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Re: Stuttering

On 21 Nov 2005 at 9:05, Doug Brashear wrote:

> Why the voltage regulator would cause a rich running solution is a mystery to
> me, though. 

The system voltage also supplies the FI brain. I don't know exactly why it 
makes it richer, but it does.

> If you haven't seen the Bosch Platinum plugs, they are different than the
> standard plug...the electrode is very thin, and doesn't stick above the
> ceramic. Seems like it would be easy to foul given the reduced amount of
> exposed electrode surface area. 

I'm familiar with the Bosch Platinum plugs. I've got some of them in cars and 
they seem to run well for me. OTOH, the standard W8ACs seem to work just as 
well, and for less money. Perhaps the Platinum plugs last longer; I don't know.

Actual plug fouling is rare since lead has been omitted from our gas. The 
fouling comes from lead deposits which are actually too thin or transparent to 
be noticed. The deposits are on the plug insulator and are insulating 
themselves when cold. Once the plug warms up a bit, however, this deposit 
becomes conductive and the spark gets shorted to ground by this coating and you 
get no more spark until the coating cools down again.

If your bit of carbon managed to span the whole SP gap then it could have 
shorted out the spark. If it wasn't all the way across, then it should have 
burned away rather quickly. Which leaves the question, "Why was it there at 
all?" So you may be running rich, which would be your root problem.

> Jim, your idea of checking the FI relay ground was a good one, though. I was
> playing with the screw a bit while the engine was running (maybe not the best
> idea?) and heard it engaging as the ground was interrupted. The relay I
> must've heard was actually under the dash, though, and wasn't the cause of
> the issue. Still, I cleaned up a few different grounds and wire connections,
> which may have helped. 

If the main FI relay loses its ground that relay will open, which will remove 
power to the FI brain, which will then remove power to the fuel pump relay. 
Since all this happens instantly, the effect will be that BOTH relays will 
click together. You'll only "hear" the one nearest you.

Jim Adney
Madison, WI 53711-3054

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