ToeNee

Hey all, just took my car out from storage after 3 months of winter and its running terrible. Firstly, the cold start is idling at 300-500 RPM and the car sounds horrible. Secondly, the tacometer is all over the place. I give it gas it goes to 0rpm but doesnt stall out. While driving on the highway the RPMs will sit at 0 but I can still drive. Thirdly, It feels like the car is running at 30-45% power. It took be very long just to accelerate to highway speed. Could this be a IACV relearn? Sparkplugs? Some sensor causing all this? Ive attached videos I took of the first drive today which was arround 15kms (~10miles) each way with a mix of highway and city driving. Any input helps thank you

1997Soarer

iTrader: (1)

Did you store your car outside or inside? And if you stored it inside, was the location climate controlled?

Did you add fuel stabilizers before you stored it?

ToeNee

I used a fuel stablizer I think it was the Sta-Bil one. It was sotred outside completed covered in a car cover and I drove over a blue tarp and folded it under the car so no animals would get in. It got pretty cold here in Quebec around -30C (-22F)

GAsc300

Lot of potential things going on. Sc300 or 400?

you know what it felt like and any work you might have done before you put it into storage and conditions it faced while sitting. These could be helpful clues for you. Water damage signs in car or engine? Wet carpet? Fuse box in engine looks okay?

check all the basics re fluid levels, battery cables and ground and charge, leaks

You’ve got some red warning light on dash, e-brake stuck on?

the way your speedometer and esp tachometer are jumping around looks like electrical issue and or your dials are on their way out. Your car wouldn’t operate if tach was dropping to zero like that.

I’d disconnect both battery cables for hour or so, put key into lock position and reconnect battery. Start her up.

After that You could try idle relearn procedure. sometimes a battery being disconnected for long time can require relearn procedures.

Few weeks ago I took my battery out of my rx330 to test some stuff on my sc300 and the rx idle was completely out of whack when I put battery back in, like I’d just messed with the throttle body. It was stalling out at idle. Did the rx330 idle relearn procedures and it went back to normal. This was the same day i removed the battery.

ToeNee

Hey, SC400, and the red on the dash is my airbag light because I just put on a IS300 wheel. just picked up some throttle body cleaner today Ill check it out and clean it. Checked all my fluids seem to be good, checked my spark plugs seems to be okay. My speedometer always did that jumping thing I think its lose but my rmps never acted up which got me scared. I'm pretty sure it has something to do with a sensor or something electrical because like you said if my rpms were at 0 I would stall out. Do you know the idle relearn process? I cercently trying to take off my IACV and also gonna give that a clean but its a pain in the *** lol. Do you know the best way I can try to make the car relearn the idle and mixture? Thanks

GAsc300

[QUOTE=ToeNee;11685578]Hey, SC400, and the red on the dash is my airbag light because I just put on a IS300 wheel. just picked up some throttle body cleaner today Ill check it out and clean it. Checked all my fluids seem to be good, checked my spark plugs seems to be okay. My speedometer always did that jumping thing I think its lose but my rmps never acted up which got me scared. I'm pretty sure it has something to do with a sensor or something electrical because like you said if my rpms were at 0 I would stall out. Do you know the idle relearn process? I cercently trying to take off my IACV and also gonna give that a clean but its a pain in the *** lol. Do you know the best way I can try to make the car relearn the idle and mixture? Thanks [/QUOTE

Sounds dumb but I’d disconnect battery for a bit like i suggested.
It’s been a few years since I’ve cleaned my 1993 sc300 throttle body but fro my notes, throttle gets readjusted just by driving. For my 2004 rx330 there was a weird step by step procedure to follow to relearn idle that worked for that car but wouldn’t apply to SCs.

I don’t know about iacv for sc400, sorry. But I’ve read that can cause issues like you experiencing so worth a try to clean.

the slow acceleration issue you describe… you think car not shifting gears correctly? Transmission issue, ecu, or iacv like you looking into.

That’s not much specific help. Keep trying different stuff, with easiest things first. 3
months isn’t that long to sit and I don’t think should create many problems unless things got wet but your car was well covered it sounds.

Duck05

Hate to sound like a “broken record”, but first order of business with our cars is assessing the ECU. A lot of gremlins occur when the capacitors leak on the PC traces.

Send to SIA to be tested/assessed and repaired/rebuilt to at least take that off the table..

https://siaelec.com/product/lexus-sc...repair-return/

ToeNee

[QUOTE=GAsc300;11685855]The car is shifting correctly it feels like more of a loss of power from the engine. I can hear the car shifting gears. Taking out the battary now while I try to get at the IACV. Do you suggest I try to get to the throttle body or its best I leave it alone.

GAsc300

The car is shifting correctly it feels like more of a loss of power from the engine. I can hear the car shifting gears. Taking out the battary now while I try to get at the IACV. Do you suggest I try to get to the throttle body or its best I leave it alone.[/QUOTE]

hey there,

the problem(s) you facing are so potentially multi determined, you gonna get lots of advice and there are lots of directions you could take to figure it out. Context is critical. Your context is the car was driving great before you put it in storage. I’m assuming that’s true anyway. Then 3 months sitting in cold-*** conditions, covered from above and below. No water damage.

during those 3 months could components really fail (ecu, iacv) or get engine altering build up (throttle body)? I doubt it. Yeah,
eventually things suddenly fail. And eventually ecu needs TLC. I’ve still been able to solve my car’s many issues without tackling ecu, so I’m in denial about ecu. Denial won’t work forever in my 1993 sc300

eventually you’ve gotta try all options til you figure it out, yes. But just go in order of most likely and easiest to solve.

