Engine start initially rough and stumbles

[deadcandance]

Hi guys I need help. 1999 4runner, 197k miles. New plugs, new wires, cleaned throttle body, no CEL illuminated. When I initially start the engine cold, it will momentarily run slightly rough and perhaps "misfire" for about 5 seconds and then goes away and smooths out. Runs perfect otherwise. When I go back to start it up it after it's warm, still seems to always stumble a little on start and run slightly rough and then smooth out. It doesn't lope or quit, just runs a but rough for a few seconds. The engine otherwise produces excellent power and runs and idles perfect. Does not ever produce a CEL.

Ignition coils? Start ignition system problem? (if there is such a thing?) Fuel injectors??

I've owned another 3rd gen 4runner and it didn't do this.

Any input greatly appreciated.

 

[judoant]

I have the same issue about every 50 starts. Does not matter if it is warm or cold. One day it did it about 3 starts in a row. Normally just once every now and then.

Might want to move this over to the 3rd gen forum.

 

[jgmx893]

I would say start with the fuel injectors. If you haven't recently or already, dump a bottle of Chevron Techron or Seafoam in the tank before your next fill up. My buddy just had the same problem in his sedan and between Seafoaming and new plugs his rough starts were fixed.

 

[deadcandance]

Thanks guys

Thanks I will give that a try. Just had the damn manifold off for plugs and valve cover gaskets I wish I had done the injectors.