What is Limp Mode?
Your engine management and maybe even your transmission is controlled by the ECU. As you know, all computers crash, all software has bugs, and mechanical equipment fails. As such, many ECU units are fitted with a 'limp home mode'. When it detects that something semi-serious is wrong, it enters the limp mode, which means that the engine won't rev beyond a pre-programmed speed, you can't accelerate very fast, or you may indeed be speed-restricted to 40 mph or similar. The transmission may even stay in one or two gears. Bad? Well, no, not really: The alternative would be to either let you drive at regular speeds, with the danger of letting you trash your car (expensive repair, means happy repair people, but angry driver), or stopping you from going anywhere (expensive recovery and stranded on the side of the road means happy recovery company, but angry driver).
Symptoms of Limp Mode:
- Slow acceleration
- Engine wont rev beyond a pre-programmed speed
- Speed restricted to 40mph or similar
- Bad/sticking VNT actuator or turbo vanes
- EGR or exhaust leak can also cause limp mode
- If the fuel filter has not been changed in the last 20,000 miles, it is possible that it is clogged and is restricting fuel
- It could be the MAF air flow sensor contributing to the problem although this normally isnt the sole cause.
- The intake is more than likely clogged with carbon and that is causing the limp mode
The car's computer is constantly monitoring sensors such as air flow, EGR flow, fuel flow, etc., and is expecting certain values. If a sensor sends a signal that is "out of bounds" through malfunction or failure, the car's computer will fall back to a safety map or cut fuelling and turbo boost to prevent damage. This is because over boosting or over fuelling could cause engine damage. A diesel is built sturdier than a petrol engine and boost spikes are normal in a diesel. Even still, any engine has limits so the computer pulls back engine power to prevent these limits from being exceeded.
Diesel Turbo Cleaner is designed to cure your limp mode and with the easy to follow instructions, it will save you £100's on garage bills, so for only £49.99 give it a try and you will be surprised with the results.