How to Replace Spark Plugs, Wires & Coils on a 1995-2004 Tacoma 3.4L V6
Random check engine light flashing under hard throttle and a shudder you swore was the driveline? On a 3.4L Tacoma, look at the ignition first.
Short answer: On a 1995-2004 Tacoma with the 3.4L 5VZ-FE V6, plugs and wires are a two-hour driveway job. The three coils sit right on the passenger-side plugs (cylinders 1, 3, 5), and wires cross over to the driver side (2, 4, 6). Gap the plugs to 0.043", torque them to 13 ft-lbs, and torque the coil bolts to 69 in-lbs.
How the 5VZ-FE ignition is laid out
The 3.4L uses a waste-spark system: three coil packs bolt down on the passenger-side bank, each one firing its own cylinder directly and a companion cylinder on the driver bank through a crossover plug wire. Odd cylinders (1-3-5) are passenger side, even (2-4-6) driver side, with #6 at the back by the firewall on the driver's side.
Tools you'll need
- 3/8" ratchet and about 14" of 3/8" extensions
- Spark plug socket
- Flathead screwdriver (for wire clips and coil connectors)
- 10mm wrench or socket
- Spark plug gapper
- Torque wrench that reads 13 ft-lbs and 69 in-lbs
- Dielectric grease, rubbing alcohol and cotton swabs
- Optional: code reader and a digital multimeter
Symptoms that sent the original author in
At 104,000 miles on the old plugs, he had a severe shudder and a check engine light that flashed for about 15 seconds under hard acceleration. A code reader pulled P0306, a misfire on cylinder #6. Keep in mind a P030X code can also come from a coil, cam or crank sensor, or low compression, so read the codes before you buy parts.
Step-by-step
- Disconnect the battery and let the engine cool completely.
- Prep the driver side. Remove the bolts holding the plug-wire brackets, then lift the vacuum line out of its hook and tuck it under so you have slack to pull boots and plugs.
- Prep the passenger side by removing the air intake tube: unclip the MAF connector, loosen the spring clamps and pull the vacuum lines attached to it.
- Pull the driver-side boots, starting at #6 (closest to the driver's seat) and working forward. Unclip the wires from the retainer clips across the front of the engine.
- Unclip the wires from the coil packs using a flathead screwdriver.
- Remove the #6 plug with the ratchet, the 14" of extensions and the plug socket.
- Gap every plug. The author's "pre-gapped" plugs came at 0.022". Spec on the 5VZ-FE is 0.043". On a dual-ground-electrode plug, gap each electrode.
- Dab dielectric grease inside the boot end where it meets the plug terminal. The thread recommends skipping anti-seize on plated plug threads: it makes over-torquing easy.
- Install the driver-side plugs by hand first with the socket and extension so you don't cross-thread, then torque to 13 ft-lbs.
- Passenger side, coil #1: remove the 10mm bolt, lever the connector's retainer clip with a flathead and pull the connector, then lift the coil.
- Replace the #1 plug the same way.
- Clean the coil boot tip and inside with alcohol and a swab, without damaging the spring inside.
- Reinstall the coil, press it firmly down, torque the 10mm bolt to 69 in-lbs and plug the connector back in.
- Repeat for #3 and #5.
- Route the new wire set. Start at the passenger side at #5 and work forward, clipping the set into the plastic timing-belt cover across the front. Leave the last clip (top, driver side) open. Fish the #6 boot across the valve cover first, then #4, then #2, and close that last clip.
- Reinstall the driver-side bracket bolts and put the vacuum line back on its hook.
- Reinstall the intake tube, plug in the MAF, tighten the spring clamps and reconnect every vacuum line from step 3.
- Reconnect the battery and start it up.
Fasteners not listed above, like the wire bracket bolts and intake tube hardware, weren't given a torque spec in the source thread. Snug them; don't guess big numbers.
Why do coils, plugs and wires together while it's apart
You're already pulling every coil and every wire. On a truck this age, the coil epoxy cracks after years of heat cycles and the wire jackets go brittle, and those failures show up as the same hesitation, rough idle and P0300-series misfires you're trying to cure. Doing it all at once means you only do the job once.
Our Ignition Coils, Spark Plugs & Wires kit for the 1995-2004 Tacoma 3.4L covers the whole job in one box: three waste-spark coils, silicone-jacketed crossover plug wires and a full set of six spark plugs. The coils use upgraded copper windings and high-dielectric epoxy resin to stand up to heat, the silicone jackets keep out moisture and electrical interference, and the coils replace Toyota OEM part 90919-02212. It's a direct fit for every 1995-2004 Tacoma with the 3.4L V6; it does not fit the 4-cylinder trucks. Confirm your year and engine, or browse all Toyota Tacoma ignition parts.
FAQ
What's the spark plug gap and torque on a 3.4L 5VZ-FE?
The thread uses 0.043" gap and 13 ft-lbs for the plugs, with 69 in-lbs on the 10mm coil bolts. Check the gap even on plugs sold as pre-gapped.
Why are there only three coils for six cylinders?
The 5VZ-FE is waste spark. Each coil sits on a passenger-side cylinder and also fires a driver-side cylinder through a crossover wire, so a bad wire or coil can show up as a misfire on either bank.
Source: thanks to TacomaJPP for the original write-up on TacomaWorld. The bay photo above (intake tube removed) is from that write-up; see more real install photos in the TacomaWorld thread.
