Hey everyone,
when starting cold, my 99 runner 3.4 v6 4wd feels like its running on 5 cylinders for about 5 seconds. Then, it clears and runs fine.
spark plugs and wires are new.. no CEL.
Feels like a fuel managemrnt issue to me....any thoughts?
thx!!

 

Not much to go on here but suspicion assuming you used Denso or NGK specific plugs for our truck and didn't try to Gap them or use anti seize on them, have correct wire orientation and decent quality wires. Since the plugs and wires are new, perhaps one of the boots on the coils or plugs isn't seated well or incorrectly, the wires that go directly to the 3 spark plugs should snap in place. Could be one of the wire or coil clips are missing on the coil side, also I have noticed corrosion in the connections of the coils doing this job, cleaned them up and added di-electric grease. If you miss the spark plug with the boot or it isn't seated properly it will still run on that cylinder intermittently. These ofcouse these are all guesses to eliminate spark plugs, coils and wires, and a bad coil could also be suspect, all you can do is buy 1 replacement coil and try it in each location and observe any change over a few days of use and repeat 3 times.. Other things that come to mind is MAF, ECU, engine grounds and battery connections, Crank sensor, teeth on crank pulley, vacuum leak on intake, timing off a tooth, ect.,

 

I just changed the plugs back to the original dual electrode plugs 2 weeks ago. The starting issue was there before the plug change.
Drivers side plugs were burned to nub.....pass side ok.
Under a load....on the highway it was sputtering.
That issue is fixed with the new plugs.

I'll check around for arching spark but it is odd that its only during start up. Now noticing it even starting warm.
5 seconds of rough...then smooths out. No other driving issue.

 

While warm I would add injector issue to the top of the list if it is an observable miss/engine shake/running rougher intermittently, it doesn't always flag it if its intermittent, the more info you provide the easier it is for us to relate, I don't know if its a 99' and up thing but I've helped a few 99's with this injector issues. My 99 low milage and 97 with very high milage never had this injector issue, knock on wood..

 

I think the major piece of info is that its only upon starting either hot or cold. Never runs rough at any other time.
Feels like a miss...then gone after 5 seconds or so.
Thx for your help.

 

Crazy........the problem disappeared a few days ago.
Starts and runs like normal. The only thing i can think of is the temps here in phx have jumped from low 80's daytime high 55 overnights to over 100 degrees / 72 overnights.
other than that....i have not touched a thing .