Engine problem

[jamiet]

Bloody typical. The car has been unused for 6 weeks apart from the last day or so. I was just driving to the MOT yesterday at local garage and as I pulled away from lights the engine suddenly felt really underpowered and lumpy, the exhaust sounded quite muted too. Took it to the MOT anyway.

It failed on emissions - CO2 really low, Hydocarbons really high. This indicates unburnt fuel. The garage checked a few things. Apparently number 7 cylinder isnt doing anything. You can remove the HT lead from that cylinder and it makes no difference to how it runs. The cylinder has good compression and good spark, and the fuel supply must be ok otherwise there wouldnt be any unburnt fuel to mess up the emissions. This sounds expensive. I'm going to get it booked in to Penisula if they have slot soon but wondered if anyone had any ideas? If it was a worn cam I wouldnt have thought it would happen so suddenly, maybe over time perhaps, but maybe I'm wrong.

Cheers,
Jamie

[griffdude]

possibly an injector sticking??

[jamiet]

If it sticks would that prevent all fuel form getting through or just some? The emissions indicate that fuel is getting through but is not being burnt.

[2 sheds]

Injectors can jam open to.

[jamiet]

Oh, right. If it was that, what it take to fix it? Ultrasonic cleaning?

[2 sheds]

Have you tried a new spark plug ? when it was taken out for compression test what was it wet, but yes i would investigate the condition of the injectors cleaning will be a good move anyway.
Peninsula are good for these issues

[davidindevon]

Difficult to be sure on anything without seeing it. What I did discover on my TR6 previously is this:-
if you feel your pipe to the injector, the sticking injector (either open or closed) will not have a pulse like the others... with spanner take it out, tap it with said spanner till it sprays properly, put it back in and tighten up. Sorted and all whilst engine running.
Apart from injector it could also be fuel regulator which can give problems on rare occasions.
A lot of help I hear you say. However, bear with me. I had exactly same problem a few months ago and like you it was immediately before it's MOT and I was too short on time to fiddle about with it myself. So chugged up to TVR Power in Coventry. Quick, friendly, easy and inexpensive as I'd forgotten my wallet! Something intermittently wrong in distributor/cap/lead to one of the cylinders. A quick change and check over to adjust a few things and it's now running like you wouldn't believe a V8 could. IMO they are well worth a visit even if you haven't got a problem! Good luck - hope you get it sorted and let us know what the problem was.

[jamiet]

2 sheds said:

Have you tried a new spark plug ? when it was taken out for compression test what was it wet, but yes i would investigate the condition of the injectors cleaning will be a good move anyway. Peninsula are good for these issues

Yeah, the garage tried a new plug but it made no difference.