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98 C280
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Discussion Starter #1
Here it is...I have a 98 Merc C280 that I have a love/hate relationship with.

Monday morning got in it and it started fine despite being below freezing that night. I drove it to an appointment. Came out about a half hour later and went back to the vehicle...key in the ignition...started normally and then stalled 1 second later. Did this at least 10 times. Gave it a little throttle once or twice on start up, but changed nothing.
Only stored code was a pending evap code P0455, which was probably from the morning before. Sometimes registers a pending code on extra cold mornings. I believe from a cracked gas tank cover seal. Never hangs around long enough to register the check engine light.
Car ignition is Mercedes infrared EIS system. Both keys do the same thing.
Had an extra camshaft and crankshaft sensor laying around as backups, so I changed those out quickly...no fix.
Had the car towed to a garage thinking it was probably fuel pressure related. They tested and said fuel pressure was fine.
I've got my battery out currently giving it a full charge to try that, but it is turning the car over so i'm skeptical that will do anything.
I've had a slight rattle which started several months ago after going through a big ass puddle, which is probably one of the cats, but car has been driving pretty normal for the most part.

What do you think?
I'm entertaining:
-clogged cat
-fuel pressure regulator
-short somewhere...fuel injectors, plug wires, bad coil pack
-maf sensor (but I would have thought that a failed maf would store a code?)

Anyone run into something like this with your W202?
 

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'98 E430, '98 BMW 328i convertible, 2008 Jaguar XK, 2013 Nissan Pathfinder
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158 Posts
Maybe clogged fuel filter? Where did they measure fuel pressure?
 

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98 C280
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10 Posts
Discussion Starter #3
I put a new fuel filter in it about 2 years ago. I guess I have put about 40000miles on it since then.
I'll have to call the garage again and ask the mechanic that was working on it what the measurements were. They checked it outside parked in the snow, so they must have checked it at the service port on the rail.
I know it is getting some fuel pressure from the pump because it has turned over at least 15-20 times. The battery was low when I put it on my noco genius charger at home. Is it possible that the fuel pump is not pumping strong enough with lower voltage from the battery?
I've seen multiple threads online describing the same issue, but without an update on how it was resolved.

It has me perplexed because the problem seemingly came out of nowhere.
 

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1996 C220 2007 ML320 CDI
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1,824 Posts
OVP relay, buy a new one. Either genuine or Kaehler. Everything will be sorted afterwards.
 

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98 C280
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10 Posts
Discussion Starter #5
Don't think it has an OVP relay Patman. The older w202's had them...but I don't think anything 98-00 had them, at least not in the V6/V8.
 

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98 C280
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10 Posts
Discussion Starter #6
Patman...I did a little digging...There is an overload protection relay...just much different than previous years. I'll check that. Thank you for your input.
 

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1996 C220 2007 ML320 CDI
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If it's not the OVP relay then there is indeed another relay on the ME-SFI cars can also be suspect. I forget what it's called though
.
 

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1999 C280, 2000 C280, 2000 C230K,2011 C300
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645 Posts
I have same problem with my daughter's 1999 C280 but not severe enough to disable the car. So whatever solution you find will be helpful.

We've had the car about 5 years, 125m. It will sometimes do the start and then die a second later. Usually it will start with the second try. On rare occasions it will take 6-8 more tries to start and then the car behaves normally. I checked a few things but it happened so rarely that we just kept our fingers crossed. Something new started happening recently. Twice now we have gotten a no crank. Turn the key and nothing. Wait a second or 2 and then the car would start and operate normally. The only continuous symptom we've had is a very slight rough idle.

Plugs and wires have been done. Valve cover gaskets, breather caps and all air hoses also. I've done the fuel filter, but the car runs so normally most of the time, this probably wasn't it. There is no OVP. Instead this car has the K40 relay which has a history of buggy solder joints. I changed this recently (old one looked fine) but haven't had much driving time since to see if it actually helped.

I thought maybe fuel pressure regulator but again this car doesn't seem to call for one like the older inline 6s. All I've suggested for my daughter to do is when starting car, turn key to position 2, then pause and put on seat belt, then start the car. Don't know if this has made a difference.
 

