Spark plug problems...

[450Nick]

Hi all,

I've been having some problems lately with my engine intermittently cutting out running on an Emerald ECU. It's been running fine for 3 years so something must have changed. It appears that the crank sensor signal is being interupted, but after replacing both the sensor, bracket and wiring, the problem still stands.

I spoke to Karl at Emerald and he suggested EMF interference caused by a lack of resisted plugs or leads on the car. Funnily enough I had my plugs changed a few weeks ago and they were replaced with standard NGK B7ECS (can't remember what was in there but I think they were resisted). So I couldn't find any BR7ECS plus so instead I got some BPR7E instead. When I just went to put them in though, I noticed that the body is slightly narrower, and the tips protrude around 2-3mm further than standard. Is this going to be a problem and would I risk hitting the pistons? Or should I just stick them in and try them (I just want to see if resisted plugs cure the problem).

[spend]

Call NGK they are pretty good at responding IME, like next day call back.

[Alan Kee]

I've seen all sorts of plugs in RV8s over the years, the std earth electrode position is fine and doesnt contact the piston. the retracted electrode versions were to reduce the chance of pre-ignition? (the tip runs cooler)

[2mad]

Leads can break down after time, i find magnecor 8.5 mm the best but not cheap.

[Pupp]

BR8ECS - keeps the stronger ground elecrode, is resistive, and is a grade colder. Sorted

[450Nick]

BR8ECS on the way.. Lets hope this solves the problem as I'm thoroughly bored of it now..!

[CHGRIFF]

HI Nick, You should be using B8's with SC.

[Pupp]

Another one just to watch for is steering fluid dripping onto the trigger wheel/crank sensor from the 'u' bend if it's weeping. Had a couple of glitches on mine where this occurred (the bend was directly above the sensor - I know yours will likely be different due to the relocated power steering pump) and I initially thought it might have been an EMI issue.

Worth just looking at the red/green LED on the ECU to see what that's showing when the problem arises...

[450Nick]

It's a bit of a funny one, when it happens the ECU crank trigger LED goes from green to off, then to red, then back to green in the space of a second or so - seemingly randomly, but with increased frequency over the last few weeks. Also, when the problem happens, if I look at the laptop screen, all figures stay green and looking ok, but the rpm value drops to 0, then back to where it was, so the ECU seems to still have power.

As I've said, I've replaced the sensor, cleaned the oilyness from around the area (no U bend to worry about, but a bit of oil from past spills etc), then I've replaced the wire too, so it has to be something else. I'll replace the plugs tomorrow and see what's what..

[Barkychoc]

Don't assume that the new sensor you have fitted can't be faulty

[450Nick]

Yes I did think this, though the problem is EXACTLY the same, which seems odd. And the guy selling them told me he's sold hundreds of the things and never had a problem before - they are very simple bits of kit..

[spend]

Checked the TW gap?

[450Nick]

Yeah tried it at ~1mm and then less than that. No joy

[450Nick]

Ok test run with the b7 resisted plugs prior to the arrival of the b8's... And I can safely say problem solved! Who woulda thunk it?! Right I'm off to get drunk.

[CHGRIFF]

Hi Nick, may not be plugs? We have had issues before whereby an Air Flow Meter failed several times and despite much effort and changing parts the problem was not resolved. The problem was diagnosed and resolved in the end and found to be the routing of the HT leads, the leads touching/running to close to the harness feeding the ECU causing the ECU to receive eronious signals and generate part failure. I believe you should always use resisted spark plugs with restisted plug extenders or whattever they are called. In your case it may be the plugs but ensure the HT leads dont run near the ECU harness as this could be the issue.

[spend]

Cheapo loom without TW wire shielded & grounded?