Intermittent stalling, rough idle, and apparant misfiring

[dredman]

OK - I've been thru most of the Protege forums. I have a 2001 automatic 1.6L model, and read the many posts about rough idling, which my car suffers from. As such, I cleaned the EGR valve, MAF and IAT sensors, even cleaned the air filter, but the problem still persists.

It happens when idling, usually in traffic. The car begins to idle extremely rough, the engine shudders/sputters and vibrates terribly, almost like it's misfiring. When you mash the gas pedal, the revs rise, but also very rough. It almost seems like it's running on 2 cylinders - it's that bad. Along with the rough running and vibration, there's also the sound of something like belts squealing (it's not that though, just had them ALL changed 2 weeks ago, along with a tensioner). There's also the smell of unburnt gas from the exhaust, which is why I assume that not all the cylinders are firing.

It used to be that revving up the engine would cure it, but then that stopped working. Then I had to resort to quickly switching the engine off and then restarting to cure it, but even that is starting to become ineffective - now I have to wait about 5-10mins before restarting to cure the problem.

This problem was happening even before I changed the belts and tensioner, although not as frequent. It's just gotten worse and more frequent over this time. The plugs are only about 10000 km old. Anyone have any thoughts?

 

[dredman]

uh, ok. I thought I went thru all the forums. Just saw a few other threads with similar problems, all leading to saprk issues (either wires or coil packs). I'll try some of their solutions over the weekend and update this thread with my findings.

 

[loveindia]

mhh.,.,.,.i think it is happening cuz of the ignition coil.,.,did u try arcing the coil wires to ground.,.,just to c if there is a proper spark,.,.,.

 

[Chawk]

What about the alternator sometimes they go bad and when the veh is running off of the batery alone it can sometimes be responsible for the veh not running on all cyllinders and can cause excessive gas to be burning in the cat. I would check the voltage of the battery when the veh is at idle it should sit around 14.2 volts then rev the veh while monitoring the volts with every power consumer in the veh like heater radio lights wiper ext.. to see if the alternator is running correctly. if it drops below 12 volts then this may need to be replaced. I dont really thing that it is the ignition coil b/c if there was a problem it would probably not start or stay running right? Anyway post the results please.

 

[dredman]

Thanks loveindia - I saw that suggestion on the 2.0 tuning forum. I bought new plug wires and tried that, but that didn't solve the problem. Now, I've basically isolated it down to the coilpack. How?? Well, I pulled the leftmost plug wire while the car was misfiring at idle, and the engine cut off immediately. So I reason that coil was giving spark. I went home that evening and switched around the coilpacks. When I restarted, luckily it began idling with a misfire immediately (it's a random, intermittent problem). So once again I pulled the leftmost plugwire (now hooked up to the other coil which I switched) and - lo and behold - it made absolutely no difference!!!
The engine remained idling the same way with the plug wire dangling in my hand. I held the plug boot to the block - there were no sparks arcing off. Thus, my diagnosis is that I've isolated the problem to the coilpack being defective (hopefully - keeping fingers crossed!!!)
Going today to purchase a new coilpack today to replace it. Once again, I'll update this thread with my findings when I change it - wish me luck!!!

 

[dredman]

UPDATE - Intermittent stalling, rough idle, and apparant misfiring

OK - so I changed the ignition coil that I suspected was defective with a new one I bought yesterday. Result: No misfiring thus far!!! YAY.

BTW, Chawk - I checked the voltage. It's a-ok. Doesn't seem to be a prob with the alternator.

However, it's only been one day, and I still get this niggling feeling like it's gonna start misfiring again, since the problem was a random, intermittent occurence (hopefully it's just me being pessimistic about my troubleshooting).

Once a few weeks or months pass and it doesn't happen, then I'll jump for joy. In the meanwhile, I'm cautiously optimistic. I'll update the thread if my worst fears materialize and the misfiring rears it's ugly head again. (Pray with me!!!)