high idle
Thread Starter
Driver School Candidate
Joined: Sep 2016
Posts: 4
Likes: 0
From: Rotorua
high idle
help please, is there any way I can change the high idle I have on start up-1900 rpm. have replaced the temp sensor but that may a difference at 1st but i'm back to square one
Lead Lap
Joined: Jul 2010
Posts: 4,525
Likes: 98
From: ca
Okay high idle at start up. So then what? Since we are not standing next to or sitting in the car all we can go on is what you tell us.
If it did funny things after a 10 minute warm up then I'd suspect things like that temp sensor, but since its doing high idle at start up the cold starting all seems to be fine to an extent. So the temp sensor is not even in the equation. I would suspect the idle air control but if it runs nice after warm up then that is probably not the problem.
As a guess one thing that does affect the before closed loop stuff is the basic program in the ecu, and that means a possible ecu problem, maybe the bad capacitors.
And are we sure the tachometer is reading the accurately?
And like Banshee says check the codes, you don't need a code reader to do it.
And just use a paper clip not a big wire like in the photo.
http://www.lexls.com/tutorials/intro/codereading.html
If it did funny things after a 10 minute warm up then I'd suspect things like that temp sensor, but since its doing high idle at start up the cold starting all seems to be fine to an extent. So the temp sensor is not even in the equation. I would suspect the idle air control but if it runs nice after warm up then that is probably not the problem.
As a guess one thing that does affect the before closed loop stuff is the basic program in the ecu, and that means a possible ecu problem, maybe the bad capacitors.
And are we sure the tachometer is reading the accurately?
And like Banshee says check the codes, you don't need a code reader to do it.
And just use a paper clip not a big wire like in the photo.
http://www.lexls.com/tutorials/intro/codereading.html
Last edited by dicer; Sep 8, 2016 at 09:41 PM.
Thread Starter
Driver School Candidate
Joined: Sep 2016
Posts: 4
Likes: 0
From: Rotorua
ok,the car starts up at 1900 rpm and warms down after 10mins or so.when I 1st changed the temp sensor, undid the battery and pulled the ecu fuse then the car would start at 1100 rpm. got up the next day and it had gone back to 1900 rpm on start up. once the car is warm it idles around the 600 rpm mark and there is no probs with driving.where is the ecu panel and bad capacitors hide?
Lead Lap
Joined: Jul 2010
Posts: 4,525
Likes: 98
From: ca
Instructor
Joined: Nov 2006
Posts: 971
Likes: 98
From: FL
I agree, ECM.
How does it rev when it's idling high like that? Does it seem to restrict itself in RPM's? Pull your ECM out and CAREFULLY disassemble it. Check the bottom of all of the capacitors for leakage of some gooey stuff. But keep in mind that not all bad capacitors leak. They can be sealed and still bad.
Your engine coolant temperature sensor is what's known as a negative temperature coefficient sensor. It's pretty much a thermistor. Your ECM sends the sensor a reference voltage of 5V. The computer then looks at how much voltage was lost after passing through the thermistor. It knows based on the voltage after the sensor what the temperature of the coolant is. It's pretty darn accurate too. The engine coolant temperature circuit can be GREATLY affected by bad capacitors as the ECM will then send out a reference voltage other than 5V. It will send out, say, 8V instead. You can obviously see how this would skew everything having to do with that circuit.
But, even worse, the bad capacitors in the ECM affect many many circuits, not just the ECT circuit. It will cause all sorts of wacky behavior. The last action in most of the engine DTC flow charts, after different tests and such, simply say's "Replace ECM." Luckily they are rebuildable at a pretty affordable cost.
How does it rev when it's idling high like that? Does it seem to restrict itself in RPM's? Pull your ECM out and CAREFULLY disassemble it. Check the bottom of all of the capacitors for leakage of some gooey stuff. But keep in mind that not all bad capacitors leak. They can be sealed and still bad.
Your engine coolant temperature sensor is what's known as a negative temperature coefficient sensor. It's pretty much a thermistor. Your ECM sends the sensor a reference voltage of 5V. The computer then looks at how much voltage was lost after passing through the thermistor. It knows based on the voltage after the sensor what the temperature of the coolant is. It's pretty darn accurate too. The engine coolant temperature circuit can be GREATLY affected by bad capacitors as the ECM will then send out a reference voltage other than 5V. It will send out, say, 8V instead. You can obviously see how this would skew everything having to do with that circuit.
