Essentials for a healthy GS400/430
11-16-18, 07:52 AM
#1
Intermediate
Thread Starter
Essentials for a healthy GS400/430
When I bought my GS400, it felt smooth and strong up in the high revs but never really exciting off the line or during part-throttle pulls. I recorded a 0-60 time of 6.7 seconds once. I attributed it to age, abuse by previous owners, and a very relaxed transmission program and throttle map. After all, these things were built for grandmas.
But, after lots of searching, experimenting, and a small mod or two, I’ve come to realize the V8 GS really hauls serious ***.
I would like to save someone the time of piecing together all of the necessary factors for good GS4 performance and put my experiences in this post.
1) Good preventative maintenance, obviously. Keep your spark plugs, air filter, MAF/O2 sensors, fuel injectors, and all basic engine components fresh and clean. Replace worn motor/transmission mounts, driveshafts and CV axles. Run 91 octane or higher.
2) Keep your charging system healthy. Low voltage due to a loose battery terminal made my transmission go all sorts of weird and caused the engine to feel sluggish. The alternators on these are prone to getting ruined by power steering leaks so take steps to prevent that.
3) Broken ACIS solenoid. On the back of the intake manifold, right in the center, is a little metal armature thing. When you start your engine, that thing should rotate to one side. If it doesn’t, the ACIS solenoid has gone dead and the intake runners remain in short mode. This noticeably reduces engine torque. Get that fixed. The solenoid is only $50 or so but the intake manifold must come off to access it.
4) Wonky fuel trim. This one is big! My car had a vacuum leak almost the entire time I’ve had it. I thought I fixed it once, but unknowingly made it worse. This caused my ECU to noticeably limit engine power below 3300rpm. I have since fix the leak, confirmed that fuel trim is perfect, and now the torque comes on strong right off the top of the throttle and pulls hard all the way to the redline.
Now that she’s perfectly healthy (minus engine mounts), she actually gives me a little thrill off the line now! The first time driving after finally getting everything correct, I gave her a little gas to get through a yellow light and almost pooped myself. I had never been pushed back in the seat that hard before.
So take my experiences, save yourself time and guessing and fix all that stuff I mentioned, and your GS4 should be actually a bit of a thrill to drive.
I still need to find a road to do a 0-60 test here. I expect significant improvement.
But, after lots of searching, experimenting, and a small mod or two, I’ve come to realize the V8 GS really hauls serious ***.
I would like to save someone the time of piecing together all of the necessary factors for good GS4 performance and put my experiences in this post.
1) Good preventative maintenance, obviously. Keep your spark plugs, air filter, MAF/O2 sensors, fuel injectors, and all basic engine components fresh and clean. Replace worn motor/transmission mounts, driveshafts and CV axles. Run 91 octane or higher.
2) Keep your charging system healthy. Low voltage due to a loose battery terminal made my transmission go all sorts of weird and caused the engine to feel sluggish. The alternators on these are prone to getting ruined by power steering leaks so take steps to prevent that.
3) Broken ACIS solenoid. On the back of the intake manifold, right in the center, is a little metal armature thing. When you start your engine, that thing should rotate to one side. If it doesn’t, the ACIS solenoid has gone dead and the intake runners remain in short mode. This noticeably reduces engine torque. Get that fixed. The solenoid is only $50 or so but the intake manifold must come off to access it.
4) Wonky fuel trim. This one is big! My car had a vacuum leak almost the entire time I’ve had it. I thought I fixed it once, but unknowingly made it worse. This caused my ECU to noticeably limit engine power below 3300rpm. I have since fix the leak, confirmed that fuel trim is perfect, and now the torque comes on strong right off the top of the throttle and pulls hard all the way to the redline.
Now that she’s perfectly healthy (minus engine mounts), she actually gives me a little thrill off the line now! The first time driving after finally getting everything correct, I gave her a little gas to get through a yellow light and almost pooped myself. I had never been pushed back in the seat that hard before.
So take my experiences, save yourself time and guessing and fix all that stuff I mentioned, and your GS4 should be actually a bit of a thrill to drive.
I still need to find a road to do a 0-60 test here. I expect significant improvement.
The following 2 users liked this post by eicca:
LavishZach (11-27-19),
Will_GS400 (11-16-18)
11-19-18, 08:58 PM
#3
Intermediate
Thread Starter
You'll notice a difference for sure. While you're in there, just go ahead and relocate the vacuum reservoir and that valve to somewhere else. That way if you have problems with it again you won't have to pull the manifold.
11-20-18, 01:50 PM
#4
When I bought my GS400, it felt smooth and strong up in the high revs but never really exciting off the line or during part-throttle pulls. I recorded a 0-60 time of 6.7 seconds once. I attributed it to age, abuse by previous owners, and a very relaxed transmission program and throttle map. After all, these things were built for grandmas.
But, after lots of searching, experimenting, and a small mod or two, I’ve come to realize the V8 GS really hauls serious ***.
I would like to save someone the time of piecing together all of the necessary factors for good GS4 performance and put my experiences in this post.
1) Good preventative maintenance, obviously. Keep your spark plugs, air filter, MAF/O2 sensors, fuel injectors, and all basic engine components fresh and clean. Replace worn motor/transmission mounts, driveshafts and CV axles. Run 91 octane or higher.
