Hilux 4x4





Misfire problem on 1999 2.7 Hilux 3RZ

A while ago my Hilux had a problem. When the engine was under load under 1,400 RPM it had a slight misfire. The moment the revs went over 1,400 it was running perfectly and performed as normal.

I was preparing for the worse. Some suggestions of the possible cause included injectors, cracked head, burned valves, etc.

Luckily I phoned our Hilux guru, Allan, first. He told me to start looking at the plugs and plug leads first before looking at anything else. He said that he have not replaced injectors on a 3RZ yet, so the possibility of it being the injectors is very small.

I decided to start at the plug leads. I saw a post on the forum where Eric (Family Dog) gave the specs for the resistance of the plug leads. I decided to measure the resistance of the plug leads to see if one is faulty. Because I was not sure how to measure the resistance I phoned Eric. I explained to Eric what the problem was and he informed me that his 2.7 Single Cab did exactly the same. He told me that the suppressors on the end of the plug leads were dirty, he cleaned that and the problem went away.

So I decided to start there and see if it helps.

First I had to remove all plug leads.

If you tried to remove the plug leads on your 2.7 Hilux you would have noticed that the air intake pipe is in the way and you will find it hard to remove the plug leads for plugs No 3 and 4.

The easiest way to do this is to remove the plug lead at the coil end first, then pull it from under the air intake pipe and only then try to pull it from the plug.

These plug leads are very expensive (A huge rip-off if you ask me) so be careful and treat them with respect.

NETHER pull it on the wire, always pull on the fitting.

If you are not sure where which plug leads goes, mark them before you take them out. They should be marked.

To remove the wire from the coil end, first push the fitting down slightly, then pull the clip towards you. Look at the picture below. First press down the fitting as shows at No 1 below. Then pull the clip towards you slightly and the clip will be released. Move the fitting up so that the plug lead is exposed. Now grab onto the rubber fitting shown at point 2 and pull it upwards in order to remove the plug lead from the coil. Remember not to pull on the lead.

Now take the plug lead out from underneath the air intake and then pull the suppressor from the spark plug. Again pull on the rubber molding as pointed out at point A below, nether pull on the lead itself.

Look at the open end of the suppressor, you might see that the inside of the opening is black. That is the debris which causes the problems.

I used a cloth and screw driver to clean it. I wrapped the cloth around the screw driver. I sprayed some "spookpis" (Q20 or Spanjard) in the suppressor. Then put the screw driver point in and turned the screw driver. I repeated this process a couple of times until it was clean.

Do this with all 4 suppressors.

Now you can just put it all back. The plug leads should be marked. If not, you will note that No 1 and 4 goes on the coil closest to the radiator and 2 and 3 on the other coil. No 1 cylinder is the one closest to the radiator and No 4 is the one closest to the cab.

When you put back the lead on the coil side, first push in the rubber end and make sure it is in all the way, then put over the clip and make sure it clips in properly when you push it.

In my case this solved the problem. Thanks Allan and Eric.

If this does not solve your problem you can replace the plugs, if that does not solve your problem replace the plug leads and if that does not solve your problem seek professional advice or ask the friendly guys on the forum.