Still having rough idle on strat up
 

1989 300E. I complained about this problem before. When I start the car in the morning the car runs very rough and even sometimes the car will stall. When starting the car I have to keep pressing the gas petal to keep the car running then I quickly put the car into drive and away I go. The ar runs rough for about 3 - 5min then the car runs great. I could turn the car on and off as many times as I want and there is no problem. The only time this happens is when I have the car turned off for long periods of time. I just did the fuel fliter, both fuel pumps and a fuel injection flush and the problem is still there. The car has 710,000km on it.

Could you please help?

Thanks,

Fab

710,000 km :eek: wtf, are you kidding. does it have original engine and trans.
well i shouldn't be surprised, i have seen mercedes where the odometer rolls over and it still runs good. anyway with such mileage i think there would be a lot of deposits on the egr valves. try removing the valve cover and cleaning it up.
when was the last time you have done a tune up? maybe it's a distributor cap, wires or plugs issue.

I replaced the trany last year and I just replaced the original exhaust on Tuesday. The engine is still original. I changed the plugs, fuel filter and air filter 6 months ago. I have not changed the wires, dist cap and rotor in over 3 and half years. Is there a way to test if the wires, dist cap and rotor need to be replaced?

I never checked the EGR valve. Where is it located and how do I test and clean it?

Thanks

Fab

Get a Windex bottle full of water.
Start the engine & let it idle.
Spray the wires & cap with water.
If there is ANY change in idlespeed?quality, or you see sparks arching, you will need to replace them. ;)

I will look at the wires and cap today but how do I check the EGR valve and where is it located?

I tested the wires and dist cap as suggested and there was no change in the idle of the car.

also
 

check the inside of the cap. and rotor if ther is one. if chewed up change. what about plugs?

tom w

Plugs have been changed. I will inspect the inside of the cap and rotor.

Thanks

I checked the inside of the cap and rotor and to me they seem to look fine. But since I did not change them in 3 years I am going to replace them. If this does not solve me problem should I be looking for anything else. Someone mentioned EGR valve. Where is it located and how do I test and our clean?

Thanks

fab

the only way to clean the EGR valves is ro take the valve cover off and clean them manually. carbon deposit on the valves can affect the fuel air mixture by absorbing some of the fuel and causing rough idle. additional buildup can case loss of compression and can lead to engine damage. the valve cover is usually located on the top of the engine usually with rubber breather hoses connecting it to the air intake.
here is a link to a website i'm sure you will find very helpful enjoy: ;)
http://skinnerbox.steaky.org/Service/W124/Index/103index.html

Check the Water Temp Sensor. Probably bad and telling the CIS-E Ecu that your engine is warmer than it really is and thus not enough fuel enrichment for cold idle. Fairly simple to check with a VOM. Once you find the chart that corresponds to the temps. If temp of block and coolant is less than 40 degrees you need enrichment. That may be even colder than 50 but I do not recall. Search on 190Rev forums for my userid and Water Temp Sensor. Not sure I ever posted the chart here.

Water temp sensor, cold start injector, idle air valve--these three components work together on this engine to provide the "choke" and extra idle air ANY gasoline-powered engine requires to start and run stone cold. Since a stone cold engine requires a rich mixture to start and run, vacuum leaks additionally serve to disprupt this process.

If the engine runs fine otherwise and has power to accelerate hard when warm, nothing's wrong with ignition system and changing plugs/wires/cap is just throwing money at the problem. It's a common solution guessed at for many, many problems here, but these components--if oe quality--are in fact nearly bulletproof.

Ohm's range from the temp chart in the /Engine Manual-Combustion Manual-07.3 Mechanical/electronic gasoline injection system (KE injection)-121 Testing electrical components of KE injection system. page 60

Temperature °C........Resistance kΩ
-20........................15.7
-10.........................9.2
0............................5.9
10...........................3.7
20...........................2.5
30...........................1.7
40...........................1.18
50...........................0.84
60...........................0.60
70...........................0.435
80...........................0.325
90...........................0.247
Same resistance values apply to KE intake air temp sensor.
I think this chart applies to these 2 sensors for all KE systems but don't know for sure.