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Re: [T3] MPS update


On 25 Sep 2003 at 3:06, David V.N. wrote:

'69 FI type 3

> From: "Jim Adney" <jadney@vwtype3.org>

> > Over what kind of time period?
> 
> Oh a couple of weeks,I'd say.Started as missing in the midrange,about
> 3k rpm's.

Using an inductive timing light, check EACH spark plug wire to verify that EACH 
plug is firing and at the right time. Note that 1&3 will appear to fire near 
the timing marks on the pulley while 2&4 will appear to fire near the similar 
spot on the pulley that is 180 deg from the timing marks.

Check the dist cap for tracking inside and out. Clean off all dirt inside and 
out.

Check the resistance thru each SP cable to the SP end. Each should measure 
about 1kOhm. Replace any of the brown bakelite connectors whose resistors have 
gone open or are cracked.

Make sure your mechanical advance is working. You should see the advance change 
as you change RPM, and you can also check it with the engine off, by grabbing 
the rotor and twisting it CW then letting it go. It should twist against a 
spring force and then snap back smartly when you let go of it. There will be a 
small amount of play in the drive, but you have to ignore that.

See if it gets better if you simply unplug the pressure switch.

> > It's probably fine, but have you actually measured the voltage?
> 
> About 14+V

Look in the RF corner of the engine bay, under the PS. There is a double inline 
connector there that brings 12V to the brain. Verify that there is close to 14V 
on each of these wires while the engine is running.

In case they are fouled, have you replaced the plugs since this problem 
started?

> > It's running WAY rich, right?
> 
> Way, way rich,

And very poor power?

When you turn your key ON, do you hear a click, and then a second click about 1 
second later?

I don't know how this will work. It will depend on what meter you have. Get an 
analog voltmeter, the old kind with an actual needle. Gently pull back the boot 
on the 3 pin connector on the side of the distributor. Measure the voltage 
between ground and each end pin while the engine is running. You have to leave 
the connector plugged in while you do this, so you will shove your probe in the 
back end of the connector. Keep the engine speed similar for both tests. Look 
for a discrepancy in the voltage range indication you get from each side.

If you've already tried 2 different sets of trigger points, then ignore this 
last test.

It's possible that you have an injector that is stuck open. The only way to 
test this is to pull the injectors out of the engine while leaving them 
connected to the fuel lines. Disconnect the wire to the points to avoid a 
"problem," and watch the injector spray patterns while someone cranks the 
engine with the starter.

If your 69 came with the Cold Start Valve that a few of the 69s came with, 
disconnect the hose to it to make sure that it's not spraying continuously.

That's all I can think of now....

-- 
Jim Adney
jadney@vwtype3.org
Madison, WI 53711-3054
USA

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