W116032 450 SE USA Benzin in Öl

Higher than idle 2560 rpm / CO value increases to 11.17%
Lambda factor idling 0.803
Lambda Factor 2560 rpm 0.697
HC 472ppm
The mixture is very rich and can not be adjusted

BR.Petr

Hi Volker,
I am not sure if the previous posts were clear, so here is some explanation. The knob on the ECU is now at the minimum. If I turn the knob, the values go up (CO) so it works somehow - I presume that the throttle switch is adjusted properly. But even at the minimum position of the knob on ECU, values are too high.

If I measure the values at increased rpm’s, CO values go up (at 2560rpm CO is 11.17% for example). More rpm’s, more CO.

Please do you have any table showing the duration of the injection pulse on the vacuum in air intake manifold?

Regards,
Petr

Hi Petr,

okay, that means that idle-run switch is closed as poti works properly. An increasing CO value with increasing rpm is strange. Your injection pulse suring idle-run seems absolutely okay. Here my ideas of possible sources for problems:

1. cold start valve open, that would mainly effect idle-run CO. Close fuel pipe to cold start valve to see whether there is an effect on CO
2. Wrong fuel pressure or wrongly operating injectors (leaking, no spray)
3. Wrong ignition timing
4. Wrong temperature sensor vaules, especially water temperatur is very sesnsitive

Seeing your injector pulse width in idle-run, it is rather short than too long. So that should not be the cause.

Hi Volker,
Regarding your points:

1. Cold start valve checked, ok.
2. All injectors are brand new. Fuelpressure stable, exactly 2 bars, fuel pressure gauge connected all the time so I can see it during operation, also how long it will keep pressure after ignition switch off etc.
3. Timing ok, checked by stroboscope, ignition advance/retard checked - by disconnecting the vacuum lines.
4. all sensors meausred, values ok.

During the test run I connected first injector to oscilloscope. It is visible that ECU regulates the pulses - from 2,5 ms to 10,5 ms, during deceleration ECU cut off injectors. Injectors are energized again when I press the gas pedal. During 3 minute log interval I found out some additional pulses which I suspect it is not correct - see pic enclosed. These aditional pulses are completely random, but I cannot see them during idle speed log, only when I run the car on the road - under load. What could be wrong, any suggestion please?

Hi Petr,

those addtitional peaks look really strange. But they do not look like normal pulses generated by ECU. That is why I do not believe in addtl. pulses on trigger contact side. But they would of course open injectors and thus inject addtl. fuel. As we only talk 3V peaks, there are 3 possible reasons:

1. Connection between cables or grounding problems
2. EMC. That could only happen when those cables are VERY close to ignition cables
3. ECU problems (highly unlikely)

Do you see these addtl. peaks on all 4 injector groups at the same time. And are you sure that it is not a measuring failure?

You're right Volker
Tomorrow make a measurement on one entire group of injectors with direct contact to the control unit.
Also, these faulty pulses do not understand.

While seeking a malfunction in electronics, but it seems that all the possibilities I am.

Check the timing even distribution and function of the valve tappets.
There must be a mistake !!!!!!!
I want her to find !!!

Thank you very much for your help
BR. Petr