fowcbler

Ok heres the situation. I own a 92 SC300 and it has 177k on it. Now when I start the vehicle, the check engine light comes on for about a minute or two then goes out and my Idle rpm's go up to 2600, sometimes lower and sometimes higher but averages about 2600. I just put new plugs, wires, cap and rotor and have a custom intake on it. I have been told its the Idle speed control, the throttle position sensor or even the Idle Air control Valve. I am just wanting to single out the proble alread and fix it. Also, the car seems to be running extremely rich. If you have any info it would be greatly appreciated.

tcrow31

iTrader: (6)

you need to go get the code pulled. Even though the light is out sometimes the code is still stored. Im thinking the code will be stored due to the fact that it seems like this is a constant reoccurring problem. If there is nothing there. then try pulling the IAC and cleaning it and the TPS and go from there.

fowcbler

Thanks for the help. I am plannin on taking it for a diagnostic tomorrow. I was just looking for any other ideas or possibly the solution to the problem. Hopefully I wont go broke off of this.

96B18B

Try Sea Foam.... it helped my 91 tercel with 199k miles...it was idling up and down during the winter or when ever it was cold... and after i sea foamed it.. It was like it had a new motor put in. Sea foam is also only like 8 bucks after tax at like schucks or NAPA.

ttsukamoto

iTrader: (1)

I had a similar problem recently, car would idle low and die. Eventually it wouldn't even start. I ordered and installed a new Idle speed motor, unfortunately that wasn't the problem and it wound up being the ECU. Bought a used one from Aliga and it started right up.

fowcbler

Ok, so I took it to a shop for a Diagnostic, and the guy there said he couldnt even get the machine to communicate with the computer. Then he tried to track it down manually and still couldnt figure it out. I am gonna throw a new TPS sensor on it, clean out the throttle body and IAC valve with some carb cleaner, the throw in some B12 Chemtool.
If anybody has any clue as to what could be goin on here, I would greatly appreciate it, cause I dont want to start throwin parts at it if its not even gonna fix the problem. Thank you soo much.

TheMole

iTrader: (13)

Your car is a 92 so its obd1. Just pull the code yourself:

https://www.clublexus.com/forums/performance-and-maintenance/22890-check-engine-light-code-retrival.html

Then match the code to ones here:

http://www.troublecodes.net/Lexus/

hlalogogo

try pushing the idle in if the idle drops down and stays down then replace it

fowcbler

Well I seemed to have fixed the idle revving. However, My sc still seems to be idling kind of high. About 1500 in park when cold, then about 1250 when warm. Now i had my battery/charging system tested and found out there was a charging problem. I got an EXCESS DIODE RIPPLE read back. I was also told the amperage in the alternator is not as high as it should be. Could the high idling be caused by my alternator going out?

tcrow31

iTrader: (6)

The high idling shouldn't have anything to do with the alternator going out. You cruise down the road at higher RPM's than that.

TheMole

iTrader: (13)

Did it happen right after you put new plugs, wires, cap and rotor and a custom intake?

fowcbler

Well it got worse when I did also whenever I touch the gas the car jerks but there is no hesitation I am startin to think I might have an ignition coil problem; any ideas?

evileagle

have you tried resetting the ecu?

fowcbler

If by resetting you mean unplugging the battery for an extended period of time, then yes, more than once actually. However, I think i figured out my problem. I found out I have a dead injector which would explain the car running rich. The reason it idles crazy and high is because the ECU is tryin to adapt to the dead injector and having to send extra fuel to the other five to compensate. I already ordered a new injector and it is on its way. Hopefully this will solve my problem. I will keep you updated. Thanks for all the help so far.