Misfire and EVAP Problems in 1999 Tacoma

Hi Everybody,
I joined to see if I could get some help fixing my truck, so this is my first post. I'm getting error codes P0300, P0301, P0302 and P0446, so it looks like cylinders 1 and 2 are misfiring, and there's a problem with the EVAP system. The P0446 code first appeared while I was driving down a bumpy gravel road with some major potholes about 10 days ago. The engine continued to function fine for a few days, and then became shaky just about 3 days ago, which is when the other codes appeared. It seems like once I reach highway speeds the engine smooths out, but while idling and accelerating it is very shaky, and it feels very underpowered while accelerating. I erased the codes and let the engine idle for several minutes, and it has a pending P0302 again.

If anybody here has had a similar problem and/or has an idea of what I could do to fix this problem, your help would be greatly appreciated. I have a decent mechanics socket set in both English and Metric sizes, as well as a large assortment of other hand and power tools, an air compressor, a code reader, and an ample garage for working in, but no specialized tools for automotive use yet. Thanks!

 

I'll assume you have a 4-cylinder (2.7) motor. Time for trouble-shooting.

You have a mis-fire in cylinder #2, which is caused by a lack of one (or more) of these things:
- spark
- fuel
- compression

Attack one at a time. Hopefully, its not compression ( $$$ )

It could be as simple as a bad spark plug, or plug wire.
Check for spark at #2 by removing the plug wire, then remove the plug, then reconnect the plug to the wire, ground the plug post, then crank for motor for no more than a few seconds. There should be a visible spark.

If you haven't done this in a long time, replace the plugs with NGK or DENSO. My dealer only charges $3 each for the plugs.

Some basic things you need, but may not have :
a Haynes manual, a multi-meter, magnetic plug socket, anti-seize, di-electric grease, metric combination wrenches.
If you plan on keeping your truck for a long time, and are a DIY'er, then spend the money on a FSM.

 

Thanks for your reply! This is actually a 1999 3.4L V6 Tacoma with 5-speed/manual transmission and TRD Off-Road package. I've been meaning to get the Haynes manual and a multi-meter. I'll have to buy the spark plug socket tool too. I have silicone grease but not anti-seize, and I have a full set of Metric and English combination wrenches. Do you have any idea why the EVAP error code might have come up before the cylinders began misfiring? Do you think that the EVAP problem could have led to the misfiring? Or could that just have been a coincidence? Thanks again!

 

I don't see how an EVAP issue could cause a mis-fire. Might be a coincidence.

I have a 2.7 motor, so no actual experience with the 3.4. Your ignition might be totally different than mine. I have 2 coil-packs that supply spark to the 4 plugs. You might have 3 coil-packs or even 6 coil-on-plugs. I hope a 3.4 guy chimes in here. On mine, I have to remove the hard intake tube to get at plug #3.

The EVAP canister (on mine anyway) is in the engine compartment, so it is easy to access. Yours might be under the bed near the gas tank . Assuming you know what it looks like, check out all the vacuum lines (for cracks/splits) and electrical connections.

BTW, depending on the code, it sometimes take 2 or more trips for the computer to re-set a code after being cleared, .

 

He has three coil packs for the six plugs. I know because I've been getting random misfire/ misfire cylinder 1 codes for more than two years. My truck has NO noticeable miss or hesitation. I have replaced the plugs, wires, coil pack, compression test, injector without success. After clearing the codes, they return after about 80 miles of driving. Other than cleaning mass air/ throttle body, im running out of options. I love this truck but this lingering problem is pissing me off.

 

Im sorry for thst lousy introduction. This NON misfire issue is a real pain in the $#%. My name is Danny, im in NYC. Ive owned my Taco since 2010. Its a great truck.