Misfire

[davehammerton]

I've had an intermitant misfire for a couple of weeks now. I drove it for a while the other day and it performed fine for a while then the misfire returned (only when applying the throttle suddenly, it can be driven around without the problem by driving on a very light throttle).

I then parked it for a while. When I went to start it again it wouldn't fire, the misfire seemed too bad and it wouldn't catch. I could smell fuel strongly so I don't think that's the problem, seems electrical.

I tried to start it for so long that the battery went dead. It took me 10 minutes to sort the jump leads out but as soon as I did it fired immediately and the misfire had gone completely and the car felt really responsive (perhaps more than usual). Had the ecu logged a fault which had cleared when the battery died?

The idle speed is also intermitantly eratic, i've cleaned the stepper motor thoroughly but this changed nothing. Do you think the stepper motor has failed? Maybe causing the fault code or the misfire itself?

I really want to get out onto the car and try out ideas and narrow down the problem but i'm only able to see it for a couple of days a month due to working away. So any ideas you may have would be much appreciated.

Thanks

Dave

[old64er]

i had a similar misfire and took the change everything route.
I changed the leads,plugs rotor arm and cap for 64 pound with the vat from a local motor factors (andrew page).
Firstly though i would check for a spark from the main ignition lead to the distributer and then if this is ok, from a plug lead.
But usually the leads take a hammering and i expect to change them every year at the most and the last lucas set were 14 quid, so its not so bad.
Most on here will tell you to go for the Magnacor leads but these are pricy and i can have a new set every year, for 9/10 years !!

[griffter]

Intermittent misfire could be all sorts of things unfortunately. Begin by checking all engine bay electrical connectors - sensors, pugs, leads, earths etc. Check the battery terminals are tight and the fuses and relays in the passenger footwell (in particular the ones which are loose in the loom). Check also that the distributor vacuum advance unit is secure on the distributor body and that the vacuum pipe is secure.

You might even find it's the battery. I fitted a new one and apart from much healthier cranking, the general pick up and response of the car seems better.

[calvinhutt]

my griff 500 had a similar problem, it was a lamda sensor. About £120 to replace. Good old TVR trial and error mechanics eh? Thankfully no longer an owner. Pain eventually outweighed the pleasure.

Calvin

[mav]

calvinhutt said:

my griff 500 had a similar problem, it was a lamda sensor. About £120 to replace. Good old TVR trial and error mechanics eh? Thankfully no longer an owner. Pain eventually outweighed the pleasure. Calvin

Ditto for me on the last bit...
To the owner of the thread... dizzy cap.