4.3 TBI running real rough.

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M Rothwell - 09 Sep 2004 21:37 GMT

I have a '93 GMC with 4.3 TBI engine. It has 185K miles on it and has
generally been trouble free. A few months ago ( about 5K miles ) I had
some hesitation around 2000 rpm and it was down on power.

I replaced:

Plugs & Wires
Cap & Rotor
EGR valve
O2 sensor

I did each of these one at a time and the 02 sensor seemed to make the
most difference.

Anyway, the truck has been running well again, UNTIL this morning. On
my way to work, I stopped at the bank ATM. It was running fine when I
shut it off, but when I started it back up it had a terribly rough idle.
It shudders terribly, and is very under powered under accelleration
until I hit about 2500 rpm, then it seems to smooth out and run fine.

Any ideas what may have happened?

Michael

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Steve W. - 10 Sep 2004 03:04 GMT

EGR is probably stuck open a bit. Pull it off and see if there is a
piece of carbon between the pintle and the seat.

Signature

Steve

> I have a '93 GMC with 4.3 TBI engine. It has 185K miles on it and has
> generally been trouble free. A few months ago ( about 5K miles ) I had
[quoted text clipped - 19 lines]
>
> Michael

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M Rothwell - 10 Sep 2004 22:20 GMT

> EGR is probably stuck open a bit. Pull it off and see if there is a
> piece of carbon between the pintle and the seat.

I found the problem. Even tho I have only about 5k miles on the the
plug wires, I have one grounding out. I opened the hood last night when
it was dark and started it up. Back corner of my engine was lit up like
a Christmas tree. I thought that I had put "good" wires on, but
apparently not.

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Tony Kimmell - 11 Sep 2004 06:06 GMT

You'll have to pay AT LEAST $35-40 for a good set of wires. Anything
less will be crap.

-Tony

> > EGR is probably stuck open a bit. Pull it off and see if there is a
> > piece of carbon between the pintle and the seat.
[quoted text clipped - 4 lines]
> a Christmas tree. I thought that I had put "good" wires on, but
> apparently not.

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