How do I check codes?1994 e420

My car is running good now that I cleaned the distributor caps and put in new plugs but it idles too high. It is idling around 1300-1400 rpms in park and doesnt kick down. The old plugs I pulled out were really
black and someone down the line pulled out the bulb for the check engine light which I replaced. Im thinking it has something to do with the temp sensor to the computer and that its not telling the car it is warm. There are 3 sensors that all go into the coolant side by side each other in the front of the motor. The first one has a single round connector that attatches at the top(which I think is for the gauge?) The second one has a black plug with 4 connections in it (assuming the computer?) The third one when I unplug it the fans come on and it has 2 connections (fans). Thanks:)
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The blue two prongs is for aux fan. the black 4 prongs is for computer... The 1 prong... if it is black, then it is for the gauge. Red one is for the engine also... something to do with cooling.
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Hello:) Thanks for the reply again. I found diagnostic plug and pressed the button for 3 seconds with the key on. It flashed 6 times then it stopped and I waited and no more codes. I pressed the button again for 3 seconds and this time it flashed 7 times with no more flashes. Pressed it again and then 8. Pressed it again and then 9. Pressed it again and then 10. When I pressed it again it went back to the 6 and continued the 6,7,8.9.10 ...am I doing this right?? Thanks Tiger! :)Nel
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Yes, you are doing it right... Here is the diagnostic code definition.
http://www.benzworld.org/forums/w124-e-ce-d-td-class/1229198-code-reader.html
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clear codes now by the unplugging the battery method for about an hour(hope this works). I may have set off some of these codes as I was working under the engine unplugging things. I have a high idle and it seems to run rich (1300-1400) rpms in park. I have codes (6)idle speed control faulty. (7)ignition system faulty. (8) engine coolant temp sensor open circuit(is this the one that goes to the computer?). (9) intake air temp sensor open circuit. (10) voltage to mass air sensor too high/low. I will clear the codes and go from there. Thanks again! :)Nel
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I reset computer and ran car for about 20 minutes and let it warm up. Check engine light was reset and came back with only 2 codes this time..(4) Air injection system faulty hot film mass airflow sensor with hot wire...what on earth does this mean...could this be because I have the aircleaner assembly off?? The other code was (6) idle speed control faulty. Where is the idle speed control? Thanks again:)Nel
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I originally suspected your Air Flow Meter is bad... so I can understand that... Make sure it is plugged in. You can try to clean it... but majority of time will not do a darn thing.
As for your idle speed... I suspect you got a massive vacuum hose leak somewhere... you need to find it... spray carb cleaner on suspected hoses... if the engine sputters in any way, you know it is leaking there.
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Hello, For the airflow meter(it looks like brand new) It has a remanufactured sticker on the side and it looks new?? How do I clean this..there is a large round plug on the side of the maf and its plugged into a black box on the side of the maf. Do I just spray throttle body cleaner down the flap or??
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The weird thing with the idle is when its cold the idle is ok for a few minutes until it warms up and then it gets higher?? I will spray carb cleaner and go from there.. Thanks:)Nel
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Mmm... leave the MAF alone for now...
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Ok...I goofed...should have read your email before I started. I went to clean the maf and decided to remove it and when I grabbed it the rubber sealing it to the throttle body seemed loose but the clamp holding the rubber sleve to the maf was tight. I pulled it off and noticed one of the fillaments isnt even connected so Im guessing its definately bad. When I looked down into the tb it was filthy! So I will clean that tomorrow. I noticed that the little round hole in the tb that has the hose that goes to the valve cover for air was clogged. I removed the valve cover and I have never seen anything like this in my life! It looked like someone packed the valve cover with grease. After cleaning it out and the little pocket that ventilates the tb I have now installed it back on. I bought a used maf tonight from a friend on ebay and will keep my fingers crossed that this fixes it. Could the clogged up hose going to the tb and a very dirty tb keep the throttle up at 1300 rpms? or maybe the rubber seal between the tb and maf was leaking?
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Well you did the right thing then... I don't understand why it is so dirty... it never suppose to be dirty. Check your air filter.
I would never buy a used MAF... the reason is there is no real way to test them.
As for installing, and removing, you are supposed to take off the hose on one side... usually the one toward the engine... at the engine side first... then pull the hose off the MAF and then take off the MAF.
IT is supposed to be secured by like giant hose clamp or something similar... I am not sure on your engine. It could be a slip joint lock.
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Thanks again and Ill let you know how it goes.
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What is the correct way to reinstall the maf? Does any kind of silicone hold the rubber onto the tb? Do I install rubber sleve onto tb and then maf onto rubber and then tighten clamp?? Thanks again! :)Nel
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I am chasing a high idle so Im guessing the blue 2prong for the fan and the single black for the gauge would have nothing to do with it. Must be the black 4prong for the computer. Dont see the red one?? You must have been working on these cars forever?? Thanks again:)Nel
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