1996 S 420 Rough Idle
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Junior Member
Joined: Feb 2007
Posts: 70
Likes: 4
2013 S550
1996 S 420 Rough Idle
OK, so here goes.
1996 S420 with 170k miles.
A few months ago as I came off the highway the car started idling very rough and the SRS and one other light triggered as well as the check engine and the gas gauge light was blinking . The car actually went into limp mode.
So I had one ignition pack replaced (MB part) at the time as well as all the spark plugs but that didn't completely correct the problem.
Almost immediately the car started exhibiting a kind of "skip" or hesitation at high speed and would bog down and buck during acceleration. I was getting real bad gas mileage and a rotten egg (sulfur) smell. All things were pointed to a MAFS but the mechanic wanted $600 bucks, so I let the car sit for awhile and then today replaced the MAFS with a cheap aftermarket brand and now she runs great on the highway and has great acceleration if you put the spurs to it.
But she is still rough at idle with jumps in RPM as many as 2 to 3 hundred jumps. The car is physically shaking.
I recently disconnected the batter to clear the check engine light that was initiated by the bad mass air flow sensor. Not sure if I've driven enough for the computer to register.
Not sure what else to do. Thinking about the rest of the ignition packs but they are so damn expensive
1996 S420 with 170k miles.
A few months ago as I came off the highway the car started idling very rough and the SRS and one other light triggered as well as the check engine and the gas gauge light was blinking . The car actually went into limp mode.
So I had one ignition pack replaced (MB part) at the time as well as all the spark plugs but that didn't completely correct the problem.
Almost immediately the car started exhibiting a kind of "skip" or hesitation at high speed and would bog down and buck during acceleration. I was getting real bad gas mileage and a rotten egg (sulfur) smell. All things were pointed to a MAFS but the mechanic wanted $600 bucks, so I let the car sit for awhile and then today replaced the MAFS with a cheap aftermarket brand and now she runs great on the highway and has great acceleration if you put the spurs to it.
But she is still rough at idle with jumps in RPM as many as 2 to 3 hundred jumps. The car is physically shaking.
I recently disconnected the batter to clear the check engine light that was initiated by the bad mass air flow sensor. Not sure if I've driven enough for the computer to register.
Not sure what else to do. Thinking about the rest of the ignition packs but they are so damn expensive
Thread Starter
Junior Member
Joined: Feb 2007
Posts: 70
Likes: 4
2013 S550
How difficult of a job is it to replace ignition coil packs? My kid studies auto mechanics in High School and has access to all sorts of tools, lifts, etc.
I can't find anything on line showing how to replace these parts.
I can't find anything on line showing how to replace these parts.
Thread Starter
Junior Member
Joined: Feb 2007
Posts: 70
Likes: 4
2013 S550
Finally got my hands on a scan tool and learned that the car is throwing a P0410 code. From what I gather this can be problematic as it could be a multitude of issues and difficult to diagnose.
Thread Starter
Junior Member
Joined: Feb 2007
Posts: 70
Likes: 4
2013 S550
hello forum.
wanted to return back and post the final resolution.
turned out the car needed a replacement MAF and it had a vacuum leak.
The cheap MAF I selected didn't do the trick, so a shooting buddy of mine who's a benz mechanic took the car. His $300 MAF worked, and he found the vacuum issue.
Car runs strong again.
Showing some transmission slip, so days may still be numbered, but at least if it goes I'll know why, and have a clear conscience.
wanted to return back and post the final resolution.
turned out the car needed a replacement MAF and it had a vacuum leak.
The cheap MAF I selected didn't do the trick, so a shooting buddy of mine who's a benz mechanic took the car. His $300 MAF worked, and he found the vacuum issue.
Car runs strong again.
Showing some transmission slip, so days may still be numbered, but at least if it goes I'll know why, and have a clear conscience.
