1999 Chevy S-10 Transmission is bucking/jerking

Tiny
TOADMISER
  • MEMBER
  • 1999 CHEVROLET S-10
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 148,000 MILES
My transmission has been shifting late and/or slamming in to third gear for quite some time. I recently brought it to a local mechanic and he stated that he could not diagnose the transmission until I changed the plugs and wires as the computer was giving missfire codes. Then on a snow storm night on my way home I got about half way of a 50 mile drive and the battery light started randomly turning on and the ABS light came on. The truck began bucking seriously and eventually stalled. The whole way I used 4 wheel in the snow. Seemed to run a little better in 2 wheel when I was able to switch (less bucking issue). Anyway, I nursed it home as AAA would not tow to my house due to the storm. The next day I changed the plugs and wires and everything seemed so much better ( I did not change the cap and rotor however). Since then shifting seems better but now (about two weeks later) the truck stalled on me while waiting in line at the dump after Christmas. Then today on the highway I felt it buck a couple of times (drops about 500 RPMS each time). I did some quick research online and found that this vehicle has some known transmission issues. I'm wondering what might be the cause/next steps. I am mechanically inclined and typically work on vehicles myself but transmissions, besides changing them escapes me. If a part needs to be changed/replaced, I'd rather do it myself than pay someone else. Could it be a Stop Check valve that is worn or needs a new Transmission Valve body or other? Any help/insight would be most appreciated. I'm afraid it is going to get worse and would like to avoid the dreaded breakdown. Thanks in advance!
Monday, December 29th, 2008 AT 8:54 PM

4 Replies

Tiny
MIKE H R
  • MECHANIC
  • 3,094 POSTS
Try resetting your computer. Dis connect the battery and let sit for a few minutes. Then reconnect, on that year vehicle it will have to driven about 50 miles befroe it completly resets. With the abs and battery light random comming on I suspect that you should check the wiring connections. With the snow they might have been pulled making connections poor. If the battery light keeps flashing then you can have the charging system checked at a local auto parts store like auto zone they do it for free.
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Tuesday, December 30th, 2008 AT 8:05 AM
Tiny
TOADMISER
  • MEMBER
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Thanks for the reply. I did as you suggested and disconnected the battery for over an hour (I realize this wasn't necessary but I had the time so what the heck). I also turn the key while the battery was disconnected to help drain any residual voltage. After reconnecting the battery and drove about 250 miles and had another snow storm at about 100 miles the truck seemed to run fine - no dash idiot lights and no bucking. Until today - about a week and a half later. My wife was on her way home from work and on the highway the truck bucked a few times and she noticed the gas guage low fuel indicator come on for a second. Which I just filled yesterday. Where should I go from here? Do you still think it is an electrical issue with the Transmission? I have had the truck since 70,000 miles and had been fine until this past October. Thanks.
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Monday, January 5th, 2009 AT 2:58 PM
Tiny
MIKE H R
  • MECHANIC
  • 3,094 POSTS
I keep thinking it is in the electrical, you say it did it after a snow storm? Check under the vehicle for any loose or bad electrical connections. Also check under the hood for the same. Disconnecting the battery for a little while helped so I think it is something electrical either getting wet or bad connection.
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Friday, January 16th, 2009 AT 8:29 AM
Tiny
TOADMISER
  • MEMBER
  • 3 POSTS
Resolution to this issue:

Symptoms:
Truck would sometimes buck. Bucking began to worsen with time. Sometimes bucking would happen on the highway and would buck once or twice. Sometimes more. As time went on, the bucking would be worse at slow speeds. Sometimes the battery light would illuminate for half a second and when the truck would buck more violently. At the worst point, the ABS light would come on for a second as well. Sometimes the fuel guage would be erratic. All of these symptoms would be intermittend. Sometimes I could go for a week without issues. No SES light durring these times. Truck would run great at an idle and run great most of the time. Moisture seemed to increase or cause the issue to worsen. Multiple misfire was the only code the computer was showing.

Resolution:
I had previously replaced the fuel pump in the summer prior so I didn't think that was the issue. I replaced the plugs and wires as the "multiple misfire" code indicated a spark issue. Still had the issue. I replaced the fuel filter and battery. Still had the issue. I replaced the cap and rotor and still had the issue. Replaced the coil and still had the issue. Replaced the Fuel injection Spider (CSEFI) with the new MFI (Multiport Fuel Injection) conversion unit. They changed the style in 2003 to this newer injection system. Still had the issue. Replaced the alternator and still had the issue. In the end, I finally had a code to go off of P0339 - Crankshaft Position Sensor - Intermittent. I changed the Crankshaft Position Sensor and all my problems/symptoms went away.

Summary of parts changed in the end:
Fuel Filter
Plugs & Wires
Cap & Rotor
Battery
Alternator
Fuel Injection Spider (CSEFI) [used new CSEFI to MFI conversion]
Crank Position Sensor

While I understand that just because this issue was resolved by my replacing of the Crank Position Sensor and it may not apply to everyone else, I would strongly recommend replacing the Crank Position sensor before spending the money on all the parts as I did. Hopefully this will help others that may be having these symptoms. A crank sensor is about $60. Better than replacing all the other parts. If you get the multiple misfire code and you have already done the plugs, wires, cap, and rotor. Then the Fuel Injection spider can also throw that code as well. In the end. My issue was electrical. I cannot beleive that one sensor could screw so much up and create so many symptoms. That one sensor made me think I needed a new computer. I almost made that plunge as well.
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Tuesday, February 17th, 2009 AT 3:40 PM

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