rough idle e320
#1
rough idle e320
I bought a 94 E320 3 weeks ago, it was fine . just yesterday i was warming it up I found it shakes and then go smooth and may be after 20 seconds shakes again and keep doing that. it do that when it is on park on D in the stop lights.I would like to find out from anybody in this forum for suggestions, why is that ? thanks for the help
#4
RE: rough idle e320
I suspect a bad Overvoltage Relay. These were a troublesome part on 123.032 and have been upgraded.
The relay is a tall aluminum can w/fuse on top.. behind the firewall panel [ blk plastic] on the passenger side. If the original relay is still there , change it to the newer part #
Old part # 000 540 52 45 [ Siemens manufacture]
New part 000 540 67 45.
I also recommend changing the 3 plug connectors/resistors under each coil. Another common problem area on HFM/SFI waste spark ignition systems.
A Dalton
Benz Tech/Collector
As SL noted , ...The wire harness issues with these was insulation degradation due to the use of bio-degradeable materials. You can usually find flaking insulation at the sensor connectors at the thermostat housing. Most of these have been upgraded by now.
Is your car showing a Check Engine light ???????
The relay is a tall aluminum can w/fuse on top.. behind the firewall panel [ blk plastic] on the passenger side. If the original relay is still there , change it to the newer part #
Old part # 000 540 52 45 [ Siemens manufacture]
New part 000 540 67 45.
I also recommend changing the 3 plug connectors/resistors under each coil. Another common problem area on HFM/SFI waste spark ignition systems.
A Dalton
Benz Tech/Collector
As SL noted , ...The wire harness issues with these was insulation degradation due to the use of bio-degradeable materials. You can usually find flaking insulation at the sensor connectors at the thermostat housing. Most of these have been upgraded by now.
Is your car showing a Check Engine light ???????
#6
RE: rough idle e320
Ok
If no CE light , your car is not Cal spec. [ Emmissions module N59], but Fed spec [ I am assuming you are in USA??
Under the hood , in front of battery..blk box with lid .. open lid and see a 16 pin/socket connector.
You can retrieve fault codes from this box with a simple $5 DIY tool.
Check that box and tell me if it has a sw/led in positions 2 and 4.
If no CE light , your car is not Cal spec. [ Emmissions module N59], but Fed spec [ I am assuming you are in USA??
Under the hood , in front of battery..blk box with lid .. open lid and see a 16 pin/socket connector.
You can retrieve fault codes from this box with a simple $5 DIY tool.
Check that box and tell me if it has a sw/led in positions 2 and 4.
#9
RE: rough idle e320
I had this problem before and it was the computer. I replaced the overvoltage regulator and that did not fix it.
For the wiring connector, I cleaned it with PCB board cleaner to eliminate poor contacting.
You should also check fuel system. A bad injector can caused misfire.
For the wiring connector, I cleaned it with PCB board cleaner to eliminate poor contacting.
You should also check fuel system. A bad injector can caused misfire.
#10
RE: rough idle e320
If you are talking about your E420. it does not have an OVP.. I think you are confusing the voltage regulator and OVP.. different part/function..
The most common misfire fault codes on 104 engines are caused by the 3 plug connectors under each coil. This is a waste spark system and each coil fires 2 cylinder at the same time, in series. So, bad coil connectors cause misfires in both cylnders
Due to there high failure rate and cheap cost [ $9 ea], we change them whenever doing a plug change.
PS . Use only Bosch Super copper core plugs in 104s , never plats ...
Bosch F8DC4.
The most common misfire fault codes on 104 engines are caused by the 3 plug connectors under each coil. This is a waste spark system and each coil fires 2 cylinder at the same time, in series. So, bad coil connectors cause misfires in both cylnders
Due to there high failure rate and cheap cost [ $9 ea], we change them whenever doing a plug change.
PS . Use only Bosch Super copper core plugs in 104s , never plats ...
Bosch F8DC4.