Car turned of while at stop light, twice this month

1994 LEXUS LS 400
179,000 MILES • 4.0L • V8 • 2WD • AUTOMATIC
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BUICK_DUDE
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Turns back on but check engine light on and the car will only stay on with acceleration and shifting manually from lowest gear all the way to Drive shifting manually at 2,000 rpm's and then down shifting to lowest gear at subsequent stop lights and traffic. Quite the mission home. Second time this month this happens. Really humbles me down for real. Was coming back from a job fair and grocery shopping. Glad to be home.

This happened last week for the first time and I replaced the battery and cleaned terminals. Moved main TPS a little up from where it was turned all the way counter clockwise to about where it was marked by previous owner. Car had been running great for the past week. Rpm's at 650-750 at idle with transmission on Drive.

Car is currently with hood open and positive battery cable off. I'm thinking the battery had nothing to do with and the RCU reset is what got it back running normal again. Dunno. Also, noticed noticed A/C compressor would not come on. Turned the A/C on while driving it home because I assumed that would raise the RPM and keep it from turning off at stop lights. I can't stop thinking this is throttle position sensor related. This car used to jerk every time I would try and pass 2,000 rpm when I just bought it and I replaced one TPS sensor which I later figured it the trac TPS sensor and not the main sensor and this got the car running great for months, the A/C would also shut off but the A/C button would flash in this instance. Thanks in advance for reading this far, I know being an internet mechanic has it's limitations and this grasshoppa is nowhere near being a masta.

Any comment appreciated even if it's a long shot.
Jan 30, 2020 at 1:00 PM
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KASEKENNY
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When this happens, does the vehicle still restart immediately? I am not sure I follow the timeline because it seems like some time as past since it had the check engine light on. Does the light come on each time this happens?

Either way I would suggest we check for codes because that will help figure this out. If your theory is correct about the TPS then there will be codes.

So before we get down the road of what it could be, let's start with codes. The only thing I am worried is since you took the battery off, it more than likely erased the codes. If this is the case, then we may need it to act up again and then check the codes.

Let me know if you know what the codes were and we can go from there. Thanks
Jan 30, 2020 at 5:39 PM
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BUICK_DUDE
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The battery has been disconnected for a day now. I will connect tomorrow and pull codes if any are still on. Picture for attention.
Jan 31, 2020 at 8:31 AM
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KASEKENNY
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Sounds good. Let us know what you find with that and we can dig further. Thanks
Jan 31, 2020 at 7:12 PM
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BUICK_DUDE
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Connected battery back up, I turned it back on the following day. I cranked and revved the engine a tad it then stayed on. Reversed out of the driveway and car turned off, cranked it back on (without the rev) and drove it around the house It stayed on with no check engine light. Left it on while I grabbed my wallet then proceeded to drive it 8 miles to my parents place. It turned off on my at the first signal lights (approximately 2 miles). Drove there and back to my place using the manual shifting and having it run rough (limp mode I assume).
Got home and it would't no longer turn on. Unplugged the battery. There it sits.
Feb 1, 2020 at 8:47 PM
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BUICK_DUDE
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Ordered the ignition coils, it seems there is a loss of power but fidgeting with the TPS (setting left to right) and the sub-TPS it changes way the car accelerates and if it stays on. Right now the car cranks up and idles fine but no power in Drive, have to downshift at start from Low and on to get it pass 40 MPH. Wish I hadn't messed with the sub TPS though. Well see, I will keep posting to this thread. If anyone has the link to the removal procedure for the ignition coils let me know. Thanks!
Feb 3, 2020 at 12:33 PM
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BUICK_DUDE
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Wasn't able to retrieve codes. Even though I have before. Do not know. I'll keep trying, tomorrow.
Feb 3, 2020 at 2:33 PM
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94 TRANSAM
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Maybe this will help you out:

