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Jim Grant's Tech Tips
'90 Chevy
Pick-up, Exhaust Smoke and Service Engine Soon Light
Q: I own a '90 Chevy pickup with a 4.3L, 6 cylinder engine.
It has over 156k miles but it runs good and starts like a charm. When
I start it up, white smoke comes out of the tail pipe and lasts for about
1 or 2 minutes but it finally clears up and then there's no smoke after
driving down the road. Then if I come to a stop ten miles down the road,
it will happen again. What could be causing this problem? Also, when I'm
driving on the Interstate and I push to 80 MPH trying to keep up with
the traffic, the caution light goes on saying "service engine soon". This
has happened to me about four times. I shut off the engine, let the truck
set and the light goes off. But when I go back up to 80 MPH, the same
thing happens. This only happens at high speeds. Can you give me an idea
why this is happening? I am planning to put in a rebuilt engine as soon
as possible if I can't find out what the problem is. ..James
A: It's
likely that the rebuilt engine is going to correct your white smoke exhaust
condition. A GM vehicle of your type and age, is known for smoking on
start-up. The condition is usually more noticeable after the vehicle has
set over night. But as time wears on, the smoke out the exhaust on start-up
will become more conspicuous. As for the "service engine soon" light,
your computer is telling you that it is not happy and wants you to have
it checked out. As far as telling? From this side of the vehicle no can
do. Have your technician connect a diagnostic scan tool into your vehicle's
computer to find out why the warning light is coming on. The computer
will have information stored, on file, that your tech can access and review.
Once that information has been obtained the cause can be diagnosed and
repaired.
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