HyadMusic

Hey guys... long story short... the three previous owners of my 1997 sc300 automatic N/A (130K miles) were totally awful. It STILL had the stock fuel filter from 1997 on it!!! I bought it earlier this year. Here is a list of the maintenance I have done on the car, totaling about 5 grand unfortunately, as I am not mechanically inclined...

Water Pump
Timing Belt
Distributor
4 New Tires
Front Brake Rotors/Pads
Oil pan gasket
Upper Camshaft Seal
Upper gasket
Power steering Hose/pump
Air Filter
Fuel Filter
Transmission Mounts
Multiple Oil Changes since September during repairs
(AC Compressor, Alternator, and Battery have been tested and are fine)
... and a few others

So here is my problem with the following symptoms

1) Very low idle down to 100 rpms...even to what looks like 50...engine vibrates... turning on the AC helps bring the rpms up
2) if I do not let the car warm up to the quarter temp marker and I try to drive it, it will shut off briefly while im moving and will come back on. It has stalled out on me twice, but never stranded me.
3)Turning the PWR ECT switch to ON keeps my rpms level and normal for some reason
4)I will be at a stop light and watch the rpms drop...then very slowly the needle comes back up to normal.
5)Sometimes the AC will increase its fan settings on its own...until I turn it down myself.
6)On start up...high rpms at 1500-1700
7)On start up...not alot of smoke like I had read others have had...but a little bit..however it's cold out so I cant tell for sure
8)Check engine light is on...but might be related to the low oil level sensor that fell apart during a previous repair...car is from Florida...high salt in the air possibly causing corrosion on parts faster...not sure
9)Now my brake lights which work perfectly, threw the brake light switch on my dash warning light, like they arent working...sometimes will come on and sometimes wont.


After reading multiple posts I say ECU..i have it under my kick plate and have seen it already, but not opened it up yet for fear (as this is my only car) that I wont be able to restart my car and get to work...so last night i ordered the new ECU (Used and tested from a company with a good reputation and return policy)..yes its the correct part number for my make and model....and will do the swap here in a week when it arrives...

So do you guys think this is probably the ECU with leaking capacitor(s)? Also, when i go to remove the ECU, what precautions (Safety) should I adhere to? I know disconnecting the battery for sure...but do I need to be grounded to switch out the new ECU?

Thanks for reading this long freaking post....I am just so tired of my SCaids =l

About to give up soon if I have an incurable gremlin. =(

SC400slide

iTrader: (11)

You're on to a good start with the ECU. Pull the CEL code.

When removing the ECU, just disconnect the battery terminal and you should be good. I didn't do anything special when I removed mine.

Report back with your findings!

HyadMusic

Thanks man I am learning as I go. I will definitely let you know what happens after I install the new ECU. Thanks for the advice!

King700se

^hit the nail on the head. Remanned or repaired ECU will do the trick. Ive heard its a completely different car once the ECU is repaired or replaced. That little guy controls EVERYTHING!

Ali SC3

iTrader: (10)

Welcome to CL, your thread has been moved to the performance and maintenance section.

HyadMusic

So today I installed the used ECU. When I started it up I noticed the slow rotating humming/vibration was gone... however when I put it in reverse it gave me really low rpms along with what sounded like belt squeaking as a timing belt or something similar would sound.. and also more low rpms within the first 5 minutes of driving. This is after a 5 minute warmup in Park. The check engine light was gone, along with the "tail lights are out" warning light on the dash. (All driving done in a normal mode, no PWR ECT or air conditioning with Overdrive On)

As 10 minutes or so crept up the low rpms were gone, I was still at around 600-650, instead of 800-850, but at no point did it sink lower than 600 or vibrate loudly, or anything like that at all. I drove around 20-30 miles before I stopped and parked. After running an errand real fast, I restarted the car and my rpms were at a normal 600-650 in Park. While driving nothing crazy happened, and rpms when I came to a stop in Drive remained at 800-850. However, I noticed that my "tail lights are out" warning light on the dash came back on. I do have aftermarket tail lights as you see in my avatar, so thats not that concerning could just be like when I installed my cipher auto racing seats and the seatbelt warning light came on.

So after I was almost home I said screw it, I am going to run the AC and see what happens, and as a result my rpms rose slightly to just about a thousand, and remained there normally with full AC blasting. A few minutes later I turned the AC off and I was still normal. I switched the overdrive off for harder acceleration and engine braking and everything is normal. The check engine light came back on too, but that's probably from my low oil level sensor not being there from a previous repair where the part broke in half from wear and tear, at least thats what I got told... I have feeling the dude hit it with a wrench by accident coming out of the oil pan. On my next day off I will go to autozone and have them pull the CEL codes for me... but my guess is the lack of the sensor is tripping the CEL.

I tried opening the original ECU to see if any capacitors were leaking, but the $@%&-ing screws are so old that i only got a third of them out, and the rest got messed up on the head and the metal was damaged from trying to unscrew it, and vice grips didnt help either. I guess I wont know for sure but My car is running better, no white smoke at all... but the real test is in the morning when i go to drive to work and it's cold outside instead of warm like it is right now. I will see if I let it warm up a little then start driving if my car shuts off then comes back on like it was doing.

Thanks for all the help as this is a cool learning experience for me!