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98 C280
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Discussion Starter #9
I'll definitely update when I find the solution Glenmore. May or may not be the same issue. I don't think the evap system code I got has anything to do with it in this case and my problem appeared suddenly with no warning of troublesome starting. I'm suspecting something electrical. I'm about to pull the K40 Relay unit and open it up to examine for bad solders. I did have the EIS unit out of my car about a year ago and sent it to a locksmith who programmed a second key for me. When I was pulling the EIS(ignition box) out...there was a connector that was slightly damaged with two small green wires. I just got an email response from the locksmith that those wires are CAN low and CAN high. I had dropped the EIS yesterday to have a quick look at it and when I removed it...those two wires were now broken free. The problem is I don't know if it was like that before I tried to remove it or if it happened when I removed it. I'm going to fix up that wiring and see what happens.
There is no fuel pressure regulator on the fuel rail in our cars...instead...i'm assuming that it is incorporated into the fuel pump itself. I'm going to have the pressure tested at the shrader valve on the rail. I believe the specs call for between 53-60psi and to hold 36psi after a half-hour of turning off the engine. So the fuel pump not working to efficiency could be the problem with the your daughters car...possibly mine too.
 

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1996 C220 2007 ML320 CDI
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K40 relay! That's the name. It's also suspect if there isn't an OVP relay. I suggest you replace it regardless of how it looks. When I opened my OVP relay, it looked perfectly fine, the solder joints looked fine. I had similar symptoms that were cured by replacing the OVP relay. The soldering joints can crack at a microscopic level, they are still bad, but you won't see it with the naked bad. Another thing that can happen with faulty relays is the pad becomes separated from the substrate, which damages the connection with the copper on the PCB. Not much you can do about that, replacement is much easier.

There is a fuel pressure regulator on the M112, it's at the fuel pump, and it has a long vacuum line coming from the engine. Otherwise its the same fuel pressure regulator as every other mercedes. I believe the correct PSI specs are between 48-54 at idle, and when you disconnect the vacuum line it should jump up by around 8-10 psi. After 30 minutes the residual fuel pressure should be 36 psi. Otherwise you either have a leak, a bad regulator, or a bad check valve at the fuel pump. Anyway, I doubt the fuel pressure has anything to do with your problem, it's much more likely the K40 relay.
 

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1995 C220
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Or the MAF. I dealt with the stall after start for YEARS, then finally put a MAF on and fixed it. Then I was left with rough idle, but that went away after I bit the bullet and splurged on a new throttle body, and readjusted the cables. You could maybe try unplugging the MAF and see if the problem changes, but thats not really conclusive, but it may force the car to a tune that doesnt rely on MAF data, so could change the start up characteristics enough to make a change.

I will say I never had the MAF keep my car disabled, so it could very well NOT be the problem, just giving you something else to check.
 

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98 C280
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Discussion Starter #12
Patman...I haven't checked the Overload Multi-fuse relay for bad soldering joints yet. I did test the K40 and fuel pump relays with 12v and multimeter and they were both good.

I fixed the EIS connection for the CAN high and low signals. No change in the start/stall, so I'm guessing that they broke loose as I was dropping the EIS to inspect it.

I called back the garage that tested the fuel pressure and asked the mechanic if he remembered the exact psi reading. He said he "thought" it was around 38-43psi. (Not quite in the ballpark it should be, but he thought it was fine enough for startup)

A big thing that I did notice today was that if I insert the smartkey and turn it to the "ON" position and leave it for 2 or 3 seconds before turning to engage the starter....that when I do turn it...there is nothing. Almost as if it forgot the key was in there. And as bad as my memory is...i'm pretty sure that is not normal. If someone could verify that for me...that'd be great. So that is pointing me back to the DAS system. Something secondary in the DAS after the 'handshake' between the smartkey and the EIS? Or something shorting out when it is engaging and the system cuts power?

If I can't sort it out in the next couple days, I have a local mechanic I know who's gonna stop by on the weekend with his scanner and hopefully be able to pull a code that isn't showing on my scanner. I'm 3 and a half hours from the closest STAR scanner, so i'm hoping to find something soon.
 

