91 4Runner running rough when cold

[popeye4]

My 1991 4Runner (3VZ-E) runs rough for the first mile or so, then smooths out. It starts fine. Is there a "cold start" injector that might be fouled? I've run Techron through the fuel system, but I'm guessing that there isn't enough time for it to clean an injector that runs for a minute or so. Any suggestions?

 

[SUBTEGRAL]

SEA FOAM it!

I don't know .. maybe make sure the ignition timing is still set spot-on?

Maybe spray some throttle body cleaner?

Maybe start using ethanol-free gasoline?

I'd Sea Foam first ...

 

[fourwd1]

Yes, there is a cold start injector, controlled by a timer.
The problem could be there , or the circuits that tell the EFI ECM the engine temp (which again affects the Cold Start circuitry).
Low coolant level could be a simple reason for that.

 

[SUBTEGRAL]

err .. what he said.

 

[Rix]

Cold start injector ONLY operates WHILE CRANKING. It's directly connected to the starter.
The thermal time switch shuts it off after so many seconds OF CRANKING.
That's not likely to be it, UNLESS its leaking while off.
More likely in a 3.0 is head gaskets.
Or leaking injectors.
Or low coolant.

 

[SUBTEGRAL]

I doubt it's his cold start injector .. but then again, what do I really know?

 

[the_dingman]

Could be coil/plugs/wires. They will perform differently under different temps, and warm up very quickly.