Took some pics of my tach, have a 97 sc400. Have had a few starting issues that would always be resolved after 2 stall outs first thing in the morning, the car would drive like normal for weeks/months after. Recenty the car stalled while coming to a stop on road and would re-start but surge up then immediately down and stall out repeatedly. Had it towed and fixed serpentine, been needing it fixed. Problem hasnt reoccurred since. Lexus checked out, have b1s1 o2 sensor engine light code before biggest incident. After fixing serpentine, mechanic said alternators at 10v, but no issue since.

First pic below show my car in drive at second white notch above zero. Is this 400 or 500 rpms?
Second pic shows in park, both after 20 minute drive. Is this 600-650 rpms?






Car does not shake when at the second notch and is really quiet in fact. I just think with the recent full stall issue, maybe itd be best to set it higher. How can I get my rpms in drive, at stop light, etc., to be the 600-650 one in second pic? Is this better???

The rpms do dip below the second notch but only when in reverse momentarily and when turning wheel at slow speed side to side when parking.

Alternator should be fixed?
O2 Sensor causing issues?
What do the notches on the tach stand for (400,500,650) ?
Should I reset idle and how do I do this or should I let Lexus do it for me?

This is the last time I will post this issue, really been stressing me out. My car has over 180k miles but has been the most reliable car ive ever had by far. Want to go back to having this piece of mind when I walk to my car or have a long drive ahead.

Thank you in advance for any ideas or help. Have searched and searched forums here and lextreme and others, just need definitive answers so I can start working from there.

Thank you again guys

 

Are you saying that changing your serpentine belt fixed your idle revving problem?

Also, your idle seems fine at 500 rpms. If the car is not stalling out I wouldn't do anything. Does your car's idle go up when the ac is on? It should raise to around 750 rpms. If so I would say all is good.

I have read that some members have been able to adjust idle by turning the TPS while the car is in park and idling. If you are not experienced with the SC I would not mess with the TPS.

 

I fixed the serpentine and the idle/stall issue hasnt re-occurred since. Not sure but maybe the serpentine wasnt turning the alternator properly, not so familiar with cars to know if this might be true.

As for the second notch, does that mean that the 2nd notch is 500rpms?
No issues but just feels low now that ive been left on side of road for first time. Even driving without radio on for last three weeks to reduce the load on the alternator. Have a dvd/nav installed, never been an issue though.

I would prefer i guess to have the idel in drive at stop light be at the level of the 2nd pic, not a big difference in engine noise and probably better for takeoffs and to keep from bogging down.
was thinking of adding chevron techron cleaner to gas and having the speed adjusted by Lexus. Just worried ill be left again. Its stressful, compared to others on here, my issues are minor, but when the cars been problem free, its just annoying to have to worry about making trips longer than 10 miles away.

Thanks for reply man

 

There is literally a thread directly beneath yours about the tachometer RPM's, read it. Also, if your o2 sensors haven't been touched in a long while, chances are they need replacing. After all,

 

In your second pic the car is idling at 500 rpms the next mark up is 750 rpms. I think you are stressing over very little. If your car cranks over every time you try then your alternator is working. Play your radio not going to overload the system. As long as it cranks and goes it probably will not let you down. Remember the car is 20+ years old.

 

Nice gauge cluster lighting. The computer may need rebuilding.

 

Yes, I thought id add the orange of the check engine light plays well off the green back lit boxes.

So, definitively, the second white mark after the 0 is 400rpms?

The first pic is my idle at stop light after driving for a bit in drive
the second is when in park after driving around 15-20 mins.

Im guessing that the third mark (white line right before the 1) is 750rpm.

As for alternator, thats what I thought. It seems to whine for a few mins after startup but only when its cold here in PA. Im sure the previously worn serpentine was the cause of some of its volt issues. I worry about radio being on because once upon a time I had a very low idle at 1st white mark after 0 due to trying to play a dvd in the system. The car didnt like that so we just use for radio and cds.

I plan to replace the s1b1 sensor, hoping that improves a few things and if nothign else gets rid of that damn light. Whats the specific part number by the way so I can find online?
I might have Lexus clean the throttle body and iacv, then I will add some chevron techron additive and I think im good to go.

Just wanted to know what the white hash marks stand for, the closest 2 near the "0" on the tachometer and if it was normal to idle low.
The car is super quiet and has always run well, it just had those 10-12 times that it started, turned off, started, turned off, started and ran for months. and then the one time where it would start, surge, then stall out when trying to put in drive, neutral, etc.

Hasnt happened since so Im just going to enjoy my music and stop worrying.
The problem is my firt car was a ford probe gt and it pretty much screwed me up for cars. Turned off on its own when brake fluid was low, had to remove complete front bumper to change a turn signal, tb would routinely get stuck under an air hose and accelerate on its own, and the radiator fell off on the highway.
Have to make peace that Lexus is not Ford.

Thank you for all the help

 

Decided Im going to replace the two front sensors at same time. Found this one on Amazon, two questions,

Are the two front sensors the same part ### (Denso 234-4169 Oxygen Sensor)
Is the Denso one in the link a direct fit without any alterations needed?

Going to job myself so would like something thats a direct fit plug in.

Link below, thanks guys