Suggestions For 1996 Sc400

[Micah]

Hi,

This is my second post, and I love to learning about my car. . .sorry. I just purchased this 96 sc400 with 205000 miles. I would like to drive it on a long trip this summer and the car seems sound (I will be having the timing belt the water pump, and an idler arm replaced next week. Just wanted to know if there is anything else I should do to it before a long trip. The main thing that concerns me is that at interstate speeds (approximately 75 mph) the car runs a about 2700 rpm. Is this normal or could I have a tranny prob? No check engine light, so I am assuming that there is no ratio error if the computer even monitors this item. Thank for any info, mainly all I want to know is if the 2700rpm to 75 mph is the correct ratio or should the rpm be lower at that speed. Any other sc400 owners encouraged to reply! Thanks!!!

[lexus082]

Hi,

This is my second post, and I love to learning about my car. . .sorry. I just purchased this 96 sc400 with 205000 miles. I would like to drive it on a long trip this summer and the car seems sound (I will be having the timing belt the water pump, and an idler arm replaced next week. Just wanted to know if there is anything else I should do to it before a long trip. The main thing that concerns me is that at interstate speeds (approximately 75 mph) the car runs a about 2700 rpm. Is this normal or could I have a tranny prob? No check engine light, so I am assuming that there is no ratio error if the computer even monitors this item. Thank for any info, mainly all I want to know is if the 2700rpm to 75 mph is the correct ratio or should the rpm be lower at that speed. Any other sc400 owners encouraged to reply! Thanks!!!

That seems a bit high. I think when I'm steadily doing 70+ mph the rpm's are just below 2000 rpm. I'm sure on of the pro's on here can give you a technical response concerning what possibly could be wrong.

[Micah]

I thought that it seemed high. I just wanted verification. Is yours the 4 speed transmission or the 5 speed (98 to 2000)

[Micah]

Found one other posting about the same issue I am having. . .2500 rpm at 70 and 2700 at 75mph. Is this just normal for the 96 sc400 or is there something wrong? I am confused. Here's the link to the posting:

RPM Posting. . .any thoughts?

[jzz30]

4th gear is the least likely to fail the rpm sounds normal. as far as i remember at a little over 2000 rpm say 2250-2500 my 4speed is going about 60.

other things to maintain may be hoses if they seem old, heater valve, radiator if it seems corroded or worn in any way.

[Micah]

Thank all of you for your replys. They are appreciated!

[lexus082]

Its a 4 speed transmission. Last night I was driving and was doing 80mph @ 1800 rpm.

I thought that it seemed high. I just wanted verification. Is yours the 4 speed transmission or the 5 speed (98 to 2000)

[Micah]

Its a 4 speed transmission. Last night I was driving and was doing 80mph @ 1800 rpm.

I thought that it seemed high. I just wanted verification. Is yours the 4 speed transmission or the 5 speed (98 to 2000)

Thank you for your reply. That sounds like you must get very good gas milage. Do you know what milage you get? I wonder how I can make my car cruise at those rpms. I am not really concerned with speed so much as highway milage.

[lexus082]

Its a 4 speed transmission. Last night I was driving and was doing 80mph @ 1800 rpm.

I thought that it seemed high. I just wanted verification. Is yours the 4 speed transmission or the 5 speed (98 to 2000)

Thank you for your reply. That sounds like you must get very good gas milage. Do you know what milage you get? I wonder how I can make my car cruise at those rpms. I am not really concerned with speed so much as highway milage.

I usually get around 23-24 miles/gallon. (75% highway, 25% city) and usually on highways 70-80 mph. On a recent trip which was mostly highway I got 460 miles to one tank of gas. If I were you and if you just bought the car and didn't know exactly when certain things were changed I would go ahead and do them so then you would know they have been done, especially with the mileage. Such as: Spark Plug wires, spark plugs, distributor caps & rotors, fuel filter, air filter, throttle body cleaning, oil & filter change, check transmission fluid color, tire pressure, and fuel injector cleaner should all contribute to better gas mileage and overall a better running car with fewer problems in the future. Sometimes people replace their O2 sensors after 100,000 miles so they remain accurate, only downside is that oem lexus 02 sensors are not cheap. There's info and tutorials on how to change most of items listed which can save you alot of money. But, the items listed above would be an excellent start if your not sure when they were last replaced.

