How to fix pinging? -- SOLVED, additional info

I originally started a thread a while back in regards to a pinging
problem in an 86 Cutlass Ciera. I used some suggestions (spraying
water thru the carb) which at the time fixed it for a while, but
recently the problems came back. Today I did the next step which was
replacing the EGR valve, which has completely fixed my pinging
problem. In fact I have a suspicion that the EGR valve may have been
bad for a while. However, I had seen some other posts before on
testing the EGR valve on this car, and after changing one today I have
found out that the EGR diaphram cannot be tested with a vacuum pump.
The instructions with the new one also stated this. I do not know for
sure why but these particular EGR valves do not hold a vacuum with a
pump. I just thought I would provide this information, incase others
are having similar problems , especially people trying to test the EGR
valve itself.

Thanks,
--
Chris

-- Original Post --

Thanks to all for the helpful info. I tried the old water through the
carb trick, and it worked like magic. I did this about 2 weeks ago
and the knocking has completely gone away. Just used an industrial
spray bottle on stream setting and ran thru some distilled water with
somebody holding down the throttle. Had to run a good 2 quarts of
water through to get it to stop knocking though. Not sure if water
can get mixed in with the oil so I changed it right after anyway to be
safe.

Found lots of posts that say this works, so I'd like to back that up!

--
Chris

(Chris Szilagyi) wrote in message . com>...
> I checked the EGR by moving the diaphram while the car was running,
> and it almost stalled the car. I would think that this means the
> passage is NOT blocked, and that exhaust is getting through back to
> the intake.. is this correct???
>
> JazzMan > wrote in message news:<9649E1FF58C8A8F3.64DF246B3C5801BC.21F362C387 >...
> > Chris Szilagyi wrote:
> > >
> > > Hello,
> > >
> > > I've found these groups to be really helpful so hopefully somebody can
> > > help me with this one. I've got an '86 Cutlass Ciera with a 2.5L
> > > 4-tech, about 160k, original everything (no rebuilds). Recently it
> > > has started pinging around 40 mph and up, only when accelerating...
> > > maintaining speed the pinging stops. I've read posts on this and have
> > > checked the following things already which are in good condition: cap,
> > > rotor, wires, plugs, EGR valve (not stuck or clogged), fuel filter,
> > > vacuum lines. There are no trouble codes stored in the ECM, and I
> > > just put in new plugs (AC Delco). The car was supposedly tuned up
> > > about 30k miles ago.
> > >
> >
> > Though the EGR valve may not be clogged, the intake passage
> > under the throttle body most assuredly is. If you remove your
> > throttle body, you should see a channel that wraps around the
> > throttle bore from the EGR valve mounting area. On my 4-tech
> > I thought the black mark was just a gasket mark, but when I
> > went to clean it off I ended up chiseling about half a cup
> > of black crap and carbon out of that channel.
> >
> > JazzMan