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Hello everyone! I’m pretty new here, and before I ask my question, yes I’ve been throughout forums seeking answers and have tried a few things but now I feel as though I need advice. 

 

Recently grabbed a ‘93 LS400 that’s been misfiring. I just had the alternator and belt tensioner replaced but the car did stall out on me due to very rough and low idle. Check engine code comes up for the mass air flow sensor and TPS, both of which were replaced and recently adjusted by my mechanic. I had heard that if the catalytic converters were glowing red that means that they were possibly clogged, possibly oil in the cylinders leaking(?). I’m not sure, I’m fairly new to these vehicles in general. 

One thing to keep note of is, the check engine light is illuminated. When I give the car gas it shows major power loss, however halfway thru second gear the car starts to pickup/ maintain speed and the check engine light goes away. Once I come to a stop, or even let off the gas for a bit the CEL comes back. Complete stop brings the rough idle back. I did read that the ignition coils could be to blame as well. I changed the one dead center in the engine, but not the second one by the battery.

 

 

My question is should I be weary of the cats? My plan was the yank them and simply straight pipe the car on back. However efficiency is all I want now considering I haven’t had time to even enjoy the car since I purchased it 😟 

 

 

1993 LS400 

188,114 Miles

 

4C8F23A6-9B59-4433-9D52-9F3ACD46A08C.jpeg

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On 8/4/2019 at 11:27 AM, SvpremeKai said:

Hello everyone! I’m pretty new here, and before I ask my question, yes I’ve been throughout forums seeking answers and have tried a few things but now I feel as though I need advice. 

 

Recently grabbed a ‘93 LS400 that’s been misfiring. I just had the alternator and belt tensioner replaced but the car did stall out on me due to very rough and low idle. Check engine code comes up for the mass air flow sensor and TPS, both of which were replaced and recently adjusted by my mechanic. I had heard that if the catalytic converters were glowing red that means that they were possibly clogged, possibly oil in the cylinders leaking(?). I’m not sure, I’m fairly new to these vehicles in general. 

One thing to keep note of is, the check engine light is illuminated. When I give the car gas it shows major power loss, however halfway thru second gear the car starts to pickup/ maintain speed and the check engine light goes away. Once I come to a stop, or even let off the gas for a bit the CEL comes back. Complete stop brings the rough idle back. I did read that the ignition coils could be to blame as well. I changed the one dead center in the engine, but not the second one by the battery.

 

 

My question is should I be weary of the cats? My plan was the yank them and simply straight pipe the car on back. However efficiency is all I want now considering I haven’t had time to even enjoy the car since I purchased it 😟 

 

 

1993 LS400 

188,114 Miles

 

4C8F23A6-9B59-4433-9D52-9F3ACD46A08C.jpeg

If the cats are glowing then they are working overtime to burn the unburnt fuel. The misfires are probably the culprit sending too much unburnt fuel into the cats.

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its either being significantly overfueled which is a possibility with the error codes, or plugged cats.  if it were a gm, i'd suspect the cats, but being a toyota, its probably not them and more like a  26 year old engine computer problem.  the best way to do this would first check the easy parts, maf if you have a scope, tps can usually be checked with a multimeter.  after that if you can check the pressure in the exhaust do that, usually requires drilling and tapping a hole or removing an o2 sensor.

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Catalytic converters glowing red simply mean that they are working properly because the unburnt fuel is burnt there. The problem is that the feed back system is not working right. Since you already have replaced the mass air flow sensor and and TPS, remainings are ignition related parts, injectors and the ECU. I would check the ECU first since it uses infamous QAS capacitors inside and they fail after aged. There were many people like you who were having the same problem with you and they now are happy with new capacitors.

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