Missfire @ around 2300 RPM

[hdw1983]

I've got a 97' Tacoma 2.4L. I've done a complete tune w/cap, rotor, wires, and a coil. Its got a new CAT. While looking at the missfire data in the scanner, cyl. 4 is is missfiring over 60 times in 30 seconds and #2 is missfiring around 25 in the same time. Cyl. #1 and #3 are about 4 or 5 missfires ever 30 seconds. We've allready tryed a couple sets of wires, swapped out the cap and rotor again and put different plugs in again. Same problem. This is really stumping us. We've tested the TPS and it checks out fine. It only breaks down around this 2300 RPM. It does have a rough idle also. We havn't done a compression check yet, it runs to good to have low compression. Origonally the truck had a random missfire code, and codes pertaining to a missfire on #1 and #4. Any help would be much appreciated. Thanks..

[Brian R.]

Are you using the recommended Denso or NGK plugs?

Check the camshaft and crankshaft position sensors.

Check connections from igniter to ECM.

Replace igniter.

[hdw1983]

Only use NGK V-Power plugs, Not the igniter or the wiring between the igniter and the ECM. Tested both crankshaft and camshaft pos. sensors and both are within range. Thanks for the input..

[Brian R.]

The igniter is usually the problem when you can't figure anything else out. How do you know the igniter is ok?

[hdw1983]

We put one off a good running truck on it.. Same year, same model, same motor and same numbers on the igniter. It does the exact same thing.

[Brian R.]

I would bring it to a shop with an ignition scope and see what the scope looks like.

Check the battery ground wire to the body off the negative battery terminal.

[bkydmech]

Originally Posted by Brian R.

The igniter is usually the problem when you can't figure anything else out. How do you know the igniter is ok?

My truck is doing basically the samething, I've done all the same stuff accept mess with the igniter. The only possible differnce is that mine runs great under heavier acceleration, I only have the problem with a light foot on the throttle, it also idles just fine. In addition to what you have done, I've checked the valve clearences (which are on the tighter side, but within the spec on both exhaust and intake). I've also cleaned out the throttle butterfly with carb cleaner. The problem remains the same. If you find something out, I'd sure like to know. I don't believe the plugs need to be NGK, I had them before all of this.

Thanks

[hdw1983]

Turns out the igniter we tested with wasn't good either.. We put it back on the truck and it did the same thing.. Kinda weird eh? But yeah, we put a new one on it.. Runs great... Thanks for the info, helped out alot. Will definetly ask your advice again. I have a 97' Tacoma but it's a 4x4 and it has the 2.7 in it with the two coil packs. It has a rough idle but acceleration is good. Any advice on my truck?

[Brian R.]

Narrow it down by seeing if it is the same cylinder all the time or alternating cylinders causing the rough idle. Pull one plug wire at a time and see if any of them have no effect when pulled.

[bkydmech]

Is the ignition coil and igniter the same thing? I saw the ignition coil online for about $84, it fits inside the distributor.

http://catalog.autopartsgo.com/?make...1996&x=36&y=17

[Brian R.]

No, coil and igniter are two different parts.

[bkydmech]

Originally Posted by bkydmech

Is the ignition coil and igniter the same thing? I saw the ignition coil online for about $84, it fits inside the distributor.

http://catalog.autopartsgo.com/?make...1996&x=36&y=17

Reseating the battery terminal on the ground side may have helped. The truck now only has a miss hit about once every five minutes. Its acceptable, the truck has 188K miles one what can I expect? The intake valves are at .006" clearence, which is at the tight end of the range, I wonder if that would make a differnece?, it runs great under heavy acceleration just like a race car. My next project will be to replace the exhuast manifold, its developing a slght crack between the 2 /3 Cyl.
Thanks