Starting issues
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Pole Position
Joined: Sep 2011
Posts: 2,084
Likes: 401
From: Nor CA
Starting issues
I was going to start a new, separate thread but felt I would get better responses here.
About 3 weeks ago when starting the SC for a weekly drive (which is about the frequency nowadays) ran into an issue getting the car running. Symptoms are a rough, rumbling idle with flashing CE and then dies. After several repeated attempts it finally clears once high idle kicks in and the CE light clears. Car runs fine and after about a 20 minute drive and return to the house/garage it is fine. Starts like a champ after the drive. Wait a day or 2 and the symptoms return.
Took the car to the trusted mechanic (who knows this car well) but they are a 70 mile drive. Of course, they could not find or repeat the issue (no Check Engine code was stored) and even after an overnight stay the car started right away. They have been getting a lot of strange issues related to battery behavior with the cars sitting long stretches and we agreed to swap in a new battery (the battery in the car was under warranty so it only cost me $25).
Drove home on Thursday (car ran great) but on Sunday morning the issue came back. Will take the car back to them for for an extended stay and hopefully the cause and a remedy can be found.
If this sounds familiar or is well known (which I could not conclusively find with a search) please provide input so I can pass it along to the shop.
Thanks!
About 3 weeks ago when starting the SC for a weekly drive (which is about the frequency nowadays) ran into an issue getting the car running. Symptoms are a rough, rumbling idle with flashing CE and then dies. After several repeated attempts it finally clears once high idle kicks in and the CE light clears. Car runs fine and after about a 20 minute drive and return to the house/garage it is fine. Starts like a champ after the drive. Wait a day or 2 and the symptoms return.
Took the car to the trusted mechanic (who knows this car well) but they are a 70 mile drive. Of course, they could not find or repeat the issue (no Check Engine code was stored) and even after an overnight stay the car started right away. They have been getting a lot of strange issues related to battery behavior with the cars sitting long stretches and we agreed to swap in a new battery (the battery in the car was under warranty so it only cost me $25).
Drove home on Thursday (car ran great) but on Sunday morning the issue came back. Will take the car back to them for for an extended stay and hopefully the cause and a remedy can be found.
If this sounds familiar or is well known (which I could not conclusively find with a search) please provide input so I can pass it along to the shop.
Thanks!
I was going to start a new, separate thread but felt I would get better responses here.
About 3 weeks ago when starting the SC for a weekly drive (which is about the frequency nowadays) ran into an issue getting the car running. Symptoms are a rough, rumbling idle with flashing CE and then dies. After several repeated attempts it finally clears once high idle kicks in and the CE light clears. Car runs fine and after about a 20 minute drive and return to the house/garage it is fine. Starts like a champ after the drive. Wait a day or 2 and the symptoms return.
Took the car to the trusted mechanic (who knows this car well) but they are a 70 mile drive. Of course, they could not find or repeat the issue (no Check Engine code was stored) and even after an overnight stay the car started right away. They have been getting a lot of strange issues related to battery behavior with the cars sitting long stretches and we agreed to swap in a new battery (the battery in the car was under warranty so it only cost me $25).
Drove home on Thursday (car ran great) but on Sunday morning the issue came back. Will take the car back to them for for an extended stay and hopefully the cause and a remedy can be found.
If this sounds familiar or is well known (which I could not conclusively find with a search) please provide input so I can pass it along to the shop.
Thanks!
About 3 weeks ago when starting the SC for a weekly drive (which is about the frequency nowadays) ran into an issue getting the car running. Symptoms are a rough, rumbling idle with flashing CE and then dies. After several repeated attempts it finally clears once high idle kicks in and the CE light clears. Car runs fine and after about a 20 minute drive and return to the house/garage it is fine. Starts like a champ after the drive. Wait a day or 2 and the symptoms return.
