Restoring Lost Horsepower For An Sc400.

[JIBBBY]

Hey people, I have a 1992 lexus SC400, it was dealer serviced up to 75,000 it now has a little over 100,000 miles. I am trying my best to get this sc400 engine running at absolute peak performance and I am wondering if anyone knows what else to look for on this car that might need attention that I missed? Since owning at 75,000, I have changed the timing belt, spark plugs, wires, shocks, springs, serp belt, distributor cap, rotor, cleaned the throttle body, changed out oxygen sensors, battery, torque converter, synthetic oil changes on trans, dif, engine, power steering and brake fluid, new radiator, catalytic converter, mufflers, airfilter, fuel filter, and that's about it.

I just found out changing the original main ground wire is a very good idea to restore lost horsepower, and now I am wondering what else I can do for the car that will help restore lost horse power. All suggestions are welcomed.

[dcfish]

Hey people,  I have a 1992 lexus SC400, it was dealer serviced up to 75,000 it now has a little over 100,000 miles.  I am trying my best to get this sc400 engine running at absolute peak performance and I am wondering if anyone knows what else to look for on this car that might need attention that I missed?  Since owning at 75,000, I have changed the timing belt, spark plugs, wires, shocks, springs, serp belt, distributor cap, rotor, cleaned the throttle body, changed out oxygen sensors, battery, torque converter, synthetic oil changes on trans, dif, engine, power steering and brake fluid, new radiator, catalytic converter, mufflers, airfilter, fuel filter,  and that's about it.

I just found out changing the original main ground wire is a very good idea to restore lost horsepower, and now I am wondering what else I can do for the car that will help restore lost horse power.  All suggestions are welcomed.

←

Looks like you have the bases covered pretty well, Nice job Here is a suggestion:

I would like to suggest that you register at www.lexus.com go to the website and download for free the manual for there car and upload to there respective forums. We could get every manual stuck to the top of there respective forum and it would eliminate quite a few unnecesary posts and streamline these boards. I know that it may take a little time/effort on the part of willing members but the payoff is well worth it. Please don't reply to this unless you are going to participate. I really think this would be very helpful to all of us. Just navigate to http://www.lexus.com/ Click on :Owners" then :Register Today" After you are signed in click on "My Car" Then "Owners Manual" Scroll down and you will see the .pdf files for the manual of your car. click and save a copy to your harddrive then upload to the respective forum. Topic title should include the year and model[ Similar to the one I posted ].

Thank you for your time and effort.

We could use an early SC manual

[monarch]

Check the engine's intake and exhaust valve clearances and adjust if necessary. Loose clearances = diminished engine power.

You should also check the engine's compression on all 8 cylinders after the valve clearance adjustment because if some cylinders have suboptimal compression then power will not be optimal.

[JIBBBY]

Hey people,  I have a 1992 lexus SC400, it was dealer serviced up to 75,000 it now has a little over 100,000 miles.  I am trying my best to get this sc400 engine running at absolute peak performance and I am wondering if anyone knows what else to look for on this car that might need attention that I missed?  Since owning at 75,000, I have changed the timing belt, spark plugs, wires, shocks, springs, serp belt, distributor cap, rotor, cleaned the throttle body, changed out oxygen sensors, battery, torque converter, synthetic oil changes on trans, dif, engine, power steering and brake fluid, new radiator, catalytic converter, mufflers, airfilter, fuel filter,  and that's about it.

I just found out changing the original main ground wire is a very good idea to restore lost horsepower, and now I am wondering what else I can do for the car that will help restore lost horse power.  All suggestions are welcomed.

←

Looks like you have the bases covered pretty well, Nice job Here is a suggestion:

I would like to suggest that you register at www.lexus.com go to the website and download for free the manual for there car and upload to there respective forums. We could get every manual stuck to the top of there respective forum and it would eliminate quite a few unnecesary posts and streamline these boards. I know that it may take a little time/effort on the part of willing members but the payoff is well worth it. Please don't reply to this unless you are going to participate. I really think this would be very helpful to all of us. Just navigate to http://www.lexus.com/ Click on :Owners" then :Register Today" After you are signed in click on "My Car" Then "Owners Manual" Scroll down and you will see the .pdf files for the manual of your car. click and save a copy to your harddrive then upload to the respective forum. Topic title should include the year and model[ Similar to the one I posted ].

Thank you for your time and effort.

We could use an early SC manual

←

Sc manual, what's to gain out of that? Is it updated? Will it tell you what wiring is getting crusty, what parts wearout at what time, etc... I am looking for hands on advise from people who did actual changes and found results, Manuals and writeups may miss a few things. That's my take on it anyway.

[JIBBBY]

Check the engine's intake and exhaust valve clearances and adjust if necessary. Loose clearances = diminished engine power.

