djthrstque

I have a 1991 LS400. Ran fine last week. Have had a valve cover gasket leak for a couple months, been putting off the job for a while. Brought it to a mechanic my parents know. Picked it up and the car idled like ****, no power when accelerating, and had smoke coming out from under the hood couple miles from the shop. Took it back and they told me there were wires shorting out because they had electrical tape?(admittedly I am not mechanically inclined) They put new wires in and it still idled rough and had no power when accelerating. Car also spudders and seems louder? Check engine light comes on and off, car will drive OK around 45mph. Do not want to take it back to mechanic as am tired of dealing with him. I have replaced also the power steering rack, ps pump, ps high pressure line, water pump, and timing belt. Any advice on diagnosing the issue? Am finally fed up with taking it to shops. Including the purchase price of the vehicle I have spent about $5000 since i purchased last November. Love the car, would hate to see it junked.

CLLEXUSS

Well if it triggered a code just hook up a scan tool see what code comes up. (you can basically get a loaner from some parts stores possibly free to use with payment held). Smoke coming out of the hood is usually valve cover gaskets leaking onto the exhaust and burning off. If oil is getting on the plugs because of bad gaskets it could cause misfire but it seems they put new wires in and still doing it? They should have seen oil if any was in there while changing wires if it was there or not. Sputters louder yea that's kinda weird the louder part. If you don't want to take it back to mechanic just get a loaner scan tool to bring up check engine codes like I say probably a free loaner. If you don't know how to use one its not too difficult you can just go on youtube and there are tutorials lots of them. It might be just a bad sensor somewhere you just won't get any ideas until you run the scan.

deanshark

Here's how to check for codes; http://www.lexls.com/tutorials/intro/codereading.html There's also a diagnostic port under the hood which is alot easier to get to. Let us know what codes come up and we'll be able to advise more.
Smoke is probably just the oil on the exhaust like CLLEXUSS said.
All the other symptoms you have, Spitting, spuddering, no acceleration, all sound like the ECU might be bad. Ecu is very common problem with the older cars and especially being down in that Florida heat.
I would also avoid that mechanic. Who puts on plug wires that are wrapped with electrical tape? Should have at least suggested to you to change them, while he had them off.
Don't junk the car, $5000 is alot to put into something just to junk it. It might just be a $50 part. How many miles and what condition is it in?

djthrstque

The car is in pretty decent condition, paint and body are all good, as is the interior, 163000 miles. I am getting codes 41 throttle positioning sensor? And 64 open or short circuit in no 3 solenoid valve. I tried getting the TPS off this morning, only for one of the segments where the screws goes in to break off. Going to order another TPS.

deanshark

I had a 41 and changed the TPS with no good results, still had code. It went away after the ECU change. Because you have the transmission code along with the TPS I would say that might have to do with the ECU. Those are 2 of the symptoms of it being bad. Check out this; https://www.clublexus.com/forums/ls-...capacitor.html and see if you have any other symptoms that you might not even be thinking of. Like it says; "crazy issues" The ECU is easy to pull out, even with little mechanical ability. Even if you do get a new TPS you still need to adjust it. http://www.lexls.com/tutorials/EFI/tps.html

djthrstque

Changed the TPS, less rough idle. Lets off smoke if I adjust the tps. Still jerks and no power. Guess I'm going to buy a new ECU.

billydpowe

iTrader: (1)

sounds like you broke a vacuum hose........................... think.

Yamae

Other than the ECU, I worry that the timing belt is not properly installed.

djthrstque

I had the timing belt replaced a couple months ago, no issues until the valve cover gasket job.

RA40

iTrader: (6)

My thoughts: check the ECU for any leaking capacitors. Then a combination of vacuum hose and electrical connectors that may need to be checked.

deanshark

Did the code 41 go away for the TPS? If not that points more to the ECU, still sounds to me like that's the problem anyway.
I keep thinking of other things it might be from doing the VC gaskets and I thought of the coil wire on the drivers side getting crushed under the top timing cover if the grommet wasn't put in the cut out hole for it. But that would, most of the time, throw a code 13 which ya don't mention. That's something you can just look in and see with a flashlight. Above the AC compressor, drivers side of engine. The only vacuum lines and electrical connectors that RA40 mention would be from the throttle body being removed to change the VC gasket.
But, as we all know, the ECU can be working perfect one minute and all of a sudden just go crazy. If you do change it, open the old one and take a pic so we can see the caps if they're leaking. Don't throw it away, save it as an emergency part.

djthrstque

Still getting code 41 after I changed the TPS. When I put the car in drive and let off the brake it will jerk forward pretty substantially.

Got the glove box and passenger's side kick panels off. Can't get the screws off the ECU's box to take a look at it. Any recommendations on how to loosen them up?

djthrstque

Plugged the computer back in and I am now getting a flashing CEL. Continuously flashing same with OD. No more codes.

deanshark

Continuously flashing means no codes. I don't know if you did but you're supposed to disconnect the battery before unplugging the ECU.
After replacing the ECU does it still drive like crap even with no codes? The codes wouldn't reappear until you drive it.
The screws on the ECU should just come right out. Mine were tight where I had to put some muscle into turning them. When ya get it open there's more screws to take out the board. Be careful when you're in there. Did you read some of the ECU thread link I posted above? It tells ya how to destatic yourself.

djthrstque

Damn.. didn't realize you were supposed to disconnect the battery. Hope I didn't just put myself in a worse position. I contacted LScowboy on facebook. He told me that the ECUs require some kind of japanese screwdriver and that while they are probably worn, they likely aren't leaking. He sent me a link and I have purchased the screwdriver. Still drives with no power, rough idle. Seems to shake and jerk in waves.