kid865

iTrader: (-1)

ok this is the deal. if i drive bout 25% throttle it ok. if i put it to the floor misfires and will not go anywere. i let off the throttle and get back on the gas at25% it ok again... i was told it was bad ecm. but the codes it show is bad tps. i changed that still the samething changed map still same.... anyone

LiCelsior

iTrader: (32)

what was the code exactly?

kid865

iTrader: (-1)

It showes the tps sensor. But put a new one in and it still showes it... the guys at lexus said it sounds like a bad ecm. but i dont want to get one if its something diff. and it kills the battary but its new like 1 wk old. it only does it when i put it to the floor..

3UZFTE

Well there are cheaper ways then purchasing a new ecu, there are a few companies that will refurbish them, some even have a 1 day turn around, search around for that. About the misfiring, the TPS could need to be adjusted, and I don't think slapping a new one on is going to fix the problem. I would spend the money have it either looked at, or start with what a trained person is telling you.

RAINBOW

My 93 was doing all kinds of similar things. One day it would run fine, then not start, then run really good, then nothing. I sent my ECU(ECM) to ATE s/a ASI in Tenn. $99.00 (they want your original)and a couple days (if you pay 1 or 2 day,I didn't) they pay for return shipping (reg.ground) anyway that was 1,500 miles ago and it's running great. I wish everyone would do this first, instead of blowing hundreds of bucks guessing on the problem. Their number is 1-866-983-6688. It's pretty easy to remove the ECU , and it's guaranteed for life as long as you don't break their rebuild seal.p.s You actually pay on ebay, and then fill out a form with your info. It's a pretty neat system, and everyone was nice to deal with........................and it's RUNNING !!!!!!!!

loperman

So kid865 did you resolve the problem? I have exact the same on my 1994 ls400! Please let us know! Thank YOU!

Yotarip

If kid865 was able to read the code then it probably was NOT a bad ecu. Kid865 didn't say whether he reset his ecu after installing the new tps nor do he say he calibrated it.

I had a similar problem with my 93ls. My check engine light was on BUT it would NOT give me a code. That was a sure sign of a bad ECU. I sent my ecu off for repair just like Rainbow. Now, over 8,000 miles later the problem has not returned.

loperman

To Yotarip:
What exactly symptoms did you have? Could you step on gas all the way? I'm going to send my ECU this weekend to rebuild it!

Yotarip

1) Check engine light on.
2) Would not give a code when diagnostics were activated (CEL would not flash, just stayed on constantly).
3) Would idle very low but smooth.
4) Would loose almost all power after 2500 rpm under load. If you raised the RPM over 3000 while in park/nuetral, it would misfire.
5) Acceleration was very slow. Barely would get to 55 MPH.
6) Exhaust under the car would get VERY HOT while driving.

3UZFTE

Ok, so your saying when you checked the CEL via the procedure of hook up a jumper wire, it did not flash at all? I am no rocket scientist nor am I claiming it's not the ECU, but #6 seems like to me if is running in open loop with the CEL being on. I would like to know more about this as I haven't had this problem yet, but these ECU's seem to be a common problem.

PureDrifter

iTrader: (10)

yotarip might have jumpered the wrong pins.

nthach

Jump pins E1 and TE1, if done properly, the CEL will flash and the O/D OFF light will stay on solid or flash dependent on O/D button position.

Sounds like the car is running lean. I'd also check fuel flow and spark.

loperman

To Yotarip:
I have the same problem on 1, 2 but don't have other problems except slow acceleration wich is because i can't push the gas pedal hard, if I do so it's starts to "jerk" like it is don't know which gear to choose!

To PureDrifter:
I can't tell for Yotarip but i did the right ones, E1 & TE1, O/D was flashing constantly and CEL just stayed on!

To everyone! I just got the car and not sure if the owner was properly taking of it! So I will do wat it takes to fix it, but dealer prices are just not reasonable!!! If any one have simular issues Please let us know how did you resolve it!!! Thank YOU!

Loperman

Yotarip

All good comments.

1) I did jump the correct pins. (E1 and TE1). I accessed the diagnostic port in the engine bay and the location under the steering wheel. Either way, the CEL would not flash. It was just on.

2)My ecu would stop working intermittently. Sometimes It would run fine for a short time then go into limp mode. At that point, the Idle Air control valve would no longer receive a signal from the ecu and remain in what ever position it was in when it last received it's signal. If it was stuck in a wide open position, the engine would run very lean (high rpm) and the egt would rise. At one point my exhaust manifolds were glowing red hot at idle. It was at that point that I removed the ecu and sent it off for repair. If the IAC was stuck in a closed position the idle would be very low or it would not be able to maintain an idle.

Now the company I sent my ecu to was very helpful. They told me that they repair the ls400 and es300 ecu's all the time. This is a common problem for these cars. Hell, EVERY LS400 that I have seen in the junkyard has been raped of it's ecu.


Loper,
Just verify that your ecu is faulty by jumping the pins in your diagnostic port. The CEL WILL flash a code if your ecu is fine. It will either flash a trouble code or an ALL is good code. If the CEL does not flash, that is a sure sign of a bad ecu. Don't expect to have every drivability issue that I had. The symptoms will be different depending on what position your IAC and EGR valve were in when the ECU decided to stop working. I had a wide range of issues because my ecu would be fine for a while then stop working at idle or cruising at 45 mph or 80 mph. Each time it would show different symptoms because the IAC/EGR valves were at different positions when the ecu went into it's coma.

The one constant symptom I had was the inability to pull a code.

Yotarip

One more thing. This member's input really helped. Seems to be very knowledgable about this issue.

cut and past from my older thread.

His username is 06taco3uz.

I'm almost certain your Engine ECU is on it's way out. The dead giveaway (excuse the pun!) is that it won't flash error codes when Tc is grounded. Assuming that the ECU has power, ground and the Tc wire is good a properly functioning ECU will ALWAYS flash codes. If it doesn't then the ECU is faulty, end of story. The other symptoms of a dead ECU (corresponding to your list above):

1) See #3 and #5 below.
2) IAC motor random jumps or stuck in last commanded position.
3) Fixed ignition timing with no spark advance.
4) Transmission solenoids disabled, transmission reverts to hardware limp mode with current gear selected by lever position (D=4th, 2=3rd, L=2nd) no automatic shifts, no lockup.
5) fixed injector pulsewidth based only on rpm which is VERY rich.
6) microprocessor is dead so it is unable to enter diagnosis mode
7) as the hardware fails problems may be intermittent, worsen based on ambient temp and get worse over time until total failure.
8) hard starting due to rich mixture (flooding) and closed IAC

FYI, inside most OEM engine ECUs there are actually two separate systems that can control the engine: the primary system that is microprocessor-based (the "computer" part) and a "backup system" that is basically "hardwired" and takes over in the even the microprocessor stops running. Generally the "hardwired" functions ignore ALL sensor inputs (temp, airflow, etc) and command fixed fuel/spark, no idle control, no trans control, MIL on. This is different from what happens when a sensor fails and the computer ignores or substitutes it's value. Both are forms of "limp home" functions, one hardwired and the other implemented in computer software.