Took the car to the trusted mechanic (who knows this car well) but they are a 70 mile drive. Of course, they could not find or repeat the issue (no Check Engine code was stored) and even after an overnight stay the car started right away. They have been getting a lot of strange issues related to battery behavior with the cars sitting long stretches and we agreed to swap in a new battery (the battery in the car was under warranty so it only cost me $25).
Drove home on Thursday (car ran great) but on Sunday morning the issue came back. Will take the car back to them for for an extended stay and hopefully the cause and a remedy can be found.
If this sounds familiar or is well known (which I could not conclusively find with a search) please provide input so I can pass it along to the shop.
Thanks!
Thread Starter
Pole Position
Joined: Sep 2011
Posts: 2,084
Likes: 401
From: Nor CA
After recreating the problem, the shop is swapping out the fuel pump and fuel pressure regulator (which are both over 29 years old) to see if those fix the issue. Will know more next week....
Thread Starter
Pole Position
Joined: Sep 2011
Posts: 2,084
Likes: 401
From: Nor CA
Replacing the fuel pump and the fuel pressure regulator did not resolve the issue so the spare ECU was introduced. That appeared to have resolved the issue but when leaving the shop the engine quit. This happened on the freeway but fortunately was able to get over to the shoulder safely. After a few tries got the car restarted and limped back to the shop.
It is suspected the spare ECU, even though rebuilt, may have introduced a new, separate issue and more troubleshooting is under way.
Most frustrating issue ever with the vehicle...... Reliability is the most important factor for me..... A hard failure that is easy to assess and then addressed would be better than this intermittent condition....
It is suspected the spare ECU, even though rebuilt, may have introduced a new, separate issue and more troubleshooting is under way.
Most frustrating issue ever with the vehicle...... Reliability is the most important factor for me..... A hard failure that is easy to assess and then addressed would be better than this intermittent condition....
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9th Gear
Joined: May 2021
Posts: 9
Likes: 1
From: NE
I've been suffering similar symptoms (random Idle surging that usually resolves, and engine quitting, but restarting after 5 - 10 minutes) with my 93 SC400 over the last 12 months. Just replaced the ECU a month ago, but idle surges reappeared, and just recently it wouldn't start after sitting for about an hour while I was at a meeting. Couldn't get It started in multiple attempts for over an hour and had it towed to a shop that specializes in Toyota/Lexus (my trusted mechanic who has worked on the car for the 16 years I've owned it was booked solid for a week). The shop called me the following morning and said it started up on the first attempt, but blew out a alot of bluish smoke. I picked up the car, drove it home (random idle surges present) and parked it. I cannot agree more with your statement about the imprtance of vehicle reliability and the frustration caused by 'chasing' an issue. I'll be interested in your update concerning the relays. Apologies if I provided too much information.
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Joined: Feb 2020
Posts: 659
Likes: 155
From: CA
I've been suffering similar symptoms (random Idle surging that usually resolves, and engine quitting, but restarting after 5 - 10 minutes) with my 93 SC400 over the last 12 months. Just replaced the ECU a month ago, but idle surges reappeared, and just recently it wouldn't start after sitting for about an hour while I was at a meeting. Couldn't get It started in multiple attempts for over an hour and had it towed to a shop that specializes in Toyota/Lexus (my trusted mechanic who has worked on the car for the 16 years I've owned it was booked solid for a week). The shop called me the following morning and said it started up on the first attempt, but blew out a alot of bluish smoke. I picked up the car, drove it home (random idle surges present) and parked it. I cannot agree more with your statement about the imprtance of vehicle reliability and the frustration caused by 'chasing' an issue. I'll be interested in your update concerning the relays. Apologies if I provided too much information.
Try filling your coolant tank to just below the overflow tube...
relays have mostly solved my issues.. no ECU rebuild yet.
Thread Starter
Pole Position
Joined: Sep 2011
Posts: 2,084
Likes: 401
From: Nor CA
Retrieved the car today.
The full list of items is:
Replaced battery as a precaution since upon arrival the car did not fail at the shop.
