Shifts points off occasionally and odd sound at shut off.

1986 CHEVROLET MONTE CARLO

2,819 MILES • V8 • 2WD • AUTOMATIC

ASTEROIDGALAXY

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I have an 86 Monte Carlo SS w/ an 383 stroker, 2400 stall convertor w/ lockup, and a 200r4 transmission. Symptoms are that I just can't seem to get the TV cable right. Most of the time during light/moderate acceleration it shifts to second around 15-20mph and third at about 30mph and fourth at 40mph. However, about 30-40% of the time it seems to shift early, like 7-13mph and second as soon as 20-25mph. Any thoughts on that? Also, when shutting the car off after driving long distances/fast, for long periods of time, or after a few high rpm accelerations it makes a weird sound. It doesn't make this sound after shutting the car off for only being on for a few minutes. When this sound is made it vibrates the car and is louder than it sounds in the video. It sounds like something rattling in a can? I have the video on youtube ( http://www.youtube.com/watch?v=u94e2FmXzt0 ). The sound is made right at the 24/25 second mark. The fans are still running throughout the end of the video.

Jun 29, 2011 at 11:42 PM

ASTEROIDGALAXY

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Here's another video with the camera on the drivers side door. Right at the two second mark is when the engine is turned off. Between two to four seconds into the video...there's a grinding sound heard and then a pop.

Jun 30, 2011 at 1:09 AM

ASTEROIDGALAXY

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Attached is another video from the drivers side door outside the car. Exactly at the two second mark is when the engine is cutoff. Two to four seconds into the video there's the kind of grinding sound followed by a pop.

Jun 30, 2011 at 1:10 AM

ASTEROIDGALAXY

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Jun 30, 2011 at 1:11 AM

RIVERMIKERAT

✓ASE Certified Mechanic
6,110 POSTS

The shifting issue could be an improperly adjusted kickdown mechanism or vacuum actuator on the trans.
The popping sound is quite evident, but next to impossible to identify. The other sound I'm hearing is dieseling. Check the timing and run some fuel system cleaner through it. You might also try using a higher octane fuel.

Jun 30, 2011 at 5:10 AM

RIVERMIKERAT

✓ASE Certified Mechanic
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In the first video, at the 24/25 second mark, I hear the engine diesel, or run-on. This is normally caused by either spark plugs that are too hot for the engine, low octane fuel or improperly set timing.

Jun 30, 2011 at 3:57 PM

ASTEROIDGALAXY

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It was either 10.3:1 or 10.8:1 compression, but I've been running 93 octane.

Jul 1, 2011 at 1:04 AM

CJ MEDEVAC

✓ASE Certified Mechanic
11,004 POSTS

An excessive high idle will cause the dieseling, and the sound I hear sound like a "Spit" back thru the exhaust.....not quite a backfire, My CJ 5 does that every once in a while, when he's cold, I call it a hiccup!

Might just be me, and my interpretation though!

The Medic

Jul 1, 2011 at 1:20 AM

RIVERMIKERAT

✓ASE Certified Mechanic
6,110 POSTS

If you're running 93, then you need to check your timing.

Jul 1, 2011 at 1:35 AM

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