Missing on 2 cylinders...need help

[Johnson16]

94 tercel, missing on cylinders 1 and 4. Pulled plug cap and no difference in idle with either 1 or 4 out. Firing order is 1,3,4,2 in the 1.5 Liter. Have spark (at least there was when I pulled off the plug while running and it arched against engine block), injectors 1 and 3 were swapped to make sure that was not a problem, new ignition coil, rotor, cap, wires, plugs. I don't know what to do next? Timing issue somehow on only 2 of the 4 cylinders? Does the spark to 1/4 and 2/3 come from 2 different sources? Still need to check compression, but that doesn't seem like the culprit given that 2 are out and at opposite ends of the block.

[Scrapper]

have you done a compresion chck on all 4 cyl?

[shorod]

Does your Tercel only have one coil (you mention "the coil" was replaced) or does it have a coil pack for each pair of cylinders? If you have two coil packs, then see if cylinders 1 and 4 share a coil. It sounds like you are wondering the same thing from your last couple of sentences. It's easier for you to open the hood an look than it is for me to go to the service manual and search.

The compression check that you mention you haven't done yet is a good idea too since it is so easy to check on an inline 4-cylinder.

If all of this checks out fine, then I'd suggest you get a noid light set and verify you have pulse to the fuel injectors for those two cylinders.

-Rod

[UncleBob]

try swapping 1 and 4 wires on the cap. Might have them 180 out.

otherwise, injector circuits are often fired in pairs, such as 1 and 4. If you have a short on one injector it will effect the mated injector.

You could also have a driver out for those two injectors. Ohm the injectors and make sure you're getting power and switching ground to all the injectors (hooked up)

[Scrapper]

the coil pack if you just look at it real quick it might look like both of them but i would look see if there just 2 by themselves or in just 1 coil pac alone im thinking it's there all in one on coilpack......

[curtis73]

94 Tercel should have two coils; 1 and 4 should share one and 2 and 3 share the other. Sounds like a bad coil. They can make a spark and be weak but look healthy when you watch it. Under the stress of compression a weak spark is pretty pathetic. You probably are also getting some spark. a 4-cylinder will barely run on just 2, if at all. My guess is that its really weak and partially burning.

[Johnson16]

Thanks for the feedback. I plan to dig into some of these ideas this weekend. Thankfully it still runs, but weak of course. The whole investigation started due to stublimg during accerlation and very very rough idle and some intermitten stalling. Occasionally I would throw Code 25 "Lean Mixture". I am only gettng about 8-10 in Hg for vacuum right now. I have noticed this problem has seemed to get pregressively worse the last couple months. And to be honest it seems to be worse with a warm engine. electrical short or something? I will give feedback later this week with what I find. Thanks again for all the good leads.

As for the coil, there is only one that controls all four. As for the plug wires, cylinder one is at about 11 o'clock on the cap. The wires are mapped according the to the cap.

[Johnson16]

One more note......I can hear (via screwdriver) that the injectors are firing on all four. Well, at least I know the solenoids clicking. Thanks again.

[ilikelife]

according to what you said, it is not abuot fuel injection, timing and ignition. maybe the leaking intake manifold passage for the cylinder 1 and 4?