InternetRoadkill

I have a 2003 RAV4 in addition to my 88 4R. I've been driving the Rav4 since it makes better mileage. But lately, the RAV4 has been acting up. The engine will sometimes die from idle when sitting at a long traffic light. There's no check engine warnings. It just quits. Fortunately, it restarts easily. I imagine that it has the same fuel injection as other Yota trucks, so I'm guessing someone has run across this before. Ideas?

2.0L L4, 53K miles.

William

I don't know about Toyota fuel injection systems specifically, but I do know about fuel injection systems in general.

Fuel injection systems have some way to control idle speed. Most, if not all, use a small electrically actuated valve that controls how much air bypasses the throttle plate (on Fords it's called IAC or Idle Air Control). The engine computer detects slight changes in idle speed and makes small changes to the valve position. If the idle speed is a bit slow, the valve opens more. If the idle speed is a bit fast, the valve closes back some.

A bad idle speed control valve will tend to show itself more when the A/C compressor clutch engages and disengages, because it can't compensate for the changing load on the engine caused by the compressor.

Sometimes the idle speed valve will gum up, causing slow action or rendering it inoperative. It sounds like that's what has happened to yours. I've had this happen before, and it's not hard to fix.

What you can do is remove it and spray some carb cleaner in it to clean it, then use a small amount of penetrating lubricant (such as Blaster) to lube it. With a worse case scenario, you might have to buy a new valve.

The idle speed valve should be mounted somewhere on the throttle body and should have an electrical connector attached to it. Unfortunately, I don't have a Rav4 to look at so that I can give you more accurate info on it's whereabouts.

I hope this helps.

toytech76

I havent experieced this on a rav, but on 2 camrys. It would idle and run fine but randomly it would die. They were both diagnosed with bad coolant temp sensors (TWA) They were sending bad data to the ecu saying the coolant was super cold or really hot. It wouldnt set a code because to the ecu, the sensors were working. It cant distinguish bad data from good data. I would check that

InternetRoadkill

A flaky TWA might explain it. I don't have a service manual yet, so I guess I need to get one. The idle is perfectly smooth at 750. It just decides to spontaneously quit without any other symptoms.

toytech76

anyone with a scan tool that shows engine data can watch what the sensor is telling the ecu when it dies. That way you can rule it out or not

InternetRoadkill

The problem is that it's unpredictable. It can go for days without incident, so I would have to leave the scanner connected in the hopes of catching it in the act.

William

I would think that a bad coolant temperature sensor would cause bad running and also poor fuel economy pretty much all of the time. If the computer thinks that the engine isn't warmed up, it could cause the mixture to be rich because the engine needs a richer mixture when it's cold.

On the other hand, a loose or corroded connector on any number of sensors could cause a problem like yours that comes and goes. Same thing with a loose or corroded ground.

Since I now understand that it is an intermittant problem, I would be checking connectors and grounds.

I have taken off connectors and sprayed contact cleaner on each half, making sure to put the straw right up to the female side so that the cleaner is forced into each one (make sure the contact cleaner is the plastic safe kind). Then I take some kind of non-conductive corrosion inhibiting grease and apply a liberal amount to both halves of each connector before I reconnect them.

With grounds, I have simply loosened each screw or nut a little and then retightened them just a little tighter than before. The friction between the metal contact surfaces will sort of wipe the surfaces clean. If you want to get more involved, remove each ground and clean each terminal, the nut/screw and all other contact surfaces with a wire brush. Then take corrosion inhibiting grease and apply it to each connector, screw/nut, etc., and reattach.

I have fixed problems this way before, both intermittant or otherwise.