86 4Runner sometimes runs too rich at start.

[billat908]

My 86 4Runner 22RE sometimes runs really rich at startup. VERY rough running, stinky, smoky exhaust, needs lots of throttle to keep it running until it gets a little better. Once it is running well enough to drive, it runs rough, and then cleans out and runs smoothly as the engine warms up. Just a mile or so. Sometimes there is a check engine light, sometimes not.

Other times, it starts and runs perfectly.

Since this is intermittent, I am not sure testing would be useful.

Would changing the coolant temp sensor for the FI be a good place to start? The fact that it clears up when the engine is warm leads me there.

BTW, is there a trick to releasing the little piano wire clips that hold the connector on the sensor? I got it off using a tiny screwdriver to pry, but I seemed to need three hands.

Now and then, when the engine is running well, it will buck for just a moment, often with the check engine light coming on. It is like the ignition was turned off and back on again. This happens seldom, say once a week, but it is unnerving. I don't know if this is related or not, though.

 

[turboSR5]

Best advice I can give you is to check your stored CEL (check engine light) codes. If it is your coolant temp sensor, then the code will be stored. As far as the wire clips go, there are special pliers for those but I just use the screwdriver to pop one side out of its groove, then the other.

 

[run4yota]

+1 on theCEL light.. get the count the number of flashes and let us know we'll figure it out. it almost sound like an injector getting stuck open or leaking intermittantly. if it came on suddenly thats a good thing because most likely it is electrical. any of the sensors could cause the enginge to run rough. so the cel code will tell you where to start.

 

[billat908]

I'm so dumb I don't know how to read the code for the CEL light. :crybaby:

I do have the factory manual, but it is at home. We are out motor-homing around AZ.

What I did do was disconnect the ECT connector and drove it for a coupla days with no trouble. The CEL light stayed on, though. I am not sure that proves anything, because the problem has been intermittent since it first appeared, but is is a positive event. I am surprised that running with the ECT disconnected seems to be OK. Sort of expected too lean or too rich or something. May drive to town today (over an hour) and buy a new ECT sensor.

The present ECT sensor is pretty ratty looking, however, the electrical connections are shiny and clean. It is possible that the radiator hose connection right above it dripped on it at one time. This has been common for me with aluminum rad hose connections. When we get home, I will clean it up properly and install a Corbin clamp. Any suggestions on an anti-corrosion paint or treatment for that area? I once had a Jag that dripped on the distributor. No amount of clamp tightening or new hoses would cure it. I finally had to have a new spigot welded on it.

 

[billat908]

Update: Drove to town this morning and put in a new ECT sensor. Drove around a lot, and it seems OK. Can't be sure, though, because the problem was intermittent.

So far, so good.

I guess if it acts up again, I'll have to figure out the check engine light flashing thing.

 

[KingJerd]

Experience is telling me the coolant temp sensor would be the culprit.

 

[billat908]

BTW, if you have a 19mm deep socket or crowfoot, the sensor can be changed without removing the upper rad hose. I had to remove the hose and use a box end wrench, as my 19mm socket was not deep enough.

Same for the sensor next to it. Cold injector timer or something like that, I think.

 

[run4yota]

to read the codes for the CEL just get a paper clip and bend it in a "U" shape. then stick one end into the "T1" connection of your diagnostc plug (the gray one by your battery under the hood that has about 20 pins) and the other end of the paper clip shoutl plug into "TE1". then go in your truck with a pen and paper and turn on the ignition, but do not start the car. when the light flashes count the blinks... i should blink once every second until the digit is done. then it will pause for 3 seconds and when it statrs blinking again you are at the next digit.. continue doing this until it starts repeading the codes... Ex: blink, blink, (3 second pause), blink, blink, blink, blink, blink, Pause.. this would indicate a code 25.

 

[fourwd1]

Experience is telling me the coolant temp sensor would be the culprit.

That would be the ECT sensor they are talking about above.

 

[T?@\7]

****, anyone got a paperclip i can borrow?

 

[billat908]

Just an update........All is good since the sensor replacement.