rjakrx Posted November 7, 2008 Share Posted November 7, 2008 I have a 2000 RX300 with 98k on the odo, during this summer it ran like a breeze. However, once winter started to hit (In Alaska with average temp in teens) the engine began to knock severely like the rocker arms were hitting. I changed the oil again (mobil 1 filter and penzoil platinum 5w-30 full synthetic), still running like crap, very sluggish, lost performance, gas mileage info down to 14.4 mpg avg. Today I went through and cleaned the MAF and added Chevron Full Fuel System Cleaner with Techron to help clean the fuel injectors. So far its a little more smooth but still sounds like a deisel engine, this knock does not go away while accelerating but is most noticable during idle in nuetral. There are no check engine lights on. Tomarrow I am going to clean the IACV and get an oil additive. So far there has been no noticable oil consumption, residue in the oil pan, or oil going through combustion. I think this might be an 02 sensor or Air Fuel Sensor issue but don't know how to check because of the lack of check engine light which I think means lack of error codes. I would really appreciate any help. Quote Link to comment Share on other sites More sharing options...
blk_on_blk Posted November 7, 2008 Share Posted November 7, 2008 I would look at the knock/ping sensor, too. They are hard to get to, though (down in the valley between the heads). You are already checking the other things I would suggest, like MAF and IACV. If I were to try to think it out in my head, I would first consider what you said about the change of temperature (if that is the only variable that has changed regarding how the vehicle drives).... but then once the engine is up to operating temperature, it should behave the same as in warmer climates. Although, the only other thing that would be different and stay different is the incoming air temperature... that would be much colder. Then that would narrow it down to some 'control' aspect on the intake... like the MAF, IACV, knock/ping sensor, etc. So, I think you are on the right track. It sounds like one of those sensors is trying to compensate for the cold weather, but it just can't quite do it... but since it's trying, the ECU hasn't detected any error nor codes. I had a MAF on my RX300 that was 'slow to respond' as my shop put it, but it didn't trigger any codes. They had it on the scope and could see it was nearly out of range, but functioning. I replaced it and the engine ran smoother. Your best bet to really 'see' what's going on is to find a shop that can tap into the ECU and read all the sensors, their response time, and see if they are doing what they should. If you find one that is slow or on the limit as far as it's reading, that might be the culprit as it might not be able to compensate for the extreme change in temperature. All in all, I think you are on the right track... but I hate to see you just start replacing parts and see what effect it has. Quote Link to comment Share on other sites More sharing options...
lexrx3 Posted November 7, 2008 Share Posted November 7, 2008 I have a 2000 RX300 with 98k on the odo, during this summer it ran like a breeze. However, once winter started to hit (In Alaska with average temp in teens) the engine began to knock severely like the rocker arms were hitting. I changed the oil again (mobil 1 filter and penzoil platinum 5w-30 full synthetic), still running like crap, very sluggish, lost performance, gas mileage info down to 14.4 mpg avg. Today I went through and cleaned the MAF and added Chevron Full Fuel System Cleaner with Techron to help clean the fuel injectors. So far its a little more smooth but still sounds like a deisel engine, this knock does not go away while accelerating but is most noticable during idle in nuetral.There are no check engine lights on. Tomarrow I am going to clean the IACV and get an oil additive. So far there has been no noticable oil consumption, residue in the oil pan, or oil going through combustion. I think this might be an 02 sensor or Air Fuel Sensor issue but don't know how to check because of the lack of check engine light which I think means lack of error codes. I would really appreciate any help. I can't say this will solve your problem but I would be running a synthetic 0W 30 in the engine. I use Amsoil's SSO 0w 30 in my 01 RX 300 with 74,000 on it and it runs great. The SSO is definitely one of the better oils out there but Mobil 1 0W 30 should be fine too. Pennzoil would be fine too but definitely a full synthetic 0W 30. You need all the help you can get in those temps. Keep the Mobil 1 filter, its one of the better ones out there. Amsoil has a very good one too. I'd be careful with any oil additives. I've been in the oil industry for many years and I can't even think of one to recommend trying. May be you've got some bad gas? Quote Link to comment Share on other sites More sharing options...
djspawn00 Posted November 7, 2008 Share Posted November 7, 2008 hopefully you don't have sludge... pull the valve cover and take a look... run some seafoam through there to quiet down the sticky lifters... Quote Link to comment Share on other sites More sharing options...
rjakrx Posted November 8, 2008 Author Share Posted November 8, 2008 hopefully you don't have sludge... pull the valve cover and take a look... run some seafoam through there to quiet down the sticky lifters... I just called lexus about it and they said I do qualify for the sludge replacement which is great to hear, but I need to take it in to the dealer to get it diagnosed. If the dealer doesn't find any sludge I will be stuck with the diagnosis bill, which I hear can be pretty spendy, I've heard the $400 range (way off?). I would like to hedge my bets and pull the valve cover to check for sludge, any steps on doing so? I don't have a manual or anything. Quote Link to comment Share on other sites More sharing options...
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