What's the rattle noise got to do with the hard shifts on the transmission

lasabre

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2003 Buick Lesabre 3800 V6 70K only on it. this problem Hard or long shifts it comes and goes, it seems
when the engine is hot normally on a long run it starts with the hard transmission
shifts, same as a P1181 code but no engine check light on yet , some articles say a MAF sensor could cause it
what's next any suggestions ?.
 
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lasabre

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Regarding the rattle;
Check Engine/Transmission mounts
Also check the exhaust system. Examine carefully the hangers and catalytic converter.
thank you now I have a P1181 code
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lasabre

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I cleaned my MAF sensor ,it seemed O for about 3 days . then back to the unexpected shifts and now a purge valve little rattle sound at Idle would the purge valve code P0440 have any control over the transmission?
 

HotZ28

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I cleaned my MAF sensor ,it seemed O for about 3 days . then back to the unexpected shifts and now a purge valve little rattle sound at Idle would the purge valve code P0440 have any control over the transmission?
Not likely!
 

lasabre

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would the purge valve code P0440 have any control over the transmission ONLY BECAUE ITS IN THE VACUME AREA WHISCH IS IN THE SAME AS THE MAP sensor?
 

Alan 55

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would the purge valve code P0440 have any control over the transmission ONLY BECAUE ITS IN THE VACUME AREA WHISCH IS IN THE SAME AS THE MAP sensor?
We are talking about two separate systems here in my opinion. There is no link between the two even if they are both vacuum operated.
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imidazol97

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Is the rattle sound coming from the purge valve?

I recall some piece of flat metal on the lower front of the firewall that was held in a way
that could rattle. Came across that when replacing the read engine/transmission mount, which
wasn't needed after all. I believe it was a heat shield between the exhaust pipe and the floor.
 
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Tony S45

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Interesting! Having somewhat the same issues.

My daughter's 2004 Lesabre with 75k miles suddenly threw codes P0463/P0496 and P1811/P1819. While 16 years old, the car has received at least reasonable maintenance care over the years.

Her local mechanic's shop which she trusts replaced the purge valve and recommended that she consider replacing the fuel pump (big $$$) and a general tune up of plugs wires, fuel filter, etc. ( more big bucks.) Codes cleared an didn't come back.

Shop also performed a transmission flush/service and stated that the test drive concluded no shifting issues.

Two weeks later = no new codes but daughters family claims the shifts below 40 mph are "hard".

I live a state away and can't get to the vehicle for a few Covid weeks.

Will the "hard shifts" in lower speeds damage the trans until we can find a reputable transmission shop to correctly diagnose? Seems that a replaced Pressure Control Valve and possibly a shift kit would solve the problem and allow this trans to last for many more years.

Where is the Trans Neutral Safety Switch which may have caused Code P1819 located?
 

Tony S45

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Going to reply to my own comment. Called out-of-state daughter and son-in-law. Told him to go out, warm up the Buick, and check the trans fluid. Sure enough, although the car was just serviced the shop failed to fill the trans with enough new fluid and it was not performing correctly. No codes.

Son-in-law topped off trans with proper fluid and now the car shifts and runs correctly. Some times it's the simple stuff and sometimes it's big bucks!

Dodged the bullet this time!
 

2007LucerneCXL

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The OP needs to stick with a post and a question. Bouncing around and asking the same question on a bunch of different posts and looking for different answers will not troubleshoot the problem any better or faster.
 
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