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

 

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.

 

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

 

I am curious about this, too, but at a much lower speed. When turning a corner without stopping, I find the trans going into 1st for a few moments even though I'm going say 8-12 mph. Seems needless.

 

The ECT selector is indeed in the middle "normal" position. The switch works insofar as it turns an indicator lamp on in the dashboard when in PWR or Snow, so I assume it's not that.

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.

 

^ 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.

 

Indeed, although this is proving tricky.

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

 

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.

 

I think I’ve found the cause of my high idle and rich running... slight exhaust leak! New gaskets ordered... hope this settles things.

 

Nice finding. Please report the noticeable short term and long term (a week after) changes after the replacement of the gasket.

Are you planning to change gaskets by yourself or at the station?

 

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!

 

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.

 

Pretty sure that would generate a code

 

and seriously effect performance lol

 

let me guess they quoted you like 3k for the job ? XD