Mystery of the '87 VW Jetta
August 18, 2009 6:44 AM   Subscribe

My 87 VW Jetta broke down, and none of the mechanics have the equipment to figure out what's wrong with it. What now?

I have an '87 VW Jetta that has about 250,000 miles, but a rebuilt engine with a lot less mileage. I've had it since December, and haven't had trouble with it, though I just noticed an oil leak before the break down.

While I was driving on the highway, it started to 'buck', or 'miss' - the car would stop accelerating and kinda lurch forward. It was fine when I wasn't accelerating. I thought maybe the problem was with the leak - when I stopped the car, the oil level was way down and I put 3 quarts of oil in it, but I think the problems were unrelated. I stopped at a gas station and had it towed in the morning. It would start just fine, but now I've heard it's not running. It's been to a total of three mechanics in Charlottesville, VA, but none of them are willing to do any work on the car because they don't know what's wrong with it and they don't have the diagnostic equipment to figure it out (they didn't charge me for looking at it, but towing is starting to get expensive). One mechanic hazarded a guess that it might be the fuel injection system or the choke. Right now it's at a Volvo dealership, the only one in town.

Should I give up on my car? I don't have any technical ability, and right now my car is about 100 miles from where I live. But it's frustrating not knowing what's wrong with it.

Does anyone have any pertinent experience or suggestions?
posted by ajarbaday to Travel & Transportation (14 answers total)
It sounds like you need to find someone with the correct diagnostic equipment.
posted by jrockway at 6:47 AM on August 18, 2009

Yeah. Why don't you call the next mechanic first and find out if they have the correct equipment and expertise before you pay to tow it there.
posted by amro at 6:52 AM on August 18, 2009

when I stopped the car, the oil level was way down and I put 3 quarts of oil in it, but I think the problems were unrelated

Being that low on oil can kill an engine, and could very well be the source of the problem. With only a quart or so left in the engine, metal rubs against metal, and it doesn't take very long for permanent damage to result.

Obviously, you need a qualified mechanic to look at it, but make sure you let them know how low your oil was so they can check for engine damage before chasing other issues. Unfortunately, it could be too late. (Experience.)
posted by The Deej at 6:56 AM on August 18, 2009

What do you mean correct diagnostic equipment? They don't have OBD (II)? That seems absurd. Why don't you take it to Flow VW, the place I just found on the Google? Surely they can diagnose it.
posted by luckypozzo at 7:06 AM on August 18, 2009

I had an 88 VW with the same engine 1.8L engine. It would run fine on a quart of oil, so I doubt the leak is the issue, unless it completely ran out of oil.

I had this same problem (engine would run, but not accelerate under load) eventually I fixed it by replacing the fuel pump and the fuel pressure regulator. I'm not sure exactly which of those did the trick, because I did them on the same day. The fuel pressure regulator is under the hood, the pump is down by the fuel tank.

My guess is that your problem is also related to the fuel system -- any competent german car or VW mechanic should be able to fix it.
posted by M.C. Lo-Carb! at 7:10 AM on August 18, 2009 [2 favorites]

Right now my VW is at Flow VW. I don't think there's another place in the area that would be able to service it any better than the dealership or have the right diagnostic equipment, so I'm hesitant to call any other place. Honestly, I didn't know they would need correct diagnostic equipment or that it would be a problem, so I didn't ask about it until it turned into a problem. The first mechanic had my car for five days before deciding it was a lost cause, and it's been at the second for a week.

I let them know about the oil and the engine, I think their search has been focused on the engine.
posted by ajarbaday at 7:12 AM on August 18, 2009

I'm not a mechanic, but I used to date someone w/a similar year make & model. The fuel pump kept going out. As it turns out, there was a recall on 1987 Jetta fuel pumps. Maybe have that checked out.
posted by Marie Mon Dieu at 7:13 AM on August 18, 2009

It's not the oil. It's defintely fuel related. Those VWs have a fuel distributor which is different than just about everything else on the planet. It's a pretty cool gadget that uses the mechanical flow of air to increase or decrease the amount of fuel. It could be clogged at one of the bolts that connects the distributor to the injectors.

It could be an injector, the fuel filter, the fuel pump or the pressure regulator, but it's fuel related. That lurching is your engine losing the air/fuel mixture for a second and then catching back up.
posted by cdmwebs at 7:46 AM on August 18, 2009

Google/call the Bug Shop, they're in Blacksburg, VA and they know their VW's. Let the dealership diagnose, and bring that info to the Bug Shop. Hell, a tow from Winston-Salem + Bug Shop repairs will probably be cheaper than stealership prices.
posted by limited slip at 8:31 AM on August 18, 2009

OBD2 didn't come out until 1995. A 1988 VW would have a pretty crude on-board diagnostic system. Most fuel injection systems don't have chokes, either.
posted by rfs at 8:55 AM on August 18, 2009

Go to the forums at Samba and ask your question there. Those are some serious VW enthusiasts. My boyfriend has an old bug and he goes on there sometimes to ask questions and he gets them answered every time.
posted by MaryDellamorte at 5:53 PM on August 18, 2009

It was fine when I wasn't accelerating.
There are a couple possibilities:
A bad ignition coil could cause a problem similar to what you're describing also. It could start and run fine for a while until the electrical load heats the coil up and it starts to under-perform. Idling or cruising, its output is sufficient, but when you increase the RPM, the coil can't reliably output enough spark to keep up.

Airflow potentiometer.
If I remember correctly, that year Jetta had Bosch CIS-E/KE-Jetronic fuel injection and it used what's basically a door attached to a potentiometer to help calculate airflow into the engine, basically like a dimmer switch. As air flowed in, it acted on the door and moved the potentiometer. If that went bad, the primative control unit won't know what's going on.

In addition to a potentiometer, the airflow sensor plate (door) acts directly on the differential pressure regulator, a mechanism that controls fuel flow to the injectors. If the little rubber diaphragms go bad in that regulator, you'll have insufficient fuel flow and suffer an inability to accelerate and even some stalling. Bad news: The regulators tend to cost about $200 new.
I don't think the whole fuel distributer has failed. It's much more likely that the differential pressure regulator has, being that it's the weak link in that system. A wise old mechanic mentor of mine told me those regulators were a common point of failure.

By the way, as far as your car goes, "We don't have the equipment" is really code for "We aren't interested in working on your old car." There's basically nothing special required in diagnosing your old Jetta.

If you were feeling adventurous, you could grab a whole unit off of a junked/used/pre-loved Jetta and slap the entire system on and see what happens. If you're not up for that, find a mechanic with gray hair who won't flinch at older technology.
posted by Jon-o at 7:50 PM on August 18, 2009

Thank you everyone for your detailed and helpful answers.

Does anyone know of a good mechanic in Charlottesville? My Jetta is a $400 tow from my place in the mountains, so I don't think working on it myself / having a friend help me with repairs is a great option. The Bug Shop mentioned in Blacksburg is also about 2 1/2 hours away.

Your responses have given me hope, and I'm going to try to find a good mechanic rather than leaving it at the dealership.
posted by ajarbaday at 6:25 AM on August 19, 2009

For all who answered this thread, the problem turned out to be with the fuel pumps. A dealership in Charlottesville that specialized in German cars agreed to work on my car. The repairs were pretty much the cost of the car, but I was able to drive it home afterward. Since then, a couple of other problems developed with the oil pressure to the engine, possibly unrelated to the initial problem.

Thank you all!
posted by ajarbaday at 7:12 AM on September 25, 2009

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