Hiya, I've got a 2004 coupe, manual tranny. I bought it April of last year, and since the day after I purchased it (go figure) the car has been acting as if it needs an exorcist. Last year I had the codes pulled at advanced auto parts, I had several cylinder misfire codes, that dreaded P0410, the CAMSHAFT code, and some O2 sensor codes (which escape me now).

So this is a fairly long post, and I apologize - but I'm otherwise on the verge of caving in and taking her to a Chrysler stealership, but I really hope to at least have it diagnosed if I can't fix it myself before I take it anywhere to save expenses.

First off, the symptoms:
-The car will hesitate and miss at all RPM ranges, most dramatically in 1st and 2nd gear.

-The car cranks, but has a tough time starting. After replacing the CAMshaft sensor (last fall) and the "FUBAR" battery (~January), the car just takes two consecutive tries and it will fire. But it's very clearly not how it should be.

-The car will sometimes rev itself. And I don't mean it will just idle high for a moment, I mean it will be running smooth and it just begins revving itself around 2300 RPMs three or four times exactly as if someone were pressing the gas pedal. Then back to normal. Between each rev, it will drop to around 500 and almost stall as it shakes.

-It will not stay running in idle. It runs rough and RPMs fluctuate. Friday I made a couple stops all within a 2-block range. Got out to get a coke out of a machine. It stalled. Got out to shut the warehouse door I left open. It stalled. Got out to grab something I forgot in my house, it stalled again. But then I drove it an hour away to visit my mother.

-Today, worst of all, I admittedly peeled out leaving the gas station where this cute chick works. A mile or two down the road, I noticed the check engine light blinking. This is the second time ever I've seen it do that. As soon as it quit blinking, the car missed dramatically (at around 60 mph) and completely lost all throttle response. If I pushed the pedal down, it would shudder as if I had a wheel wriggling about. It seemed as if it was coming from behind me. A lot like trying to take off from a stand-still in 3rd gear. At first, I thought I scored my differential doing that bad-*** burnout. But I threw it into neutral and gave it some throttle, it still shuddered but not as dramatic. The car was slowly losing speed, RPMs were only kept up due to the wheels still rolling while in gear. I probably made the biggest mistake ever by lightly holding down the pedal to attempt to maintain speed, instead of pulling over and shutting her off. She rolled that way a whole 5 miles to my house (got lucky there), but when I came to a stop - the engine was rocking violently, making a sound I immediately thought was rod knock.

Shut it off in a panic, went in to grab my scan tool, read the codes.. Started it back up. First or second try, I don't remember. NO SYMPTOMS WHATSOEVER. Took the car around the block, sure it missed hard again when I punched into it but otherwise it ran better than usual. I also experienced the symptoms just randomly disappearing temporarily just after I changed out that camshaft sensor, and the couple months while I was jump-starting the car because the battery in it was junk, the car ultimately ran fantastic. I guess it's because the computer was disconnected from the power source during these procedures, but now that I've got a good battery in it, the electronics always have voltage.

Know that I've been on this forum since I discovered it shortly after purchasing my babe, so I've been reading up constantly on different issues and a lot of them sound convincing.. But I'm just not sure.

Now for the codes:
0 Pending.
P0410; Secondary Air Injection System
P0446; Evaporative Emission System Vent Control Circuit
P0303; Cylinder 3 Misfire Detected
P0306; Cylinder 6 Misfire Detected
P0305; Cylinder 5 Misfire Detected
P0304; Cylinder 4 Misfire Detected
P0301; Cylinder 1 Misfire Detected
P0300; Random/Multiple Cylinder Misfire Detected

The P0410 and P0446 were present prior to this incident. P0410 is intermittent but this P0446 came up a few days ago. Which might help diagnose my intermittent overflow-when-fuelling issue, but that's something I'll touch on another day.

I wish to do the maintenance and repairs on this car myself as much as I possibly can with my experience (which is not nearly as much as anyone on this forum, lol). Other than my ongoing monthly payment, I have very little money into this car - just that one sensor, and a battery. And even though the entire time owning it has been sort of tough, I absolutely love it. So you likely understand that I want to keep this car going for as long as I can.


So... what do the geniuses on here say?

 

I'm not sure if this will be any help but I was having a problem like this about a year ago. Every time I stopped to get gas and went to start it would misfire and stall out and not stay running unless I sat there revving the gas for a few minutes. I was getting evap codes and misfire codes. Anyway to make a long story short I replaced the gas cap with a new one and never had the problem again.

 

From how this car responds to some things, I suppose it shouldn't surprise me that it could be something so subtle as that. For 20-40$ for the part, probably even cheaper for a non-OEM one, I guess it wouldn't hurt to try and see if it acts any differently..

