These are the actions you should take, in the order you should take them:
- Check if Limp Mode has Been Engaged – The overdrive light will be flashing
- Check Fluid Levers – Both the engine and transmission fluid levels
- Check Wiring – Look for damaged wires
- Check Air Filter – No blockage
- Check the Fuel Filter –Not clogged
- Timing Belt – Look for excessive wear
If your cargo van won’t go over 50 mph, it could be due to several reasons, but more likely than not it is due to the computer placing the van in limp mode.
Limp mode is a term which has been given to a vehicle’s ability to help restrict damage to the engine or transmission by reducing their capabilities.
Manufacturers place several sensors throughout the vehicle’s different systems, and link them to the vehicle’s computer. If a sensor reports to the computer a potential problem, the computer engages the “limp mode.” This will restrict the vehicle’s ability to accelerate or increase its rpm excessively.
It is hoped these restrictions will avoid further damage and enable the vehicle to safely reach (limp to) your home or your mechanic’s workshop.
It is of course possible that your van won’t go over 50 mph, but the computer is not aware of a problem due to a faulty sensor, which is why there are other actions you may need to take as well.
Check if Van’s Computer is in Limp Mode
If the computer has instigated limp mode, it will also make the overdrive light continuously flash to bring your attention to it.
One of the sensors will have detected a potential fault which left unchecked may severely damage the vehicle. Inhibiting the van’s ability to over rev or over speed could avoid major, expensive damage occurring.
If your van is in limp mode, it is temporarily safe to drive with the restrictions,, but the potential problem should be found and attended to as soon as possible.
Over Riding Limp Mode
Although not recommended, it is possible to override the limp mode, but if you do, you should still investigate and address the potential fault at the earliest possible time.
First Option to Override Limp Mode:
- Find a safe, level place to park, and with the engine still running, check your transmission fluid level.
- Whilst checking the fluid level, you should also check the quality and color of the fluid. If the fluid looks or smells burnt, it will need to be changed.
- Shut off the engine for at least 5 minutes.
- Use this time to check the engine and any other fluid levels.
Sometimes topping up the fluids could solve the problem, but if not the 5 minutes the engine is switched off may be long enough for the computer to reset.
- Park the van safely and then switch off the engine.
- Remove both cables from the battery.
- Hold the 2 cables together for 15 seconds.
- Reconnect the battery cables to the battery.
- Start the van.
Holding the 2 cables together will have drained any current from the computer and thereby eliminate any codes it had stored.
Note: If you have an OBD scanner it will be easier, quicker, and safer to eliminate the codes using that.
If your cargo van won’t go over 50 mph and the computer has not initiated limp mode, it will probably be due to a faulty sensor. A faulty sensor will mean that the computer is not aware of a potential problem and so has not taken preventive actions.
You will therefore have to check the possible different scenarios yourself.
Low Engine Oil and Transmission Fluid Levels
You will need to check the engine oil and the transmission fluids for quantity and quality.
If the engine oil level is low, the engine will not be getting full lubrication. As well as possibly affecting your ability to accelerate, it can also cause the engine to overheat.
If your transmission fluid is low, the transmission fluid pressure will also be low. Low pressure in the transmission system will adversely affect the transmission’s ability to operate correctly.
Wires in your van can get broken or damaged by different types of loose debris, heat, or even by leaking battery acid.
A broken or damaged wire may not be able to send the correct signals to and from the computer. This will cause the van not to operate as you expect or signal it to.
Blocked Air Filter
In order for your van to accelerate properly, it must be receiving the necessary air to fuel mix. If the air filter is blocked, insufficient air may be mixing with the fuel making it less effective.
Dirty air filters are often the cause of acceleration problems on vehicles.
You can clean the air filter as a temporary fix, but you should still replace it with a new one when you can.
Clogged Up Fuel Filter
Another reason why your cargo van won’t go over 50 mph is due to a dirty or blocked fuel filter.
The fuel must of course be filtered before it enters the fuel system to ensure there are no contaminants.
Over time though, the fuel filter will become partially or fully clogged up with contaminants it has arrested. This will prohibit the flow of fuel to the engine.
Insufficient fuel reaching the engine will cause the van’s acceleration to be impaired, not reaching speeds you would expect.
Timing Belt Has Moved, Is Loose or Damaged
Your timing belt plays a crucial part in your van’s performance. If the timing belt has moved, it will cause the valves to become out of sync.
When the valves are out of sync your van’s efficiency suffers and can cause the van not to accelerate as it should.
Although still called a belt, many timing belts are in fact chains. If the chain has skipped a link, it will become less effective, but its effectiveness can also deteriorate if the chain has stretched due to excessive wear.
The check engine light will come on if the chain has skipped a link; however it won’t if the chain has just become loose.
If your timing belt is loose, it may be due to a faulty tensioner. A timing belt is linked to a tensioner whose purpose is to assert pressure on the belt to keep it tight and therefore effective. Over time the tensioner may become worn and faulty, causing it to reduce pressure on the timing belt.
Both the timing belt and its tensioner on your cargo van are awkwardly located and so while not particularly difficult to replace, will take time to do so. It is therefore recommended that if you do have to replace your timing belt’s tensioner, you should also replace the timing belt at the same time.
Both the belt and the tensioner are relatively inexpensive in themselves. The time involved to replace them however, may be reflected in your mechanic’s bill should you opt not to change them on your own.
If you do feel up to the task and want to save money on a mechanic’s bill, full instructions on replacing the belt can be found here.
Hopefully the reason your cargo van won’t go over 50 mph will be one of the above rather than a serious problem with your engine or transmission.
While the computer’s ability to place your cargo van in limp mode may seem an inconvenience at the time, the excess expense it can save you will more than make up for that inconvenience.
Knowing how to override the limp mode may be useful, but doing so can eventually become expensive. Therefore only do this in extreme circumstances, and investigate the cause of the limp mode initiation at the earliest possible time.
Checking and topping up the oil and fluid levels is easy and inexpensive, but if any top up is required, you should look under the van and in the hood for signs of leaks. This should be done on a regular basis even if your van is performing well.
Both the air and oil filters on your cargo van are easy to access,so cleaning or replacing them is possible without the assistance of a professional.
While you may need professional help to check the timing belt and its tensioner, there are usually warnings that these are the problem.
As mentioned, the check engine light will come on, but only if a link has skipped. If the belt has only become loose due to wear or a faulty tensioner , you will usually experience some backfiring of the engine as well as reduced performance.