Why does my Vanagon Buck or Miss and lose power?
Many Vanagons experience a similar problem of bucking, rich running and power loss. This page is to help troubleshoot this problem and determine it’s cause so that it may be corrected.
1. Any and all normal wear items should be checked and replaced if they have excessive wear on them. Spark plugs, plug wires, distributor cap, rotor, fuel filter, oxygen sensor and air filters should all be checked first. If you can eliminate these normal wear items from being a possible source of your problem then you can move on to the next step.
2. After eliminating these relatively cheap wear items as a possible cause of your problem then the next step is to check all of the engine grounds. These are located on the driver’s side head. There should be several small ground straps attached to the head along with a larger ground strap that goes from the head to the firewall under the coil. All of these straps should be there, and the connections should be clean and tight. If this doesn’t fix your problem go to the next step.
3. Next check your ignition switch. There have been times when these have failed intermittantly. Usually a large key chain that is heavy with keys can cause premature failure of this switch. These are only $9 from me and easy to test if they are bad. Simply unfasten the lower cover on your steering column and remove it. Now unplug the black plug that hooks into your ignition switch. Plug in the new switch and start the car using a screw driver (be sure your key is in the ignition and to the “on” position or you won’t be able to steer the van). Now drive the van in similar situations where you were having your bucking problem. If they reoccur then you have ruled this switch out.
4. The next step is to trouble shoot your fuel injection system per the Bentley Manual. The tool you need to do this is a multimeter which can easily be had for $30 from your local Radio Shack. The things that commonly go bad to cause the engine bucking syndrome are:
The Air Flow Meter (located on the plastic air box)
The temperature II Sender (located in the thermostat housing and it has a blue connector on it).
The throttle position switch (located on the throttle valve).
If you need a Bently Manual in order to get the charts to troubleshoot you FI system I have these for sale (part number is LPV800148 in my online store). I could also fax these pages to you if you agree to buy whatever parts you find you need from me. If so please email me with the year of your Vanagon. I encourage you to buy the manual as you will need it for many other things down the road and it is a good investment.
It is possible that you have a problem with some expensive item like your ECU or distributor. If you have ruled out everything else then you can feel better about purchasing a new or rebuilt one of these expensive items. I sell rebuilt ECUs and also new distributors or just the hall unit (which can be replaced in your exsisting distributor). Email or call me at (856)-327-4936 if you need help.
I hope you find this page helpful. If you do please support Van-Again with your parts purchases.
Want to join the discussion? Feel free to contribute!