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98 C280
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Discussion Starter #13
georgebuhr....I was thinking about the MAF...maybe a sudden failure. I did try to start the car a few times with it disconnected and there was no difference. I'm not sure if the car would recognize if the connector was removed and go to a 'default' setting. And there is no code set for the MAF...but I don't know if they can fail without setting codes. I've had my crankshaft sensor twice since I've owned the vehicle and never had a code set for that.
 

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98 C280
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Discussion Starter #14
W202 1998 C280 EIS starts and stalls starts and dies P1570 SOLVED

SOLVED...JUST IN TIME FOR A MERRY CHRISTMAS!

It was electrical....EIS CAN wires

-I had tried crankshaft/camshaft sensor replacement as I had spares in my dash and they are related inputs to starting sequence...No change
-There was fuel pressure
-Changed an engine coolant temp because when I had brought up climate control diagnostics menu...was showing "LO" for sensor reading instead of numeric value, which I thought might had meant an open/faulty circuit. ($20)...no change...and still measured "LO" on the new sensor so must only show a numeric value above a certain temperature...FYI
-Checked all fuses and relays and overvoltage K40 module....no change
-Removed MAF connector...no change
-Pulled ECU and TCM to examine for oil/moisture damage...cleaned small moisture corrosion on bottom of ecu board with MAF cleaner...no change
-Changed the battery because although my other battery was only 2 years old was dropping from 12.4 to 11.9-12.2 V range after just a few attempted starts....no change. (Got refund on old battery...upgraded to AGM :D)


It turned out to be the EIS CAN HIGH/LOW connection(Tiny Green & Green/White wires...smallest connection on EIS)
About a year and a half ago I had removed the EIS to have a key made out of province. That small green connector had broken at the time of removal as it is EXTREMELY delicate, but I had done a quick repair and never had any issues with it since. I had pulled down the EIS after having the fuel pressure checked and changing the crankshaft and camshaft sensor with no luck. When I pulled it down from the dash...the wires for the CAN HIGH/LOW were out of the connector but I thought I must have pulled them apart in the process as it was dark and there is lots of stuff for them to get hung up on when you are trying to pull it down out of the dash. I had quickly tried to hold the wires in the connector port in both configurations to rule this out, but It made no change at that time(could not have been making good enough connection).
A couple days after...I pulled the EIS from the car and fixed the connection at the EIS and made it a little longer to make it easier to reassemble and to rule this out. At that time...I had emailed the guy who did work on my EIS to ask him which side was which(there is one green wire and the other green/white). He sent me a diagram...which i'm pretty sure I followed, but turned out to be wrong. I had ruled out the CAN wiring at this point.

Changed the battery today and it didn't change anything and then decided to switch the wires for the CAN high and low as I had put quick disconnects on each wire where the wire extension met the originals. I was just desperate at this point as I really thought that I had them in the correct spot from the diagram I got.
The only thing that made me go back to the EIS was a code that I wasn't able to pull from my scanner, but came up on my friends snap-on solus reader. P1570...which is connection between DAS and ECU. My internet search had led me to all kinds of different causes for this code...including shorted wiring, fuses, and bad connectors, faulty ECU, sensors inputs, etc.

ANYWAY>>>>>
Bingo...fired up smooth first time. No more stall and the starter was engaging whether I turned key immediately or waited a long time. I did switch the wires again back and forth to confirm that this was the fix.

The problem all started because the tiny, tiny green plastic connector for those wires had cracked when I took it out about a year and a half ago. I had put a little super glue on the cracked connector when I put it back in and it never gave me any problems since, but the freezing cold -25'C temperatures must have made the wiring more rigid and torqued it free while it was sitting.

Hope this helps someone at some point. This could happen to anyone with EIS ignition switch...1998 to present. That dam connector is extremely delicate. If you have similar symptoms with similar P1570 and especially if you have done anything to EIS...check your CAN wiring from EIS to ECU.
 

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1995 C220
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Thanks for posting the solution; too many posts on here never do that. Hopefully this helps someone in the future.


Sent from my iPad using Tapatalk
 

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1996 C220 2007 ML320 CDI
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Well, EIS does communicate DAS information stored on the key over CAN-bus to the ECM (this is also true of IR flip-keys from 96-98). Thanks for sharing this simple fix!
 
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