Lexus IS250 4GR-FSE Engine Carbon Build-up (merged threads)
11-09-10, 03:48 PM
#376
Advanced
Join Date: Mar 2008
Location: Illinois
Posts: 613
Likes: 0
Received 0 Likes
on
0 Posts
Noticed that if the AC is not on, the RPM are very low with the foot on the brake(brake lights on), like 550-600 and engine is not quite smooth at that speed. So here is my theory:
All those times when we come to a stop and
1. the AC is not engaged due to the AC cycle
2. the 1st gear is engaged abruptly at the moment the speed is almost zero
You will experience
- Low idle with vehicle shaking as if it was about to stall
because of the excessive loads (brake lights on + 1st gear engagement action) coming into the equation all at the same time and not enough rpm to support the electrical load. Additionally, if the headlights happen to switch on at this time, the RPM flutters.
thoughts?
All those times when we come to a stop and
1. the AC is not engaged due to the AC cycle
2. the 1st gear is engaged abruptly at the moment the speed is almost zero
You will experience
- Low idle with vehicle shaking as if it was about to stall
because of the excessive loads (brake lights on + 1st gear engagement action) coming into the equation all at the same time and not enough rpm to support the electrical load. Additionally, if the headlights happen to switch on at this time, the RPM flutters.
thoughts?
11-10-10, 04:11 PM
#377
And here is the nail.
When the car is HOT and radiator is also running, it really flutters badly. To me this means that engine does not have enough power to handle all that load all at once. Is it because of the fuel map im effect when engine is too hot?
When the car is HOT and radiator is also running, it really flutters badly. To me this means that engine does not have enough power to handle all that load all at once. Is it because of the fuel map im effect when engine is too hot?
11-10-10, 06:23 PM
#378
Advanced
Join Date: Mar 2008
Location: Illinois
Posts: 613
Likes: 0
Received 0 Likes
on
0 Posts
^ I'm not too sure about the IS but most cars automatically run the radiator fan more when the AC is turned on. Has to do the the condenser. So the AC ON or FAN ON could be considered "almost" the same electrical load on the engine.
Cars run rich when cold and lean out when they are hot. Overly lean conditions can cause backfires through the intake. Some vehicles can richen up the mixture to help cool the engine but I highly doubt that can happen to an automotive in the USA. Emissions regulation that would not allow it i guess. Misfires are bad for emissions too.
Cars run rich when cold and lean out when they are hot. Overly lean conditions can cause backfires through the intake. Some vehicles can richen up the mixture to help cool the engine but I highly doubt that can happen to an automotive in the USA. Emissions regulation that would not allow it i guess. Misfires are bad for emissions too.
Last edited by Gaugster; 11-10-10 at 06:29 PM.
11-10-10, 07:05 PM
#379
Just as a comparision, the v6 on my mazda6 never fluttered at idle under any load. The idle speed was stable as it could ever be.
From what i understood it ran pretty rich.
From what i understood it ran pretty rich.
11-11-10, 10:37 AM
#381
Pole Position
I imagine they do this, or at least say they're going to charge you even if they don't end up doing it to prevent hypochondria.
11-11-10, 11:05 AM
#383
Pole Position
I don't know how carbon buildup could possibly be an issue on a car with 5k on it. My GS had over 60K on it before they cleaned mine and even then it wasn't even that horrible, just annoying once in a while and idled rough after starting for the first time after sitting overnight.
11-11-10, 11:48 AM
#385
^ I'm not too sure about the IS but most cars automatically run the radiator fan more when the AC is turned on. Has to do the the condenser. So the AC ON or FAN ON could be considered "almost" the same electrical load on the engine.
Cars run rich when cold and lean out when they are hot. Overly lean conditions can cause backfires through the intake. Some vehicles can richen up the mixture to help cool the engine but I highly doubt that can happen to an automotive in the USA. Emissions regulation that would not allow it i guess. Misfires are bad for emissions too.
Cars run rich when cold and lean out when they are hot. Overly lean conditions can cause backfires through the intake. Some vehicles can richen up the mixture to help cool the engine but I highly doubt that can happen to an automotive in the USA. Emissions regulation that would not allow it i guess. Misfires are bad for emissions too.
Try this:
When the car is hot, driven at least 20 minutes or so.
Come to a stop.
Keep your foot on the brakes.
Switch on the rear defroster.
Keep the A/C on.
Turn the steering about 30 degrees.
Switch on the lights.
if possible, switch on the wipers too!
11-11-10, 06:17 PM
#386
Advanced
Join Date: Mar 2008
Location: Illinois
Posts: 613
Likes: 0
Received 0 Likes
on
0 Posts
Doesn't this car have 2 fans? One for the coolant and the other secondary for the A/C ? The problem is when both of them are on at the same time.
Try this:
When the car is hot, driven at least 20 minutes or so.
Come to a stop.
Keep your foot on the brakes.
Switch on the rear defroster.
Keep the A/C on.
Turn the steering about 30 degrees.
Switch on the lights.
if possible, switch on the wipers too!
Try this:
When the car is hot, driven at least 20 minutes or so.
Come to a stop.
Keep your foot on the brakes.
Switch on the rear defroster.
Keep the A/C on.
Turn the steering about 30 degrees.
Switch on the lights.
if possible, switch on the wipers too!
Think we're a bit off topic here....
11-11-10, 06:51 PM
#387
lol - your cracking my up man. Ya I believe the radiator has two fans. How or if they are sequenced, idk...? I would curb check my ride doing what you suggest so sorry but can't really help you there... I did check my battery and visually the test port shows okay. You should add crank the stereo to your list. Think we're a bit off topic here....
Think we're a bit off topic here....anyways, I noticed engine idle speed flutter under this circumstances so trying to see if they are related or not. Battery is good on mine. checked that out. no buildup and voltage is fine.
11-15-10, 10:57 AM
#388
Any way this is definitely turning interesting.
So i started using chevron exclusively but could not see any quick results so the impatient bstrd in me threw in 20 oz of techron concentrate too. Let it run the whole tankful and one more chevron tank and still saw no difference.
The impatient me then threw in a bottle of the new Lucas deep clean with a new tank of chevron gas last week. By the time i got to 'E', the engine idle had improved. Wtf.
I also checked the oil level and that is good but my mobil1 synthetic oil has turned dark and it has only 1000 miles on it.
Does rhis cleaning really worked? Or am i dreaming?
11-15-10, 02:48 PM
#389
Advanced
Join Date: Mar 2008
Location: Illinois
Posts: 613
Likes: 0
Received 0 Likes
on
0 Posts
Well even the can of techron states that two applications may be required. It could be just a marketing tool to get people to buy more of the product or may really be needed in heavy build up situation.
Just drive it for more miles and see if it is really cleared up and is better....
Just drive it for more miles and see if it is really cleared up and is better....