.

1) Remove the ash tray/cup holder assembly.

Open the storage door under the ash tray, remove the ash tray, and pull open the cup holder. Remove the 4 screws that hold the assembly: 2 of the screws are in the top behind the left and right ends of the cup holder, one is in the lower right ashtray opening and one is hidden just behind the lower left corner of the trim around the cigarette lighter socket. Wiggle and force the assembly down, lowering the left side first and getting it out diagonally. Disconnect the cigarette lighter plug and the lamp wire plug. The lighter plug pulls right off, the lamp plug has a catch you have to depress on one side, then pull off. Set the assembly aside.

2) Remove the radio/vent assembly.

Pop off the fuse box lid, the catch is just under the center front edge, depress the catch and lift the lid completely off. (If you didn't already know that, reconsider the decision to do this job yourself.) Remove the four screws at the top front. The two outer screws are for the trim panel and the two inner ones are for the control assembly. The trim panel also has two gold-colored screws underneath where the cupholder was removed. Look underneath, they're towards the front and go upwards. Be careful, the holes punched in the steel dash framework are not deburred and are very sharp. Lift the radio/vent assembly up and forward. Unplug all the radio connectors and set the assembly aside.

3) Now it gets interesting - loosening the control assembly.

Remove the two lower screws holding the control assembly in place. It should now be loose but still connected by several wire bundles and control cables. DO NOT remove any of the control cables, and the only wire bundle you have to unplug is the one going to the fan switch. Pull the knobs off all the control levers. Remove the faceplate, it's held by plastic latches on the sides and bottom. Remove the clear plastic light guide, it is held by a latch on one side and a tab on the other. Unplug the fan cable which is back and to the left. On my Previa this plug, and also the replacement part, had thin layer of foam around them. This plug, like most of them, has a small catch on one side that you have to depress to pull it apart. You should be able to manipulate the control assembly up and down a few inches and tilt it to view the top and bottom, but it will not come out.

That's it for the easy steps. The switch body itself is barely visible at this point. Before we go on, I have to name the two primary access holes to the fan switch.

The Slot. Notice that there is a wide slot in the left sidewall of this compartment that you can reach into, from just in front of the rectangular vent pipe opening on the left. You have to do much of the switch and cable manipulating through this opening; that's where the long fingers will come in handy. I will refer to this opening as The Slot. You can reach through here and get to the fan switch back side and connector.

The Hole in the Top. This is the opening in the top of the control assembly between the rear heat control lever on the left and the 3 electrical pushbuttons on the right. Through this opening you can see the whitish fan switch and the right side of its connector. You can also see the wires to the two lamps.

4) Remove the short fan switch cable.

This very short cable runs out of the back of the switch and is clipped to the back of the control assembly. Look at the replacement part to see what this cable looks like. Notice where the plug latch is located and where it hooks on the switch body. You have to reach in through The Slot, depress the catch without seeing it, and pull out the plug. It helps to also push the plug out with the screwdriver from The Hole in the Top. After it is disconnected, reach underneath the assembly to push the cable to the right to unhook it from the rear catch. Set the cable aside; you won't need it if you got a replacement with the fan switch.

5) Remove the two lamps.

For some indecipherable reason probably having to do with ease of factory assembly, the two little green lamps that light up this control panel are wired into the fan switch. You will curse this feature a lot very shortly. To remove these lights the lower one twists clockwise and then pushes in, while the upper one just pushes in. There are four little catches around the outside of the upper lamp's socket that you may have to press in a little to free the lamp.

6) Remove the fan switch.

There is a little trick here that stumped me when I tried replacing this switch on the first attempt. Slide the Rear Heat control lever all the way to the left and look at the lever arm, visible on the top of the assembly. Underneath this lever arm, just behind the front panel and about half-covered by the arm is a tab made of the black plastic control assembly housing that acts as a catch to keep the fan switch in place. Lift this tab with the flat blade screwdriver and push the switch to the rear by pushing in on the switch's control lever from the front. The switch body should easily slide back and out of its track. Two years. Now the switch can be removed from the assembly by sliding it out to the left and through The Slot. You will have to wiggle it into a diagonal position to get it through The Slot, and this will take some pushing. Before you can remove it completely you have to fish out those two lamps using the hook tool through The Hole in the Top. Back the switch into the vent pipe to clear the lever arm, then remove it and set it aside without throwing it across the yard.

