My 89 Chevy 1500 Silverado jerks when put into gear from park to drive why?...

[cynthia21005]

...More details below plz help? Also why does it jerk when on the road at 50 mph? We just had these things fixed on it : It used to jerk worse, but now the jerking has very much diminished. What could be making this happen?

Tuneup
New gas filter
E.G.R Control Valve Solenoid
Air filter
Spark plugs and wires
This is also an automatic truck without a 4x4.

 

[Scoops]

Usually an abrupt jerk at a high speed IS caused by a lack of ignition, or spark. My brother-in-laws Dodge van had this problem and it ended up being the coil wire shorting out intermittently against the engine due to poor insulation of the wire and improper routing of the wire.
Another clue was that the jerking was worse on damp days which allowed the spark to short out easier.
Hope that helps.

 

[Richard S]

Have you checked the automatic transmission fluid? Low levels can cause strange things to happen. Old burnt fluid can also cause slippage, when was it last changed? Any vacuum leaks ? this can also cause strange things to happen. Just a few thoughts to consider.

 

[jdselvage]

There are alot of things that can make it jerk or surge. May not be engine problem but problem with trans. Biggest problem I can think of on this truck is vacuum leaking on the tbi gasket. Leaks in the back. Causes alot of problems most of which is surging and high idle. Which is what could cause the harshness when you put it in gear.

 

[Jarvis]

your truck may be idling high. also make sure your holding the brake pedal firmly when you shift from park to drive. it may be shifting a little delayed. the cause of that could potentially be the solenoids in your transmission sticking with age. but don't look at that until a last resort because thats a rebuild and will get a little more pricy. first solution, get a transmission flush,they tend to do wonders for old transmissions, and your supposed to do it about every 30,000 +miles i think, but i may be off, (different cars get different results) either way thats your best start and ill bet itll clear it up if your tranny's getting sludgy. the cost should be aorund $100 all-in-all well worth it