Strange bucking @ low RPMs

[v8318cid]

Here's a dome-scratcher for you. 92 2.3l. At low RPMs, the engine kicks hard when accelerating (goes away for the most part at higher RPMs, but not entirely). There's an audible ping or clanking sound that seems to sound like a hammer hitting the water pump pulley, and no its not spark knock. There doesn't appear to be anything in the way anywhere that I can find, and it doesn't have a problem when the truck is sitting still. I can rev it all day and have no problems, even with the A/C running. I've timed the engine correctly, and finally got the coil packs wired properly. The timing belt is as tight as I can get it, although I can't proof it out (no clue how much belt deflection there should be...). Best guess I can come up with is either a slack timing belt, or possibly a bearing that is about to seize, although I can't tell if its in the transmission (manual 5-speed, probably Mazda based on the DRAIN/FILL plugs on it...) or a pulley. Any ideas? Thanks.
***Update*** Nix it. Secondary coil turned up bad. Part of the reason I kept getting PIP failure when I had the wires plugged in correctly... Runs like a champ now, even with A/C running.

 

[Harris]

I had the exact same issue back in March. The only problem with mine was I tested the coil packs using the wrong method and listened to some, shall I say, unsound advice from a mechanic uncle and replaced the fuel pump. *sigh* Oh well, it's got a new fuel pump.

 

[Friiy]

I have pretty much the same symptoms right now.. I have found that the exhaust side coil pack Is dead on the number 3 position.. I have ordered a new coil pack and plug wire set... I hope this will fix my problem..

Just something you may want to check..


---Friiy

 

[v8318cid]

I've fought the coil packs on this truck for over 1.5 years. Part of the problem was that I've found numerous diagrams for how the wires should be arranged and, of course, none worked properly. Since the secondary coil was bad (and I didn't know it), it kept giving a fail code when the #1 wire was installed properly. I tried the test procedures that people listed, primarily about checking primary and secondary resistance; all results looked good. Lesson learned : when replacing coil packs, replace all of them at the same time. Second lesson : document the wiring pattern before disposing of the factory coil packs...