 

I'm gonna head home and pull the RCM and check it out. I've never done soldering before but I think I'll be able to identify bad connections. I should have done this at the very beginning like every thread I've read has told me to lol.

It would make sense if the fuel pump relay was cutting out due to a bad connection. The car will usually miss when taking off shortly after start-up (I live just meters from the highway), and it might do it for a few miles but it usually will quit for a good time. This issue occurs every driving cycle but at random, so it's tough for me to diagnose.. but the way the car fails it just doesn't seem like it can be anything other than an electrical/computer issue.. Of course, the fuel filter could be getting old or the pump itself might not be giving the output it should and that could add to the situation.

I don't get out much but trips in the Crossfire are always greater than 15 minutes from A to B. When I drive an hour on the highway like I do most weekends, the car runs decent at first but will drive poorly with the dramatic hiccups for the first few minutes. Then it will be fine and I forget about it until I'm about half an hour or so into the drive when it starts hiccuping some more. But when I arrive, I like to shut the car off right away and let it sit til the morning before I try and go anywhere again because I fear it will just get worse if I try to drive it a second trip starting warm.

 

My cousin looked over the board and saw some badly cracked connections on one of the corners, he cleaned them up a bit..

Plugged it all back in and the hard start seems to have suppressed, though it still seems off. Car still jerks in 1st and 2nd but I haven't noticed the hesitating at highway speeds. Idle seemed to be okay at around 500 RPMs, usually it would idle at ~750 and if it idled any lower it would shake more noticeably than it is now. Granted I've only road tested it for about two miles in one trip, from a cold start. I'll review what folks have said about the RCM repair and take it in to a professional to double check.

And more road testing. Which I'm more than glad to do in a Crossfire.

 

Haven't been home this weekend, drove an hour away in my daily driver and the transmission went out as soon as I got to where I was going.. I don't care but this leaves me without a car at all until I can get my Crossfire going, which feels unlikely in a timely period..

Before I left I looked under the hood and noticed that the coil pack on the passenger side front of engine (I believe cylinder 1?) was fairly loose on the valve cover, didn't have my computer with the service manual nearby so I didn't want to mess with it without knowing the proper torque specs. But this gives me the idea that the car had been neglected by service techs or previous owners in the past.

But what I don't understand is that several random cylinders will misfire, and it seems that they will not fire again until the car is shut off and started back up. The first time this happened a week or so ago I had 5 cylinders misfire, and I drove home on the 1 that was still firing. Took my girlfriend out for supper Wednesday evening, not a mile out of town and 3 cylinders misfired and I drove home easier on the other 3. Since that was my first time driving the car since the first scenario, the MIL was cleared. But it came on blinking a few times, and as soon as it stopped I lost those 3 cylinders. I don't have my freeze frames with me as I'm not back home yet, but I'll update that when I get back..

On top of both my cars failing this week, having this flu bug that's going around, and some other personal issues.. I'm losing motivation fast.. I can only hope the town mech won't need a DRB3 to look at my car.

EDIT: I forgot to add that when the car takes a second or third try to start, the code P0410 (2nd air inj system) is given and lights the MIL. I don't know what purpose the air pump really serves but I'm doing some research on the service manual about it now.

 

Misfires have been cured by replacing the crankshaft position sensor, fuel pump, air leaks, fuel filter etc.
The secondary air problem is caused by the solenoid in the RCM getting burnt or a bad contact in the secondary air pump wiring.
The vent control is the solenoid on the system failing I think. It is under the hood on the fender in front of the driver if I recall correctly.

 

As a follow up to 100/80's post above, spend $45 and get a new Crank Sensor - but don't buy one at Autozone - get the original BOSCH part:

https://www.germanautosupply.com/sto...sensor-82.html

I can't re-read all of your posts, but will ask - how old is the battery? Bad batteries cause all sorts of nonsense in these (and other) cars.

The air pump code can be ignored for now, it won't stop the car from running. Also, you really want to go over ALL connections/lands/joints on the RCM. I'd reheat and reflow every one of them. Taking a look at the relay contacts is a good idea, too. I know most of us don't have a relay burnishing tool to clean them up, but if any look REALLY pitted/burned/bad, a new relay is indicated. I think 180 has a source for them.

 

And ABOVE ALL stay away from the dealer, unless you can find a Mercedes dealer that will admit the car is an SLK320 and look at it.
Other than that, take it to a local garage known for MB experience IF you MUST take it somewhere.

