Hi. I've been diagnosing by reading the forum and other resources just wanna pick your brain on this sound out of the engine compartment. Any advice is appreciated.
Intro if you got time to read,
2003 SL55 sitting for 6 months now since the start of the pandemic. Before that it was a daily driver.
Known minor valve cover gasket leak since last year.
The consumer battery is one year old and in good shape. The starter battery turned out gone due to bad cell. Replaced a month ago.
I started letting the car run for half an hour every week after the starter battery was replaced. Also trickle charger was attached (should've done it earlier).
2 weeks ago noticed white smoke out of the exhaust and rough idling.
SDS shows misfire #6 and #7.
Ordered valve cover gasket and spark plugs both sides.
Meanwhile, thought maybe it's just due to old gasoline in the tank. Drained the tank and filled w/ 3 gallon of fresh gas. Didn't fix it.
While still waiting for the parts to arrive, checked driver side spark plugs and coil cables. They looked OK w/ engine oil on the last plug (which was expected due to bad valve cover gasket).
Prior to this point the car would crank but had a hard time firing up. Now I had no crank. Just a click. This made everything worse, untill I had one single long start (maybe took 5 seconds) and the car fired up. White smoke just like before.
Now I'm waiting on the parts and hoping for the best.
I checked all fuses, tested fuel pump relay, I can hear fuel pump priming after turning the ignition ON and was able to actuate the fuel pump through the SDS. All look good. Don't know how to check the fuel pressure w/o starting the car and w/o manually actuating the fuel pump.
One thing I noticed today was a constant high pitch sounds out of the engine compartment when the ignition is in ON position. If I'm not confusing myself, I had this sound before right after turning the ignition to On but it would go away after a few seconds. Now it's noticeable as long as key is in On position. Any idea what the noise might be?
This one seems to be a tough one but I'm guessing it's probably a simple fix. I replaced valve cover gaskets both sides and all spark plugs. Issue persists. I have two questions if anybody could chime in.
First is about fuel. When ignition is in ON position am I supposed to have fuel in the passenger side fuel rail? There's a bleeding valve at the end of the rail. Am I supposed to see gas squirting if I press the pin in the valve stem?
Second question is on the clicks when ignition is ON position. Anybody knows what these clicks are about? There's a video of the clicks. Go to sec 30
Hey sorry for the issues. My sl is having random starting issues too and I know my starter battery is bad so have to change that soon...
as far as the noise and ticking it is the throttle body doing its normal adaptive routine. You can google it and it’s common along many Mercedes models
i do not know the answer to question one unfortunately.
Hey Amir_AMG, really appreciate your input. Searching on google says "a" car (I couldn't find specific answer for R230) is supposed to have fuel pressure as soon as ignition is ON. I don't have pressure though. What I did was actuating the fuel pump manually through the SDS which I could confirm fuel out of the bleeding valve. You can also actuate the fuel pump through bypassing the relay T in the fuse box behind the passenger seat. What you want to do is to jump pins 30 and 87. At this point I think it's semi safe to rule out the fuel issues and go after other components.
I haven't had a successful start since spark plug replacement but I see brand new fault codes registered shown in the pic below.
Your throttle body could be sticking and not able to open all the way? In your video it was extremely dirty. i would clean it up with some Throttle body cleaner (I believe there is a proper way to do this to not mess it up more) or just remove the whole TB and clean it fully
I'm giving the crankshaft and camshaft position sensors a shot. Planning to replace them both. Not sure where exactly they're located though. I took two pictures if anybody reading this could verify my guess.
Camshaft position sensor
Crankshaft position sensor (the sensor itself was hard to reach to take a pic so I took the picture of the socket)
Good point on the throttle body. I cleaned it up when working on the spark plugs. I took a video of it working. Seems working OK to me. Ignition is On and pressing the gas pedal. Go to sec 15
the one on top of the throttle body is the IAT sensor which is $20 and worth changing too as it’s easy to get to. (Intake air temperature sensor). Here is a DIy
Amir_AMG Thank you for helping on this issue. The code P2093 pointed me to change the camshaft position sensor. I'm not claiming to be mechanic. Just trying to do as much as I can before taking the car to the shop. This is what I found on the P2093 and P2094 code. One is referring to high voltage and the other is due to low voltage,
"The purpose of the camshaft position actuator control circuit is to monitor variations of between the camshaft/s and the crankshaft and send a corresponding signal to the ECU. This process is accomplished with camshaft and crankshaft position sensors which convert varying degrees between the camshaft/s and the crankshaft into a voltage signal that is used by the ECU to adjust the timing and optimize the performance of the engine.
