W124 300 nightmares, maybe electrical?

[vadkit]

Hi guys! I have this 93 W124 300E 3.2 motor. Owned and loved it for more than 10 years, now it belongs to my wife. So here we go. First it have a problem with the idle, when in park sometimes rpm are just jumping ftom 800 to 1500 all by itself and now when she drives it for more than 25 miles, so car gets nice and hot something gets cut off, engine starts to shake like crazy, and speeds go down to 30 mph and wont get any faster. She drove it home tonight and motor was not running normal. I tried to shut it off and then immediately restarted and it was running normal again. I have no idea and I need help.
Please advise.
Thank You.

[nulu]

sounds like your armass airflow meter is going out, next time it happens , disconnect connection leave it off and restart , drive like normal and see if you can run it over 30mph, by disconnecting , computor reverts to a fixed operation ie ignores airmass, when mine when out thats what it felt like , surging and stalling, especially hot, or another possibility is overvoltage relay, its next to battery behing with a red fuse under a plastic cover = change it

[vadkit]

Originally Posted by nulu

sounds like your armass airflow meter is going out, next time it happens , disconnect connection leave it off and restart , drive like normal and see if you can run it over 30mph, by disconnecting , computor reverts to a fixed operation ie ignores airmass, when mine when out thats what it felt like , surging and stalling, especially hot, or another possibility is overvoltage relay, its next to battery behing with a red fuse under a plastic cover = change it

Thank You! Will try that first

[vadkit]

Originally Posted by nulu

sounds like your armass airflow meter is going out, next time it happens , disconnect connection leave it off and restart , drive like normal and see if you can run it over 30mph, by disconnecting , computor reverts to a fixed operation ie ignores airmass, when mine when out thats what it felt like , surging and stalling, especially hot, or another possibility is overvoltage relay, its next to battery behing with a red fuse under a plastic cover = change it

I tried to disconnect MASS sensor today, no difference at all, now it does it on the driveway just couple minutes after starts. How about overvoltage relay, can i test anyhow with a voltmeter? Thank You very much!

[nulu]

After carefully reading you first post it sounds like an ignition coil , or whats called a spark plug connector is failing, when that happens the ecu shuts down the misfiring cylinders so your 6 is now a four cylinder, take it to a shop so they can run an engine smoothmess test and if its acting up it will show the dead,s cylinders, ive had my 94 e320 for 18 years and its very reliable and easy to dignose, lets us know what fixes it, a bad coil will cause shaking and with 2 cylinders down will be slow, you have 3 coils and 3 connectors

[silverteam]

It seems like the throttle actuator is bad. Why don't you google these symptoms?

[vadkit]

Originally Posted by nulu

After carefully reading you first post it sounds like an ignition coil , or whats called a spark plug connector is failing, when that happens the ecu shuts down the misfiring cylinders so your 6 is now a four cylinder, take it to a shop so they can run an engine smoothmess test and if its acting up it will show the dead,s cylinders, ive had my 94 e320 for 18 years and its very reliable and easy to dignose, lets us know what fixes it, a bad coil will cause shaking and with 2 cylinders down will be slow, you have 3 coils and 3 connectors

The coil finnaly shoed up. And after some swopping, of course it was whe last one. Interesting, now when she started to run normally, check engine popped up given me #7 code. Does anybody know what that means? Thank You!

[nulu]

ignition system faulty, i googled it and someone had a sheet