Hey whats up club lex I hope someone can help me. Here's the stroy (we all have one). About a week ago I took my car to lexus because when coming in town from Chicago ( I live in tulsa) aout 100miles out my check egine light came on. No biggie car still ran great but of couse I wanted to get it checked out. So I take it to elx and they tell me its the oxygen sensors. The rear left and right. Well they wanted $570 for the job and plus I didn't have time that day. So I told my self I would do it the following weekend. Anyhow that next week I drove back out of town and like many of us SC400 owners..... I drive hard. So I'm coming back in town to tulsa after leaving chicago and the check engine light goes OUT. but then all hell breaks loose. SLowly my car is loosing power. Normally I'll cruise at 110-120mph when coming thru Missouri but slowly I could couldn't get pass certain speeds. FIrst I couldn't break 100mph I'd give it more gas but it just wouldn't go any faster. Then 80mph. So about that time is was time to get gas. Then I noticed when I pulled up to the pump that the car was "chuggin" rumbled like it had a flowmaster or sumthin...but worse. More like it was missing. Anyhow to make a real long story shoter by the time I got back to tulsa about (60 more miles). I couldn't get pass 30 or 40mph and if a hill came you could kiss that goodbye. So i figured i'd change the o2s as soon as I got back and that did nothing. Shes running SUPER rough. not drivable. I took it to lexus of tulsa doing about 30mph. And they tell me its the plug, spark plug wires, distributor caps, and rotors. And they wanted $800+. Now I know it wasn't the plugs because I just put in Bosch Platinum 4s the day before. So I got it home today and change the cap, rotors, and wires. And still NOTHING! Runs like crap even though it was time for those items. If I floor it she will not take herself pass about 4600rpms and it takes for ever to get ther she sounds like a lawn mower. DOes anyone know what this is. I keep pouring in money and I'm getting no results. Someone pls help I'm lost and running out of time before I'll really need her again. Thanks in advance guys. I already know I shouldn't of drove her back out of town again on bad o2s what could I of broke?????

 

Sort of sounds like timing to me, I would have it checked out.

 

i would also put the factory recommended plugs. the others do not compare to the ngks.

 

I dunno... maybe you fried your cats if the oxygen sensors really were way off?

Now you say you changed the plugs the day before the o2 sensors died? OK maybe the plugs aren't working right and you've been getting unburned fuel cooking your cats..?

 

Bosch Platinums are JUNK! Either get OEM Nippondenso plugs or NGK platinum or iridiums.

 

Do what Gazi said!

You did say that you started having this problem the day AFTER you changed plugs, right? ALWAYS go to what you repaired LAST. Or even TOUCHED. 48 years of working on cars speaking here. Still not an expert though.

You need a better shop to do your diagnosis. If a shop does not want to diagnose your problem for an hours labor, you don't want to do buss. with them anyway. Even my local Lex dealer will do that for me.

Good luck and let us know.

JohnEd

 

I forgot to mention that I changed my plugs a couple of months ago and have a high rpm miss. Thanks Gazi....I'll put in the NGK's this week end.

I used to ride a wicked dirt bike way back when and if you fouled out and didn't use NGK's we wouldn't help you. The other brands were so bad that everyone had been warned. I tried others and the diff was PROFOUND. When your source is a single cylinder....well, it lets you know real quick if you screwed up. Nippondenzo's worked also when they first appeared. My cammed 71 Z car wouldn't hold a tune for more than a week without NGK's

Thanks again Gazi.

JohnEd

 

i had this exact problem. my distributors were shattered so i took it to some mechanic. When they replaced them they removed my timing belt and when replaced they messed up my timing. i didn't know that so i took it to my mechanic and she said it was most likely the cats, i got those replaced all three. Problem solved for 1 day. then it happened again. took it back to her and she found out that my timing was off. Needless to say i never returned to that other mechanic. ohh and had to get all plugs replaced too.

 

Forgot this due to a senior moment. I recently posted a "cold soak" starting problem that I traced to a defective "igniter module". What I had was an engine that had 4 good firings and 4 erratic firings out of eight. The engine made seriously NO POWER and was rough as a cob. By pulling one coil wire it ran with a terrible 4 cylinder lope but it ran with a regular beat. When I tried that with the second coil I got a really rough and barely running engine that was erratic. It sounds like your Lex is running on 4 cylinders with the other four hurting as much as helping. Give this a try and see if the engine runs the same way with either coil unplugged.

I would still get the NGK platinums in there that Gazi recommended.

I hope you have already solved this and I wasted my breath.

Good luck

JohnEd

 

I have 92 SC400 and had a similar problem. I was running about 65 on the Hwy and lost about 50% of the power. It felt like the car had sucked a plastic bag or something into the air intake. I couldn't see any visible problem, but by the time I made it 2-miles to the house I notice a strange burning smell. Oddly enough, the engine wasn't running hot. The car would idle a bit rough, but not too terribly bad. For several months prior to the power loss, it had a little quick stumble, or shiver to the idle that occurred at intervals of about 30-seconds or so. Anyway, next I notice a pinging sound when I first turn it off, like dirt bikes make when they are first cooling off. I later found out that the sound was the cats cooling off from being super-heated. I had a friend drive the car to the mechanic while I followed. I noticed what looked like bright orange lava colored wool coming out of the exhaust. The mechanic replaced the cats and finally traced the problem to a bad coil. He said that the SC's have two and apparently they will run, start, idle and drive with only one. Oh yea, and while running on the one coil, they will dump raw gas down through the engine and into your cats making them erupt like Mt. Saint Helen. A 60-dollar coil and two catalytic converters later, the power is back. But so is that pesky little intermittent engine stumble which seems to be progressing into an occasional between-shift roller coaster jerking thing. Any idea what would cause a ride in a 92 SC400 to be like setting beside wet shivering dog on a run-away mine train?

 

Aside from the spark plugs, what other aftermarket, non-Lexus parts have you installed? Were the O2 metering sensors "Denso" brand?

Have the vehicle tested with a good analysis machine. It will determine whether the problem is ignition or fuel caused. The machine will additionally sense for excessive back pressure.

Many times, the more parts thrown at a problem increases the chance of installing new defective parts.