Well I noticed the engine wasnt idling too well. So, bored on a saturday afternoon - off to repco for a set of NGK's finest.

BTW the plug i run is a BPR6FS, 1 heat range colder than the standard. Regapped to 0.9mm.. compared to a std plug BPR5FS gapped @ 1.1mm...

Upon removal of the old plugs, the outer edge of the plug had serious carbon deposits. The actual electrode etc was not covered in carbon (and no evidence of detonation, yay!)

Now, is this likely to be a symptom of the colder plug? i.e. the plug not reaching the 'self cleaning' temperature... because I cant really afford to keep the engine on boost all of the time but it would appear my daily driving habits arent seeing sufficient temperature building up in the plug. Is this a common problem with forced induction motors?

Should i just boost it more often to prevent this? Are there EFFECTIVE substances for cleaning carbon deposits off of plugs? Any risk to other components of the engine? Thoughts, comments please.

A better cdi ignition...
MSD are $440 and easy to fit..
Then you can run .050 gap...
Unless you have multy spark I would close gap to .035 ...IF its not missing on full boost then leave it as is...But generally .030 to .035 with std ignitions.Prevents spark blowout....
Some water injection keeps chambers clean....

Last edited by EBXR8380 on Tue Jul 19, 2005 12:15 am, edited 1 time in total.

Excellent.

*4.9 EF scurries off to grap a metric-imperial calculator*

Gap is currently at .036, sings sweet as a bird on full boost (only looking at 6-7psi here) - so fair to say this should be ok?

So the small gap with std ign makes carbon deposits worse?

Yeah, water injection is setup but not switched on at the moment. It's only a simple misting spray at the inlet of the blower, not a fancy hi pressure inlet spray... you think will still help?

The smaller gap makes spark stronger but I'd say with that boost I'd say std temp plugs. Fouling is also caused by too rich at low rpm..Whatever heat range carbon shouldn't build up around plug ..Within reason...XR6 plugs are slightly colder than GLI engines plugs I would use them..As every 100 h.p over std is about right for one temp range colder...
Check your valve seals, mixture,PCV lines....An oil seperator might be usefull....
Having said smaller gap is stronger a wider gap is more efficiant BUT only if its strong enough...

YEP water injection cleans pistons etc..Notice how clean the cylinder that blows head gasget is?..Yes water and metho 50/50 % water...

You may be getting a bit of oil blowby through the PCV system, this is fairly common. Usually when you take off the intake there is a smear of oil through the ports but on a blown engine this would be worse. As said, a catch can may be a good idea if you keep having this problem.

check ya air/fuel ratios at idle. Your probably running too rich give carbon deposits and poor idle

Yeah good point, I guess you got that MAF sample tube thing sorted, are you runnign the 19lb sample tube now?

Grant, i believe this to be true. I played around with all of the tubes i have, and im running the one that has definately been tuned for on the memmaster chip (all other sizes wont even go into closed loop and choke/splutter when you step on it).

Air/fuels are fine at idle, HEGO switches back and forth around stoich ratio. A/Fs under full load were 12 to 12.5 last time she ran dyno with wideband... probably time to get her back up on one to make sure all is ok...

With PCV - there is little evidence of oil in the air intake before blower (grant, i assume you're familiar with where the breather line is plumbed? just before blower inlet...). Could a faulty PCV valve be letting oil back in the other way under vacuum? i.e. into throttle body? Worth replacing the valve anyway?

EBXR, sounds like im pretty close to the mark with plug choice then... makes *roughly* 300hp at engine compared with *roughly* 200hp in standard trim.

So, i'll get the water inj back up and running. Ive read a lot of stuff on the corral about using windscreen wiper fluid - they're not serious are they?!? Or is that for manifold/port water injection?

Thanks for your time guys.

Yeah the breather from the rocker cover to before the blower generally isn't an issue until higher boost levels from what I have been told, its the PCV valve in the rear of the lower intake manfold which feeds into the underside of the upper intake. I am running 1 seperator on that PCV line and then another breather/seperator for the rocker cover lines.

What kinda separator do you run grant? Ive seen a few tutorials to just plumb in a fuel filter into the PCV line... your thoughts?!?

Guys on Corral seem to think oil/water separators from air compressors work well....

Lol, CAPA after $400 for an oil/air seperator.

I run a fairly large alloy canister in the PCV line which is a bit to big IMO, going to look for the air compressor type today maybe (will let you know what I find and prices), not a big fan of the fuel filter setp because I can see it gettign blocked fairly easily which will shut the PCV system down. I will then probably run the alloy canister for the valve cover breathers (I am tapping in another line into each cover to help venting) but as I said that is probably only a concern above 10psi.

I have welded an alloy pipe 80mm higher, so PCV is NOT as close to oil....But the PCV doesn't work on boost assuming pcv works ?...Its the other vent off rocker covers that need oil seperator...Before going to aircleaner...
Oil in combustion chambers is bad news, creates detonation....
Seems we have an echo here too!!!