[BlueMax]

I drive an 04 MCS with the JCW kit installed 2 months ago (car has only done 18000 km). The engine is wonderfully response, smooth and sounds fantastic. I nursed it for the first 1000km's but have been close to redline on a number of occasions after "run-in". I am running it on 95 RON unleaded only (for about a month now, before that 93 RON unleaded which was the highest available rating at the time). A while back I noticed quite a few little black spots on the rear of the car but knowing how easily the rear end becomes dirty I washed the car and though nothing of it. It happened again and I wondered what I had driven through but after cleaning it the weekend and driving a short distance, the black spots were back again. I rubbed it with my finger and it was still wet. It seems to be a fine spatter of unburnt fuel or maybe oil. The insides of the exhuast tips and pipes are dry. I checked the oil level and it has not been overfilled. The correct spark plugs, injectors and ECU software have been installed. Anyone else have this problem?? Any comments/ideas? It never happened before the JCW install.

[Westy]

The main components coming out of your exhaust are CO2 & water vapour. Is it just water droplets with carbon soot in suspension?

[St00ge]

sounds like oil. When you wipe it off the back, does it feel greasy?

You can get oil out the back if you have a leaking head gasket

[brett]

If you had unburnt fuel going out your exhust, you would have a flame going out the back. like the V8 Supercars do. Which would be great

[St00ge]

Quote: Originally Posted by brett

If you had unburnt fuel going out your exhust, you would have a flame going out the back. like the V8 Supercars do. Which would be great

all MCS's get unburnt fuel in the exhaust, that's wat causes the popping noise.

[BlueMax]

Have any of you experienced it on your MCS's? The spots/specks are so small (pinhead size 0.5 - 1.5mm diameter) that it is difficult to establish if it is oil or lets rephrase - partially burnt fuel? Also the fact that the pipes are not at all oily makes me perplexed. I have also though about carbon soot being a possibility but how do I determine what it is exactly. It is not as if there is a huge black spray following me or smoke.I cannot see it being the head gasket - the exhaust manifold bolts to the cylinder head and the passages run to the valve holes. A leaking head gasket will not cause oil to get into the exhaust manifold are am I missing something? A leaking valve stem seal my cause it, but then again it is a brand new cylinder head??

[Root Ginger]

Only thing I can think of to determine if it's the exhaust is to put a rag over the exhaust and rev it up to see if you can get the same deposits on the rag.

Only way to tell what it is would be is to get it analysed I guess?

[BlueMax]

Will try that Root Ginger, good idea. It is very strange, at the moment it is slightly annoying, as long as it is not the sign of something bad to come. Wonder if blipping the throttle for the fun of it may have something to do with more "popping" fuel going through the exhaust?! Been blipping quite a lot since having the Works installed.

[Root Ginger]

Can't say I've ever heard of this problem before and I'm sure it would of come up. I've got a black Hartge S so wouldn't have seen any spots I guess on the dark body work.

[Root Ginger]

Just had a thought, do you use any gel or spray on the tyres?

[BlueMax]

I am not using any tyre gels or sprays, hate the way it slings off. I am not doing anything different than before the JCW install. I plan to try the rag idea tonight. I really do not think it is oil, a leaking piston ring will be noticable and will result in smoking and oil in the pipes I reckon. I am going to pull the spark plugs to see if there is some deposits on them. Interestingly I built an aircraft (my other toy) using a Rotax 100HP fourstroke engine and I have similar specks on the airframe/undercarriage area in the vicinity of the exhaust exists. Maybe we have crap fuel in South Africa. Been running 93RON unleaded on the aircraft engine. Thought I would get more views on this issue in this forum?

[Westy]

Do the spots dry or stay wet? If they dry then they will be water or fuel based, if they don't evaporate & stay wet then they will be oil.

[BlueMax]

The spots are easy to remove when still "fresh". Even fuel takes a while to fully vapourize. When left on for about 2-3 weeks I had to use a clay bar and polish to get some of it off. Normal water and car wash did not remove it. My feeling is it is fuel based. I am going to have a good look this weekend at anything that may cause this and report back on anything found.

[Mike Edwards]

I get these on the viper stripes on my car - they don't come off. Seems to be soot.

[Eds]

I noticed a very light amber stain (like a nicotine color) at the exhaust tip after I had my Shark Injector installed and moreso after hard runs. It is not wet though and I would classify it only as slightly soothy and thin. I guess it is because of the fuel enrichment made by the upgraded ECU.

Eds

[BlueMax]

I think the consensus is soot. We have only had 95RON fuel available for 3-4 weeks where I live and I have been using BP. Will be trying out Shell on my next tank due for fill-up by the weekend and see if this makes a difference. Never know what additves the various fuel companies use to up the octane rating. Issue may also be related to the bigger bore JCW tailpipes and the airflow around them as opposed to the std beer can shape. Mechanically there is nothing wrong with the car. Very happy with the JCW!

[BlueMax]

Did a systematic check over the weekend on the parts that were affected by the JCW installation. All spark plugs are correct and do not show any strange deposits. All wiring connections and injector installation seems fine. Very little oil in the intercooler flanges. I did find two bolts not properly tightened on the exhaust manifold and one bolt was missing altogether, do not know if it was not fitted or was loose and fell out? Installed a new bolt. Do not know if the ECU enriches the fuel mixture if there is a leak at the exhaust manifold.I also filled up with Shell 95. Still got some specks after some short drives over the weekend but subjectively it seems to be better. Will monitor it this week and plan to go to the dealer on Friday if the problem persists - and also give them a piece of my mind about the missing bolt.

[St00ge]

hope it all gets sorted out for you mate....

[BlueMax]

Thanks. I will post if a solution is found - hopefully soon!

[Mr.Pedro]

Quote: Originally Posted by St00ge (original)

sounds like oil. When you wipe it off the back, does it feel greasy?

You can get oil out the back if you have a leaking head gasket

Man...i'm not sure though, i can see oil spots near the head gasket(like a leakage) all over the pully area too..it's black spots (plus checked the engine oil it's really black!!! being that it's juz been serviced recently. Adding to that, i got my jcw tuning kit fitted before 2500km(straight from the mini garage here in Melb wen i first bought it)...

Really curious, man..please, in need of some advice from u guys(expert) i have very little knowledge in this particular area..

Cheers.