Help my rough running engine...

Hello again.

99 Tacoma, 2.7 3rz, 177,000 miles.

Running so rough it shakes the truck. Started a few days ago, but went away within seconds. Now, it's doing it the whole time, through all gears, ranges, and engine speeds. Checked the codes and got this:

0100
0110
0120
0300
0304
0401

Holy multiple codes, batman. Where do I begin? I'm suspecting the coil packs... Any ideas?

 

Well Lets size this up
P0100 Mass or Volume Airflow Circuit Malfunction
P0110 IAT Circuit malfunction
P0120 Throttle Position Sensor/Switch A Circuit Malfunction
P0300 Random/Multiple Cylinder misfire Detected
P0304 Cylinder 4 Misfire Detected
P0401 Exhaust Gas Recirculation Flow insufficient Detected
Thats all i can do right now for ya sorry someone else might chime in
Sittingbull2

 

Thanks for that.

I'm wanting to test the coils tomorrow... Are the coil packs the same? That is, can I take the two off and swap their position? I want to see if the "misfiring cylinder" changes after I reset the codes, and I've read that I need to swap the wires, but I'm a little confused as to how I do it..

Looking at the coil packs online, it seems that there are two part numbers, one for cylinders 1 and 3 and the other for cylinders 2 and 4. That leads me to believe they are different. But I'm not sure exactly what to swap around in order to test the coils.

 

If you have coilpacks, you cannot swap wires. Not sure on your engine, but if you have differnt coilpacks, then you can't swap them around to test, except with the same part numbers. the easy way to check is to disconnect the #4 while the engne is running. if no change, then that's a good indication for the #4 coilpack. post a pic of the coilpacks for help.

 

Yeah, I have the dual coil packs. Since they are two different part numbers (1 is for 1 and 4 cylinder, the other is for 2 and 3) I figured they are different and I can't swap them.

 

Man, I'm not surprised it's running rough. Coil packs is not what I would go to first, although they are easy to test. Plugs and wires? I'd start there. I bet that takes care of the misfire codes. Then I would pull the throttle body and clean the living hell out of that, and replace the gasket. For the EGR stuff, you may very well have a bad EGR valve but there are several other things in your emission systems loop that can cause that 0401 code: vacuum modulator, vacuum switching valve, exhaust gas pressure sensor, or a simple vacuum hose leak (which is not simple to find, at all).

Don't swap wires to test coils. Use a volt meter and test the resistance, think the spec is around like 225,000 ohms.

Have you tried Seafoam before? http://www.tacomaworld.com/forum/1st-gen-tacomas/63790-seafoam.html Has smoothed out my idle in the past.

Good luck, I think you'll smooth it out A LOT with plugs and wires, because that misfire is your main problem.

 

Huh?

Fixed the problem though. CLeaned the TB, put new plugs and wires on... Couldn't find anything suspicious with the ohm meter, so I broke down and got a #1-4 coil. Guess what?

That fixed it. Engine is revving a leeeetle high at idle right now, but I'm going to drive it a bit and see if that solves itself. Thanks for all the replies and help.

 

The coils ohmed perfect. I found out though, that even though they ohm out to spec, there could be an internal point where the spark has burned through. That won't show up with an ohm test.

 

All I meant was, with that particular set of codes, I'm not surprised it's running rough. I'm sure you take great care of her

That's good intel on the false positive test of the coils. I had a cyl 4 misfire a while back where the wires fixed it, but I was suspecting coils also. Hence my initial doubt of whether a coil had failed.

Glad it worked out