Jump to content

Engine Missfire


Recommended Posts

4 hours ago, nelmo said:

If you tested the wiring, what are you going to find if you take the loom out? And can you take the loom out? I'd have to dismantle my car to do that 🙂


Hi, as it’s intermittent (assuming it’s wiring) then my thoughts are if I take the wiring out then I can take a good look at it.  

Not too much effort to take out the engine loom to be honest, scuttle is removable and the rest is easy.  I’ve taken it out and so far found no faults.  I have however replaced the driver wires for all injectors and both sides of the coil, and the 12v supply to each.

If the problem still exists afterwards then it’s time to speak to emerald.

Link to comment
Share on other sites

Replaced the wiring for injectors and ignition, I didn’t find any faults in the loom and I checked every pin.

Now I have no high pressure fuel pump, no 12v supply.  I wonder if I have found my issue....

I have an immobiliser fitted that’s spliced into both the hp fuel and the starter, both controlled off separate relay.

The starter motor works fine so I know the immobiliser is getting the signal from key and disarming.

Can anyone confirm that both the HP and LP fuel pumps are connected to the same relay? The LP pump works.

I’ve checked and double checked the wiring and I think I might have a faulty relay in the immobiliser itself.

Link to comment
Share on other sites

  • 2 weeks later...


I kept the imobilser in the end, turns out I had used one of my “dummy” wires. My own fault but after realising today I now have power to the fuel pump.

I seem to have solved my problem, the issue now is I don’t trust it.  Need to bite the bullet and go for a decent drive.  Sat on the drive she performs as expected upto 3k, haven’t tested much over as I don’t want to annoy the neighbours too much.

Driving round the block at 30 she seems OK as well, which wasn’t the same before.

Hopefully when I’ve plucked up the courage to take her out properly I’ll give a positive update!



  • Like 1
Link to comment
Share on other sites

  • 2 weeks later...

Hey all, I’m sure this issue has now been sorted but thought it worthwhile to give an over view of my electrical nightmare a couple of years ago. 
having allowed myself to be talked into buying the GBS plug and play loom to give the Zero better electrical reliability, I stripped the car and ran my newly acquired GBS loom to replace my home made jobbie complete with emerald and engine bay loom.

First thing, bad earths, my fault, in my xenophobic attitude to be a beautifully clean job, I’d forgotten to earth properly.

Second thing, I had what Daniel had, a flipping misfire - mine was under load. At first, brilliant but then the misfire started and became worse to the point of refusing to start. Like Daniel, I replaced the entire HT circuit, coil pack, plugs, leads, crank sensor with new. At this stage the car was 3 years old and had covered 1100 miles...

after 7 months!! Yup, 7 months right up to July if that year, I found the issue more by chance than anything. Having gone through pretty much point for point as Daniel, mine was found to be the ignition relay losing connection under load. Cranking the engine, I had spark, fuel, in fact everything was perfect. Plug in the coil pack and it failed. One quick twist of a screw driver and fault fixed - I could not believe it at first as the relief was overwhelming. Just goes to show that when the manufacturer says that these things are fully tested, I believe them that they are right and in this case they were, but under load...

Thirdly, I replaced my fuel lines and changed the fuel filters. And, yup, I started to get a misfire around 30 miles later. Actually it was after a car and coffee meet at GBS a couple of years ago. Got there ok but on way home started running badly and I mean it would just stop, symptom slightly different in so much that the misfire was definitely fuel starvation or so it seemed at the time. Turned out that the fuel filter - new sytec had an incorrect filter and starved the engine of fuel. 

happily, once one gets over the initial Fix and gets some mileage, those woes eventually disappear.

Good luck with it all Daniel, sounds like finally you have a resolve, keep believing.

Cheers and for my next tome... turbo!

  • Thanks 1
Link to comment
Share on other sites

Thanks for the feedback, I might check the relay connection, you mention a twist of the screwdriver - what did you tighten? The relay clips in doesn’t it, or was it the connection into the fuse box?

Happy to say my cars still running well without Missfire. I’ve done about 100 miles now as the weathers been bad, but it’s 100 without problems :).  Confidence returning.

Link to comment
Share on other sites

Happy days, feels great when you get there. 
For mine, it was closing the terminals in the fuse box so the relays were tight when fitted. It was purely by accident that I discovered the issue. I had wired the relay to earth directly which cleared the misfire but when it was running I accidentally nudged the relay and the fault replicated. Removed the direct to earth and fiddled, voila! Fixed

Link to comment
Share on other sites

  • 6 months later...

Hi Daniel, how's it going? Car still OK? 

Did you basically just rewire the injector plugs? Because I think I have the same problem and I've gone through most of the same fixes as you, except I haven't touched the injectors yet. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Create New...