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MINI r56 n12 waving engine speed

2246 Views 4 Replies 3 Participants Last post by  mike1967
In my mini r56 with a 1.4 70kw N12 engine, when it comes down from revolutions, the motor fluctuates from 750 to 600 revolutions for 3-4 seconds. I have not been able to deal with this problem for a long time. Timing replaced - no improvement. Replaced pressure sensor in the intake manifold - no improvement Variable phase valves replaced - no improvement New engine controller - no improvement The entire electrical installation has been checked - no improvement Adaptation from Vanos and Valvetronic - no improvement There are also no errors in the engine. Do you have any ideas? Sorry for my English.
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You throttle bore sometimes if you are putting additives in your engine namely. Air filter recharge fluid. That you spray on a rechargeable Air filter for the engine will gum up the post at both ends of the throttle body that hold the disc shaped door(butterfly).
Or your throttle body could have just gone bad. compare your symptoms with this.
worth checking the fuel tank vent valve its on bottom of inlet manifold might be faulty,, but all this is might be,, need to scan car and live data it see what doing what try and work it out correctly,
Hey, the throttle is new, and so is the vapor valve in the tank. no error codes.
When driving with a computer, the only problem is that when it comes to idle, the RPM drops below 650rpm and it fluctuates for 4-5 seconds and the problem is gone. sometimes it is idling and the revs drop automatically to 650. This only happens on a hot engine.
Its revs are set to 800 but that didn't help either.
need to scan it live data see what its doing no point guessing or throwing parts at it.. if doing it when at running temps would suspect a 02 sensor or temp sensors maybe ,,
how the system works where engine cold the coolant temp sensor shows temps the ecu knows to use a preset choke cold start map until engine reaches a set temp around 60c it begins, ie the engine under this temp runs faster,,, the 02 sensors are a closed circuit type and dont do nothing until 600c ie ie a 02 sensors for signal makes its own voltage from hpow its made ie around 1.6volts and 0.45volts normal for correct fueling when exhaust is hotter than 600c, now wide band 02 sensors as mini have also have a heater circuit this is used for when the 600c is not reached so ecu can monitor the voltage and fuel car,, ie car when at full running temps switches to closed loop running,
this all said what can effect this working wrongly , 1 is the cat is blocked with oil burn crud this is common and reduces the hot gases reaching the down stream 02 sensor this can cause fueling issues as down stream 02 runs slower than up stream and is more important for fuel trim over time,, the up stream runs faster and controls mixture trim faster than down stream,
another issue might be cat has a hole in it on live data can tell if both sensors read the same voltages,,
or when blocked the 02 sensors will show one at top of volts and other at bottom.. live of a 02 sensor makers say 60 to 120k less on oil burning cars or cars with coolant leaks etc,
also the fueling system has a another tempo sensor that measures outside temps as ref point and also has a inlet maff temp sensor as well for temps in the inlet manifold,
as you can tell not the easy thing to work out even someone who works on them all the time will have a merry dance with it, also would only use someone who really knows the facts and dont use the try this approach
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