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Discussion Starter #1
2002 4x4 Toyota 4Runner sr5 V6 3.4L

Im having idol trouble.
CHECK ENGINE, VSC, & TRAC OFF lights have been on for over a year but havent shown any problems.
Engine was running great!!! Very smooth, consistent, and strong!
I put a brand new battery in maybe a month ago, & tested the alternator at that time, which was about 13.5, but I was told it was ok.
Engine was great, sounded healthy,
took it in to fix a minor oil leak, thought it was valve cover gasket, turned out to be valve cover cover itself. So that was replaced.
(knew I was about due for spark plugs/tune up, but they didnt end up handling it for me like I asked)
When returned to car after the job, and started engine again, suddenly engine was showing symptoms of cylinder intermittently misfiring... (vibrations, intermittent shaking, bogging down, weakness in power,etc)
I just replaced spark plugs.
wires seem ok.. Not dry rotted, in proper order.
Now performance is better. No shaking, but still idoling strange, somewhat low, with low throttle surges...
So I had all codes cleared. These reappeared:
I dont appear to have any vacuum leaks...
Air filter is ok. uncertain what to do next..

I wonder, is there anything electrical behind/under the intake manifold that possibly could've not gotten plugged back in properly, that would cause this, or is it possible something happened to effect my throttle body sensor? ...with the new spark plugs, im not really losing power when im driving, but when I'm idoling, on and off again it gets low, and sputters as if it could stall, with randow low surges in rpms...
seemingly as if the balance of elements is off?...
I dont feel like they couldve messed up my coil packs, seeing as they only opened the drivers side. Im not certain though. ..And cant afford to replace them for fun at this moment...

Is there anything anyone can suggest to point me in the right direction of my problem???
...this vehicle means a lot to me, I travel the country, and really would rather not put any added strain on the motor.
Thankyou for any assistance offered, and for taking time to read my issues.

1,539 Posts
The C codes are not engine related except for C1201, which means there is an engine code. An engine code turns of trac and sets a C1201.
P0304 is a cylinder #4 misfire. The #4 is the middle one on the driver side. You can swap the first coil (#2) and #4 and see if the misfire moves to number 2 which would set a P0302 (cylinder 2 misfire) proving the number 4 coil is the problem.

1998 T100 SR5 2WD
13,682 Posts
Welcome to the forums! :)

Seeing that the driver's side valve cover and gasket were replaced by the shop, the spark plug wires would be suspect at this point. I'm guessing that the passenger side valve cover gasket was not worked on? As stated by chuckoff, the code is fer a misfire on cylinder 4 which is the middle cylinder on the driver's side. I would git the NGK spark plug wire set (blue wires) and replace all 3 wires. ;)

Were the new spark plugs have the dual ground (highly recommended since this engine is a wasted spark setup and the spark plugs fire twice per cycle and will wear out twice as fast)? If not, I recommend the NGK or Denso dual ground spark plugs. Snap some piccies of the business ends of the spark plugs and post them. ;)

BTW, is the Check Engine light flashing when you are driving? If so, do not drive the vehicle in this condition! The engine is definitely misfiring and eventually will cause major damage to the catalytic converter as well as the engine. ;)
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