SC93

1993 Lexus sc400, 90Kmiles and in excellent condition.

This has been a great car with very few problems over past 20 yrs. Power steering pump overhaul which I did myself and some A/C repairs. New tires and regular fluid changes has been about it.

Well about a month ago I started the car and it was running at 1500 RPM at "idle" and would not drop down to the 700 range after warm up. I took it to the road and it would not accelerate above 3000 and had no power. I lumbered back and when I pulled in to a full stop the engine died. Never in the history of this car did the engine outright die on me. I started the car up again and everything came back to normal. During the trouble period the check engine was on but after the restart it went out.

So, over the past 30 days this happened again 4 different times...would run great then tank. On the fourth occasion, I managed to limp my way to a reputable service man's garage and woudn't you know, the engine died and the engine light went out.On restart the light did not come on. He ran a OBD and it showed nothing. After I explained the symptoms, he said he had experienced this on other cars and suspected a dirty throttle plate sticking in the air duct housing . He opened the duct up and cleaned the throttle plate (some but no a lot of residue) and housing with cleaner fluid, lubricated the adjacent moving parts and sent me on my way.

Well some two weeks went by and no probs. Then yesterday I washed the car and left it out in the hot sun(I live inFlorida) and some 2 hours later when I started the car, on comes the engine light and the same routine...car struggles for several minutes, dies and on restart everything normal again and car ran great.

I am mad at myself because I had studied up on how to do a manual OBD by jumping theE1 and TE1 ports ( read the blinking light intervals) at the diagnostic terminal but failed to follow thru at that moment with engine light on. So, I am waiting for a recurrence of prob so I can do the manual check and maybe find a clue as to what is happening.

One thought I have is maybe it is a bad ignition coil that ocassionaly breaks down and being in the hot sun yesterday it temporarily "shorted out" so to speak. I have inspected the MAF sensor and all the plugs and they appear to be ok.

I researched almost all the posts here related to this problem and have gained some real helpful information and think this is a good site. I wanted to start this thread and keep you updated as to my progress and maybe hopefully someone can give me some new leads and later on if I solve the problem I can contribute to the data base.

2jznosht

Good luck with it. Sounds like an issue with spark or the ecu

6N1SC

iTrader: (3)

I agree, probably spark (I have heard of those symptoms with ignition coils) or the ECU.

PERRYinLA

That's correct - ignition coils are the first thing to check.
Yeah yeah, I know this is a old thread - spare me the obvious comment.
I had this same issue this past week, and in researching it on this forum I've noticed a lot of threads on this forum that describe the same symptoms, but don't always point to the most likely cause, probably because it sounds so far-fetched.
But if your V8 suddenly has....
- loss of power, rough idle, vibrating engine
- hesitation in the throttle
- change in exhaust tone and bad, gassy/dieseling smell
- rattling/pinging sound coming from the catalytic converter area when gas pedal is tapped
- and yet the check engine light does not go on

...the first thing to check are the two ignition coils on the top center and lower driver's side of the engine!
As mentioned elsewhere, the original coils tend to go on high-mileage cars, especially the driver's side one (because of the high heat).
Along with an extra serpentine belt, it's a good thing to carry in your car as a spare - even though one failing may not fully disable the car, you don't want to drive far with a failed coil - you could ruin the catalytic converter!
The OEM coils cost ~$70+, but if you don't need overnight delivery, you can get a generic equivalent for less than $20 online.

KahnBB6

iTrader: (5)

PERRYinLA, great advice for anyone who may experience the same issues with their SC400!

However the ignition coil and igniter are different parts just to clarify. The ignition coil on each side is what acts directly on the spark plugs through the distributor on that side of the 1UZ and the igniter is is a small, very simple computer in the ignition system that communicates the IGF signal back and forth with the main engine ECU on each firing cycle.

The ignition coils go bad with long term age and high mileage yes but the igniter unit usually does not unless there is a very abnormal problem with the ignition circuit's grounding to the chassis (such as a ground wire on that circuit missing).

Also, since the last poster in this thread before you mentioned it especially these days in the case of SC300/400's these symptoms can be ECU capacitor failure related if replacement OEM-spec cap service to the engine ECU has not already been performed. As these cars continue to age it is not a question of "if" but "when" that will be an issue. It's best to get new capacitors into the ECU very early into any symptoms or better yet as preventative maintenance before any symptoms ever show up. Again... unless the ECU cap service has already been performed.

Also seconding the mention of keeping a spare brand new serpentine belt in the trunk! That is *always* a good thing to have an extra of just in case!