K series misfire - NOW FIXED

[paul richards]

1.8 k Supresport EU2.

Developed a misfire at LM Classic. tickover rough and running rough at low revs. Pulled like a train at high revs. Renewed plugs and no improvement.

Assumed it was a a problem with ignition, probably leads breaking down in view of heat. Managed to get home (mainly fast roads and motorway) with little problem, but rough on ordinaryt roads for last 5 miles or so.

I have now renewed plugs, HT leads, rotor arm and distributor cap and no better.

I noted that plugs 1 and 2 were sooted up.

Broke for lunch and returned and wouldn't start. Noted a lot of fuel in plenum and strong smell of fuel. Removed plugs (no. 2 sooted up and no. 1 wet with fuel). Turned over engine with plugs out and lots of neat fuel pumped out of no.1.

Seems like my problem is fuel related and I know little about fuel injection.

Ideas?

 

Paul Richards

Area Representative - L.A.D.S. (Lancashire and District Sevens)

LADS Website

Growing old is compulsory - Growing up is optional

 

Edited by - Paul Richards on 28 Jul 2010 19:06:50

[Jason E]

what about the coil pack , i have just changed mine on eu3 along with ht leads and it appears to have sorted it

[Kevsta]

Could be lambda? Mine went and it ran REALLY rough! Actually it was like it was running on three cylinders!

 

If you have a spare then would be worth a try. Might be best to plug the car in and find out though - better than replacing everything (guess who doesn't have the port and has been there and spent the money!)

 

Kev

[Archie Procter]

Lambda - depends on your map, with some it makes no difference at anything under 3k revs.

 

As you get different things at different revs it lends itself more to something electrical/ECU than something mechanical which would tend to happen all the time. Any one of the sensors/leads/part of the loom could be giving the ECU false information leading to over-fuelling, incorrect timing etc. It may be a question of systematically changing/testing components, or getting an ECU expert in to have a look. I know one if you need his details.

 

It's also worth checking the fuel pressure at the injector rail, the regulator can get crushed which leads to overly-high pressure (they should be 3bar I think) and thus over-fuelling, and one of the injectors could be sticking. IIRC you can buy a whole new injector rail for not a silly amount of money and the regulator isn't too dear either.

 

As you've probably gathered I have had both the above scenarios on a 1.6kSS EU3... ☹️

[Shaun_E]

Definitely check the coil - I went through about 4 in the last few years before changing to a wasted spark set-up.

 

Yellow SL #32 - member of Drowned Rat Racing

[paul richards]

Pleased to report that car is now running as normal.

coyoteracer11 - you were on the mark with fuel pressure regulator.

With help from Dave H. (The Polisher) we fin ally tracked down the problem to the fuel pressure regulator which on my EU2 1.8 is a cast aluminium adjustable one. I won't bore you with the details, but the problem was a small split in the diaphragm which was allowing fuel to pass through and via the vacuum pipe was finding it's way into the plenum, which because of the slope of the engine was running towards no. 1 cylinder and flooding it. Hence plugs 1 and 2 were black and sooty indicating a rich mixture.

Clearly the split got much worse in the end allowing lots of fuel to pass through, especially when the fuel rail was pressurised and the engine not running to burn off the excess fuel.

New regulator around £60 , but no longer stocked by Caterham or Redline, although latter will now be obtaining. Managed to get a new diaphragm from Glencoe Ltd for £20 inc. P&P.

 

Posted this in case it helps others

 

 

Paul Richards

Area Representative - L.A.D.S. (Lancashire and District Sevens)

LADS Website

Growing old is compulsory - Growing up is optional

 

Edited by - Paul Richards on 28 Jul 2010 19:18:02

[Fyldeflier 1]

Excellent news 😬 *thumbup*

 

John.