[lexus082]

Also, I was trying to duplicate the rpm's you are running at and I was on the highway traveling up a steep mountain @ a steady 100mph pace and my engine stayed at 2250 rpm. In my opinion (which may not be correct) I still think your engine is running at a slightly higher rpm than normal. I don't think I could duplicate the rpm's you had at a constant speed unless I was going around 120+ mph. But thats just my two cents. Unless there is a difference between the 94 and 96 years. I know the 96 1UZFE engines had slightly more hp rating than the 94's. I don't really know, but I don't think that would make a difference in the rpm's though.

Its a 4 speed transmission. Last night I was driving and was doing 80mph @ 1800 rpm.

I thought that it seemed high. I just wanted verification. Is yours the 4 speed transmission or the 5 speed (98 to 2000)

Thank you for your reply. That sounds like you must get very good gas milage. Do you know what milage you get? I wonder how I can make my car cruise at those rpms. I am not really concerned with speed so much as highway milage.

I usually get around 23-24 miles/gallon. (75% highway, 25% city) and usually on highways 70-80 mph. On a recent trip which was mostly highway I got 460 miles to one tank of gas. If I were you and if you just bought the car and didn't know exactly when certain things were changed I would go ahead and do them so then you would know they have been done, especially with the mileage. Such as: Spark Plug wires, spark plugs, distributor caps & rotors, fuel filter, air filter, throttle body cleaning, oil & filter change, check transmission fluid color, tire pressure, and fuel injector cleaner should all contribute to better gas mileage and overall a better running car with fewer problems in the future. Sometimes people replace their O2 sensors after 100,000 miles so they remain accurate, only downside is that oem lexus 02 sensors are not cheap. There's info and tutorials on how to change most of items listed which can save you alot of money. But, the items listed above would be an excellent start if your not sure when they were last replaced.

[Micah]

Well, its at the dealership now... I'll let you know what they say about the car when I get it back. Probably won't be done today, though. Thanks for all your help! You've been great!

[jerryrigginson]

I have a 93 and the rpms sound just fine. 2grand at 70+ I think these people may have been drinking.

[lexus082]

I have a 93 and the rpms sound just fine. 2grand at 70+ I think these people may have been drinking.

Not drinking, he stated "2500 rpm at 70 and 2700 at 75mph" I couldn't even get my rpm's up that high when I was going a 100 mph up the side of a mountain. RPM's stayed at 2250 at a 100 mph.

[Micah]

Hello,

Just updating all of you on what the dealership had to say; just got my car back. They said first that the vibration is not abnormal with a car with so many miles and that there is nothing wrong with mine. They just replaced the water pump, timing belt, idler pulley, and a tie rod (1200 dollar bill that I was happy to pay as I hopefully will not have to invest any more for quite some time). They also said that the drive shaft has some wear on it and the bushing have some slack in them and was causing the clunk into and b/w gears but was no cause for alarm. They said that it was mechanically sound and I shouldn't have any problems from it for a while. I am most likely still going to replace the spark plugs in the near future to see if that helps the engine shudder. I don't think that the car has quite as much pep as it should (a small car with a v8 engine). Today, I went to pass a mazda millenia and I guess they got agitated that I was passing them so they sped up (a bit of smoke was coming from their exhaust). My car was able to pass them, but I wasn't able to get past them very quickly (I barely accelerated faster than they did). I don't know anything able mazdas millenia, but I think that my car should have whooped its tail! I believe that all of these symptoms are related, so I am going to take the next step and replace the spark plugs.

