Not running smooth after warmup

[bkydmech]

This is an add problem and I think it relates to the recent cold weather, the truck runs ok when its cold, but after about 20 minutes of running the #1 cyl is missing. I changed the plugs (NGK) and that helped slightly, but the #1 plug was a darker color before I changed out to the newer plugs so thats how I determined the problem is on that cylinder, above 3000 rpm it also runs great so I know there is nothing mechanical wrong with the cylinder, the 1500-2000 rpm range seems to be the problem range. any Ideas on where I can start? I also added some fuel injector cleaner and that seemed to slightly help.

[OBATDDSD]

Originally Posted by bkydmech

This is an add problem and I think it relates to the recent cold weather, the truck runs ok when its cold, but after about 20 minutes of running the #1 cyl is missing. I changed the plugs (NGK) and that helped slightly, but the #1 plug was a darker color before I changed out to the newer plugs so thats how I determined the problem is on that cylinder, above 3000 rpm it also runs great so I know there is nothing mechanical wrong with the cylinder, the 1500-2000 rpm range seems to be the problem range. any Ideas on where I can start? I also added some fuel injector cleaner and that seemed to slightly help.

Try swapping #1 plug wire with a new one or with #2 or one of the same length and see if goes away or misses at a different cylinder.

[bkydmech]

Yes, I should have mentioned I also tried that, its also a new set of plug wires which I thought would fix the problem. I should also state its a '96 tacoma 2.7l with 175K on it, its been impeckably maintained and is not burning a drop of oil.

[OBATDDSD]

I have a 95 2.7 s/c 188,000. No cracks in dist cap? Have you done a compression test anyway just to be sure. Have you ever adjusted your valves?

[bkydmech]

I checked all that already, new Distributor cap and wires and rotor. The valves were also within spec, you have some good ideas don't get me wrong. BTW, valve clearance on these trucks will change very little in the first 200K miles if properly maintained and cared for, this is advice from a mechanic at the dealer, and the bucket style shims are very hard to work with and you need a special tool to extract the shims.'

The problem turned out to be bad gas, or filling up with the stuff at the bottom of the tank (water), it plugged up the injector on the #1 cyl. Now its almost back to normal with running chevron with techrom through it.

[Flash75]

Thanks for posting the solution to your problem. I wish everyone would post their solutions to problems. We try to make an intelligent guess based on the data provided and our previous experiences, so when someone provides a solution it adds to every-ones knowledge base.

Clifton