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#1
10-22-2005, 01:59 PM
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98 S420 (W140) Hard starting
Hi,
My 98 S420 with 49K miles on it has some starting issues. Starts right up when cold. However after driving for upto 15-20 minutes, when I try to start it cranks for over 10-15 seconds and doesn't start. I turn off and start again it cranks for another 10-15 seconds and starts at the tail end. Any ideas or suggestions ??? Thanks smk_texas 
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#2
10-22-2005, 03:24 PM
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Quote:
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#3
10-22-2005, 06:27 PM
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Jim. Thanks for the response. Is there a way to test the leaking injector ??? I know the fuel pressure reuglator runs about $69. Do you know how much the injectors cost for this car. Is it too hard to replace. Any help would be appreciated. Thanks
smk_texas 98 S420 49K 93 400e 137K
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#4
10-22-2005, 06:32 PM
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The fuel pressure regulator is usually the culprit in a fault like you describe. My tech advised me that this part is one of the FEW badly designed elements on the M119 engine. Most of the engine is bullet-proof and will last forever.
It has a very fragile membrane that brakes easily and when this happens tends to flood cylinder No. 8. Hence, when you start the car it hesitates for a few seconds while it burns the excess fuel accumulated on that cylinder. How to tell if this part is the problem? Your problem when starting should happen after driving the car and then letting the engine sit off for about 10 minutes or more. If you turn off the engine and turn it on right away it should start fine. It is not an expensive part, as you posted before, although as far as I understand, when changed, the computer codes need to be reset.
__________________
A. Rosich CL 500, 1998  S 500 L, 1998  E 320 T, 1995  [Sadly sold  ]
Last edited by A. Rosich; 05-15-2007 at 11:19 PM.
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#5
10-22-2005, 09:05 PM
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If you haven't 'disturbed' any connections to the injectors (which you probably haven't), then they are most lilkely ok.
I wouldn't advise 'playing' with any of them unless you are going to replace them all or take them out to be cleaned. If you disturb them, without replacing all of the gaskets and o-rings for sure they will leak. They are not cheap!! I'd concentrate both mine and Armando's advice re the regulator. It's a cheap part and a 'clean' fix. Last edited by JimF; 10-23-2005 at 11:22 AM.
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#6
10-22-2005, 09:42 PM
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Thanks very much Armado & Jim. I greatly appreciate your advice. I will replace the FP regulator next week and keep you posted. About resetting the computer I only have a cheap OBDII scanner that I purchased from autozone. I am not sure if that will work on this car. Do I need a different scanner ??? Please advice. Thanks again
smk_texas
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#7
10-23-2005, 11:24 AM
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Even the 'cheapies' should do two (2) things; read and reset DTCs. I wouldn't think that yours is any different.
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#9
10-23-2005, 08:42 PM
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Hi Jim,
How have you been? Haven’t spoken if a while. I have a similar problem with my 99 S420. However it is hard starting when it is cold, normally I have to crank about 5 seconds, turn off ignition and re crank another 5 seconds before it starts. After it is warm it starts on first crank. Also, during idle the engine will occasionally hesitate, lose RPM, then return to correct idle. Any idea what my problem is? Thanks Eric
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#10
10-24-2005, 11:57 AM
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I been ok . . .
. . thanks for asking. And I trust you are the same??
I had a 190E that had that symptom and it was the "cold-start" valve; it leaked constantly so when it had sit overnight, it was very hard starting. Not sure about the W140s?? Never had the problem with my present car so don't know. Is there the equivalent of a cold-start valve??
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#11
10-24-2005, 07:48 PM
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Jim,
I don't know. It only started a few months ago. I thought it might be an injection problem at first. However that would mean I would have problems at all speeds I would think. The car runs excellent at all other times except during idle. Every once in a while it acts like it is starving for fuel or air. Guess I am going to take it to a mechanic, since I also have the SRS idiot light on constantly now. The only way to figure that one is to get the error codes from what I understand. Thanks Eric
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#12
10-24-2005, 08:50 PM
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I forgot what . .
. . year/model and checked your profile; '99 S420.
Could be a bad EGR??? Bad vacuum line?? Bad plug?? One bad spark cable?? With your '99, you don't have as many separate modules (ECUs) as I have so it should be easier to diagnose . . . but not necessarily less expensive. Even if it's an 'injector' (don't think it is), it could show just at idle and not be noticable at highway speed. The SRS light is probably the "driver's seat belt module". . normally is. As you said, you need a scanner to reset it. But it will come back! Last edited by JimF; 10-24-2005 at 11:38 PM.
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#14
10-28-2005, 01:16 PM
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Jim, Eric or Armando,
I got the parts last nite. I am trying to replace the fuel pressure regulator in my 98 S420. I can't seem to get it off the housing it is seated on. Do I pry it off or is there someother technique. There seems to be a metal ring holding it down. Please help. Thanks. smk_texas
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#15
10-28-2005, 10:57 PM
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Hi Folks,
I had to go buy a snap ring plier to pull that ring off which I did. After that it took less than 5 minutes to put the regulator in. The best part was it FIXED the problem. No more starting problems. Thanks Jim, Armando & Eric. smk_texas 98 S420 93 400e
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