I’d wait on throttle body and wait on replacing iacv. I don’t know how to clean iacv but I know people can and it sometimes helps.

maybe just maybe your cars ecu took the battery being disconnected for so long as sign it needed to relearn it’s idle. And if it’s safe enough to drive, maybe a few short drives later things will get back to normal.

Other stuff that can make weird issues happen…
Check ground wires, check vacuum lines,‘check throttle cable, air intake cracked anywhere

Easy to say, Good luck, but good luck.

ToeNee

hey there,

the problem(s) you facing are so potentially multi determined, you gonna get lots of advice and there are lots of directions you could take to figure it out. Context is critical. Your context is the car was driving great before you put it in storage. I’m assuming that’s true anyway. Then 3 months sitting in cold-*** conditions, covered from above and below. No water damage.

during those 3 months could components really fail (ecu, iacv) or get engine altering build up (throttle body)? I doubt it. Yeah,
eventually things suddenly fail. And eventually ecu needs TLC. I’ve still been able to solve my car’s many issues without tackling ecu, so I’m in denial about ecu. Denial won’t work forever in my 1993 sc300

eventually you’ve gotta try all options til you figure it out, yes. But just go in order of most likely and easiest to solve.

I’d wait on throttle body and wait on replacing iacv. I don’t know how to clean iacv but I know people can and it sometimes helps.

maybe just maybe your cars ecu took the battery being disconnected for so long as sign it needed to relearn it’s idle. And if it’s safe enough to drive, maybe a few short drives later things will get back to normal.

Other stuff that can make weird issues happen…
Check ground wires, check vacuum lines,‘check throttle cable, air intake cracked anywhere

Easy to say, Good luck, but good luck.[/QUOTE]

Finally got the IACV out and cleaned it. Attached before and after pics. Ill look into other simple things before looking at the ECU like you said. If anything else comes up Ill send another reply and Im going to start it up on the weekend Ive had the battery disconnected for about a day. Thanks for your help

RXRodger

iTrader: (2)

Fuel pump ECU
MAF
ECU

just a few items that come to mind with those symptoms.

GAsc300

I’m pretty sure the sc300s relearn idle from doing some regular driving. Same May be true for your sc400. As long shot, Here’s a video with a version of the general Toyota idle relearn process that worked for my 2004 Lexus rx330
when it’s idle went nuts after a battery change.


Here’s a second one they may be slightly different:

ToeNee

Hey, going to try this on the weekend for sure. Got everything put back after cleaning the IACV and the car is now idling semi-like normal but It still feels off. Dont know how else to put it but it feel like there is mucus or something that it needs to caugh out? Before it felt as though it was running on 25% power now it feels more like 35-40%. Going to drive it more maybe it will fix my problem with the "mucus". I also checked my exaust to make sure it actually didn't have anything to caught out. The RPMs are still hitting ""0"" when I give it any gas and then going back to normal when I take my foot off.

GAsc300

Keep at it! And don’t forget to look for other obvious things in engine bay:
vacuum lines out, dirty air filter, cracks in air intake (bottom hard to see), ground lines pulled out, transmission has ground wire under car (could that have gotten pulled off by tarps placed under car? (probably not)), throttle cable look right,…stuff like that

Good job cleaning iacv!

keep thinking things through, you’ll figure it out
maybe driving will relearn throttle body, maybe that weird Toyota relearn procedure will help, maybe some obvious throttle body problem will be apparent when you check that out

A few months ago my starter failed and I opted to replace the contacts and do maintenance on other internals. The sc300s much easier than the 400s but still hard enough to access. It worked great for couple months, then failed in a different way. Found a rebuilt denso starter and got that on a few weeks ago, all good after fixing some ground issues near battery. Then today, coolant leak from super hard to access line in back of engine near firewall. Spent all day getting lines out and lots work still to do.

Point being you ain’t alone figuring this stuff out and working on it solo. Sure can be frustrating and I hope we both get our cars back on the roads soon.

1997Soarer

iTrader: (1)

Ok so you said you stored it outside but had the proper amount of fuel stabilizer. Assuming it ran perfectly fine when you stored it, there are 2 factors that are related directly to outside storage over winters that might be a factor here. Assuming you have not developed a mechanical or electrical issue like bad caps in the ecu, a dying fuel pump ecu, or a semi clogged fuel filter.

No matter how hard you try to prevent it, rodents will find ways of getting past covers. They don't normally chew our wiring which is a good thing, but what they can do is try to build nests in spots in the engine bay, like around the EVAP stuff, in the intake box, or under the intake manifold on 1UZ motors (or in the spark plug valley on 2JZs). When they do this, they will bite thru wires that are near their nests. So you need to take a good look thru the runners of your IM and see if there's junk under there. I think its more common for animals on UZ motors to bite thru the knock sensor wiring and sometimes the fuel injector wires.

The second issue is moisture. The cover does a great job of shielding the paint but the moisture of freeze-thaw cycles and extreme cold to above freezing days will cause moisture to stick to EVERYTHING under the car and in the engine bay. I hate this because when I store my IS300 outside during harsh winters I have to start my car on the warm days to burn off all the moisture that forms in the engine bay. That crap was surface rusting my engine bay bolts and my ceramic coated exhaust manifold. The surface rust is mostly an eyesore but this moisture will cause corrosion on exposed copper and the grounds, and if this corrosion is excessive it will throw sensors out of wack. So go over your wiring harness and look at all the grounds in your car and see if you can clean them up. You might want to buy a can of electronic cleaner to spray the grounds down after you remove them. After removing them, put them back. If a bolt is severely rusted, replace it with a new one. Every new bolt you put in will decrease the resistance of the wiring harness and that means your sensors will be more accurate and the ecu will be able to adjust accordingly.