After thinking I had a plug go down I changed all six tonight only to find my misfire is still there. I swapped two coil packs to rule that out and I checked there was actually a spark, and there is.

 

What next? Compression test?

 

Rather than a mechanical failure I'm hoping its a failed injector, is there anything else I can check? Would the ecu show any codes for a bad injector?

 

Thanks

TPS, MAF, clean all the plugs in the engine bay. Timing. The sensors on the front water pipes sometimes get blown off slightly by the fan. Ptu.

 

There's a few things lol. You got a diagnostics program?

Hmmm, no I haven't, I have just got code 55 from the ecu so that was no help lol.

 

I know which cylinder is down - middle one on passenger side, I swapped the coils over from the one in front of it and the mis fire stayed on that cylinder...

If your certain you have a spark, the next thing is fuel.

You can do three things, turn the engine on. And place a long handled screwdriver on the injector it should pulse or click. They ll should and it should be the same click. Next is clean the connector and injector terminals, i bet they are green. You can also take a multimeter, select ohms and test the resistance coming back, the injector should give you around 13ohms, significantly higher or lower and it's jammed open/shut. That should give you a result.

The third test is one I've not done myself, so you would need to look it up, take a 9v battery and some wire hook up the injector to the battery and it should squirt fuel into the bore which will be visable through the plug hole. As I say I haven't done this myself so you need to look it up.

If the injector comes back fine, and it's still not firing. You need to check your getting a signal/power to the injector. If all that checks out fine, then compression is your last variable really. However this is unlikely. If you had lost compression you would be burning oil or water or both, not only would this make the plugs look horrid, I'd expect you to notice this when you fitted the new ones. You would also likely be doing a good impression of a red arrow.

I'm with Bird. The vast majority of missfires are down to dirty connectors, usually injector, coilpack, PTU or maf connectors. Give them a THOROUGH clean. It'll unlikely be injector failure as is seen in the US as we don't have the ethanol based fuels that screw up pintle-type injectors, not to say they don't go wrong over here, but it's rare for one to just stop working.

 

Spend time cleaning up these connectors before you go any further. It won't be a thankless exercise either even if it's not that.

Make 100% sure you have the ECU connector properly seated. Do you know which cylinder it is ? Have you checked the injectors are all operating (or at least clicking) ?

Thanks guys, going to investigate further later on this evening.

 

I have just had my strethecope on all 6 injectors, all have a very pronounced clicking apart from the problem cylinder, there is a clicking but it is a lot fainter than the other five...

As everyone is saying, start with the cheaper obvious stuff and eliminate..... If the injector and coil pack plugs and connections are clean, check they are getting correct voltage at the right time.....

If not then check and clean ECU connector.....

If that still doesn't cure it then check the wire from plug to the ECU, use a multimeter with electrics all off..... find colour of each wire from the coil / injectors then find where that colour goes into the ECU....

Set the multimeter to buzzer setting for resistance, one wire from multimeter to (say for example) black with red stripe at coil end and then other end of same wire in the ECU plug....

This will make the multimeter bleep/buzz so you know there is a connection.....

And repeat for all the wires.....

It will take some time and write down the wires you have already checked......

This maybe teaching you to suck eggs if you already know this.......

Russ

Many thanks, getting straight on it after work this evening :)

I bought ellodaves old zed with a missfire. I thought it was an injector but it actually turned out to be a chewed up rubber o ring letting fuel into the cylinder constantly and flooding that cylinder. When your engine is running do you have a strong smell of petrol out of the exhaust?

Not noticably more than normal no, o ring on the injector I am assuming? Thanks

I had exactly that I ring thing, massive fuel leak got worse quickly over 2 says then misfired violently. At that point it becames obvious once it started to spray all over the engine!

 

It was a nightmare to get that injector out it was cyl6.

I don't think it will be that, different symptoms, mine went from running perfect to a dead cylinder over night, I will post up what I find this evening, thanks for all your help.

That's the same as mine as it was the lower o ring that had gone on mine flooding that cylinder causing a missfire.

Sounds like you have an injector problem, most likely electrical, least likely failed injector I reckon.

Got the injector out and there was no resistance across the two pins.

Got the injector out and there was no resistance across the two pins.

 

Also, I got 130 on the problem cylinder when it compression tested. Is this pressure good for stock power only, I was possibly thinking of a stand alone ecu and larger injectors, but with this figure I am guessing this will have to wait until another year when funds allow...

130 is pretty low 150 to 170 is considered healthy.