Weird Bucking and Erratic Tach

CMac89

Registered User
I was driving around town and the car started to do a slight single buck. Ignored it. Then later on it started doing it worse, but whenever it happens the tach goes erratic, the temperature gauge was rising, and the check engine light comes on all while it is bucking.

Turned the corner, it died. Tried to start it and the starter was acting like the battery was bad. Looked under the hood to check stuff, came back and it started right up. Turned another corner and it started bucking and died. Tried to start it and the starter did the same thing. Then I came back and it started again. haha

Anyways, I did a code test and got an 85 and an 88. Any body know what these codes are?

I was thinking bad battery. The alternator tested good, but the erratic tach and flashing CE light coming on had me thinking along the lines of Cam Sensor or DIS. I started it and drove about a mile home with no problems after all of that.

Another thing which I don't know if it relates, whenever I was driving home from the shootout the car would slightly buck mostly while I was cruising.
 
85 = Canister Purge Circuit Failure
88 = Electro Drive Fan circuit failure.


My car has been doing the bucking while driving, and cruising...but the tach isn't really erratic. The car never dies either....

By erratic, do you mean it drops with the bucking? Like...from 1800rpm to about 300-400rpm?
 
I had those symptoms on my blue 90 SC and swapped out the Cam Sensor... It cleared it up.... Not sure if the DIS could be causing this possibly.....
 
I had this problem back in May. The car would buck, I'd pull over and shut it off then try to restart it but all it would do was crank. Then 3 or 4 tries later it would start up, but I'd have no tach. The tach would eventually come back, but it would take a little while. Mine never stalled when turning a corner, but sometimes when sitting at a light it would just suddenly die, then when I tried to start it I'd get the same symptoms as I did after I shut it off when it was bucking. Anyways... I replaced the DIS and got no results, then replaced the cam sensor and it was fine. I haven't experienced any problems since then! :)
 
I was thinking the Cam Sensor was bad too, but because of the way the starter was acting is why I made this thread.

It doesn't crank and crank it sits there and does the rapid starter clicking against the flywheel. Sounds like a woodpecker. That is what I meant by sounding like the battery was dead, but it isn't.

Timing does control how the motor cranks over on startup, too; so.........
 
I had this problem back in May. The car would buck, I'd pull over and shut it off then try to restart it but all it would do was crank. Then 3 or 4 tries later it would start up, but I'd have no tach. The tach would eventually come back, but it would take a little while. Mine never stalled when turning a corner, but sometimes when sitting at a light it would just suddenly die, then when I tried to start it I'd get the same symptoms as I did after I shut it off when it was bucking. Anyways... I replaced the DIS and got no results, then replaced the cam sensor and it was fine. I haven't experienced any problems since then! :)

I've replaced both and still have mine. :(

Anyways. CMac your best bet is to start with the Cam Sensor as it's cheaper. OR...if you have another SC nearby that you can swap the DIS off of.

Personally, with it needy a minute or so to 'cool' I wouldn't doubt it being the DIS.
 
I had the DIS tested the second weekend ago and it was good. Doesn't go bad until it goes bad, I guess.
 
Another problem I noticed whenever driving it is the ANTILOCK light comes on. It will either stay on or flash on then off after the motor misses or bucks.

Seems to do it whenever I turn, too. That doesn't make sense to me though.

Ideas?

BTW, Thank You guys for the replies.
 
Another problem I noticed whenever driving it is the ANTILOCK light comes on. It will either stay on or flash on then off after the motor misses or bucks.

Seems to do it whenever I turn, too. That doesn't make sense to me though.

Ideas?

BTW, Thank You guys for the replies.

Not sure what all would make the antilock light come on, but it sounds like an electrical connection to me then.

I had a few wires that were bare at the distribution box, maybe check there?
 
I just figured it out. Every time I try to fix something I look at the hardest things first. I changed out the DIS and the cam sensor only to find out that my ground cable came out of the terminal on the battery. So I was getting an intermittent ground. I'm sure that fixed it.

Maybe that was the reason my dyno run was so screwed up at the shootout and was missing out on the way home.

I'm going to add a couple more grounds just in case that happens again. You can never have enough grounds.
 
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