1990 240dl bad idle-stalling

glowbug · Post by **glowbug** » 03 Sep 2010, 07:27

I just purchased a 1990 240DL automatic, my first of the 200"s I had a 850 previously, so I am not too familiar with them, I love it But I have some what of the same issues, I brought it home and I decided to check the air filter, when doing so I removed the whole air intake tube not realizing to disconect the battery before unpluging the MAF, I started to clead the tube the screen in front of the MAF reinstalled everything and the car ran funny, well I unplugged the batt let the old comp reset itself, and it seemed to run okay but rough idle, I can drive the car but at idle it starts dying, I checked the hoses to the Brake servo it is okay, I did the spray down the engine with the carb cleaner and found no leaks, but I did notice when I unplug the MAF it seems to run a bit better not by much, what gives?/? anyone??
I am going to swap the spark plugs, Dist. cap and rotor today, and check the idle control valve. If any one has other suggestions let me know, thanks

glowbug · Post by **glowbug** » 03 Sep 2010, 09:42

UPDATE, I replaced spark plugs,Dist. cap and rotor(dizzy) w/ Bosch. I removed the throtle body and cleaned it, I removed the idle control valve and cleaned it, checked all intake tubes(ok) checked the 25amp fuse and cleaned the terminals(behind the battery) , I started it up and it start but now it will not idle it dies. I ran it for a few minutes and let it idle again and same it dies.
So I unpluged the MAF sensor, and it idles with no problems. Runs a bit rich but it runs great.
Am I to Assume that it is my Mass Air Flow meter after all ?"??????????????????????????????????????????????????

Post by **billofdurham** » 03 Sep 2010, 11:18

It certainly looks that way. Have you checked for any fault codes stored?

Bill.

glowbug · Post by **glowbug** » 03 Sep 2010, 22:24

no I did not have a device to check with, should I invest in one? I do plan on possibly holding on to the car far a while it has 163K on the odo, but runs so smooth and well cared for, one owner car, well maintained, I do not know much about them, as I have been more of a Mercedes diesel fan, Old Volkswagens and of course Classic Mini Coopers. So with that stated is this a desireable vehicle for reliability? Here in the states we have so many choices and affordable. But I have invested this much I might as well go on and finish it, if you can think of something I might of overlooked please do not hesitate to give me a pointer or two, thanks

Retired MVS Contributor · Post by **Retired MVS Contributor** » 04 Sep 2010, 07:25

glowbug wrote:no I did not have a device to check with, should I invest in one? I do plan on possibly holding on to the car far a while it has 163K on the odo, but runs so smooth and well cared for, one owner car, well maintained, I do not know much about them, as I have been more of a Mercedes diesel fan, Old Volkswagens and of course Classic Mini Coopers. So with that stated is this a desireable vehicle for reliability? Here in the states we have so many choices and affordable. But I have invested this much I might as well go on and finish it, if you can think of something I might of overlooked please do not hesitate to give me a pointer or two, thanks

You do not need any special devices to read the codes...There is a built in "flashing LED" code reader under the hood on the left side near the firewall...You need the documemtaion for reading it which can be downloaded from this site...Disconnecting the MAF while the battery is connected will not hurt anything as long as the ignition key was off...There is a large (about 2 inch diameter) pleated black plastic hose connected between the MAF and the throttle body...This hose often cracks on the bottom where it is out of sight...This allows unmetered air to enter the intake and throws everything out of whack...Remove and flex that hose to check for cracks or chafing from the cables running under it...

glowbug · Post by **glowbug** » 05 Sep 2010, 07:00

Check, did that earlier forgot to mention in the post, I verified all connections, good seal on all hoses, including on brake servo(booster). Thanks for the black box info, I read earlier how to clear check eng lights but did not read up on code reading thanks I will look at it. and reply

glowbug · Post by **glowbug** » 05 Sep 2010, 09:33

Okay, did the test, on port #2 the tests as follows 1st test fault code is 121 according to the info I got from this site 121 code is a faulty Mass Air sensor or a O2 heating element (?????) where is the O2 heating element??

On port #6 code reads 111 which is good( phew)

Should I just go ahead and replace the MAF.????

Retired MVS Contributor · Post by **Retired MVS Contributor** » 05 Sep 2010, 09:59

The heater is buit into the oxygen sensor itself...

glowbug · Post by **glowbug** » 12 Sep 2010, 14:34

changed the MAF and "Voila" all systems are a go, I do thank you gentlemen for all your help.

Post by **billofdurham** » 12 Sep 2010, 14:58

Thank you for the update.

Bill.