Changing down gear too readily
12-15-20, 03:50 AM
#1
Driver School Candidate
Thread Starter
Changing down gear too readily
I am finding my 2005 LS430 is dropping a gear for the slightest acceleration and seems to forget it's a torquey V8.
For example, on a flat at 65mph if I "resume" cruise control to 75mph, it'll drop from 6th to 5th.
Worse, on a very slight incline it'll drop to 4th for the same 65-75 increase.
I would expect a luxury car with such a strong engine to hold its gear. Is what I'm experincing normal, or should the car muscle through?
Jeremy
For example, on a flat at 65mph if I "resume" cruise control to 75mph, it'll drop from 6th to 5th.
Worse, on a very slight incline it'll drop to 4th for the same 65-75 increase.
I would expect a luxury car with such a strong engine to hold its gear. Is what I'm experincing normal, or should the car muscle through?
Jeremy
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Tharper1 (12-15-20)
12-15-20, 03:23 PM
#2
What you are experiencing is not normal at least as far as slight incline. Is the ECT button above the gear selector **** in the middle (normal) position? If it was in the "power" position it will shift earlier.
My '05 virtually never downshifts to 4th and will hold 6th or 5th up a 5-6 percent grade at 50-60 mph, like a diesel.
My '05 virtually never downshifts to 4th and will hold 6th or 5th up a 5-6 percent grade at 50-60 mph, like a diesel.
12-15-20, 05:26 PM
#3
Lexus Champion
If you are in pwr mode then it will prefer to shift down to be ready for speed increases whenever it senses and incline. It's not a bad thing that it shifts down and if you are using more than very light pedal it will so that's it's ready
12-15-20, 08:12 PM
#4
I am finding my 2005 LS430 is dropping a gear for the slightest acceleration and seems to forget it's a torquey V8.
For example, on a flat at 65mph if I "resume" cruise control to 75mph, it'll drop from 6th to 5th.
Worse, on a very slight incline it'll drop to 4th for the same 65-75 increase.
I would expect a luxury car with such a strong engine to hold its gear. Is what I'm experincing normal, or should the car muscle through?
Jeremy
For example, on a flat at 65mph if I "resume" cruise control to 75mph, it'll drop from 6th to 5th.
Worse, on a very slight incline it'll drop to 4th for the same 65-75 increase.
I would expect a luxury car with such a strong engine to hold its gear. Is what I'm experincing normal, or should the car muscle through?
Jeremy
12-16-20, 12:48 AM
#5
Driver School Candidate
Thread Starter
What you are experiencing is not normal at least as far as slight incline. Is the ECT button above the gear selector **** in the middle (normal) position? If it was in the "power" position it will shift earlier.
My '05 virtually never downshifts to 4th and will hold 6th or 5th up a 5-6 percent grade at 50-60 mph, like a diesel.
My '05 virtually never downshifts to 4th and will hold 6th or 5th up a 5-6 percent grade at 50-60 mph, like a diesel.
I do also have what seems like a rich running engine as the exhaust smell is a little fruity and I have a high idle until fully warm - I wonder whether that may be closer to the root of the problem... I'll keep exploring.
12-18-20, 09:02 AM
#6
^ I would try to sort out the rich running engine first, then see if the transmission issue persists. Check for stored codes, inspect your air filter, clean the MAF filter, pull a spark plug and inspect, etc.
12-18-20, 09:06 AM
#7
Driver School Candidate
Thread Starter
I've replaced air filter (as part of an oil service), replaced the MAF with another from a good car, replaced the spark plugs and cleaned the throttle body. No joy.
My next step will be to remove the throttle body completely and have a go and the small idle holes, replacing the gaskets as I go.
After that I'm stumped.... perhaps a leaky injector? I have no codes at all, clean as a whistle, frustratingly!
Cheers,
Jeremy
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12-18-20, 09:47 AM
#8
Instructor
Do you know it's running rich or are you just going by smell? A cheap $100 or less scanner will give you live data so you can observe short and long term fuel trims and know for sure. Hard data is better than assumptions.
12-20-20, 01:32 PM
#9
Driver School Candidate
Thread Starter
Found it
I think I’ve found the cause of my high idle and rich running... slight exhaust leak! New gaskets ordered... hope this settles things.
12-20-20, 05:59 PM
#10
I think I’ve found the cause of my high idle and rich running... slight exhaust leak! New gaskets ordered... hope this settles things.
https://youtu.be/TwfS0cJUo5E
https://youtu.be/TwfS0cJUo5E
Are you planning to change gaskets by yourself or at the station?
12-29-20, 09:47 AM
#11
Driver School Candidate
Thread Starter
I'm waiting for the gasket in shipping - but did put some exhaust repair paste on temporarily to see what the effect would be. Immediate improvement for a day... and then it managed to blow a hole through the patch and back to behaving as it was before 
Anyway, that confirms it is the cause of the poor running - so when the gasket and bolts finally turns up, I am expecting a good result!
Anyway, that confirms it is the cause of the poor running - so when the gasket and bolts finally turns up, I am expecting a good result!
12-29-20, 01:12 PM
#12
I'm waiting for the gasket in shipping - but did put some exhaust repair paste on temporarily to see what the effect would be. Immediate improvement for a day... and then it managed to blow a hole through the patch and back to behaving as it was before
Anyway, that confirms it is the cause of the poor running - so when the gasket and bolts finally turns up, I am expecting a good result!
Anyway, that confirms it is the cause of the poor running - so when the gasket and bolts finally turns up, I am expecting a good result!
They used stethoscope to do a quick check up of exhaust manifold and other areas. They didn’t find anything, however, one genius came and said that all two catalytic converters are blocked. They claimed that 430 F temperature is a direct indication of this fact. I asked them if they are 100 percent sure, for which they said they have no doubt. I asked if they see something else that could indicate their statement is true. No other tests were performed.
I wonder if what they said is true. Any insights will be appreciated.
12-29-20, 02:13 PM
#13
Moderator
Something interesting happened today. On my way home I decided to stop by at the exhaust shop to have them check if there is any exhaust leaks in my car.
They used stethoscope to do a quick check up of exhaust manifold and other areas. They didn’t find anything, however, one genius came and said that all two catalytic converters are blocked. They claimed that 430 F temperature is a direct indication of this fact. I asked them if they are 100 percent sure, for which they said they have no doubt. I asked if they see something else that could indicate their statement is true. No other tests were performed.
I wonder if what they said is true. Any insights will be appreciated.
They used stethoscope to do a quick check up of exhaust manifold and other areas. They didn’t find anything, however, one genius came and said that all two catalytic converters are blocked. They claimed that 430 F temperature is a direct indication of this fact. I asked them if they are 100 percent sure, for which they said they have no doubt. I asked if they see something else that could indicate their statement is true. No other tests were performed.
I wonder if what they said is true. Any insights will be appreciated.
