450Se D-Jetronic idle issue
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Joined: Mar 2021
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From: New Zealand
1975 450se
450Se D-Jetronic idle issue
Hi all,
I have recently purchased a 1975 450se (D-Jetronic) to upgrade with my wheels and air suspension from my 1976 280Se which sadly has been found to be very rotten across the underbody and molested under the dash to the point of no return.
To provide some backstory on the 450Se I had purchased it from a "home mechanic" who worked on it and "tuned it" themselves, this tune included winding the idle air screw right out and turning the rich/lean screw right the way to Rich causing it to over fuel and flood when sitting in traffic or when sitting at a set speed on the open road.
I have since adjusted the Idle air screw, rich/lean screw and throttle linkage to balance out the idle, I have also replaced the spark plugs and cleaned up the Dizzy points and rotor which has given me a much more controlled idle.
However randomly I will get a drop in Revs causing the motor idle to float, come flat again but then float again and I just cant seem to figure out the cause so any help is welcome.
Other things I have done:
- Checked all vac hoses to ensure no holes or leaks
- Removed checked and confirmed the idle air controller opens and closes with the water temp
- Unplugged the cold start injector incase it was getting false triggers (did not stop it)
- Unplugged the air cleaner temp sensor incase it was giving false readings (did not stop it)
- Checked intake butterfly was not moving (was not floating at all)
If anyone has encountered this before and has some advice that would be great, in short it appears that I am either overfueling randomly or starving the air supply randomly as I have had multiple events of the car dieing due to flooding.
I will try add a video to better explain the issue
I have recently purchased a 1975 450se (D-Jetronic) to upgrade with my wheels and air suspension from my 1976 280Se which sadly has been found to be very rotten across the underbody and molested under the dash to the point of no return.
To provide some backstory on the 450Se I had purchased it from a "home mechanic" who worked on it and "tuned it" themselves, this tune included winding the idle air screw right out and turning the rich/lean screw right the way to Rich causing it to over fuel and flood when sitting in traffic or when sitting at a set speed on the open road.
I have since adjusted the Idle air screw, rich/lean screw and throttle linkage to balance out the idle, I have also replaced the spark plugs and cleaned up the Dizzy points and rotor which has given me a much more controlled idle.
However randomly I will get a drop in Revs causing the motor idle to float, come flat again but then float again and I just cant seem to figure out the cause so any help is welcome.
Other things I have done:
- Checked all vac hoses to ensure no holes or leaks
- Removed checked and confirmed the idle air controller opens and closes with the water temp
- Unplugged the cold start injector incase it was getting false triggers (did not stop it)
- Unplugged the air cleaner temp sensor incase it was giving false readings (did not stop it)
- Checked intake butterfly was not moving (was not floating at all)
If anyone has encountered this before and has some advice that would be great, in short it appears that I am either overfueling randomly or starving the air supply randomly as I have had multiple events of the car dieing due to flooding.
I will try add a video to better explain the issue
