Question-------------------------
Followup To
Question -
As stated before engine wiring harness along with actuator, MAF sensor and 02 sensor all were replaced within the last month. My question was about the overvoltage relay and problems that it could cause in Idle.
Tom Leach
I have a 1993 300 E 2.8 w/o slip Mercedes Benz, I took my car into shop for surging idle and my engine wiring harness shorted out so I had it replaced. The shop told me that I had a bad 02 sensor and I had the shop replace the 02 sensor, but the car still surges. I put back in the old sensor and still have the same problem. Surge is still there. I was than told that I had a bad MAF sensor and the voltage is too much "1.5 warm engine.” I advise them that I could put this part in. The part did but did not fix problem. The car surges in gear and out and while driving the car hesitates as if it stops running for a brief moment and runs rich. I took the car back to the shop. I advised them of the problem. The shop told me that I had another Bad MAF. HUM. Sent back the MAF and replaced with a new one but still have the same problem. I started checking and found the harness to the throttle actuator bad no surprise. I replace the throttle actuator not cheap. The problem is better but surging. While the car was apart, I check the vacuum hoses and replace any that looked damaged I replaced gaskets to intake, fuel injectors "O" rings. Same problem, codes are 4,5,9,13.
I put a rheostat in the MAF and can reduce voltages, but the car has no power. The rheostat stops the rich fuel and surging. Nevertheless, with the voltage in specification, the car has no power and is not drivable. I remove the rheostat.
HELP what about the over voltage protection relay? I am lost. One note I cleared all codes, and I unhooked the battery each time before doing service to my engine.
Thanks for any help
Tom Leach
The part number in this car now is the Newer style 0005406745. I also noticed that the BYPASS hose looks like it is in a vacume squeezed together starving.? I am lost now.. Help..
Answer -
Bast advice:
Read this thread:
93 300E with idle surge,needs MAF, Wire harness, throttle actuator?
http://www.mercedesshop.com/shopforum/showthread.php3?p=752259#post752259
Then join: http://www.mercedesshop.com/shopforum/forumdisplay.php3?f=1
You will enjoy being a forum member.
MB engines from 1993-1995 suffer from the biodegradable, deteriorated wire insulation, inside the outer sheath = you may need to search the entire engine compartment harness for shorts.
AnswerThe OVP relay and the temp sensor that feeds the computer where in the thread.
I would replace both + pull the battery and inspect wires in that area with greatest care.
The only harness replaced is on the engine, others can have the same problem.
Please define BYPASS hose?
Are you speaking of the engine cooling system heater bypass hose?