The failure returned and it appeared to be fuel system so the 29 year old parts of the fuel pump and fuel pressure regulator along with the water temp sensor were replaced. These worked after replacement but the original condition resurfaced (the problem was always intermittent). The spare ECU was installed and it appeared to resolve the original issue.
As stated above, car died on the freeway but was able to return to the shop. During extensive troubleshooting, just tapping on the main relay the car would shut off and after replacing that part the car has remained stable. Also, they observed rumbling idle and cleaned the throttle body which fixed that condition. During the ride home the car ran flawlessly and the hope is will remain reliable going forward.
So, the ECU failed exasperated by the old relay.
The spare ECU was actually the original one in the car that had failed back in 2013 and I had sent it out to be rebuilt/repaired. The one that failed this time was put in by a shop that I no longer use (for poor service) and as it turns out that ECU part number does not match (but it worked for over 7 years) so I will need to do some research before investing in this one for a spare. The original part number was 89661-24331 and the other one is -24332; so close but not identical, but I will need to assess if this is an issue. Anyone having knowledge on the topic please advise.
Thanks to all those that provided tips and input.
The full list of items is:
Replaced battery as a precaution since upon arrival the car did not fail at the shop.
The failure returned and it appeared to be fuel system so the 29 year old parts of the fuel pump and fuel pressure regulator along with the water temp sensor were replaced. These worked after replacement but the original condition resurfaced (the problem was always intermittent). The spare ECU was installed and it appeared to resolve the original issue.
As stated above, car died on the freeway but was able to return to the shop. During extensive troubleshooting, just tapping on the main relay the car would shut off and after replacing that part the car has remained stable. Also, they observed rumbling idle and cleaned the throttle body which fixed that condition. During the ride home the car ran flawlessly and the hope is will remain reliable going forward.
So, the ECU failed exasperated by the old relay.
The spare ECU was actually the original one in the car that had failed back in 2013 and I had sent it out to be rebuilt/repaired. The one that failed this time was put in by a shop that I no longer use (for poor service) and as it turns out that ECU part number does not match (but it worked for over 7 years) so I will need to do some research before investing in this one for a spare. The original part number was 89661-24331 and the other one is -24332; so close but not identical, but I will need to assess if this is an issue. Anyone having knowledge on the topic please advise.
Thanks to all those that provided tips and input.
Last edited by Duck05; May 17, 2021 at 02:50 PM.
Thread Starter
Pole Position
Joined: Sep 2011
Posts: 2,084
Likes: 401
From: Nor CA
In researching the ECU part number, it appears both a 24331 and a 24332 are for a ‘92 SC300. The 24331 must have been the first generation part (as I purchased the car right when they were available) replaced later on with 24332. The failed part is at a rebuilder now and when returned will be the spare.....
Thread Starter
Pole Position
Joined: Sep 2011
Posts: 2,084
Likes: 401
From: Nor CA
Car has been stable and starts reliably since getting it back. Cleaning the throttle body feels like the car runs “stronger” (but that could be wishful thinking on my part). With the local gym reopening after months of closure will use the car 2-3 days a week.
The failed ECU sent out to be repaired/rebuilt and will become the spare.
Now we just need some car meets to resume....😀
The failed ECU sent out to be repaired/rebuilt and will become the spare.
Now we just need some car meets to resume....😀
9th Gear
Joined: May 2021
Posts: 9
Likes: 1
From: NE
I topped off the coolant as you suggested and replaced all the vacuum lines (a couple were cracked a little one end). I've only driven it 50 miles since, but no idle surging so far. I'm still going to purchase the relays (while they're still available) based on your experience with them.
On an unrealted issue, I need a Transmission Throttle Cable (sometimes referred to as a Transmission Kickdown Cable or Transmission Line Pressure Cable). Lexus discontinued the part (35520-50010) - Club Lexus searches, salvage yard networks, and eBay searches have proven fruitless. Any suggestions on where to source and/or the appropriate forum to post the need on Club Lexus?
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myLEXsc400
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Apr 19, 2016 07:29 AM