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>From: <usspirbh@ibmmail.com>
>My daughter has a 1971 type-3 squareback with fuel injection. It is now
>time for her to re-new her license for the car, which also requires a
>smog check. The following is a digest of my odyssey. By the way, I
>don't consider myself a novice to 'wrenching', but I can assure you
>that I am totally lost here. Now, the saga begins...
>
>By the way, the engine was rebuilt about two years ago and has less
>than 20,000 miles on it. Muffler has less than 100 miles.
>
>1. Take car to smog-check shop.
>2. Fails - hydrocarbons too high.
>3. Take car to VW dealership (I'm in a hurry to get this fixed).
>4. Dealer says total leakdown on cylinder 3, needs engine rebuild.
>5. Take care home. Hmmm, leakdown on cylinder 3. I check valves and
> sure enough, exhaust value clearance set incorrectly. This thing
> is never closing. Cool. Re-adjust all valves.
>6. Back to smog-check shop.
>7. Fails - too rich at both idle and high rpm.
>8. OK, now the car goes to local independent VW shop.
>9. He gives car complete tune-up, plugs, points, condensor, oil change,
> and re-adjusts valves (he says). Compression is now even on all four
>10. Back to smog-check shop.
>11. Fails - too lean.
>12. Back to independent. He replaces pressure, air, and temperature
> sensors.
>13. Back to smog shop. Still fails. OK at idle, but too lean at high RPM.
>14. I take the car home!
>
>Other things that have been replaced in the past at the request of VW
>dealership. This was to resolve another problem.
>1. Replace computer, air pressure sensor, and temperature sensor (sound
> familiar?). The real problem was a bad wiring harness, which I
> discovered after doing a continuity check on all the wiring from
> the computer.
>
>Current status:
>1. Engine seems mechanically sound.
>2. Electrical parts replaced:
> a. Generator and voltage regulator.
> b. Computer (rebuilt - I think the original was OK).
> c. I think every sensor on the engine has been replaced.
> d. Air pressure value.
> e. New points, plugs, condensor, wires, cap.
>3. When cold, engine idles smooth.
>4. When warm, engine starts to run rough - hmmm.
>5. If you disconnect the wire to the intake air temperature sensor
> (located on the air intake distributor, left side, between intake
> manifold tubes), it returns to smooth.
>6. Fuel injectors have not been replaced. I performed the injector
> test where you listen for the clicking at the injector when you
> move the throttle control. From what I can determine, I could
> only get clicks out of two of the injectors (one on each side),
> but I was told this was OK. I figured that if the f.i. was not
> working, it wouldn't run as smooth as it does. (?)
>
>Once again, I am tempted to take it back to the dealership just for
>diagnosis, but after this last time of suggesting I needed an engine
>overhaul ($2600), and what it really needed was $1.50 worth of valve
>cover gaskets, a feeler guage, and a few minutes of time, I'm hesitant.
You indeed deserve a commendation for persisting in your effort. I hope
this persistence does not go unrewarded.
It is correct that you will only get two injectors to fire at a time from
the throttle switch. To pick up the other two, rotate the engine one
revolution or the distributor 1/2 revolution. The injectors that fire
depend on which trigger point is closed.
There is very little that I can think of that someone has not already done.
One possibility is that the fuel pump can't deliver quite enough fuel to
maintain the pressure at ~30 psi when the car is at speed and the load on
the engine is high for a sustained period of time. You could test this by
attaching a pressure gauge to the gauge pickoff point between #3 and #4
injectors, and have someone watch it while driving at 55, or even a bit
uphill. The pressure should be constant under all conditions. The
regulated pressure can be simply adjusted if it is wrong.
If the pressure falls under load, you should check, or just replace, the
fuel filter under the gas tank. It's a rectangular box in the line to the
pump. Very cheap. If that is the problem, you should also give the ~1" dia
hose behind the fuel filler pipe a close look. If it is cracked, or shows
signs of leaking, it should be replaced: VW # 311 201 179A. Breaks in that
hose will let gas out on left turns, and water/dirt in when driving in the
rain/dust. Make sure the gas tank has a clear breather path. In fact do
that first, it could affect the ability of the pump to deliver fuel.
Let us know.
Jim
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Melissa Kepner Jim Adney
jadney@vwtype3.org jradney@njackn.com
Laura Kepner-Adney
Madison, Wisconsin
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