Changing the sparkplugs
A dangerously corroded sparkplug
Changing the sparkplugs
I've been putting this one off for ages as it looked quite complicated. I have the electronic service manual but was still dubious until... I found a guy on YouTube doing the job on a Nissan Note which has a more or less identical engine bay so I finally got on and did it. Here's how... Slight update: I've turned these pic's into a YouTube video here.
Tools you'll need: 8 and 10mm sockets, a 5 inch socket extension bar, a long magnetic 8mm/14mm sparkplug socket and a roll of workshop tissues.
[A] Undo the two 10mm bolts and remove the engine cover. If you get your fingers under the two outer edges, it lifts off vertically.
[B] This reveals the inlet manifold assembly. This has all got to come off eventually...
[C] Remove the two plastic poppers that hold the cold air feed tube to the chassis. A flat blade screw driver under the central part will lever up the popper and it can be lifted out completely.
[D] The support for the air tube is a push fit into a rubber grommet situated on the chassis under here. Just pull up firmly on the support and it wil pop out of the grommet.
[E] The cold air feed pipe can now be lifted off and put somewhere safe. This reveals the air intake that goes into the 'dirty' side of the air filter box.
[F] Using clip pliers, release the PCV hose from the connection on the rubber air tube.

This tube vents excess oil vapour and fumes from the crankcase into the inlet manifold where they are drawn into the engine and safely burned off.
[G] Now loosen the two jubilee clips that connect the electric throttle control actuator to the air tube and the air tube to the air filter housing. They are situated here...
[H] ...and here. You can now remove the connecting air tube.
[I] Being extremely careful not to let any muck get in the electric throttle control actuator, remove the four 8mm bolts that connect it to the inlet manifold.
[J] Unclip the pipes from the double pipe clip below the electric throttle control actuator and carefully move the electric throttle control actuator out of the way to the right. At this point I covered it with a plastic carrier bag because it was raining slightly.
[K] Remove these two screws and carefully pull the EVAP canister purge volume control solenoid valve (quite a mouthful that one!) out of the manifold.

This is the valve that opens when the ECU decides the carbon canister needs purging. It allows the vacuum of the inlet manifold to draw the petrol vapour from the canister into the air intake to be safely burned off by the engine.
[L] It's now time to start freeing up the manifold. Using your clip pliers, undo the vacuum hose and pull it off the back of the manifold.

This pipe provides the vacuum that activates the brake booster. If you forget to reconnect this pipe afterwards the engine will run like a bag of spanners!
[M] Remove this 8mm bolt from the left hand side of the manifold.
[N] Remove this 10mm bolt from underneath the electric throttle control actuator.
[O] Remove the five 10mm bolts from along the front of the inlet manifold. You'll need a five inch extension bar to reach four of them. The right hand bolt is a pain as the wiring loom is in the way.

Tip: These five bolts are exposed to road spray and were badly corroded and extremely tight. Use a 6 point socket, not a 12 point, or you'll round the boltheads off. The reason they're so visible in the pic is that I've replaced them since doing this guide. When re-assembling everything afterwards, re-install bolts in this order to 14ft/lbs.
[P] Being careful not to force it, or snag any other engine components, remove the inlet manifold from the engine.
[Q] The brown gunk around the inlet ports can only be varnish from the just under 2 tons of petrol that's gone into EACH of the four inlets over the last 100,549 miles. Pretty good going I reckon!
[R] Back to the job in hand, these are the spark plugs for the HR16DE engine. They are long-life iridium tipped and are around a tenner each from Nissan but I snagged a full set off eBay for £24 delivered . There are always many vendors to choose from, but some of the best deals can be found on eBay.
[S] Doing one plug at a time, unclip the power connector and undo the 10mm bolt that holds each coilpack in. Pull the coil pack stright up out of the hole. Remove the old spark plug and screw the new one in carefully, tighten to 18ft/lbs. Replace the coil pack and refit the 10mm bolt (Nissan say 8ft/lbs but I tightem them to 10ft/lbs).
[T] This is one of my old plugs, the light sandy dusting around the tip shows the engine is in excellent fettle. I'm not convinced these plugs have ever been changed though, either that or they're rather poor quality. One of the old plugs was badly corroded at the tip of the spark bridge, I've added some pic's at the bottom of this page.
[U] Using clean rags or workshop tissues, clean as much of the gunk as you can from around the inlet ports.
[V] While I was cleaning the inlet ports, I thought to myself 'Hmmm?' and ran into the house to find my LED Maglite torch. You can actually see the inlet valves, how cool is that?!
[W] This is the inlet manifold gasket you'll need. This miniscule amount of toughened rubber cost nearly £23 from Nissan, I kid you not... This isn't an optional part either. This gasket is what allows the engine to maintain vacuum.
[X] Brush as much muck off the inlet manifold as you can and carefully remove the old gasket. The new one just pushes into the groove left by the old one.
Once you've seated the new gasket in the manifold, putting your car back together is just a case of following all the above in roughly the reverse order .
A dangerously corroded sparkplug
[A] One of the plugs I changed was in an extremely poor condition. I think if I'd run it for a few more thousand miles it might have lost the tip. This could have caused terminal valve or piston damage so I'm extremely relieved I caught in time! The plug was a standard Denso Iridium and had been run for around 46,000 miles. I've heard scare stories about these plugs on the internet and think I'll give them a wide berth from now on. My engine's just a standard, normally aspirated 1.6 so it's not as if it's been run in an Evo running 30 pounds of boost!
[B] This second pic taken from a different angle shows how the close the tip was to detaching from the rest of the plug. From now on I'm going to use NGK Iridium plugs AND reduce the change interval to maybe 25,000 miles. Risking engine failure for the sake of £25 just isn't worth it.