2) Keep your charging system healthy. Low voltage due to a loose battery terminal made my transmission go all sorts of weird and caused the engine to feel sluggish. The alternators on these are prone to getting ruined by power steering leaks so take steps to prevent that.
3) Broken ACIS solenoid. On the back of the intake manifold, right in the center, is a little metal armature thing. When you start your engine, that thing should rotate to one side. If it doesn’t, the ACIS solenoid has gone dead and the intake runners remain in short mode. This noticeably reduces engine torque. Get that fixed. The solenoid is only $50 or so but the intake manifold must come off to access it.
4) Wonky fuel trim. This one is big! My car had a vacuum leak almost the entire time I’ve had it. I thought I fixed it once, but unknowingly made it worse. This caused my ECU to noticeably limit engine power below 3300rpm. I have since fix the leak, confirmed that fuel trim is perfect, and now the torque comes on strong right off the top of the throttle and pulls hard all the way to the redline.
Now that she’s perfectly healthy (minus engine mounts), she actually gives me a little thrill off the line now! The first time driving after finally getting everything correct, I gave her a little gas to get through a yellow light and almost pooped myself. I had never been pushed back in the seat that hard before.
So take my experiences, save yourself time and guessing and fix all that stuff I mentioned, and your GS4 should be actually a bit of a thrill to drive.
I still need to find a road to do a 0-60 test here. I expect significant improvement.
But, after lots of searching, experimenting, and a small mod or two, I’ve come to realize the V8 GS really hauls serious ***.
I would like to save someone the time of piecing together all of the necessary factors for good GS4 performance and put my experiences in this post.
1) Good preventative maintenance, obviously. Keep your spark plugs, air filter, MAF/O2 sensors, fuel injectors, and all basic engine components fresh and clean. Replace worn motor/transmission mounts, driveshafts and CV axles. Run 91 octane or higher.
2) Keep your charging system healthy. Low voltage due to a loose battery terminal made my transmission go all sorts of weird and caused the engine to feel sluggish. The alternators on these are prone to getting ruined by power steering leaks so take steps to prevent that.
3) Broken ACIS solenoid. On the back of the intake manifold, right in the center, is a little metal armature thing. When you start your engine, that thing should rotate to one side. If it doesn’t, the ACIS solenoid has gone dead and the intake runners remain in short mode. This noticeably reduces engine torque. Get that fixed. The solenoid is only $50 or so but the intake manifold must come off to access it.
4) Wonky fuel trim. This one is big! My car had a vacuum leak almost the entire time I’ve had it. I thought I fixed it once, but unknowingly made it worse. This caused my ECU to noticeably limit engine power below 3300rpm. I have since fix the leak, confirmed that fuel trim is perfect, and now the torque comes on strong right off the top of the throttle and pulls hard all the way to the redline.
Now that she’s perfectly healthy (minus engine mounts), she actually gives me a little thrill off the line now! The first time driving after finally getting everything correct, I gave her a little gas to get through a yellow light and almost pooped myself. I had never been pushed back in the seat that hard before.
So take my experiences, save yourself time and guessing and fix all that stuff I mentioned, and your GS4 should be actually a bit of a thrill to drive.
I still need to find a road to do a 0-60 test here. I expect significant improvement.
When I gunned my GS it didn't do much. Maybe a small peel off and nothing else. I sometimes wonder buying this car with 124k miles is there anything limiting power or how to get more power. Car also has an exhaust system. Not sure what, I wanna slaw flowmaster from previous owner of course. What's an ACIS Solenoid? I don't see anything online.
Also how hard would all of what you listed be hard for a someone with no experience working on cars?
Last edited by JMan23; 11-20-18 at 01:55 PM.
11-20-18, 03:00 PM
#5
Intermediate
Thread Starter
Off the line it’s not exactly a thriller, but the two GS430s I drove yesterday that are in way better shape than mine feel the same.
The magic happens above 2000rpm.
The magic happens above 2000rpm.
11-20-18, 03:59 PM
#6
3) Broken ACIS solenoid. On the back of the intake manifold, right in the center, is a little metal armature thing. When you start your engine, that thing should rotate to one side. If it doesn’t, the ACIS solenoid has gone dead and the intake runners remain in short mode. This noticeably reduces engine torque. Get that fixed. The solenoid is only $50 or so but the intake manifold must come off to access it.
11-20-18, 09:36 PM
#7
Intermediate
Thread Starter
You can check if yours is working by simply starting the vehicle and watching for the actuator on the back middle of the manifold to rotate. It's between the manifold and the firewall, probably obscured by the heater hoses. If it stays in the upright position, the VSV is probably broken.
The following users liked this post:
Will_GS400 (11-21-18)
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11-21-18, 09:27 AM
#8
https://www.ebay.com/p/Genuine-OEM-Toyota-Lexus-No-1-Vacuum-Switching-Valve-25860-46010/2248384336?iid=222793442238&chn=ps
I'm guessing op is talking about the above. Not sure how to install that though or where it's exactly supposed to be located. I don't work on cars, not sure how hard this would be.
I think I'll start by measuring my 0-60
I'm guessing op is talking about the above. Not sure how to install that though or where it's exactly supposed to be located. I don't work on cars, not sure how hard this would be.
I think I'll start by measuring my 0-60
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