What do I look for next ?

As soon as I got my Taco about 6 months ago I replaced plugs, wires, filters, just to make sure everything was good on it. Well lately when I hit a hill and the truck down shifts I can feel it starting to skip and sets a CEL light. It idels and runs smoothe otherwise. The first time it set the light I had it scanned and it said cylinder 3 missfire , so I thought coil, and replaced it. Well.. it did it again, this time it said cylinder 6. I replaced that coil. Damn thing is still doing it. I haven't had it rescanned yet, but now it has new plugs, wires and 2 of the 3 coils replaced. What else could cause this skip when it down shifts and revs up ? Note it will also skip if I pull off with it on the floor, I just hardly ever do that so the only time I notice it is on down shifts.
Thanks

 

Are any of your plugs fouled? Best rescan it too. Brand new plugs can still get fouled. Just an easy thing to (re)check.

You might want to do a compression test on all your cylinders.

 

I haven't pulled plugs yet because they only have a couple thousand miles on them, but I will do that soon to see if any of them look bad. I just rescanned it and it still says cylinder 6 misfire after I replaced the coil for what I think is #6. I replace the coil fartherest back from the front. That is # 6 isn't it ?

Code it's throwing is P 0306

 

Pulled plugs and they looked like they were burning very clean. Ran a tank of fuel through it with seafoam and did the seafoam through the vac line. Started looking for any vac leaks and I haven't found any at this time. Anything else to look into ? There are 2 vac lines on the top of the intake that are just blocked off. Should they be ?

 

I have the same 2 blocked off so im geussing yes, but good luck figuring out youre problem

 

Thank you.

 

This ^


or check to see if your MAF sensor checks out to FSM, within specs.

 

OP, are you using the stock Denso or NGK dual-electrode plugs?

 

Plugs are just single post plugs. I can't remember what brand. I would be happy to have the injectors rebuilt. What company will I contact to have that done ?

 

Do the look like this (dual ground plugs):



Using single-electrode or other non-spec plugs can cause problems. Just want to make sure this is not a contributing factor.

 

Not at all. Just regular old school style plugs. I am going to replace them this week I think. The guy at parts store told me it didn't really matter , so I took the cheap route, but I knew better.

 

Its for emissions but it was not used. Only place it would be used is in california thats is questionable( i havnt seen it so i cant say for sure).

 

I'm pretty sure you need the twin electrode plug with both gaped appropriately.

 

OK. Thanks. I'll be getting plugs this weekend and swap them out.

 

I swapped out single electrode for the proper dual electrode plugs last fall and truck seems to start much better with a bit better power but the one thing I have been doing and did it in my 289k Jimmy as well was fuel injector cleaner every second or third fillup. It does make a difference and its one of the first things mechanics around here do when someone complains about a loss of power.

 

i had the same thing it was my 3rd cylinder injector, i replaced all coils and wires and plugs, then did all injectors and that finally fixed my problem runs so much better and im getting better mpg too.. i am actually going to sell my old injectors for 75 dollars.. one of them is bad but for all 6 its not a bad price.. or ill sale you only the however many you want to buy.. they are off of a 96.