I've been working on my brothers '00 Taco 3.4 with a manual. He complained of a rough idle, felt like it was miss firing around 1700-2000 rpm and smoothed out after 2300 or so. Changed the plugs checked the PCV and cleaned the MAF. Ran smooth as silk yesterday. Today it's rough again. Previously there was no CEL but today there was and it came up that the coil pack for #1 and #6 was bad. Changed that and it's still running rough. CEL back on says the same thing. What else could it be. I did do a search but nothing else quite matches this problem, at least I don't think they do.

 

Try checking the plug wires for worn spots and double check that they are connected firm..Could just need new wires..Just a thought..

 

I'll check that, but would that give a code for a bad coil? Faulty codes do happen I guess.

 

My Moms LC did that and it was a bad injector.....something to look at.

 

What things can cause the a code indicating a miss fire in #1 and #6 other than a bad coil pack, plugs or wires? Because I've already changed those. If there was insufficient fuel reaching that cylinder could that show up as a miss?

 

You can run out of fuel and it will show as a misfire. Try checking the fuel psi, it couldn't hurt. Fuel pump could be taking a crap or full fuel filter restricting flow just enough. If u check the press make sure the psi doesn't drop when you cut the key off. That would be a bad valve in the fuel pump. Seen it a bunch. Be sure your wires are good. Good luck.

 

Thanx for the help I'll check this out and report back.

 

mine had a similar problem i changed my timing belt and it fixed it. check that out...

 

Yeah the timing belt and water pump were done about a month ago.
Thanx anyway.
The good news is that though it's only been a day.....so far so good.