I got the parts. It would help to replace them both and rule them out. Crankshaft position sensor was replaced but the camshaft position sensor is hard to reach with all the cooling system hoses and pipes in the way. Any thoughts on this?
Just a thought - Did you notice any fuel smell accompanying the white smoke in your successful starts?
A stuck fuel injector could cause the misfiring and rough run, and potentially flood and hydro lock a cylinder leading to your no crank condition experienced before. The little valve on the fuel rail is a test port. Get a regular fuel pressure gauge and hook it up. Cycle the ignition switch from off to the on/run position for a couple seconds once or twice (the fuel pump should whir for a few seconds each time to prime the system) and observe the fuel pressure at rail. Is it holding pressure or dropping off?
you said you had checked the plugs? All clean no fuel smell on them? The plug with oil on it, that was on the porcelain or the electrode? (Unless the plug was super loose oil from a leaking valve cover wouldn’t be getting down on the electrode)
Thanks for the reply. Very thorough explanation. Let me add a few comments.
Just a thought - Did you notice any fuel smell accompanying the white smoke in your successful starts? I did. Strong fuel smell.
A stuck fuel injector could cause the misfiring and rough run, and potentially flood and hydro lock a cylinder leading to your no crank condition experienced before. I was kind of tempted to go that route and replace all of the injectors but haven't got a chance yet. Plus the part isn't necessarily cheap.
The little valve on the fuel rail is a test port. Get a regular fuel pressure gauge and hook it up. Cycle the ignition switch from off to the on/run position for a couple seconds once or twice (the fuel pump should whir for a few seconds each time to prime the system) and observe the fuel pressure at rail. Is it holding pressure or dropping off? I have the fuel pressure gauge rented from autozone. I'll give it a try tomorrow.
you said you had checked the plugs? Checked and replaced. All clean no fuel smell on them? Not clean. Engine oil on the last two plugs each side closer to the back of the car. The plug with oil on it, that was on the porcelain or the electrode? Electrode only. Nothing on the porcelain. (Unless the plug was super loose oil from a leaking valve cover wouldn’t be getting down on the electrode) Hmm. So what else could it be?
Camshaft position sensor was replaced as well. Had to take the belts and the idler pulley out to get to the sensor. Didn't fix the car though. Should've listened to Amir_AMG but I had the part and was worth trying. One thing I noticed was engine oil on the socket that goes to the sensor. My guess is I've had this valve cover gasket leak for a long time but since I was driving the car everyday, the leaking oil would burn before having time to accumulate. Now that the car been sitting for over 6 months, leaking oil got time to penetrate all over.
Fuel pressure test with fuel pressure gauge is complete. Here's the result,
When ignition ON,
Fuel pump prime whir sound, no fuel pressure on gauge, no fuel pressure when bleeding valve pin is manually depressed.
When ignition ON and fuel pump actuated with SDS,
Noticeable continuous fuel pump whir sound, no fuel pressure on the gauge, hissing sound coming out of driver side of the engine around the injectors, gas squirting out of the bleeding valve when pin is manually depressed but cannot tell how strong of a flow.
Fuel pressure test with fuel pressure gauge is complete. Here's the result,
When ignition ON,
Fuel pump prime whir sound, no fuel pressure on gauge, no fuel pressure when bleeding valve pin is manually depressed.
When ignition ON and fuel pump actuated with SDS,
Noticeable continuous fuel pump whir sound, no fuel pressure on the gauge, hissing sound coming out of driver side of the engine around the injectors, gas squirting out of the bleeding valve when pin is manually depressed but cannot tell how strong of a flow.
Sounding more and more like stuck injector to me - hissing sound is likely fuel escaping/spraying out. Pressure cant build because it sprays straight through.
No external fuel leak/strong smell in engine bay? If not, my first guess is it is spraying into into cylinder 6 or 7 where you had the misfire faults logged before. Remove those plugs to start and try to smell inside the bore if you can, a length of cotton rope to reach down In and pull back out might work well and should wick up any pooled fuel.
If fuel is found in the cylinder(s), I would crank the engine over with those plugs out and a rag over to eject any pooled fuel in the cylinder as well. A flooded out cylinder will stop the engine from cranking cold dead. If the motor was running and too much fuel fills the cylinder from a stuck injector, it can hydro lock and destroy the engine. White smoke is common for excess fuel.
No external fuel leak/strong smell in engine bay? If not, my first guess is it is spraying into into cylinder 6 or 7 where you had the misfire faults logged before. Remove those plugs to start and try to smell inside the bore if you can, a length of cotton rope to reach down In and pull back out might work well and should wick up any pooled fuel.
No, I don't smell gas from the engine bay.
