Advice On Removing Ecu From My Ls

[LS 0181158]

I am still having check engine light problems with my 1993 LS 400. After an extended sit, car is normal for the first 15-20 mins., then the CEL with rapidly flash on and off and the car will jerk violently in time with the flashing, alternately losing and regaining power many times per second. This makes it impossible to attain more that 40-45 mph on the highway. The light does not stay on consistently for the most part, but flashes on and off rapidly. Sometimes the problems goes away for a few minutes, only to return later. As I mentioned earlier, the car runs VERY RICH when this happens, blackening the back bumper and burning through gas at a mind-blowing rate.

At most recent visit, Lexus dealer pointed me toward a bad ECU ($1500). I don't know if this was just to get me to leave, but on the previous visit they suspected the MAF sensor, which I replaced. On this second visit, they claimed the car was not throwing any codes and condemned the ECU as a result.

Does this indeed sound like an ECU issue? I found a place online that claims they will rebuild your '92-'95 Lexus ECU for $265, although they will not charge you anything if there is nothing wrong with it or it is unrebuildable. However, I've also heard of ECU's being picked up at junkyards for $150.

Am I barking up the wrong tree here?

If not, where is the ECU located in my 1993 LS 400 and how do I get it out? Any precautions besides disconnecting the battery and avoiding static discharge?

[93ls400walt]

I am still having check engine light problems with my 1993 LS 400. After an extended sit, car is normal for the first 15-20 mins., then the CEL with rapidly flash on and off and the car will jerk violently in time with the flashing, alternately losing and regaining power many times per second. This makes it impossible to attain more that 40-45 mph on the highway. The light does not stay on consistently for the most part, but flashes on and off rapidly. Sometimes the problems goes away for a few minutes, only to return later. As I mentioned earlier, the car runs VERY RICH when this happens, blackening the back bumper and burning through gas at a mind-blowing rate.

At most recent visit, Lexus dealer pointed me toward a bad ECU ($1500). I don't know if this was just to get me to leave, but on the previous visit they suspected the MAF sensor, which I replaced. On this second visit, they claimed the car was not throwing any codes and condemned the ECU as a result.

Does this indeed sound like an ECU issue? I found a place online that claims they will rebuild your '92-'95 Lexus ECU for $265, although they will not charge you anything if there is nothing wrong with it or it is unrebuildable. However, I've also heard of ECU's being picked up at junkyards for $150.

there is a lot of info on ECU's in the forums. Just enter a " keyword " in search topic box.

Am I barking up the wrong tree here?

If not, where is the ECU located in my 1993 LS 400 and how do I get it out? Any precautions besides disconnecting the battery and avoiding static discharge?

[/quot I have a 93 ls that did not have a check engine lite on. But experienced many of the symptoms that you describe. Jerking espically going up hills. Hard to get above 60 MPH. I found corroded dist cap ports and plugs. A tune up replacing wires, caps, rotors and plugs solved these problems. Also just cleaned the throttle body, easy to do at tune up,all parts are already removed. Used valvoline systhetic carb cleaner. Claims safe for O2 sensors and CATS. Now I have a perfectly smooth idle. No rocking felt on the shift lever or steering wheel. May be worthwhile to inspect these items.

Edited January 1, 2006 by 93ls400walt

[LS 0181158]

Thanks 93ls400walt;

I will try your suggestions if I get a chance. I really am beginning to lean toward a bad ECU, though, because these symptoms are not present consistently--there's no consistent, reliable rough idle, no loss of power under certain repeatable driving conditions--the car is either perfect or it is acting up on a spectacular level. The problems I described are very alarming and don't "develop" over any time period--they appear like snapping your fingers, and may go away just as quickly. Sometimes they don't occur at all, for quite a while. I would say this is definitely an electrical problem--computer, wiring, connections, something like that; not a mechanical, wear or dirt accumulation issue because as I said, the car would behave shoddy all the time if it were.

Thanks for your suggestions though. I will definitely check those things if I get a tuneup done.

[93ls400walt]

Thanks 93ls400walt;

I will try your suggestions if I get a chance. I really am beginning to lean toward a bad ECU, though, because these symptoms are not present consistently--there's no consistent, reliable rough idle, no loss of power under certain repeatable driving conditions--the car is either perfect or it is acting up on a spectacular level. The problems I described are very alarming and don't "develop" over any time period--they appear like snapping your fingers, and may go away just as quickly. Sometimes they don't occur at all, for quite a while. I would say this is definitely an electrical problem--computer, wiring, connections, something like that; not a mechanical, wear or dirt accumulation issue because as I said, the car would behave shoddy all the time if it were.

Thanks for your suggestions though. I will definitely check those things if I get a tuneup done.

My car symptoms would come and go in an instant, And also would not occur for a while. I don't remember if you reset your ECU. To do so disconnect the battery negitive terminal for a few minutes the re-connect and start your car. My dist caps looked perfect on the outside and I almost did'nt touch them. Bou when I removed the coil wire the terminal broke off and was full of corrosion. I was actually glad to see this. As I was now hopefull that I had found my problem. Good luck. Walt

Do a forum search in the keyword box for ECU. Tons of info.