But, even worse, the bad capacitors in the ECM affect many many circuits, not just the ECT circuit. It will cause all sorts of wacky behavior. The last action in most of the engine DTC flow charts, after different tests and such, simply say's "Replace ECM." Luckily they are rebuildable at a pretty affordable cost.
Trending Topics
Racer
Joined: Sep 2008
Posts: 1,286
Likes: 212
From: Chandler, AZ
Make sure to double check your intake piping after the MAF sensor. My flexible (or rather not flexible, brittle and dry rotted) rubber boot connecting the MAF pipe and pipe to the throttle body was cracked underneath letting in air past the MAF sensor.
I was luckily able to get a replacement at a toyota dealer since Lexus wanted $87 for it. After asking nicely, the parts guy dropped the price down from $55 to $35 for the rubber intake coupler. It's about an inch short but since its a bellow type coupler like stock, it's able to stretch a bit.
Part number I used was 17882-20161
I was luckily able to get a replacement at a toyota dealer since Lexus wanted $87 for it. After asking nicely, the parts guy dropped the price down from $55 to $35 for the rubber intake coupler. It's about an inch short but since its a bellow type coupler like stock, it's able to stretch a bit.
Part number I used was 17882-20161
![Name: IMG_20160907_185454364_zpsuofdn8ip.jpg
Views: 1035
Size: 201.3 KB](https://www.clublexus.com/forums/"https://www.clublexus.com/forums/"https://www.clublexus.com/forums/"http://s145.photobucket.com/user/kai21787/media/IMG_20160907_185454364_zpsuofdn8ip.jpg.html""")
![Name: IMG_20160907_185444854_zpslsgkxsgi.jpg
Views: 1016
Size: 180.2 KB](https://www.clublexus.com/forums/"https://www.clublexus.com/forums/"http://s145.photobucket.com/user/kai21787/media/IMG_20160907_185444854_zpslsgkxsgi.jpg.html"")
![Name: IMG_20160908_172704954_HDR_zpshfrpyd1d.jpg
Views: 1085
Size: 234.9 KB](https://www.clublexus.com/forums/"http://s145.photobucket.com/user/kai21787/media/IMG_20160908_172704954_HDR_zpshfrpyd1d.jpg.html")
![Name: IMG_20160909_031640586_zps0x8gvd5u.jpg
Views: 1004
Size: 170.8 KB](https://www.clublexus.com/forums/"http://s145.photobucket.com/user/kai21787/media/IMG_20160909_031640586_zps0x8gvd5u.jpg.html")
Last edited by Losiracer2; Sep 9, 2016 at 03:13 PM.
ClubLexus Stories
Celebrating Lexus & Toyota from Around the Globe
Top 10 Lexus & Toyotas to Drive Before You Die!
Joe Kucinski
Top 10 Lexus/Toyotas With The LEAST 5-Year Depreciation
Joe Kucinski
Lexus LC500 Convertible Auction: A Preview of Rising Values?
Brett Foote
GX 550 vs TX 550: Best 3-Row Luxury Lexus Family Hauler
Michael S. Palmer
9 Best Lexus Models You Can Buy for Half Price (And 1 You Shouldn't!)
Joe Kucinski
2026 Lexus NX Buyer's Guide: Models, Features, Prices & More!
Brett Foote
Top 10 Reasons to Buy a Lexus TX 550h+ (& 3 Reasons to AVOID!)
Michael S. Palmer
Top 10 Lexus & Toyota Models of the 1990s RANKED!
Joe Kucinski
10 Great Toyotas That Could Have Been Lexus Models
Joe Kucinski
Lead Lap
Joined: Jul 2010
Posts: 4,525
Likes: 98
From: ca
Yeah that can cause problems, but I don't think (keyword) it would cause a cold idle problem, with lack of airflow past the mass sensor it would back off fuel delivery. So whats the news on it??????? Did you check for codes??
Thread
Thread Starter
Forum
Replies
Last Post
LScowboyLS
LS - 1st and 2nd Gen (1990-2000)
5
Dec 20, 2011 07:06 PM