You should also check the engine's compression on all 8 cylinders after the valve clearance adjustment because if some cylinders have suboptimal compression then power will not be optimal.

←

[/

Thanks monarch- the valve clearance I have not checked, put the compression is outstanding on each cylinder.

[dcfish]

Hey people,  I have a 1992 lexus SC400, it was dealer serviced up to 75,000 it now has a little over 100,000 miles.  I am trying my best to get this sc400 engine running at absolute peak performance and I am wondering if anyone knows what else to look for on this car that might need attention that I missed?  Since owning at 75,000, I have changed the timing belt, spark plugs, wires, shocks, springs, serp belt, distributor cap, rotor, cleaned the throttle body, changed out oxygen sensors, battery, torque converter, synthetic oil changes on trans, dif, engine, power steering and brake fluid, new radiator, catalytic converter, mufflers, airfilter, fuel filter,  and that's about it.

I just found out changing the original main ground wire is a very good idea to restore lost horsepower, and now I am wondering what else I can do for the car that will help restore lost horse power.  All suggestions are welcomed.

←

Looks like you have the bases covered pretty well, Nice job Here is a suggestion:

I would like to suggest that you register at www.lexus.com go to the website and download for free the manual for there car and upload to there respective forums. We could get every manual stuck to the top of there respective forum and it would eliminate quite a few unnecesary posts and streamline these boards. I know that it may take a little time/effort on the part of willing members but the payoff is well worth it. Please don't reply to this unless you are going to participate. I really think this would be very helpful to all of us. Just navigate to http://www.lexus.com/ Click on :Owners" then :Register Today" After you are signed in click on "My Car" Then "Owners Manual" Scroll down and you will see the .pdf files for the manual of your car. click and save a copy to your harddrive then upload to the respective forum. Topic title should include the year and model[ Similar to the one I posted ].

Thank you for your time and effort.

We could use an early SC manual

←

Sc manual, what's to gain out of that? Is it updated? Will it tell you what wiring is getting crusty, what parts wearout at what time, etc... I am looking for hands on advise from people who did actual changes and found results, Manuals and writeups may miss a few things. That's my take on it anyway.

←

The gain is for everyone who uses these forums, Active contributions to the club are always welcome. Most members just ask for help and usually contribute only after a long period of time of "Learning" here. This way you can contribute sooner and be a productive member.

[ArmyofOne]

Hey people,  I have a 1992 lexus SC400, it was dealer serviced up to 75,000 it now has a little over 100,000 miles.  I am trying my best to get this sc400 engine running at absolute peak performance and I am wondering if anyone knows what else to look for on this car that might need attention that I missed?  Since owning at 75,000, I have changed the timing belt, spark plugs, wires, shocks, springs, serp belt, distributor cap, rotor, cleaned the throttle body, changed out oxygen sensors, battery, torque converter, synthetic oil changes on trans, dif, engine, power steering and brake fluid, new radiator, catalytic converter, mufflers, airfilter, fuel filter,  and that's about it.

I just found out changing the original main ground wire is a very good idea to restore lost horsepower, and now I am wondering what else I can do for the car that will help restore lost horse power.  All suggestions are welcomed.

←

Looks like you have the bases covered pretty well, Nice job Here is a suggestion:

I would like to suggest that you register at www.lexus.com go to the website and download for free the manual for there car and upload to there respective forums. We could get every manual stuck to the top of there respective forum and it would eliminate quite a few unnecesary posts and streamline these boards. I know that it may take a little time/effort on the part of willing members but the payoff is well worth it. Please don't reply to this unless you are going to participate. I really think this would be very helpful to all of us. Just navigate to http://www.lexus.com/ Click on :Owners" then :Register Today" After you are signed in click on "My Car" Then "Owners Manual" Scroll down and you will see the .pdf files for the manual of your car. click and save a copy to your harddrive then upload to the respective forum. Topic title should include the year and model[ Similar to the one I posted ].

Thank you for your time and effort.

We could use an early SC manual

←

as soon as i get my computer, i will do this for the ES250. also, if anyone neeeds a manual for it, i will send it for free, all i need is an address.

[dcfish]

Hey people,  I have a 1992 lexus SC400, it was dealer serviced up to 75,000 it now has a little over 100,000 miles.  I am trying my best to get this sc400 engine running at absolute peak performance and I am wondering if anyone knows what else to look for on this car that might need attention that I missed?  Since owning at 75,000, I have changed the timing belt, spark plugs, wires, shocks, springs, serp belt, distributor cap, rotor, cleaned the throttle body, changed out oxygen sensors, battery, torque converter, synthetic oil changes on trans, dif, engine, power steering and brake fluid, new radiator, catalytic converter, mufflers, airfilter, fuel filter,  and that's about it.