 

I didn't know the CPS also caused misfires but it explains how the car gets more and more difficult to start as it gets warmer. I'll definitely have one shipped, and trust me - I've read too many times on here of folks not using genuine bosch parts and having troubles instantly. So I've got a ton of MB and bosch part numbers written down in my owner's manual lol.

And I replaced the battery in January or February, the Bosch one that was in it had an 11/06 sticker on it and it wouldn't hold a charge a moment after shutting her off. I'll change out the CPS this week and if that doesn't work, I can drive it to the town mechanic so he can take a look at the mechanical side of things.. But if it's an electrical or computer issue that's beyond either of us, the nearest MB dealer/service center is 25 minutes away. And they don't have good reviews on Google. Joy.

 

The Mercedes dealer will warrant his bad reviews when he waves you and the Crossfire away from his lot.
None of them seem to service Crossfires, I guess they have been told by Mercedes that they must not touch a Crossfire.

 

Thank you so much for your input so far guys. I've ordered a bosch crank sensor from AutohausAZ just now and hope to have it in the car Wednesday or Thursday night. If it doesn't fix her, I've got a spare I s'pose. I also spoke to my neighbor who operates a tow truck/mechanic shop this afternoon and he's sort of iffy about working on it himself, but might know a guy..

Out in eastern Iowa there's not a whole lot of options to get a car like this fixed and if it weren't for the multitude of answers on this forum I probably would be collecting some insurance money soon.. But I remain optimistic.

 

So I called around, spoke on the phone with a guy who was quicker to point out the crossfire had MB influences than I was. He was at least familiar with the car and seemed certain about spark plugs.. At 92K miles it certainly is time to change them out. When I can get a ride to autozone I'll pick some up and give 'em a shot.

 

Sounds about right - my car is almost to 104,000. It runs fine, but the CHECK ENGINE light has been on a lot, yesterday it flashed at me - never saw THAT before!
Read codes - none there. Odd - why was the light flashing and then on for about 20 seconds?

Anyway, last week it threw P0300/304/305/306, and in the past month I've seen P0401 - the famous air pump code, and a few P013x/P015x codes.

So, before I spend $$ at a garage, I'm ordering 12 plugs, 12 plug wires, and two O2 sensors. I will also yank the RCM out and resolder the hell out of it and look for bad relays.

Only after that will I even consider paying someone to look at it.

 

I just placed an order at Autozone for 12 Bosch iridium plugs #9600 for 6.99 each to have shipped to my home.. With a little luck and quick hands I might be able to see my lady friend this weekend if shipping allows.. It feels so weird not being able to go in and pick my stuff up lol. I'm going to see if I can go without changing the wires out for now, those run fairly high in price.

I also noticed some time ago while watching the live data on my scan tool, I had one O2 sensor from each bank throwing erratic voltages while the other pair were staying the same within .005 volts at .750? It was either both upstream or both downstream, I don't know how the numbering works on those. Is this relevant?

 

My plugs came in yesterday, my crank sensor was supposed to be here today but I woke up 3 minutes after the post office closed.

I changed out the 6 plugs on the passenger side cylinders, and drove the car around a bit. No problems, no rough idling until I got on the main road, when the CEL came blinking and I turned the car around, where it stalled sideways in the middle of the highway. Started right up and drove a 1/2 mile home with no issues.

I'll change the other 6 plugs later, it seems the passenger side is supposed to be easy and it was tough without any ujoint socket extensions. First time I've ever changed plugs on a car though, good feeling buttoning the coil packs back up.

I might pull the TB off this afternoon to clean it up a little, might go invest in some seafoam too..

But for now I'm borrowing the company Smart car..joy

EDIT:: took the car out after looking at a few things, drove around town twice with no symptoms, third way around it started missing again. Like a valve isn't fully open when it should be.. You can hear the exhaust loud and clear as it should be, say around 3000 Rpms, then when it misses, it will suddenly silence, and pull back as if the throttle was dropped... Set my obd2 scanner to start recordinglive data when a DTC set, but it never set. I'm now 12 miles away enjoying Taco Bell while she cools off. Guess we'll see

 

I thought a flashing CEL meant problem requires urgent attention.
I'd get rid of that car and buy that SRT you have always wanted.

 

Trust me, I really want to get an SRT crossfire, I'm always checking eBay and cargurus.com for srt6 listings, but I can't take on another car payment right now.. I still owe 7400$ on the one I've got and it now books for 5500. It's pretty demotivating to think of it that way lol.

 

Any thought of an SRT is off the table until I see what my medical bills are.
On the up side, given my medical diagnosis, saving for retirement has become less of a priority - I don't think I'll see 83 like dad did.

 

That is awful news to hear, I was not aware you were ill.. Regardless of your ailment, I hope the tide turns in your favor soon.