That is what I suspected.

Is there a link in how to update this system?

My 971 is have these issues too. Starts great then lumpy with smoke.

Not sure if there's a DIY on this forum or not. The .97 glow plug relay uses an extra pin in the control wiring plug that runs out to an extra temp sensor in the head. Essentially all you need to do is add the extra wire and temp sensor and swap the relay out.

The poor man's version of afterglow is to lift the purple wire on the .96 glow plug relay control wiring harness. The purple wire is the starter interrupt signal, so lifting it forces to the glow plug relay to run to it's full 30 second cycle, even if the engine has been cranked.

Be aware that afterglow can help mask injection or compression problems but will not eliminate it.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

W124/OM603 Afterglow DIY

You can try lifting the purple wire to do a test but not as a fix. It will leave the gp on for 30 sec even with hot engine. It will burn out gp quickly.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.