Mercedes 126 Repair – The High Idle Saga


A single of the most common Mercedes 126 repair issues is a higher idle. Generally, the perpetrator is digital, but in some cases a basic mechanical adjustment of the throttle linkage will remedy the trouble. Of program, older engines are probably to experience from consumption vacuum leaks of varying severity, and these also can trigger idle issues. We shall look at vacuum leaks in one more report.

Electronic Results in OF Substantial IDLE

  1. The idle manage module, situated driving the fake bulkhead upcoming to the Abdominal muscles manage device, is the most common trigger of issues. The module processes a assortment of inputs and controls the voltage sent to the idle manage valve, which bodily regulates the amount of air supplied to the consumption ports any time the throttle valve is closed. It is unquestionably helpful to have a recognized doing the job device available for diagnostic purposes. While there is no a single place of the circuit board that we can place to as a regular spot of cracked solder joints, there are 4 capacitors which are likely to die with age. New models expense well over $200 and even rebuilt models are very costly. I strongly suspect that, in most conditions, all the rebuilders do is switch the capacitors.
  2. The idle manage valve can experience from two issues. The electrical solenoid can are unsuccessful or, additional typically, the valve merely will become gummed up with oily deposits. (Some of the crankcase ventilation fumes are routed as a result of the valve.) A very good soak in carb cleaner will commonly remedy this ailment. Be cautious not to expose the electrical aspect of the valve to the solvent.
  3. Very hardly ever, there is an difficulty with the lambda manage device, the closest point these autos have to an Eu. The idle manage device is linked to the lambda controller and “appears to be for” indicators therefrom. Typically, if there is an difficulty with lambda manage the motor will be functioning inadequately anyway (due to incorrect gasoline mixtures). If the lambda controller is not functioning at all, the most common explanation is a failure of the over-voltage defense relay (OVP) situated in the fuse box. There may also be a weak floor link. The device itself appears to be exceptionally trustworthy, maybe due to the fact it lives in a cooler local weather — upcoming to the front passenger’s ft.
  4. If the idle trouble takes place only when in a single particular equipment, the starter-lockout change on the facet of the transmission may be faulty.
  5. If the trouble takes place only when the A/C is employed, there may be difficulty with the hold off relay in the fuse box, which is meant to increase motor revs when the compressor engages, thus stabilizing idle velocity beneath heavier accessory loads.
  6. Finally, the throttle placement change (TPS) on the facet of the throttle body may be defective. This is quite abnormal and we should really be grateful for that, considering that substitute of the TPS calls for removal of the whole consumption manifold. From time to time the change is merely out of adjustment and can be tapped again into the ideal placement with a lengthy punch.

The TPS informs the idle manage device when the throttle valve is closed, partly open, or huge open. Electrical continuity exists throughout a single pair of 3 pins, throughout one more pair, or not at all. If the proper indicators are not getting sent, the change itself could possibly be properly great the trouble may merely be that the throttle linkage is out of adjustment. The change is exceptionally sensitive even the slightest opening of the throttle is more than enough to split continuity throughout the pertinent pins. So it will not consider significantly excessive stress from the linkage to disrupt the program. Make certain that the throttle valve is in reality closing against its quit.

A single other simple aspect to look at – and a single which tends to be neglected in this context – is your ignition timing. As well significantly ignition progress will most unquestionably have an impact on idle velocity. On the Gen I autos, there is a good deal of scope for adjustment, and the engines can cope with quite a bit of progress ahead of they begin to detonate (ping). All over 10 degrees of initial progress is ideal. Bear in intellect that the vacuum progress device adds about sixteen degrees of progress at idle (when manifold vacuum is higher). Once in a while, the progress device can trigger issues, the main a single getting a rupture of the inside diaphragm and generation of a vacuum leak at that place.


Source by Richard M Foster

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