Lexus IS250 4GR-FSE Engine Carbon Build-up (merged threads)
09-16-10, 08:22 AM
#301
In my opinion, toyota engines have always produced more carbon than say a Ford duratec.
No scientific proof, just the amount of soot on the tail pipes I see on a toyota vs other cars.
No scientific proof, just the amount of soot on the tail pipes I see on a toyota vs other cars.
09-16-10, 08:23 AM
#302
If they changed header, can the dealer replace it on a 2008 IS250 under warranty?
09-16-10, 08:28 AM
#303
Mr. Toyota had a simple policy. Follow the leader and when close enough, zoom ahead and be #1.
10-04-10, 11:35 PM
#304
First post UPDATED 
UPDATE: I have had the dealership perform the latest service bulletin LSB, as far as its effectiveness goes, it took care of the issue. It's now been several months and 10,000 miles later and I have only had the car surge once but never again. Also I have not done an oil change since they performed this service so it's still on what ever oil the Lexus dealership used. That will change as of this week, but in essence I can say that the rough idle and the surging at stoplights has seized. Vibration has also notably gone down from what it used to be when the car was at a full stop in a stop light. I will update the progression as time goes. If you have had this service done please share your experience in terms of fixing most of the issues that are present.
Last edited by XhyDra; 10-04-10 at 11:39 PM.
10-05-10, 07:54 AM
#305
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So I did some research. Apparently Lexus Toyota took some cars in Fl and CA and tore them apart in regard of the carbon problem. Not sure what the outcome was. But they're not completely convinced it's the due to carbon buildup.
I quickly skim it but it mostly talks about having port and direct injection. And what's the caused for carbon is mostly due to variable valve timing.
I will continue to run some other tests on my is awd.
I quickly skim it but it mostly talks about having port and direct injection. And what's the caused for carbon is mostly due to variable valve timing.
I will continue to run some other tests on my is awd.
10-05-10, 11:12 AM
#307
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ok....
so i just spent the last four hours in lab trying to figure this problem out. and this is what i did to the car:
i took apart the throttle body and stuck tape in it simulating carbon build up.
on cold start the pcm opens it more then as it heats up and goes into closed loop it backs off the throttle..
this is what i've learned: when its in open loop the window where it allows the throttle to be is open more than when its in closed loop. once its in closed loop: the pcm desires a certain idle by opening and closing the throttle however if i stuck just the right amount of tape(without setting a DTC) the throttle is at its maximum opening percentage. if i add anymore it would just put the car into limp-in mode/fail safe. being its right at the point where it cant open the throttle anymore it compensate through timing. this was the only way i was able to duplicate the rough idle. bc i cleaned my throttle and engine with some top engine cleaner (Seafoam). i havent seen it happen again (yet i dont think).
also someone made the comment about adding a fuel additive. idk if that will do very much bc it is direct injection. its not going to clean your valve any. i know with this engine they do re open the intake valve to push some of the unburn fuel back up the intake and sucked back in to burn again what was unburnt but idk how much that will affect the valve. i suspect NOT a lot unless we can do more studies on it.
as far as the manufacturers standpoint is that they arent fully convinced its carbon causing the issue. it might be a/f mapping. which was my initial thought but i wasnt the person that engineered this engine. they really need to go in and figure something out whether is mechanical or electronics.
so i just spent the last four hours in lab trying to figure this problem out. and this is what i did to the car:
i took apart the throttle body and stuck tape in it simulating carbon build up.
on cold start the pcm opens it more then as it heats up and goes into closed loop it backs off the throttle..
this is what i've learned: when its in open loop the window where it allows the throttle to be is open more than when its in closed loop. once its in closed loop: the pcm desires a certain idle by opening and closing the throttle however if i stuck just the right amount of tape(without setting a DTC) the throttle is at its maximum opening percentage. if i add anymore it would just put the car into limp-in mode/fail safe. being its right at the point where it cant open the throttle anymore it compensate through timing. this was the only way i was able to duplicate the rough idle. bc i cleaned my throttle and engine with some top engine cleaner (Seafoam). i havent seen it happen again (yet i dont think).
also someone made the comment about adding a fuel additive. idk if that will do very much bc it is direct injection. its not going to clean your valve any. i know with this engine they do re open the intake valve to push some of the unburn fuel back up the intake and sucked back in to burn again what was unburnt but idk how much that will affect the valve. i suspect NOT a lot unless we can do more studies on it.
as far as the manufacturers standpoint is that they arent fully convinced its carbon causing the issue. it might be a/f mapping. which was my initial thought but i wasnt the person that engineered this engine. they really need to go in and figure something out whether is mechanical or electronics.
10-05-10, 11:54 AM
#309
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10-07-10, 12:26 AM
#313
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u guys r in luck.. is350 awd is now available.
10-16-10, 11:00 PM
#315
A little update on the progress of my IS250, as of a few days ago the car has rough idled three times during stops. It maintained the rough idle until I accelerated. This wasn't like the ones it had experienced before, it was a lot more unstable, the car would shake as if it wanted to shut off, and I could hear that the injectors were slowing down. Another thing I noticed was the interior lights flickering when this was happening. As soon as I accelerated it completely went away.
To help rule out things, and or include causes here's a list of what needs to be done and has been done;
- Spark plugs, I'm 10k overdue.
- Battery was replaced late last year by dealer.
- Need to do an oil change, and clean air-intake filter.
Other than that theres a possibility that it could be a returning issue or one of the above needs to be addressed.
Several things to note, gas mileage is still good, on a 150mile highway trip with PWR ECT on going 75-80mph (no cruise control) the computer read 35mpg. So if it was the spark plugs it wouldn't render such good gas mileage. It doesn't make too much sense.
I'll be changing the oil, air intake filter, and cabin filter tomorrow so I'll report back on that. Also in the oil change I will be using Amsoil 0W-30 Signature with their new Engine & Transmission flush. In case you missed my last post I have 10.5k on whatever oil the dealer used when they did the top engine cleaning.
To help rule out things, and or include causes here's a list of what needs to be done and has been done;
- Spark plugs, I'm 10k overdue.
- Battery was replaced late last year by dealer.
- Need to do an oil change, and clean air-intake filter.
Other than that theres a possibility that it could be a returning issue or one of the above needs to be addressed.
Several things to note, gas mileage is still good, on a 150mile highway trip with PWR ECT on going 75-80mph (no cruise control) the computer read 35mpg. So if it was the spark plugs it wouldn't render such good gas mileage. It doesn't make too much sense.
I'll be changing the oil, air intake filter, and cabin filter tomorrow so I'll report back on that. Also in the oil change I will be using Amsoil 0W-30 Signature with their new Engine & Transmission flush. In case you missed my last post I have 10.5k on whatever oil the dealer used when they did the top engine cleaning.