[lexus082]

Did you have them check if your engine's rpms were higher than normal? I'm just curious as to what would cause that to occur if there is in fact something wrong. If you are going to install spark plugs... When I first changed my plugs I put in Bosch Platinum 4 type spark plugs and because I thought that they were a better spark plug. And then after reading up on the forums that it was highly recommended to use oem plugs I decided to take out the Bosch plugs and replace them with OEM Denso plugs from the dealer. So I did the same job twice within 6 months. Also, your plug wires if they are oem they should have a production date on them and you can tell if they are the original spark plug wires. I just remember you stating that you like learning about your car so I figure I would type this up. I used to own an accord and used a Haynes manual to do repairs and such and never knew as much as I know now from being a member on this forum for the last two years. Enjoy your SC. If you follow what I listed as a start it should run and perform better. Also, keep in mind the car is a very heavy car which plays a big factor. Good Luck

Hello,

Just updating all of you on what the dealership had to say; just got my car back. They said first that the vibration is not abnormal with a car with so many miles and that there is nothing wrong with mine. They just replaced the water pump, timing belt, idler pulley, and a tie rod (1200 dollar bill that I was happy to pay as I hopefully will not have to invest any more for quite some time). They also said that the drive shaft has some wear on it and the bushing have some slack in them and was causing the clunk into and b/w gears but was no cause for alarm. They said that it was mechanically sound and I shouldn't have any problems from it for a while. I am most likely still going to replace the spark plugs in the near future to see if that helps the engine shudder. I don't think that the car has quite as much pep as it should (a small car with a v8 engine). Today, I went to pass a mazda millenia and I guess they got agitated that I was passing them so they sped up (a bit of smoke was coming from their exhaust). My car was able to pass them, but I wasn't able to get past them very quickly (I barely accelerated faster than they did). I don't know anything able mazdas millenia, but I think that my car should have whooped its tail! I believe that all of these symptoms are related, so I am going to take the next step and replace the spark plugs.

[Micah]

Thank you for your reply! I do enjoy working on my car (at least over the summer. . .I get bored as I am off over the summer, I am a teacher). You have been a great help, and I was able to locate a site for reference on the rpm v/s mph. Here is the site: http://www.wreg.com/global/story.asp?s=2590415

They noted that they were traveling 65 mph at 2400 rpm (I'm sure this was done when the car was new so it should be accurate). This sounds close to my rpm. My main concern was that the transmission might be slipping, but the more I read the more I believe this car is just geared high in the rearend for more performance or something. The engine sound a little better since the dealership did the work to it (it was making a scraping sound when idling. . .probably the idler pulley they replaced). I have denso in it right now, but I am not sure how to know if they need replacing. They look ok to good compared to most of the faq articles I've read. I'll ask napa tomorrow when I go to get the plugs. I'll be replacing them with new iridium plugs if needed and I believe they need it b/c I can see some carbon building up on them (they look pretty clean though). Back to rpm, though. I was just used to my 02 grand prix. It ran at significantly lower rpm and performed almost as good (although the sc400 may be a little faster). I just thought it would be like a camaro or something having a v8 in it. Not that I'm not satisfied. I love how the car handles, how it rides and the acceleration is very good. Its just not like a sports car I thought it was, but thats ok if that's how it is supposed to run. It is much more comfortable than my grand prix, but I just wish I could make it get the fuel economy that my grand prix gets. Thanks for everyones responses; I do appreciate the time all of you took to read my responses and type yours. I have learned much about this car from this forum and hope that it will continue to be as helpful for everyone else as it has been for me.

[Micah]

Hello, just an update. I replaced the wires and plugs. Brand new iridium plugs and napa premium wires. The car runs pretty much the same maybe a little less vibration (or it may just be me). I think that jzz30 is correct about the motor mounts even though the dealership didn't find anything wrong with them. I'm starting to get used to it, so I probably will not even notice it after a little longer. As for the rpm, I believe that it is normal for MY car, yours must be geared differently than mine (wish mine was geared like yours). The dealer even said it was normal, so I don't believe anything is wrong with it. I believe that I'll be very happy with it. I bought it for a very good price (little over 2000) and it runs and rides great. Next step is repaint it as it has a dent in the left rear quarter panel (I believe the previous owner ran it through a fence). Thanks for the help!

[Micah]

4th gear is the least likely to fail the rpm sounds normal. as far as i remember at a little over 2000 rpm say 2250-2500 my 4speed is going about 60.

other things to maintain may be hoses if they seem old, heater valve, radiator if it seems corroded or worn in any way.

