TheMayer

Background:
I bought the car ('03 230 Coupe 6spd) a few months ago with 136k miles on it and have since put 5k on it. As far as I can tell from owning it a few months it has been running perfectly normal, aside from some cases of very slightly unstable idle when cold, (what I haven't confirmed to be) a slight chain rattle on a cold start for 1-2 seconds, and the leaky intake cam magnet.

Problem:
I go to crank the car yesterday morning like normal and it starts right up (no chain rattle), idles normally for 1-2 seconds, then starts idling rougher than any 4-cylinder I've ever experienced. Best way I can describe it is an all cylinder multiple misfire? Or perhaps a very aggressively cammed V8. I lightly tapped the gas to see if it would smooth out, didn't help so I shut it off. I noticed that the exhaust had shot out a noticeable amount of black dust on the driveway up to a few feet behind the car. I plugged in my cheap scanner and it didn't show any codes.

My thoughts:
1) It jumped time? Which would be my luck because i have an appointment to get a new chain pulled through Wednesday morning.

2) (I still need to research this issue further) Whatever the defect with the '03 head is, happened?

3) (a stretch, I know) The cat converter blew apart and is blocking the exhaust, creating enough back pressure to cause the idle problem and explaining the soot from the exhaust.

4) One of the hoses for the intercooler(s)/SC popped off and could be causing the rough idle? But I figure I would have heard a lot of SC noise if this happened?

Sorry for the long post, but I really appreciate any feedback on this!
Thanks

TheMayer

bump. Anyone got any ideas?

VVF

See, the MAF sits directly behind the airbox, metering the intake air.
If a hose popped off after the MAF (downstream), it is letting unmetered (and unfiltered) air into the engine.
Also any boost from the supercharger is wasted (although there is not much of a boost at idle, and not much SC noise).

I think for (1) and (3) there would be codes.

Did you have the timing chain appt today? Let them look at this problem as well

TheMayer

Something came up and I had to reschedule the chain appt. to monday, but I talked to the guy about the problem and he recommended I get it towed to his shop if I can't find an obvious cause such as an intercooler or PCV hose thats broken. If I can't find the culprit I guess I'll actually get to use my AAA for once.

On a side note: If it did jump time, would it even still run?

optimusprime m1

Ill will say your cats blown ,have you other bits on the floor thats blown out with it like fibre glass,if so its the internals of the cat..

TheMayer

No fiberglass or anything other than the dry black soot stuff. I didn't see any smoke or anything either, but I didn't look back while it was running.

optimusprime m1

Hi Mayor in saying fibre glass it was just the material inside,i dont realy know what it is but it looks like fibre glass. I have only seen this once. Would it be a big job to remove silencer from engine end,and see what its like running.I would only do this as the last thing if you dont find some other culprit. And you could try a cat cleaner .

TheMayer

By silencer, are you referring to the muffler/resonator in the exhaust, or that piece in the intake that quiets the SC down (that I can't remember the name of)?

VVF

You don't even need to remove the supercharger baffle.
Just disconnect the hose on the bottom on passenger side - it has a spring type c-clamp, very easy to work with.

optimusprime m1

VVF thank you you must think the same as me. Blockage in cat .Or the soot is from un burnt fuel .

TheMayer

For those who are still subscribed,

I finally got the car to a shop last week and was told that the STAR machine indicated a faulty crank position sensor. So that is being replaced and he will give me an update once its done. Then he will open the timing cover to replace the chain and see if it jumped.

optimusprime m1

Thank you for letting us know . Tell us the outcome of you star visit.

TheMayer

Spoke to the shop yesterday morning. He had another '03 in so he swapped the MAF, plugs, coils, crank position sensor, and throttle body from that one to mine with no effect.

He then removed the timing cover to find the timing is dead on, and there was no unusual wear on any of the guides, sprockets, or the chain. So I decided to hold off replacing the chain until I figured out the problem.

When putting the cover back on he noticed that one or both (didn't ask) of the cam magnets had been leaking into the connector for quite some time, which as you all know, wicks its way through the harness and into the o2 sensors and the ECU. He said he pulled off the ECU and oil was dripping out of it, same for the o2 sensors, I think it's safe to assume that an oil-filled ECU and ruined o2 sensors could cause the problems I'm having..

Anyway, he called the dealer and they said it was "highly likely" that the damage from the leak will be covered under the campaign that gives you the pigtails for the magnets! Needless to say, the car was towed to the dealer yesterday. Fingers crossed.

If the work is covered, all I'll have in this repair is $161 to the first shop for his time and a timing cover gasket set, and $95 for the tow to the dealer!

I'll update further when I hear from the dealer.

TheMayer

That was fast, just got off the phone with the dealer.

They are covering everything besides the two cam magnets!!
-New computer
-New main harness
-Both o2 sensors
-Oil level sensor
-The extended pigtails for the magnets
-Apparently even an oil change

He said "Yeah you are getting $7,500 worth of parts and labor for the cost of the new oil filter." I could not be happier!

Thanks for all of the advice!

optimusprime m1

Thanks for letting the forum know how you got on at MB.Realy glad your on the road again.

VVF

Just a note - dealer will get a check from MBUSA, so they are not doing it for free. Great deal anyway

TheMayer

Update: Got a call from the dealer this morning, they got all the new parts on and I owe $14 at this point. However they are saying it's still running rough "like its misfiring or something" and the CEL is off. He said they'd like to diagnose it for $250 but I can't bring myself to pay that.

What I'm wondering is do I really have to tow this thing again, or could I drive it on the highway for about 30 minutes back to the house?

optimusprime m1

Them. i would get them to put it on the star test and find just what it is then you will have it back in a1 condition.

TheMayer

Yeah, I want it to be hooked up to star, but if it means paying that much just to tell me its got a bad coil or something simple like that, I'd be mad at myself for not trying to figure it out first.

TheMayer

Update:

Star indicated a miss on cylinder 3, compression test showed compression on 3 as well. I guess the head is coming off and getting a valve job. Timing chain will bet getting replaced as well while its apart. Got quoted roughly $1,600 for the valve job plus the cost of the new chain and tensioner.

I hate to spend that much on a relatively low-value car, but it should be bulletproof after its all said and done I'd think? All new engine wiring, computer, and sensors. New timing chain, updated top end, and never having to worry about the auto trans problems (6MT).

Any other major issues with this car that I haven't addressed yet?