Does the 87 190 Dt 2.5 have a rack damper adjustment? My problem is a lope at idle that started recently. And sometimes the engine goes into a fast idle mode with an increased rough idle. about 950-1000 rpms. (the engine is at operating temp)

I've replaced the following:
1. both fuel filters
2. delivery valve seals
3. rebuilt injectors
4. motors mounts about 4 months ago.

I'm also wondering if the mass airflow sensor has anything to do with idle on a diesel. I unpluged it while the car was running and no change was noted.

Any help or suggestions appreciated.

The EPC for your model shows an electronic idling control solenoid in the position of the rack damper. So, while I'm not really familiar with your model, it would appear not to have the rack damper (at least according to the parts book).

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

you have no rack damper.

It seems like your idle may have something to do with the idle adjustment on the firewall. It is a castelated dial with some numbers - I think 1 through 6.

I have never had the problem that you discuss, so my experience is limited.

alec

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84 300TD - 235k - Farbe "Surfblau" bought at 213k
87 300SDL - 131k - Farbe "PimpGold" bought at 115k
00 Klepper Faltboot Expedition Double

My 1987 300D would also occassionally idle at ~950 RPM. I never new why, but the electronic idle control (ELR) knob near the brake booster was inoperative. I swapped engines because of another issue and the knob now changes the idle speed. Using two cans of diesel purge helped clear up a less than smooth idle at 950 RPM. The air flow sensor and temperature sensor (inside the air flow meter) controls emissions on 1987 models - EGR, ARV. I don't even think your car has a ARV (that was used with the trap oxidizer on the 300D's).

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Brian Toscano

Thanks for the info, but I'm starting to think the rebuilt injectors that I installed are faulty. I never had the rough idle problem until they were installed. I guess i will have to follow through with the warranty.

The fact that it started AFTER the injectors is key information! Rebuilt injectors should be tested prior to installation to make sure that they are all within range. 5 bar is max difference if I remember correctly. They can be shimmed. This is part of the installation process and not necessarily a warranty issue.

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Brian Toscano

Here's one for you..........I decided to drop the car by the German Auto Center here in town and they found nothing wrong.

They told me most that come through the shop have the same light vibration at idle. ......So, I guess I must be use the to the smoothness of my old BMW. (hehehe!!!!!!)