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Loss Of Power And Engine Sounds Choppy


nightrider89
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Hey guys and gals. New member and first post! =)

I have a problem with a 92 LS400 @ 150k mi. I cannot really point a figure to whats wrong. So my dad was driving the car one morning, and all of a sudden, there is a loss of power and the engine sounds choppy. The exhaust smells of gas and there is a loss of power. This thing is seriously a lot slower than it was when I took the car out yesterday. I am guessing it might be a misfire and running rich. The car was driven in this condition slowly. There is some white smoke --I suspect this is from the coolant.

I bring it to a mechanic and he says that he thinks in my fuel injectors not delivering the fuel into the cylinder. He checks my spark plugs and they are still good. I suspect spark plug wires. And from what I gather online, most threads point the finger at the ignition coil. lol... I wanted to come here for a second...er... third opinion and see what the general consensus of what the forum members here think

Have these symptoms ever happen to anyone on here? Any help is appreciated.

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It could be what you said and could be caused by other things too. One huge suspect item is this

http://www.clublexus.com/forums/ls400/656360-all-my-crazy-lexus-issues-solved-ecu-leaking-capacitor.html

I'm not sure I agree with the how to test here, but it works for him. This is a test for the ignitor and the coil.

https://www.youtube.com/watch?v=VG3EZJlyjl8

Running rich would be injector delivering fuel. I wouldn't suspect injectors less it was sitting for months not running.

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Welcome to the forum, Brian!

It is going to take some methodical testing to figure out what exactly is wrong. Since I do not know the maintenance history of your car, it could be a lot of things. Many times, these things are quite simple and not so bad as you might expect.

One of the first things I would check would be your distributor caps and rotors. If these wear items have not been changed within the last 50k miles or so, you might consider just replacing them as a general maintenance item. It could be a coil as well but these are not general replacement items.

The concerning comment that you made was that of "white smoke". That generally speaking, can indicate coolant being vaporized and is often associated with a blown head gasket. But that is a long shot at this point. It can happen but is not very likely. You say your dad was driving, when all of a sudden this problem occurred. Well, I have a question for you...moments before this incident, he did not happen to have a wide open throttle event (WOT), did he? Like passing someone or getting onto the Freeway? Sometimes, on an older engine, that stress will blow a weakened gasket.

However, as I said before, think 'simple' because often the remedy is just that. Based upon what the mechanic said, I would be looking for another.

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It could be what you said and could be caused by other things too. One huge suspect item is this

http://www.clublexus.com/forums/ls400/656360-all-my-crazy-lexus-issues-solved-ecu-leaking-capacitor.html

I'm not sure I agree with the how to test here, but it works for him. This is a test for the ignitor and the coil.

https://www.youtube.com/watch?v=VG3EZJlyjl8

Running rich would be injector delivering fuel. I wouldn't suspect injectors less it was sitting for months not running.

I hope its not the ecu. and will check the ignitor and coil. seems to be easy enough.

Welcome to the forum, Brian!

It is going to take some methodical testing to figure out what exactly is wrong. Since I do not know the maintenance history of your car, it could be a lot of things. Many times, these things are quite simple and not so bad as you might expect.

One of the first things I would check would be your distributor caps and rotors. If these wear items have not been changed within the last 50k miles or so, you might consider just replacing them as a general maintenance item. It could be a coil as well but these are not general replacement items.

The concerning comment that you made was that of "white smoke". That generally speaking, can indicate coolant being vaporized and is often associated with a blown head gasket. But that is a long shot at this point. It can happen but is not very likely. You say your dad was driving, when all of a sudden this problem occurred. Well, I have a question for you...moments before this incident, he did not happen to have a wide open throttle event (WOT), did he? Like passing someone or getting onto the Freeway? Sometimes, on an older engine, that stress will blow a weakened gasket.

However, as I said before, think 'simple' because often the remedy is just that. Based upon what the mechanic said, I would be looking for another.

dont think the distributor cap has been changed yet. Is there a way to test whether its bad or not? and he doesnt drive that hard...ever... which is good for the car. I have never had a head gasket blow on any vehicle but it sounds like if it was blown, it would always smoke on start up? this doesnt happen until running the vehicle for some time. It happened when we were just doing some light revving. (the mechanic suggested some FI cleaner to see if it solves the problem). after about 5 min it started to smoke.

Could it be the the spark plug wires. My thoughts are: if there is a misfire or running poorly, but checked the spark plugs and they are still good (did them not too long ago)... it could be the wires not able to send the electric current to allow for a spark which leads to no combustion and would also send that remainder gas down through to the exhaust?

Also to check spark plug wires: do I just pull them off at each end and test for resistance?

EDIT: got some more information from my dad. he said he was at a stop. the RPM dropped and he started to smell something like rotten eggs and gas. going to test the ignitor this weekend.

ALSO I read online that a member had a similar problem and it could be related to a cracked EGR pipe? And that could be the source of the gas smell! But I do not have a CEL....?

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  • 3 weeks later...

http://www.clublexus.com/forums/ls400/715345-how-to-check-your-ecu-without-removing-it-from-car-by-yamae.html

This should be your very first test to do. Then go from there. The ecu controls everything that you suspect causing the problem.

So eliminate the main thing first. Else your just going to be running a loosing race, and trying to fix things not needing fixing that is if it is the ecu. Read the links I sent. If your so inclined you can't possibly fix the ecu just read the info I linked to. After you rule out the ecu then go after the other things you've mentioned. A good test type scan tool can find the problem for you, it is a that will run tests and eliminate or condemn the items tested. But again it needs a good ecu to work with.

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