I've had a surging idle problem with my '87 190D 2.5Turbo since I bought it last winter. Normally, I can't see the tachometer move, but I can definitely feel the surging, and with the hood open, I can see the stop lever oscillating up and down with the surge. It seems to me that the stop lever oscillating up and down might indicate an internal IP problem, but that's mostly speculation.

Any ideas for fixing this issue would be appreciated. The fuel filters have been changed. I have verified that the ELR functions, although I'm not convinced that it functions correctly. If I unhook the ELR, the idle speed drops considerably. I recently purchased the socket to change delivery valve seals, but I don't have a good idea whether the delivery valve seals can create this condition.

I have used the search feature, and this problem doesn't seem entirely uncommon, but I haven't read about anyone who has successfully eliminated this problem from the 602 or 603 engines.

Any help is appreciated.

SteveM.

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'93 190E/D 2.5 Turbodiesel 5-speed (daily driver)
'87 190D 2.5 Turbo rustbucket - parts car
'84 Dodge Rampage diesel - Land Speed Record Holder
'13 Ram 2500 Diesel
'05 Toyota 4Runner

everything else is fine, but the idle surges to the degree where it is felt but does not register on the tach. It is a subtle hum up & down.

Does anyone have any ideas???

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Stable Mates:
1987 300TD 310K mi (Hans)
2008 Jeep Grand Cherokee OM642 165k mi (Benzrokee)

Sorry but no replies just bumping the thread

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Stable Mates:
1987 300TD 310K mi (Hans)
2008 Jeep Grand Cherokee OM642 165k mi (Benzrokee)

As I had mentioned in previous posts, mine does something similar sometimes when dropping into idle at an intersection or stop light. If it's at idle, it never wavers. It's just the transition that randomly results in a little fast idle that slowly, slowly drops down to regular (if I hit the throttle before it does this and then back off, it immediately goes to regular idle). Not sure if this is similar to what your 603 is doing.

I'm pretty sure mine is an EDS issue, which can occur with several components. My indy says he sees the overvoltage protection relay (located behind the battery in the plastic cavern of electronic fun) is often the culprit. With the weather as it is I haven't had time to play with it.

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1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--370,000 miles
2005 Jeep Liberty CRD Limited, light khaki/slate--140,000 miles
2018 Chevy Cruze diesel, 6-speed manual, satin steel metallic/kalahari--19,000 miles
1982 Peugeot 505 diesel, 4-speed manual, blue/blue, 130,000 miles
1995 S320, black/parchment--34,000 miles (Dad's car)