7) Put in the new switch.

At this point a typical manual will say something like "Install the new switch in the reverse order" and then move on to adjusting the hood latch or whatnot. But there are those stupid lamps to deal with so I will press on. I used a combination of a pull wire and the hook tool to get them in place. I cannot describe exactly what I did, though somewhere in there came most of the cussing. I will describe the procedure as best I can. Take the 2 feet of wire and pass one end of it through The Hole in the Top, past the place where the switch was, out the left side of the assembly and through The Slot. Wrap the end that went through The Slot around the two lamps' wires, just behind their sockets. Wrap them well (3 or 4 wraps) because you are going to be pulling them through the assembly by that wire to keep them ahead of the switch body. You can't just stuff them in there ahead of the switch because they get all jammed up and going in the wrong places, and you have very little access to get them going right. You might be able to manipulate them just using the hook tool through The Hole in the Top, but the pull wire helps. At least it did for me, before I pulled too hard and it let go and I had to start again a couple times.

Put the switch body into the vent pipe, rear side in first; I think I had the top of the switch facing to the left. Put the switch arm through The Slot, pulling on the lamp wires to keep them moving ahead of the switch. Turn the switch so it is topside up as you get it through The Slot and into the left side of the assembly. Keep pulling the lamp wires out of the way. I got one loop of wire caught between the switch body and the control assembly frame at the bottom of the switch body, which I found out later because it made the wires too short to install the lamps. I had to unlatch the switch and slide it backwards to free the wire. You could see the stuck loop through the bottom of the assembly, so keep an eye on that lower opening as you install the switch. I considered just cutting off those lamp wires and living without a lighted control panel, but I already had the switch jiggled in through The Slot.

Get the switch lever arm through the front panel opening, check those lamp wires again, then slide the switch forward until it clicks into place, keeping it pressed upwards so the small projections on the sides of the switch body stay in their tracks. Fish the lamp wires along the right side of the switch and down the little tunnel that leads to where they mount through the panel. Be sure to fish the lower lamp first, the one that pushes and turns to lock in place. Lock that lower lamp by putting the bulb through the hole, aligning the two little tabs, then pushing from the back with your fingers. Lock the lamp in place by holding from the back and pushing counter-clockwise on one of the tabs with the flat screwdriver until it is fully rotated in place. The upper lamp has to be fiddled with the hook tool to get it to poke through its hole, then push it from behind hard until it seats properly. There was some more cussing required at this step - that lamp is hard to get fingers on.

Get the short cable and insert the plug in through the back of the assembly, clicking it into the rear of the switch. I don't recall the exact path the short cable takes from the switch and out to the rear left of the assembly, but you understand why I'm not going to take it apart and look. Feel around the back and slide the cable leftwards into the rear clip. Then reconnect the other end of the short cable to the wire bundle. At this point you should reconnect the power if you disconnected the battery, then turn on the ignition and make sure the fan works at all the speed settings. Breathe a sigh of relief.

8) Reassemble the control assembly.

Replace the light guide, be sure to put the tab side in first, then click the other side in place. Click the faceplate back on all around. Push the control knobs back on all the levers. Make sure all the levers still move through all their settings and all the switches perform their functions. Make sure those two little lamps light up when you turn on the headlights. Put the assembly back up where it belongs and put in the four screws, two at the top and the two on the lower arms. Check every control again.

9) Replace the radio/vent assembly.

This is a good time to clean and lubricate those vent shutters and replace the radio with a more modern one. Otherwise, reconnect the all radio wires and make sure the radio works through all the speakers. (I forgot this step and did not discover the radio did not work until all was reassembled. That's when I decided an upgrade was called for, so I could claim that I meant to re-disassemble everything. Yeah, that's the ticket.) Press the assembly back into place and put the top 2 screws in. Reach underneath and replace the two lower screws. Put the top lid back on the fuse box. Reprogram all the radio station buttons, because all the settings are lost when you disconnect the power.