http://www.lexls.com/tutorials/intro/codereading.html
Feb 3, 2020 at 5:04 PM
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Still can't retrieve codes. Bad ECU? I can't clear the codes by unplugging the battery for a day. I'm replacing the coils tomorrow. Will keep updating.
Feb 4, 2020 at 8:30 AM
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BUICK_DUDE
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Got two 10mm bolts off the bracket can't see if other bolts. The upper radiator spigot had been broken and I just found that out too. I'm in this for the long haul, lol. thanks for reading.
Feb 14, 2020 at 4:58 PM
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KASEKENNY
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These things are a can of worms sometimes. Thanks for the update. Keep going because anything can be fixed.
Feb 14, 2020 at 5:55 PM
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BUICK_DUDE
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Yep haha, I got the ignition coil off. it is the original and the screws are beginning to strip. so I am cleaning and once I get some lubricant spray will soak the screws on the bracket to remove easily.
Feb 15, 2020 at 12:25 PM
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BUICK_DUDE
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Will jb weld work? Maybe retrofitting another outlet on there? That piece is toast.
Feb 15, 2020 at 5:11 PM
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KASEKENNY
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Is that the outlet for the radiator? If so, I would not try to JB Weld it unless you have a large mating surface for the new one to splice onto. If you have just a small area then more than likely it will fail. Otherwise you may be okay.
Feb 15, 2020 at 5:34 PM
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BUICK_DUDE
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I am going to need this temp fix before I replace the ignition coils.
Feb 15, 2020 at 5:38 PM
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KASEKENNY
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Just don't get the hose clamp over the repaired section or where the crack is because that pressure directly over the crack could compromise it. If you let it set up completely (like overnight) then you should be okay because it is not directly on the bend of the fitting.
Feb 15, 2020 at 5:49 PM
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BUICK_DUDE
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I let it sit for 12 hours then added a second layer covering a larger area around the crack this morning. Just need to see if the coils fix the lack of power from stand still. I will put it back together tomorrow. ECM recapped is on back burner for the moment as well as the radiator, I do not know. Picture for attention.
Feb 16, 2020 at 4:03 PM
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BUICK_DUDE
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Replaced both ignition coils. Same problem. Radiator inlet jb weld fix lasted all of 1 mile while test driving.
Feb 18, 2020 at 2:08 PM
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94 TRANSAM
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To fix a radiator with JB or I use marine tex you have to sand the radiator real well with 80 grit then wash it with brake clean to remove oil and grease then put a layer of glue then put a piece of fiberglass cloth over the glue and then work it in with a stick until its set in the glue good. then add another layer of glue and let it set up. That will last years.

Rich
Feb 18, 2020 at 2:51 PM
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BUICK_DUDE
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Good DIY going to try.

so I installed the two ignition coils and no change. Later found out that I could of removed the coil boot and listen for any change in engine rpm to see if there was a spark coming from them. I wanna send the ECM for "recapping" and replace the radiator, but that might not fix the issue. I see this is just gonna turn into and endless money pit due to my mechanic inexperience and lack of tools but At least I learn Heh heh heh.

The Timing belt looks like the original at 178,000 miles! So I assume everything else is OEM. :) Really like the car tbh not ready to sell or piece out yet.
Feb 19, 2020 at 4:41 PM
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BUICK_DUDE
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Would fiberglass tape work?
Feb 24, 2020 at 10:06 PM
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KASEKENNY
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I doubt it. However, it is worth a try if you are not able to replace it at this point.
Feb 25, 2020 at 5:42 PM
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BUICK_DUDE
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Tried and failed. Ordered the radiator, went with denso.
Feb 28, 2020 at 2:19 PM
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BUICK_DUDE
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Replaced battery, car turned on no check engine light. works great, shifts great. Just need to replace the radiator. Still might be an ECU problem. Replaced the air filter, gas cap and upper brake light bulbs. approximate delivery of radiator is next Tuesday (March 3 2020). Going to replace the thermostat and gasket then.
Feb 28, 2020 at 2:19 PM
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KASEKENNY
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Progress is good. Keep going. Thanks for the update.
Feb 28, 2020 at 2:22 PM
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BUICK_DUDE
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Installed radiator. Red antifreeze. Distilled water. Took a while to fill it up. New rad cap. New hoses. It's no longer overheating. check engine light at 2,000. Need to adjust the TPS again. Doing it manually is a pain. Risk sending car into limp mode. Anyone have any tips?
Mar 28, 2020 at 8:28 PM
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KASEKENNY
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I attached the entire process. It is a little involved to adjust the TPS but it is all there. Thanks
Mar 29, 2020 at 7:52 AM