About the radiator. How do I tell if it is corroded. It has no filler spout (first car I have ever had like that). My temperature needle in my car stays right around the middle tick mark (halfway). Does this sound normal? All my other vehicles normally stay around the lower 1/4 somewhere when operating correctly and this car doesn't have any degree markings. . .just tick marks and a C and H or something. I just changed the timing belt and the water pump (when I say me, I paid toyota to do it). 205000 sounds like it could be time for a new radiator as I believe the normal service life is around 130000 miles, am i right? Just want it to run right. Thanks for any help!

[jzz30]

well i you can only tell by obvious reasons like if the lower bit of the radiator is corroded away becasue of leaves and things that have collected and brocken down in to dirt allowing the radiator to be in contact with moisture. so if you want to know you have to look at it pull it out if you need to. and the needle staying half way is normal.

also if you dont mind me asking how much did it cost for your t-belt and waterpump replacement

[lexus082]

Not too sure on how to tell you if its corroded or not, (EDIT) JZZ30 just did. (EDIT) The middle mark is where it should be. Mine is slightly lower than the middle mark. And I've even noticed when its actually hotter out my temp needle actually says my engine temp is decreased. Not too sure why on the hottest days of the summer my temp needle indicates that the engine temp is lower compared to when it is normal summer time temperatures. Like one day it will be slight lower than halfway if the temperature is @ 90F and then when its 100F outside the temp needle will indicate the engine temp to be cooler than when it was 90F. I do know for a fact (personal experience unfortunately) that these radiators sometime develop a slight leak. Its usually on the top. I was planning on replacing mine soon, but one day I was climbing up that same mountain that I told I was monitoring the rpm's and my radiator bursted a leak. I had to pull over asap. (Like I said earlier its a steep mountain.) Anyway... be sure to check the top of the radiator for any hints of dried red/pink coolant. Also, the coolant reserve tank lids commonly develop a leak also. Its kind of ironic that these cars are built so well thats someone could compile a very short list of the components that will fail. Power steering pump leak, alternator frying from p.s leak, climate control and radio screens bleeding, coolant reserve tank lids leaking, radiators developing small leak, instrument panel needles failing, door panels cracking etc.

[Micah]

Thanks for the great replies! The whole job cost me $1027. That included replacing the water pump, timing belt, some pullies that the timing belt ride on, and a burned out bulb in the rear tail lights (parking light, my dash still says I have a burned out bulb even though none are, I just ignore it as none of my other cars, besides my camry, even have that feature). again, thanks for the replies! I think my radiator is OK then b/c the coolant looks clean and it looks new still (no paint chipping or corrosion on it).

BTW, the last time I had to have a timing belt on my camry done it cost me 150 dollars at that same dealership (about 5 year ago). Talk about inflation! LOL

[lexus082]

Thanks for the great replies! The whole job cost me $1027. That included replacing the water pump, timing belt, some pullies that the timing belt ride on, and a burned out bulb in the rear tail lights (parking light, my dash still says I have a burned out bulb even though none are, I just ignore it as none of my other cars, besides my camry, even have that feature). again, thanks for the replies! I think my radiator is OK then b/c the coolant looks clean and it looks new still (no paint chipping or corrosion on it).

BTW, the last time I had to have a timing belt on my camry done it cost me 150 dollars at that same dealership (about 5 year ago). Talk about inflation! LOL

I've read on here somewhere that if you don't use oem toyota/lexus bulbs that could cause that indicator light to come on. I remember reading that the wattage on lexus bulbs is slightly lower to increase the life of the bulb.

[Micah]

ah, good to know. I'm just going to ignore it, though. May even just remove the bulb.

[lexus082]

Yeah, that will work too. I have a 94 and upgraded to the 97+ tail lights with the 97+ tail lamp out module and my "indicator" light is on as well. Due to an electrical issue with the front side markers being INOP. It gets anoying after a while I just haven't taken out the bulb yet.

[jzz30]

the sc timing belt and waterpump job requires that you take off everything on the front of the motor. by the time you get the waterpump off which is the last thing that can come off on the engine you have taken off your ac compressor, all of your components that are driven by your serpentine belt, and timing belt, and its tentioners