10) Replace the ash tray/cup holder assembly.

Plug the cigarette lighter and lamp plugs back in. Note the lamp connector can go back in either orientation. Insert the assembly diagonally with the left side lower. Wiggle and force it back up into position and put 4 screws back in place. Put the ash tray back, close the cup holder, and close the lower storage drawer. Check that everything still works. Celebrate.

11) Epilogue.

Repair the old fan switch and toss it in the junk drawer. My old switch failed at the connector contact, melting the connector casing a bit. It must have arced for a while, working intermittently before the contact was lost completely. If you just trash the old switch pull out the two little lamps and save them, just in case one of the new ones burns out.

under the air intake shroud found under the hood;the heater box must also be removed to see it. it's white wheel- then 'll be visible--need shop manual for instructions!

Automatic transmission fluid is added through the transmission dipstick tube which is located under the driver's seat. Release the driver's seat and open the engine access cover. The engine oil dipstick is also located here. Remove the Automatic transmission dipstick, use a funnel and add fluid slowly, a little at a time. Do not overfill. Make sure you use proper type of automatic transmission fluid. Make sure vehicle is on level surface and warmed up when checking. Also, refer to your owner's manual for proper procedure to check your transmission fluid. Engine may need to be running with transmission in park or neutral. Be sure to use your emergency brake. Automatic transmission fluid expands as it gets hot, so better to add a little than a lot.

where do i find the thermostat

It's on the dashboard, above the radio.

You didnt give year and engine of your Previa. But I'm going to assume that it's supercharged (S/C) model. Superchargers are notorious for supercharger whine or whistling. Also it could be a vacuum leak, or a loose air filter seal letting air in.

Another possibility is a restriction in the exhaust. I have a 95 with this feature -- it has whistled ever since the rear catalytic converter rusted out and had to be replaced. Some piece of this is probably stuck in the muffler and causing the whistle whenever there's enough air (exhaust) moving past it.

The speaker size is 5 and 1/4". Above the map pocket, you will see two squarish panels, pop these out and remove the screws. By the door handle, there is also another screw, remove this. Carefully, put a flat head screwdriver between the door panel and the frame and pull away, the rest is held by plastic clips. By the way, there is a top part and a lower part of this. You really need to remove only the lower part. The top, just pop it open, and inside, you will see one more screw that secures the lower panel, near the center. Remove this also, and the whole lower section should be loose. Don't forget to disconnect your power windows connection, this is a simple un snap with the screw also. When you put your new speakers in , put some insulation around it too, it helps a lot in making the sounds more audible - any mat will help.

Your transmission is slipping. Could be just low on fluid so check that first. If not get in to a shop and have it serviced. Unless you are really skilled let the professionals get into the transmission. I just passed a guy on the freeway who stopped in the middle of the road. He no longer worries about his transmission stopping. Now he is looking for a new car. Same with the 3 cars that hit him.

you have bad contact in ground cable of the brake lights

You might also like to check that there has not been a bulb replacement lately that uses a single contact in a double contact socket. This would have the effect of shorting the brake and tail light inputs and thus turn on ALL lights when brakes are applied or the parking lights turned on.

Not sure, but its most probably the aircon compressor oil that's leaking - this also means that the aircon will lose its cooling ability soon (in other words the coolant gas will be lost). Engine oil leak is usually detected in the vicinity of the engine itself.

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it is not too bad remove the gearbox then remove the engine mounting bolts and the fuel pipes unbolt the front prop-shaft unplug the engine wirering connection then comes out the same way down as the gearbox it will take about 5 hours tops

It's in your owners manual

White smoke indicates water indicates water in the mix! If your head gasket is ok then it could be you have upset the fuel mixture and you are burning too lean, the lambda sensors are getting upset with the exhaust fumes and then the engine management is unhappy and kills the engine when you stop (or chugs when you travel). Get it to a garage and have it tuned.

i've got same problem with my '93 previa with 184,000 miles on it. i read somewhere the problem could be a sticky choke. will tell you more after i fix(hopefully) it sometime next week.