Update on '00 Impala engine/trans. shudder...

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Tzu

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Oct 12, 2012
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near Buffalo, NY
I previously posted about our Impala 3800 with the p1811 (long shift time) and told of the engine stalling randomly, jerkiness when taking off and intermittent rpm drop during highway cruising. No CEL at all, but a couple of sensors later and still nothing changed, except I lost some money. Dealer did not even notice or say anything about MAF sensor when it was scanned there? I unplugged the battery for a week to reset computer and it still randomly missed upon first start up. So I unplugged MAF sensor and the car ran ALOT better. Took it for a ride and no bucking or hesitation at all. Average mpg went from 23 before to 26 with the sensor unplugged. The transmission still shifted the same, but at least I feel comfortable driving the car again. The original lasted 7 years/130,000 miles and the Autozone one went 7 years/90,000 miles. Time to drop another $130 for another one. Thank GOD there is a simple way to check the sensor. Only time RPM bounced was coming off 55mph and let it coast down like coming to a normal stop in the country. Never stalled, but idle was definitely off until I came to a complete stop. Then idle was great. Hope this helps someone else.
 
In your first post about this problem, I figured that the transmission was the problem.
How nice that you've discovered that it was really the MAF.
A fairly cheap and easy repair that will keep this Impala on the road for maybe another 100K.
 
I did pay with a credit card because money is a bit tight at the moment. I specifically asked before I made the appointment if their factory scanner will pin point the exact problem, and they said yes. I would have never checked the MAF and did my home test without our home computer. It's scary to have to rely on dealerships if you have no choice, but in my case, the internet helped me ALOT.
Originally Posted By: michaelluscher
If the dealers blatent misdiagnosis cost you that much
I hope you payed with a CC, dispute them
 
I'll be happy with 75K
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The transmission worried me because it could have pushed me to get rid of the car altogether, when it is in pretty good shape otherwise. Went to a junkyard today to find a used MAF, but because they have $50 core on each one, every car was missing one. I thought I could gamble on a cheap try. The unplugging experiment worked the best!
Originally Posted By: fdcg27
In your first post about this problem, I figured that the transmission was the problem.
How nice that you've discovered that it was really the MAF.
A fairly cheap and easy repair that will keep this Impala on the road for maybe another 100K.
 
It's pretty amazing the difference, isn't it? Glad you were able to find a resolution!

You say the transmission still shifts the same, would you refresh my memory?
 
The transmission wasn't really shifting bad before the trouble started, but when my wife mentioned the car kept stalling on her and running rough, I didn't know what to think. When I replaced various sensors that other forum guys said fixed their cars, it had no effect on my car and still bucked or shuddered on acceleration, still with no CEL. My dad's Pontiac did the same thing right before he junked it. I was out of ideas, so I had the dealer scan it and their computer said the P1811 popped up and the transmission is toast. $3,000 to fix so that is where the shift kit came in to try and get rid of that code. The last MAF sensor threw a code so it was easy to identify the problem. This time it didn't.
 
They put it on their computer and after almost 1.5 hrs, they found the long shift code come up that was stored in the car's memory. They test drove it before hooking it up to confirm what I told them. It came to $107 for a diagnostic fee. If this fixes my car, I just saved a bunch of money in 15 minutes ( this is NOT a GEICO ad
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Originally Posted By: Merkava_4
What exactly did the dealer do anyway ?
 
My appointment was for 8:30am and after paying for it, I left the parking lot at 10:11am. I saw the car go in the bay, and after 1 hour passed, I asked what they found and I was told they are still looking over the data? I saw friends I knew in there waiting too on a recall, so time went quicker than it could have.
 
Before I scheduled it in, he said ball park is around $100 but they WILL find the trouble. I felt it was worth it considering I spent almost that on a couple different things already. They looked professional so I took their word. If I had them replace the trans like they quoted, they said the diagnostic fee would be waived. What a deal..........not.
 
The dealer's final diagnosis was a new transmission to be installed for $3K. I realize being 14 years old and higher mileage makes certain things feel worn, but all the hesitating, random stalling, and general driveability problems they said were tied into the transmission code P1811. So far disconnecting the MAF sensor at home fixed those problems. Putting a new sensor in this morning and calling it done.
 
Installing that shift kit will more than likely keep that P1811 code away, and replacing the MAF will keep your engine running correctly.

Now it's time to invest in a scan tool of some sorts. This will pay in the long run in the way of fewer diagnostic fees and lower repair costs.
 
I went through something similar. Two scans no codes. Shift kit installed and PCS installed. Still long engagement and then bam into gear from a start.
Its actually getting worse especially as the weather warms up.
 
I thought mine was engine related since it would run rough at random times either in drive or park, and engine hot or cold. The transmission diagnosis was the worst case scenario that so far I have not had to deal with. Do you think the computer that changes the shifts and pressure could be at fault? It seems like you have done more than I did and it still acts up. Maybe I just got lucky? I hope you can find the problem.
Originally Posted By: rshaw125
I went through something similar. Two scans no codes. Shift kit installed and PCS installed. Still long engagement and then bam into gear from a start.
Its actually getting worse especially as the weather warms up.
 
Originally Posted By: Tzu
The dealer's final diagnosis was a new transmission to be installed for $3K. I realize being 14 years old and higher mileage makes certain things feel worn, but all the hesitating, random stalling, and general driveability problems they said were tied into the transmission code P1811. So far disconnecting the MAF sensor at home fixed those problems. Putting a new sensor in this morning and calling it done.


I would think that if you change the MAF sensor and it's a fix, the dealer owes you your money back for the diagnostics.
 
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