1997 Previa Help

[annelid]

Hi

We are having problems with our Previa. Basically it keeps stalling on us. It mostly happens if the car hasn't been used for a day or two, and it doesn't happen all the time. Sometimes we get a few yards down the road and it stalls, sometimes we can drive 1/2 mile and then it stalls. It doesn't seem to be predictable. When the engine has heated up we don't have any problems.

So I hope someone can offer some advice.

Many thanks

Anne

[propnut]

When you first start the car what happens, does it start fine and idle at slightly above 1000rpm or does it miss and run rough ??. Does your orange engine check light stay on, when was the car last serviced and how much mileage has the car done???? Finally when you next start the car from cold ask someone to stand behind it and see if any smoke comes out as soon as you start it and if so what colour and whether or not there is a strong smell of fuel.

[annelid]

It starts fine but doesn't idle very well, (If we are parked up) it can go up to 1400 to start with and then slowly goes down, to sometimes 800 and then generally it stalls

The engine light does not stay on

Mileage is approx 112,000

No noticeable smoke but there is a strong smell of fuel

Last service Jun 07, MOT Oct 07

Anne

[propnut]

Ok, well without seeing the car I can only hazard a guess that perhaps you have leaking injectors but what I would suggest is that you have the car serviced PROPERLY and ensure they change the spark plugs with the correct platinum units. These cars MUST be serviced every 6000miles if used on the open road and sooner say 4500 if most of the driving is done around town.

The correct spark plugs have a 60000 mile life span but at 112000 unless you have records that this has been done it is worth doing again.

Air filter

Fuel filter

oil filter

oil

must all be changed and I would have the garage do a fuel pressure test on the injector rail as well.

Engine timing must be checked as too should the distributor cap, ignition leads and rotor arm.

Here the deal if the plugs are marginal and you have a situation where you have a lot of fuel and a cold engine the spark provided may not be sufficient to keep the car at a sufficient idle, hence why I say start here. The distributor cap, rotor arm and ignition leads are all part and parcel of the spark plug circuit.

Another thing that these cars are prone to is coking up of the throttle body. The role of this item is to control and monitor the amount of air that gets to the engine under different conditions at your mileage this should be taken off and cleaned. It is also worth checking for air leaks in the vacuum pipes and have the PCV valve checked for operation (your mechanic will know what this is)

Did this start happening all of a sudden or has it been a gradual issue. MOST IMPORTANTLY have you noticed the car using any water???

[annelid]

Thankyou for all that info, very helpful.

The stalling has been a gradual issue, and there is no water loss

Anne

[annelid]

So we have had a full service done, including spark plugs changed. They also put a fuel treatment in to do the de-coking to avoid having to do it manually.

So, 2 weeks later, and the car has started stalling again.

So what now? Do we get someone to clean the throttle bit properly?

Thankyou for your help.

Anne

[propnut]

Anne, if they told you that their "fuel" treatment would get rid of the carbon accumulations in the throttle body (decoke) then they are good bulls******s. No fuel whatsoever gets anywhere near the throttle body.

I am sorry but the only way to rectify an issue like this is to get someone who really knows what they are doing to go through the engine in a systematic fashion and do a full diagnosis. In addition to the throttle body their are other things in addition to what I outlined above that could cause it e.g. the EGR valve, a heater circuit on the primary Lamda sensor is going and others. There was another guy on a different forum who had a troublesome issue like this and spent a fortune on supposed experts only to discover that the timing had been incorrectly set but the fact that this was out had been hidden by something called the knock sensor that was compensating for it. Something that the "experts" should have started with.

Unfortunately you need to consider what the car is worth to you and how much you are willing to spend on it. At the age these cars are now they really are only ideal for those with deep pockets or those who are mechanically minded. Your problem could be a 10 minute job to diagnose or a 10 hour job and unfortunately you may be better off with a Toyota agent (can't believe I am saying this) at this stage.

Personally I would still start with a good sit down with the throttle body, a tooth brush and some carb cleaner and get it spotless + change its gasket. There is a component known as the idle speed control (ISC) valve in the throttle body whose name speaks for itself. The throttle body gets gummed up with carbon due to something called the Exhaust Gas Recirculation valve which takes in exhaust gases and puts them back into the air intake system. This gumming up (coking) impedes the operation of the ISC.

I cannot guarantee that cleaning this will resolve anything but it is somewhere to start. If your partner is good with his hands then get him to read through this.

http://www.autozone.com/az/cds/en_us/09008...irInfoPages.htm

Just as an addendum, you said it has run fine for 2 weeks. One thing some fuel additives do is clean fuel injectors. It is entirely possible that what they put in your system was fuel injector cleaner which may have temporarily solved a sticking injector problem. The most likely candidate is the cold start injector as this gets horribly gummed up. Now on the same point you mentioned initially that the car ran fine when hot. Well this too may have something to do with a gummed injector as when hot most petroleum based sediments soften but when cold they solidify. Try going down to Halfords and buying some Petrol injector cleaner, they are all much of a muchness and follow the instructions. If once again you see an improvment have the injectors looked at starting with the cold start injector.