Question about BMW Cars & Trucks
You must have missed the problem. There are a certain amount of things that the onboard computer can identify and Code with a "Check engine" light. Since you did not indicate you found a "check" light, then the problem must be with other causes that are not monitored by the onboard computer.
You should check the Vacuum level with the engine warm and running. Vacuum is not monitored, but is an important part of the operating engine. A simple Vacuum gauge is all that is needed.
A compression test of the cylinders will show if the valves and rings are operating properly. Low compression will result in low power.
You did not put in a Year or Model of BMW. A weak fuelpump or improper setting on a good fuelpump will certainly affect power whether it is an electric pump or mechanical.
Did you change the FUEL filter? Check tire pressure? Clean fuel injectors?
Some of the newer models use Electronics to time the valves and engine. On older models, timing chain stretch is possible unless you have gear to gear timing without the chain.
Be careful with cleaners through the air intake, some Electronics will be destroyed if anything but Electronics cleaners are used.
The use of subgrade fuel will affect power. Gasahol is becoming increasingly unavoidable, and lacks the punch that pure gas has.
If, after all of these things are checked, you do not find the cause, Dealers have computers which are attached to the car and the Mechanic DRIVES the car and all systems are recorded.
These devices cover far more than the onboard computer and the Mechanic can even ask questions of the car through the computer.
It may be a little expensive but consider this.
You have a car worth probably tens of thousands of Dollars and you have spent less than $100 on it in parts so far. These were normal maintenence items anyway and did not solve the problem. Now the guesses start getting expensive. It is probably cheaper to pay someone to test the car for the bad part, than to guess your money away on stuff you do not need.
I hope my solution helps you. Some of the compression tests can be done with a cylinder balance test Electronically for a preliminary idea. But if all cylinders are equally weak, you will need a pressure gauge test on each cylinder.
Please rate my solution and I am curious to what you will find, so once you do repair the problem; let me know and I can share with others having the same symptoms.
Posted on Oct 25, 2012
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Posted on Jan 02, 2017
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