Checked all spark plug wells when plugs were replaced. I was looking for oil leaked into the well. I'm sure I didn't notice any sign of gas.
I don't have the parts to replace the injectors but I might as well try to take things apart and see if I can clean them. You think that helps or waste of time? Something like this video,
No, I don't smell gas from the engine bay.
Checked all spark plug wells when plugs were replaced. I was looking for oil leaked into the well. I'm sure I didn't notice any sign of gas.
I don't have the parts to replace the injectors but I might as well try to take things apart and see if I can clean them. You think that helps or waste of time? Something like this video,
I wouldn’t just go for replacing all the injectors unless your diagnosis leads to them being faulty. Tossing parts at a problem is an expensive and laborious way to attempt to solve something.
you could try cleaning them, I have no experience with that. Before that I would try to figure out where the fuel is going. I know you checked the plug wells before, I would still pull those the drivers side plugs and check again - it’s easy. It’s not the plug well or the plug itself I’d be trying to find fuel but through it and inside the combustion chamber, hence why I think a piece of cotton rope would work well.
From your earlier posts it seemed the motor was eventually not spinning over at all? Which is why I was thinking a flooded fuel induced hydro lock condition, which will stop it from cranking entirely.
If you hear the hissing and fuel comes out of the test port when pressed there is fuel getting there, but no pressure is building. So that’s what you need to figure why.
If after checking and you are certain the cylinders are all dry, you need to be looking upstream in the fuel system as to why it isn’t building pressure. Fuel filter is obvious starting place next is the pump itself.
Also, if they are dry and it still isn’t cranking/spinning (not starting) over at all using the starter try spinning it by hand to see if it turns over. If it is turning over by hand but the starter isn’t Turning it over maybe a fuse/fuse link popped from all the starting attempts. I think there is a maxi fuse under the passenger floor I’ve heard mentioned but I thought that was for charging to the bcm not between starter motor and starter battery. I can look it up later there is a pdf on the dual battery setup that’s easy to find.
Hope some of this helps I’m just trying to think it out along with you, good luck man.
Spot-on diagnosis @dRockSL55. Really appreciate it.
Pulled a few plugs out from #6 and #7 cylinders. Gas was dripping from the end of the spark plugs. What would you suggest apart from taking care of the injectors? Any idea on the clean up of the mess w/ the flooded gas?
Spot-on diagnosis @dRockSL55. Really appreciate it.
Pulled a few plugs out from #6 and #7 cylinders. Gas was dripping from the end of the spark plugs. What would you suggest apart from taking care of the injectors? Any idea on the clean up of the mess w/ the flooded gas?
Since the car isn’t your daily driver right now, I’d consider pulling all the injectors out and ship them out to be professionally ultrasonically cleaned and tested. Any that are Tested to be faulty can then be replaced. The cleaning might get the faulty injector(s) working again, though me personally I’d probably just want to replace those ones with new and clean the rest.
If you are planning on modifying the car for big power later on, you could consider upgrading to new bigger 550cc injectors with tuning but if not I would just keep the stock ones.
If the sitting around wreaked this much havoc to your injectors, definitely plan on changing the fuel filter as well. How much fuel is in the tank? I would dump a bottle of Techron fuel system/injector cleaner in there at the very least as well and ideally get some fresh 91/93 in the tank.
As for cleaning up the flooded cylinders - you could try a large syringe with a hose attached to reach down in the cylinders through the spark plug bore to get the bulk of the fuel out. Be sure to check the other cylinders as well just in case. Before reinstalling the plugs, cover the plug openings with rags and crank the engine over to eject any fuel pooling that’s remaining (and make sure your motor is still turning over fine! Though I’m sure it will be okay) I deal with this with small engines all the time and it works great.
Also make sure to change the engine oil as it will likely be filled with gas now.
i think you are on the right track though so hopefully should be sorted out soon enough.
My SL has similarly been sitting a lot during all this, while I always try to start it up at least bi-weekly for a half hour or so your post definitely scared me enough to go out and give it a good run!
Yea, the car used to be a daily driver but not anymore since the pandemic started. The headache of dealing w/ issues alone isn't worth not taking it for a spin once in a while.
Any suggestions on the injectors cleaning services? Costs? Is it not easier just to replace them all if the price of cleaning and replacing is somewhat close?
I have maybe 5 or 6 gallon of gas in the tank not a full tank that's required for chevron cleaner. I can add more gas though. The gas in the tank is fresh. The old gas was drained out.
After your previous message I was planning to remove the plugs and crank the engine. Is the syringe process you mentioned a must?
