TBI machines like 89 o-tang even with stock timing. I personally run mine a
bit advanced for some seat-o-the-pants HP, and I run 89 exclusively. However
when I had stock timing the truck ran MUCH better on 89, it would sputter &
stall on 87.
I would check your timing. Disconnect the timing advance wire (brown wire
that goes to the dizzy) and check that your engine is at 0*. If it isn't
that...

GMC Gremlin

Could be any one of several things. Contaminated fuel, improperly
controlled timing for whatever reason, etc.. And if you haven't pinged on
reg (87) you won't all of a sudden need it. See if you got a code.

I had this on my 89 s10 and it was the air filter was dirty and had a hole
in it.

.
.
==========
(Sounds like a Porsche)
asked:

(quest. #1)
What causes pinging?  


Took my 87 Chevy pickup (4.3 ltr) up a steep hill today and man she
pinged heavy all the way. Hadn't really noticed it too much before just
the odd time.

(quest. #2)
I shouldn't need premium gas for it should I?
Dave

=================Answers to the quiz:

1)
most often this symptom is due to improper
maintenance...
(improper= neglected)

2)
no, you shouldn't.

Answer to the questions you didn't ask:

1)
given the symtpoms,
most likely carbon buildup inside the combustion chamber.

2)
change the plugs...start using Chevron gas
for the next couple of months and see if
that hill still causes you a problem.

~:~
MarshMonster
~:~

Thanks for all the tips guys.  I've put some premium in it for now.

Note to MarshMonster...
We don't have a Cheveron gas station in Canada where I am (Alberta) so I
checked the web and decided Shell has a pretty good premium fuel... more
than five times the minimum amount of cleaning agents required by government
standards.

GMC Gremlin and Whitelightning...
No codes were set.  For sure she is carboned up (black smoke) but I thought
I blew it all out last summer.

Also last summer the cat was plugged solid... since been taken care of.
That took awhile to figure out... she wouldn't shift out of 2nd.  A vacuum
gauge showed not enough vacuum to let the tranny shift.  The truck would
leave a red light no problem but then would just fall on its face.  After a
couple of mechanics looked at it and couldn't figure it out (still had to
pay them) I found one that diagnosed and fixed the problem in 15 minutes
(the cat being plugged up).

The pickup has less than 60,000 miles on it.  It was an old  'City owned
truck' that I picked up at 'City' auction.  Should have been well maintained
but I'm wondering about that now.  For sure she was washed all the time... I
had her painted and there was zero rust.

I think the valve guide seals are gone... puff of blue on the morning start
up.  That seems to be getting less as time goes on (I've put about 5000
miles on it since I got it).  She does use oil tho and when I add some there
is a bit of sludge I can see in the valve cover... more often oil changes
for awhile I guess.

The truck might have sat for a year or so before they decided to auction it
off.  Being green I figured I was going to get a trouble free almost new
truck (60K miles).  Oh well I quite like it.

Dave

lean air/fuel mixture, over advanced ignition timing, excessive carbon build
up in the combustion chamber or on top of the piston, defective engine
controls........................
too many fuel additives

Hi,
    Your pinging problem is caused by bad detonation. Octane ratings
signify the atom structure of the gas. The higher the octane rating the
simpler and more efficient the structure is. That's why higher octane
runs smoother. Retarding your timing (runs hotter, but reduces pinging)
or running your engine cooler will eliminate this also. Enriching your
mixture will also help. The pinging is basically like a little hammer
hitting the tops of the pistons. I wasted both pistons on my Sportster
from excessive pinging. If it continues you will most likely break or
melt your pistons. This in not a joke, but water injection will fix your
problem. Edelbrock makes a water injection system that's called
vara-jection. It's an electronically controlled water injection system.
It squirts water into your intake and atomizes your fuel better. It also
gives you a denser charge which creates horse power as well as clean
your engine insides. It also improves gas mileage. I ran one on a turbo
charged Kawasaki and it ran great. My bike would start pinging badly at
155 mph. The water injection stopped the pinging and gave me a lot more
power. Any auto parts store should carry a book called Turbocharging.
The water injection system is in the book. I think it's put out by HP.
When we were at war with the Germans their planes had water injection on
them. Their planes could out power and climb higher than our planes.
Summit racing carries it. You can reach them at 1-800-230-3030. Good
luck to you.
Jessie