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Discussion Starter #1
Hey guys. This last couple weeks I've been having a little trouble with my car. It seems in 4th gear (and only 4th) that around 1500 rpm, it feels like the car starts catching. Like something isn't working quite right. Car shudders a little.

Well today, as I'm driving and I'm trying to come to a stop, I feel the car jerk to almost a completely stop. On the dash while this was happening it said my car was in Park. It then went back to drive and continued to drive normally. I never reached a full stop though.

I called my GM dealer to check on my power train warranty which is still active til July. I made an appointment to get everything looked at and I am also going to talk to them about if the computer needs flashed.

Anyone have any thoughts?
 

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I know we have a problem with tranny flairs, its more like its slipping but this is different all together.

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Hey guys. This last couple weeks I've been having a little trouble with my car. It seems in 4th gear (and only 4th) that around 1500 rpm, it feels like the car starts catching. Like something isn't working quite right. Car shudders a little.

Well today, as I'm driving and I'm trying to come to a stop, I feel the car jerk to almost a completely stop. On the dash while this was happening it said my car was in Park. It then went back to drive and continued to drive normally. I never reached a full stop though.

I called my GM dealer to check on my power train warranty which is still active til July. I made an appointment to get everything looked at and I am also going to talk to them about if the computer needs flashed.

Anyone have any thoughts?
I know we have a problem with tranny flairs, its more like its slipping but this is different all together.

Sent from AutoGuide.com Free App
OP has a V6 G8, you have a G8 GT, they do not have the same transmission.

Not sure if the 5L40E on the G8 V6 has flare issues. Hopefully the dealer will get you sorted out.
 

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Discussion Starter #7
*Update*

This isn't so much with the transmission stuff, but my car has gone into safety twice in the last two months. Happened the second time today. Mechanic said it sounds like throttle body needs replaced. They're running tests Tuesday when it goes in for transmission diagnostics.
 

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*Update*

This isn't so much with the transmission stuff, but my car has gone into safety twice in the last two months. Happened the second time today. Mechanic said it sounds like throttle body needs replaced. They're running tests Tuesday when it goes in for transmission diagnostics.

I replaced my throttle body for a Safety Mode symptom and that worked wonders but when mine went into safety mode it never came back out until i replaced it.

As for your 5L40-E, it could be that your direct clutch drum is probably cracked at the weld and leaking pressure causing clutch chatter. If this is the case, the clutches will soon burn and you will lose 4th altogether.

It is also highly possible that what you perceive as being 4th gear is really the lockup torque converter applying. This could be caused by a bad valve body that wore out the TCC bore (common- in fact when I had my 5 speed I put a sonnax kit which uses a steel sleeve and an oversized valve), a bad torque converter, or you may simply need a tune up.

The issue with Park and Drive sounds like you may have a temperamental internal mode switch (aka range sensor, MLPS, neutral safety switch, etc). This also happened to me at random times but hardly worth fixing at the rate it was happening to me.

If you need any more info let me know. But the next step would be a pan drop to do an inspection for clutch debris.
 

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Discussion Starter #10
Well diagnosis from GM is that the Throttle Body is bad. I would hope so since my car went into Reduced Power mode 10 times since Thursday. It's covered under the Powertrain so I get a free repair and rental.

As for the transmission they believe whatever I was feeling for catching in 4th was just from the throttle body. They said if it persists after this new repair they will take further action.

I got no answer from them about the car trying to put itself in park unfortunately.
 
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