Hey, I have a 1992 sc400 that I bought about a year ago. And after a few months I experienced the same problem a lot of other people have on here. I have searched and came across this post which had the exact same symptoms as my car.

https://www.clublexus.com/forums/per...g-all-bad.html

So this morning I went and bought a new ignition coil and replaced it. The car is not running any differently now. But I should mention while pulling the old coil out I did break the plastic piece around the old coil's bottom connector. which in turn broke the plastic piece on the female connector on the car.And I dont seem to have the same amount of spark out of the coil as before. I have a feeling this may be my problem but I wanted a second opinion.

I am not very familiar with this car yet so any help would be greatly appreciated. Thanks in advance.

 

i think about 50% of the coil wire connectors on my car have broken clips and it sparks just fine. if your talking about the car's harness to the coil, then you may want to make sure its fully secure.

what do you mean you don't have the same spark out of the coil? i thought you said the car is not running any differently. you should describe whats happening.
your car has 2 coils. you may want to check the other one as well, or swap them to see if any codes change. maybe you replaced the wrong bank.

 

Ok let me start over. I was rushed with the first post and didnt get to put as much detail as I should have. When the problem happened I was driving the car and suddenly the power was just not there. it struggled in the lower RPM range and then seemed more normal with the high RPMs but not completely normal. I pulled over to check it out and the cats were glowing red. So I limped it to my aunts house which was less than a mile away.

I thought the cats were clogged at first but there is no way they could both do that suddenly. When the car is in park and idling it is very rough and it seems to be struggling to stay running. When I rev up the engine you can smell the unburned gas and there is a thivk white smoke coming ot of the tailpipes. (these are very similar symptoms as the guys car which I put a link to in the first post)

Yesterday and after spending a lot of time on here searching and reading different articles I went out and started checking the coils. When I unplugged (the top plug) the drivers side coil the car would not start. On the passenger side it would start. Which led me to believe the passenger side coil was bad. So when I replaced that this morning with a new one it is not running any differently than before replacing the "bad" coil.

As far as what I meant by its not sparking as much with the new coil, when I tested the passenger side coil yesterday and the car started the spark coming out of the coil seemed much more intense (for lack of a better explanation) than with the new one connected

Sorry for the lenghty post but I wanted to be as detailed as possible

 

so he result was the coils?? because mine is acting kinda funny im thinking its clogged cats. when its in park, it idle kinda weird like you hear the exhaust kinda put put put put, if you can imagine what i mean? like it spits.

 

Last night I took the new coil and put it on the drivers side and the old coil on the passenger side, and it still would not run right. I took the old one and put it on the passenger side and it still wouldn't run right.

Heres the thing when I unplug the top plug on the passenger side coil the car will start but not run any differently than before(i.e. loss of power, sputtering, unburnt gas). When I unplug the drivers side the car wont start at all. So I assumed it was a bad passenger side coil. Is there something else it could be? I am at a loss. Today I am going to go through the entire ignition system and try and find the problem

Mistahxken - For me I'm pretty sure its an ignition problem. The unburnt gas is going into the catalytic converters and burning there which is causing my cats to glow red hot. But i know what you mean about the way it drives with clogged cats. When my moms cats went out on her car there was a noticeable power drop, it would struggle to make it up a slight incline

 

Test indicates that the passenger side is the culprit.
So make sure you have the original drivers side coil on and replace the passenger side with the new one. If your saying you did that and its still not working then you need to go to the next step of checking each individual plug to make sure each cylinder is getting spark (same test you probably should have done with the original coil). its a straight forward process. if you find a plug not giving you a spark try swapping the plug leads with one known to work. if that doesnt fix it then probably time to open the distributor and check the contact leads and the rotor. your problem could very easily be after the coil. but you have narrowed down the side at least.

 

Yesterday I went through the passenger side ignition system and discovered that none of the passenger side plugs are getting spark through the distributor, so I went and picked up a new cap and rotor and replaced it and shes running good as new. Thanks for the help and I hope this helps anyone with a similar problem.

 

I had a feeling you were gonna say that after the coil didn't work. glad you found it.
I would get a cap and rotor for the other side as well. nothing like a 1uz running strong.

depending on how much gas went through that side you may want to replace the o2 sensor and take a look at that cat.

 

Oh yea you're completely right I plan on doing that along with a complete tune up. Its long over due. Thanks for the tip on the O2 sensor, I didn't even think of that.

 

thanks for the great post. Looks like Ill be shopping for a distributor as well. The car is marvelous -for getting me home on 4 cylinders!

 

Someone please help. How exactly do you do this test to check if the plugs are getting spark or if your distributor caps are working? I keep hearing that you take off the plug wire but from where? Is it the plug boot from the spark plug itself or is it the plug wire off of the distributor cap?

 

i think it is from the plug side. first, just take off the cap and look at the terminals inside the cap and also at the rotor in the middle of the distributor. do the metal contacts look worn down or not smooth anymore? if your having the same kind of issues and they look worn or old, you should just change them out, thats what worked for the op. best to do both sides at once so you dont get the problem again on the other side. check/replace your plugs while your at it too.

 

Thanks Ali. I wish i lived in VA so you could help me with my car. Im trying to find other MD people on here to try to help me.

 

My IS200 1999 developed a mis after running for about 15 minutes. Spark plugs replaced, injectors serviced, new 6 ignition coils put, but the problem still there.All these done by the Lexus agents. What could be the cause

 

Has anyone thought that a bad ignitor could be the culprit since they control the coils, rite? Because I have the same prob but on the driver side, im in the process of figuring it out, ruled out cats (hallowed them out) and coils (ohm tested and compared to a brand new coil) maybe one ignitor is out so only half the cylinders are firing??? Opinions