1997 Jetta GT - sensor problem? Help!

On May 23, 2:23 pm, "The DPR" > wrote:
> My 97 Jetta GT is having problems. Backfiring when accellerating or under a
> load (uphill), lacking power at lower rpms, and while this is happening it
> makes a sort of putt-putt sound that sounds like it is coming from
> under/behind the front passenger seat. Much worse in the rain (this tells
> me "electrical" but when I look under the hood everything seems dry).
>
> I did some basic stuff. Checked the wires, changed the oil and air filter.
> The air filter was gross, covered with crap blown back from the engine; I'd
> never seen an air filter dirtier on the engine side than the intake side.
> Threw in a bottle of dry gas. Helped a little. Not enough.
>
> Took it to a local garage. They did a pressure test - good. Checked plugs
> and wires (which were only a few months old) - good. Checked the MAF -
> good. They decided I needed a distributor. To their credit, they told me
> their supplier wanted $300+ for one and that I could probably find one
> cheaper, which I did. They put it in yesterday and I picked it up today.
> Problem not solved. May be even worse, though I think that's probably
> psychological.
>
> I don't want to take it back to a garage without more information and
> without trying things myself. I tried disconnecting a couple sensors to see
> how the engine reacted. Looking down on the engine you have the four spark
> plugs (I'll call them P1 - P4) and then a sensor just in front of them to
> either side (I'll call them S1 & S2). They're arranged like this:
>
> P1 P2 P3 P4
> S1 S2
>
> What are the two sensors? They look identical but might serve different
> purposes.
> When S1 was disconnected the engine ran very rough. When S2 was
> disconnected it didn't make any difference.
> Is this normal? Does this mean S2 is bad?
>
> And if so, how does this relate to the symptoms? Why, for instance, is the
> problem much worse in the rain?
> Is there anything underneath that's electrical I should check?
>
> Any advice would be welcome. Thanks.
>
> Jim

Shot in the dark, AKA SWAG:

Are you missing or do you have any damaged ground straps?

Peter Wieck
Wyncote, PA