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#1
03-19-2008, 01:23 AM
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1993 300E 2.8 Cold Throttle Response
Hello,
I have a 1993 300E with a 2.8L gas auto and 180k miles. My main issue with the car is throttle response when the engine is cold. Until the engine is fully warmed up, when driving the engine slowly accelerates without regard to how far down I push the accelerator. Once the engine is hot, throttle response is fine. A couple strange issues are when the engine is cold, the throttle response is poor until I hit 2800 RPM. Once the engine hits 2800 RPM, the engine finally "takes off" and accelerates dramatically. I'm thinking the issue may be a vacuum leak issue but I have yet to find any visible leaks or cracked hoses. Also, I have some hard starting in cold weather. If the engine does not start on the first crank without any throttle, then I have pump the throttle to get the engine to start. I don't think I should have to use throttle when starting a fuel injected vehicle. I have a code reader with the blinking light from Ebay (works great), but after I reset the faults and fixed some issues, I'm showing no current faults for several weeks. I have also replaced the spark plugs, plug wires, air filter, water temp sensor, and air intake temp sensor. I've done a lot of research on these boards and in books but before I pay to have a tech to go hunting for the problem, I would appreciate any possible suggestions you might have. Thanks, John B Last edited by jbjork70; 03-19-2008 at 11:49 PM. 
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#3
03-20-2008, 08:28 AM
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Quote:
You may want to have your mechanic adjust the fuel distributor lower chamber pressure to .45 bar ( 6.5psi ) instead of .4 bar ( 5.8 psi ) This will compensate for the years of operational wear. You'll need a CIS-E fuel pressure gauge to make the adjustment.
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http://i19.photobucket.com/albums/b1...c/GOWIDE-1.jpg 1971 280SL ROADSTER 1988 300CE TWIN TURBO WIDEBODY 1994 E320 CABRIOLET 1999 C43 AMG 2005 G55K AMG 2008 CLK63 AMG BLACK SERIES
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#4
03-20-2008, 10:55 AM
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<
The car is HFM/SFI w/104 DIS engine. Check codes on pin 8 of Diagnostic Module and post.
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A Dalton
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#6
03-20-2008, 01:09 PM
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14
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A Dalton
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#7
03-20-2008, 03:00 PM
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Arthur,
Thanks for the response. I checked pin 14 and I had one new fault I have not seen before: Fault 11. My fault book reads "Pin 14 Fault 11 - Closed Throttle recognition signal to engine control module (HFM-SFI or Left LH-SFI); Fuel safety shut-off to engine control module (HFM-SFI or Left LH-SFI)." I cleared the fault without a problem. Any idea what this means? Thanks, John B
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#8
03-20-2008, 03:50 PM
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Check that you have a little slack in the throttlew cable at idle and check that you have the new style OVP.
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A Dalton
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#9
03-20-2008, 04:44 PM
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Arthur,
Yes there is play in the throttle cable while at idle. As for the OVP, I think I have found it after reading some of the other posts. Mine sits behind the battery, close to the firewall. It is a small, square black plastic box with a white plastic top along with a clear plastic cover. Under the clear plastic cover is one fuse, although it looks as though there is room for two fuses. The fuse is a 15 amp, blade-style fuse. Not the regular tube, bullet style like in the main fusebox. The fuse appears to be in good shape. What should I do next? Thanks again for the help, John B
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#10
03-20-2008, 06:29 PM
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OVP is the tall, rectangular one..should be aluminum body.
Pull it and see if it is the Modified relay 000-540-67-45. If it is 000-540-52-45 , change it regardless. That could be your start problem, and might have a running problem. http://catalog.worldpac.com/mercedesshop/sophio/image.jsp?title=Overload%20Relay&url=http%3A//img.eautopartscatalog.com/live/P205670038APA.JPG
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A Dalton
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#11
03-20-2008, 10:39 PM
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It sounds as if the fuel mixture is not sufficiently enriched for a cold engine. I have the same car. I once accidently left the coolant temperature sensor disconnected and had similar symptoms. The engine would die when started cold, usually several times. I don't recall what the cold drivability was like. In my case the diagnostic codes pointed directly to the ECT sensor; the ECU knew the value was implausible.
I wonder if there is a failure mode here where the ECU thinks the engine is warm even though it's not? I don't know the specification for the sensor, but expect it can be checked with a simple DVM. Is the wiring harness original or replaced? - JimY
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#12
03-20-2008, 10:41 PM
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Quote:
__________________
http://i19.photobucket.com/albums/b1...c/GOWIDE-1.jpg 1971 280SL ROADSTER 1988 300CE TWIN TURBO WIDEBODY 1994 E320 CABRIOLET 1999 C43 AMG 2005 G55K AMG 2008 CLK63 AMG BLACK SERIES
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#13
03-21-2008, 12:41 AM
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Arthur,
I will remove the OVP and check to see if it has been updated. I will post here tomorrow what I find. JimY, Not sure if the wiring harness has been replaced. It hasn't been replaced since I've owned in the last year. It looks as though the temp sensor is working though. It has been suggested that I might have a bad O2 sensor or a vacuum leak. Would either of these cause the sluggish performance? Thanks for the replies, John B
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#14
03-22-2008, 03:27 PM
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Arthur,
I removed the OVP and checked the part number. The car has the new OVP 000-540-67-45. I also re-checked my diagnostics after driving the car for two days and both pin 8 and 14 had no faults. Please let me know if you can think of anything else to check. Thanks again for the relies, John B
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#15
03-22-2008, 03:33 PM
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<
Did a single flash come up on both????
__________________
A Dalton
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