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Old 02-28-2008, 09:07 PM
Registered User
Join Date: Sep 2004
Posts: 31
Power loss until car warms up

1989 190 2.6

I have a problem with my cars lack of power. When I start the car in the morning its fine for about 2 minutes until the cars temp hit 50, then the car hesitates. I have to pump the gas pedal up and down to get the car going. It seems like I'm pushing on air and the car isn't getting gas, but when the cars temp hits 80 the car is fine and back to normal. I can shut the car off and restart and it will be fine as long as the car temp doesn't drop below 80. It seems that anything between 50-80 on the car temp its not getting the correct fuel mixture. any help??
Took it to the dealers here is what I had done:
Replaced wires
Replaced plugs
Replaced dist cap
Replaced rotar
Replaced air flow meter (adjusted potentiometer)
Tested Fuel Pressure (system 80 psi, L/chamber 75 psi
Tested EHA current 20 ma key-on, 2-5 ma @idle, fluctuates w/accel-decel
Tested Lambda Control - good occilates
Tested Temp Sensor - 2.94 52@ 70F
Tested Fuel Volume - Good
Tested Fuel Sample - Good
Tested Both Fuel Pumps - Running
Tested Exhaust Back Pressure - OPSI @idle & 3000RPM
Tested Temp Sensor - Good
Tested O2 Sendor - Good, but is lazy EHA

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Old 02-29-2008, 08:01 AM
Join Date: Mar 1999
Location: Tucker, Ga USA
Posts: 12,153
Might try adding a 300-450ohm resistor to the wire that goes to the coolant temp sensor. That wire is green with a red tracer.
MERCEDES Benz Master Guild Technician (6 TIMES)
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44 years foreign automotive repair
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190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
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Old 03-01-2008, 12:21 PM
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Join Date: Jun 2007
Location: Just north of Indianapolis, Indiana
Posts: 216
* As you probqbly know, temperature sensors are thermal resistors. The resistance changes as a function of temperature. So "checking" one means measuring the resistance through the full temperature range. If you only check the sensor with the engine at operating temperature, and the sensor is broken/stuck in that reading, you'll get the appropriate resistance and still have the engine problem at colder temps.
* Thoroughly checking a temp sensor (not just taking a spot reading) is time consuming and a logistical hassle. Temp sensors aren't that expensive and are usually far easier to replace than to thoroughly check. If the symptoms point to a possible faulty temp sensor I just replace them. In fact, on higher mileage engines I routinely replace temp sensors as part of preventive maintenance (in the same way that I would replace plug wires). Realize that you've got maybe a $40 sensor providing information to manage several thousand dollars worth of controllers and actuators.
* Also, a new temp sensor can get rid of a variety of intermittant, mysterious and ideosyncratic symptoms.
ASE Master Tech
Quality Enterprises
Mercedes Svc. & Restoration
Sheridan, IN
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Old 03-01-2008, 12:59 PM
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Join Date: Aug 1999
Location: Florida / N.H.
Posts: 8,804
< >>

Test heater circuit at O2 sens....
A Dalton
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Old 03-03-2008, 07:27 AM
Registered User
Join Date: Sep 2004
Posts: 31
Can I replace the sensor myself? If so where is it located? anyone have any pictures?

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