S420 bad idle for 20 seconds
09-17-2017, 10:28 AM
#1
Newbie
Thread Starter
Join Date: Sep 2017
Posts: 1
Likes: 0
Received 0 Likes
on
0 Posts
W140 S420 1997
S420 bad idle for 20 seconds
Hi Guys
Have a 97 S420 which I have had for 12 years or so, symtoms I'm having are as follows
Starts fine, runs fine until I stop at a junktion or lights, idles poorly for 20 to 30 seconds then smooths out have tried _
New plugs
New MAF
Replaced several coil packs
Replaced oxygen sensors
Ran injector cleaner through a tank of fuel
Get no check engine lights
Have run and OBII test codes P0308, P0302 and P0300
So thats cylinder 2, 8 and random misfire
Haves swapped coli packs from side to side no difference, checked the date of manufacture on the upper engine wiring harnes may 97 so should be the updated one
Have been told that the ECU may need reseting, has anyone had anything like this
Hoggy
Have a 97 S420 which I have had for 12 years or so, symtoms I'm having are as follows
Starts fine, runs fine until I stop at a junktion or lights, idles poorly for 20 to 30 seconds then smooths out have tried _
New plugs
New MAF
Replaced several coil packs
Replaced oxygen sensors
Ran injector cleaner through a tank of fuel
Get no check engine lights
Have run and OBII test codes P0308, P0302 and P0300
So thats cylinder 2, 8 and random misfire
Haves swapped coli packs from side to side no difference, checked the date of manufacture on the upper engine wiring harnes may 97 so should be the updated one
Have been told that the ECU may need reseting, has anyone had anything like this
Hoggy
09-18-2017, 03:33 PM
#2
Out Of Control!!
I would have diagnosed the idle circuit before I went BS purchasing parts that would not solve the problem!
I just wish you purchased those parts from me!
I just wish you purchased those parts from me!