It’s been about 10 years since I’ve had injectors cleaned when I was hopping up Fords, at the time it was only around $20/pc for what we incorrectly called “EV1” and “EV6” injectors with New caps and orings - so it was a cost effective option especially if picking up used, working sets.
Looking around, it seems pricing on new fuel injectors is cheaper than I remember. FCP Euro has individual Injectors for around $50/ea or complete replacement kit for our cars for Around $400. You could replace the faulty injectors and clean the rest and save a couple hundred bucks. Your call. I totally understand the replace them all and be done with it mentality if that’s the route you want to go - plus no wait for turnaround so it gets taken apart and Put back together in one go.
I’m not sure how much troubleshooting you want to put into it Before tossing in the parts or equipment you have, but at the simplest you can use a voltmeter just to make sure the ECM Or a wiring short isn’t trigging those Injectors to stay on while your ignition is on before you buy new ones. If you have an oscilloscope you could monitor the injector pulse width while cranking and compare to other cylinders as well. But most likely they are just clogged/stuck from debris.
Syringe process definitely isn’t a must, just a suggestion to minimize the mess. Cranking the engine over with the plugs out will blow the cylinder out clean, as would compressed air with a blow gun if you have one. Some brake cleaner should clean the plugs right up.
Appreciate your comments. They help a lot.
I looked around online and seems the cost of professionally cleaning the injectors is anywhere between $25 to $35 per piece. Considering the cost of shipping etc it's not worth the try given that you'd still own cleaned but used -and maybe 17 y/o- injectors. Who knows when they were replaced last.
From what I see it's only injectors on cylinder 6 and 7 that are faulty. The rest seem to be fine.
Removed all the spark plugs on the driver side, covered the plug wells w/ microfiber towels, pulled the fuel pump relay, cranked the engine a few times, and yes of course a whole mess was made. Wiped the gas off and put the plugs back in.
I'll give the injectors a shot anyway see if I can clean them w/ CRC electronic cleaner spray.
Do you know how much voltage goes into the injectors? Is it the usual 12v or less?
Appreciate your comments. They help a lot.
I looked around online and seems the cost of professionally cleaning the injectors is anywhere between $25 to $35 per piece. Considering the cost of shipping etc it's not worth the try given that you'd still own cleaned but used -and maybe 17 y/o- injectors. Who knows when they were replaced last.
From what I see it's only injectors on cylinder 6 and 7 that are faulty. The rest seem to be fine.
Removed all the spark plugs on the driver side, covered the plug wells w/ microfiber towels, pulled the fuel pump relay, cranked the engine a few times, and yes of course a whole mess was made. Wiped the gas off and put the plugs back in.
I'll give the injectors a shot anyway see if I can clean them w/ CRC electronic cleaner spray.
Do you know how much voltage goes into the injectors? Is it the usual 12v or less?
It’s 12v/battery voltage, but for milliseconds at a time. The ECM triggers the ground wire to each injector with battery voltage being supplied while car is on.
good luck with the cleaner spray let us know how it goes.
Went through some busy days and didn't get a chance to work on the car a whole lot.
Tested all the injectors. 12 volts applied to each of them. All good except two. Not sure which ones though. I should've numbered them by cylinder # when I took them out. The problem w/ the faulty injectors was they'd pass the fuel even w/o voltage applied. A good injector blocks the fuel when not hot. Both injectors were replaced w/ the stock OEM parts from FCPEuro (the blue Bosch injectors) costing around $50 per piece. Dealer was asking $200+ per piece. That was a "no thanks" for me.
Also fuel filter was replaced. Absolute pain in the neck if you don't have your car on a post jack. Crawling under the car and reaching out for the fuel filter in that tight space was no fun.
BUT, replacing the injectors didn't fix the car. I don't think it's the fuel pump either. I'm guessing there's a vacuum somewhere right before or after fuel reaches the engine.
One thing that keeps happening is a flood of fuel around the injectors on cylinder 6 and 7 that I had misfire. It happens every time I turn the key. That tells I have fuel pressure to the injectors (although I can't tell how much of a pressure). It also tells fuel is escaping the system somewhere along the line.
Any ideas what it could be? What if the cylinder head or engine body was cracked? Would you have fuel sitting on the top of the engine around the injectors?
Yellow arrow shows where fuel flood is around both injectors 6 and 7.
The most common mistakes when installing the injectors are :
1. not installing the seals (top & bottom) correctly, or pulling an old injector out and leaving a seal ring in the rail and not noticing it when installing new injector with new seals.
2. not correctly seating the injector
3. not correctly installing the retaining clip.
That being said, the engine should start regardless.
When you attempt to start the engine, does it roll? can you upload a video?
What are the current fault codes ?
What are the actual values telling you when starting ? (browse through the pages when starting)
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