Running Issues: Which Injection or Ignition Part On My Vanagon is Causing the Problem?

We get calls and emails all the time from folks with a 17- to 30-year-old fuel injected Bus or Vanagon who are experiencing running and/or reliability issues. They want us to tell them, over the phone or in an email, which component to replace. If only it were that easy...

In the '60s and early '70s, vehicles were very basic: carburetor, coil, points, cap, rotor, plugs, etc. Intermittent problems were pretty much non-existent. It either ran, or it did not. When it did, all was cool and groovy. When it did not, you checked the basics: fuel, spark, compression. Whatever was missing... well, that was your problem—and there were typically only one or two components it could possibly be.

In the 1970s, things got a little more complicated. Something called "smog" became a new reality, and fuel started to get pretty pricey. So, engines needed to be a lot cleaner and a lot more efficient. So, vehicles got a lot more complicated. Electronic fuel injection replaced the carburetor. Electronic ignition replaced the points. High-tech devices were added to the exhaust, like catalytic converters and oxygen sensors. Vehicles were getting more and more complicated, and different manufacturers were going in different directions to solve the various problems. Consumers were getting hammered at the repair shop with HUGE bills to fix their complicated vehicle that their mechanic was ill prepared to fix, let alone diagnose. By the late '80s, passenger vehicles had full blown engine "management" systems—but nobody was in charge.

Around 1990, a consumer protection law was passed requiring an "on board diagnostic" (OBD) system on all passenger vehicles sold in the USA. Part of the system was the introduction of the infamous "check engine light" (CEL). That is, in fact, how you can tell if your vehilcle has an OBD system: it will have a CEL, too. Now anytime the engine hiccuped, even intermittently, the CEL would come on and stay on until the problem was fixed. At first this requirement was percieved as an insult to good mechanics everywhere: just another form of "Big Brother" intrusion into our lives. Many thought it was just another "smog device," an additional hurdle to jump through when getting your vehicle through the bi-annual emmissions test. Over time, though, the system has improved to the point where it is relied upon by mechanics everywhere. The other very important thing that happened was standardization. All in all, the advent of true engine management systems, along with an OBD acting as "upper management," has turned out to be a very good thing. Okay, enough with the history lesson: Now, what the hell is wrong with my Vanagon?

No Bus or Vanagon, not even the 1990 and '91 models, have any form of OBD. Late fuel injected Buses and all Vanagons are part of the aforementioned generation of vehicles that have much of the high-tech stuff, but none of the super-high-tech stuff. That is, a management system with no "upper management." This generation of vehicles are the trickiest to diagnose and fix. This is one reason VW dropped the Vanagon altogether, as it would have been too expensive to redesign it with an OBD. When a component fails or a connection is faulty on a Bus or Vanagon, it can be difficult to pinpoint. It takes an experienced mechanic with lots of spare parts: a dying breed, a dwindling supply.

The best advice for anyone trying to correct a running issue is to first replace all maintenance items. Make sure everything is up to date, including filters, fluids, all ignition components (plugs, cap, rotor, wires). And, use only OEM quality parts. It is easy to waste a lot of time and money chasing a problem by replacing expensive fuel injection components, just to find it is a regular maintenance item that was causing the problem. Every Vanagon we sell at GoWesty gets all the maintenance items replaced; every one is back to zero miles maintenance-wise, no exceptions. Click here to see what is included in a GoWesty, super-duper, ultra-thorough, triple-throw-down, go-nuts-crazy major service you see mentioned on all our for-sale vehicle ads. This is all stuff that has to be done periodically anyway, and even if it does not solve the problem, it is by no means wasted time and money.

Once all that stuff is covered, the next step is to visually check every single fuel injection and ignition electrical connection and all ground connections to the engine. That is, actually unplug every Bosch connector and look at the pins for signs of corrosion or dirt. Critical connections, like the plug at the electronic control unit (ECU or "computer") and blue fuel injection temperature sensor (water-cooled models), are especially important. We always replace the two electrical connectors inside the plug going to the fuel injection temperature sensor on every Vanagon we sell, or in which we install a rebuilt engine, no exceptions.

Beyond that (unfortunately), it is just a matter of experience; knowing what item causes what sort of symptom, and what items are most likely to fail. Based on our experience and knowledge, every Vanagon we sell gets a full page of reliability enhancing items, preemptively. These are items that we know from experience are likely to be involved in a vacation cut short. Click here to view a "reliabilities" page of the items every Vanagon gets before we sell it. This particular example applies to '86-91 2WD Vanagons with manual transmission, but the principle applies to all models (it's just  that the part numbers are different). Read the notes on the estimate itself, as it explains how we arrived at this list, and the order in which the items appear.

So, sorry, no magic bullet, just a history lesson, and some sound advice....


Email from customer (09/21/07)

My mechanic here in Bozeman narrowed the problem down to a faulty wire on the O2 sensor.  The problem on the wire was proximal to the computer.  It appears another mechanic did a wire check and inserted a probe into to the casing. According to the mechanic, the probe pierced the special sheath on that wire causing damage the inner wire.  This sent mixed messages to the computer, causing the surging.  He spliced off the bad end, and re-attached it.  It runs very well now.

I want to thank you and all the folks at Go-Westy who provided feedback, especially in such a timely manner.  It helped greatly.

I'm a happy "camper" now, and the Utah desert is calling.

All the Best,

Dr. Robert Lemley
Bozeman, MT






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