I just found out changing the original main ground wire is a very good idea to restore lost horsepower, and now I am wondering what else I can do for the car that will help restore lost horse power.  All suggestions are welcomed.

←

Looks like you have the bases covered pretty well, Nice job Here is a suggestion:

I would like to suggest that you register at www.lexus.com go to the website and download for free the manual for there car and upload to there respective forums. We could get every manual stuck to the top of there respective forum and it would eliminate quite a few unnecesary posts and streamline these boards. I know that it may take a little time/effort on the part of willing members but the payoff is well worth it. Please don't reply to this unless you are going to participate. I really think this would be very helpful to all of us. Just navigate to http://www.lexus.com/ Click on :Owners" then :Register Today" After you are signed in click on "My Car" Then "Owners Manual" Scroll down and you will see the .pdf files for the manual of your car. click and save a copy to your harddrive then upload to the respective forum. Topic title should include the year and model[ Similar to the one I posted ].

Thank you for your time and effort.

We could use an early SC manual

←

as soon as i get my computer, i will do this for the ES250. also, if anyone neeeds a manual for it, i will send it for free, all i need is an address.

←

Thanx Army, You Da Man, I knew You would kick in on this project. Thanx a mint.

[91L3xus]

Same here, I just registered my ES250 on the site.

[dcfish]

Same here, I just registered my ES250 on the site.

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Guys, How many years was the ES250 produced? There may be a difference in manuals. So we could use one each from the different years

[91L3xus]

I think they were only sold as 1990 and 1991 models, but the 1990's might have began production in 1989. If Army or anyone had a '90, maybe he could check his VIN sticker; I have a '91 and mine was produced in 1990.

[dcfish]

Hey people,  I have a 1992 lexus SC400, it was dealer serviced up to 75,000 it now has a little over 100,000 miles.  I am trying my best to get this sc400 engine running at absolute peak performance and I am wondering if anyone knows what else to look for on this car that might need attention that I missed?  Since owning at 75,000, I have changed the timing belt, spark plugs, wires, shocks, springs, serp belt, distributor cap, rotor, cleaned the throttle body, changed out oxygen sensors, battery, torque converter, synthetic oil changes on trans, dif, engine, power steering and brake fluid, new radiator, catalytic converter, mufflers, airfilter, fuel filter,  and that's about it.

I just found out changing the original main ground wire is a very good idea to restore lost horsepower, and now I am wondering what else I can do for the car that will help restore lost horse power.  All suggestions are welcomed.

←

Looks like you have the bases covered pretty well, Nice job Here is a suggestion:

I would like to suggest that you register at www.lexus.com go to the website and download for free the manual for there car and upload to there respective forums. We could get every manual stuck to the top of there respective forum and it would eliminate quite a few unnecesary posts and streamline these boards. I know that it may take a little time/effort on the part of willing members but the payoff is well worth it. Please don't reply to this unless you are going to participate. I really think this would be very helpful to all of us. Just navigate to http://www.lexus.com/ Click on :Owners" then :Register Today" After you are signed in click on "My Car" Then "Owners Manual" Scroll down and you will see the .pdf files for the manual of your car. click and save a copy to your harddrive then upload to the respective forum. Topic title should include the year and model[ Similar to the one I posted ].

Thank you for your time and effort.

We could use an early SC manual

←

as soon as i get my computer, i will do this for the ES250. also, if anyone neeeds a manual for it, i will send it for free, all i need is an address.

←

Army, Was your ES250 a 90? 91L3xus is going to get the manual for the 91. Thanx guys

[91L3xus]

"We're sorry, but we don't currently offer online manuals for models prior to 1996."

Sorry guys, no go on the manual for either I guess. Just the maintince schedule. :cries:

[dcfish]

"We're sorry, but we don't currently offer online manuals for models prior to 1996."

Sorry guys, no go on the manual for either I guess.  Just the maintince schedule. :cries:

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They said "currently" right? I'll call headquarters and get the dirt. Thanx

[JIBBBY]

That's ok when I got you guys and these forums I don't need the manuals, but I am suprised that I am not getting much feedback on this post. I thought this post would benifit all readers. Maybe I did everything I need to due to get my engine running like it has 0 miles on it. Somehow I don't think so, but maybe these are awefully good motors? I was thinking what about other electrical components that may require attention after 12 years, maybe cleaning the injectors, tuning, transmittion attention, etc..that is the type of info I am seeking off this post. Is there a mechanic in the house!

[SKperformance]

Without nowing exactly what has already been changed and worke don it is hard to be definative.

That being said ,

Ground wires from the battery to chasis and body should be changed

all fluids

brake

coolant

oil

powersteering

tranny

a motorvac

and oil treatment to flush before oil change