PauleyH

Hi all new to the site. I had a timing belt replacement on a 1999 LS400. The belt is aligned correctly but the car has a rough fluctuating idle . Any ideas how to fix. Thank you

4litre

iTrader: (1)

Are there any errors popping up on the dash? If so, have them scanned if you have a scanner. If not, you can get it scanned for free at your nearest auto parts store. We need to have an idea of what it could be to assist you.😎

PauleyH

A position sensor was replaced as that code showed up . But now there are no codes. All engine indications are within parameters on the data sheet read out . something may have been damaged during the belt change but the garage can't figure it out either. Thanks for your help.

PauleyH

Correction . A CRANK SHAFT position sensor was replaced. Could the order in which the belt was assembled with tensioner have caused this . The garage is lost. They admit they have no idea

Losiracer2

check all of your under hood vacuum lines for any cracks. When I first got my 97 LS, I had to replace pretty much all of them since they were rock hard. Your PCV valve would also be a good spot to check since that deals a lot with engine breathing. You'll have to remove the cover to see everything obviously.

I would've gone the Lexus OEM route, but for just 3 vacuum lines I looked up, they wanted almost $100. So I tried to find the best fitting bulk hose I could and cut and routed everything that way.

PauleyH

Thank you for the advice I'll try that

Legender

Check the thread on rough idle (solved). Clean that MAF sensor. This cured my fluctuating RPM at idle problem also earlier this year.

PauleyH

Thank you I'll post the outcome to help others in the future .

MedicalDoc

Also check for vacuum and exhaust leaks (specially the y pipe).

PauleyH

Ok will do. Thank you very much

dicer

Shop did it and gives up? Time for a total refund. Or they pay for the dealer to give it a go.

PauleyH

It seems the issue with my rough idle is seals around fuel injectors. Can the rubber seal be bought separate to the injector or do I need to buy both .

bradland

I think I'd get a second opinoin on the diagnosis but here's the info you asked for...
23291-20010- https://www.lexussouthatlantaparts.c...329120010.html
Aftermarket available at Rockauto- https://www.rockauto.com/en/moreinfo...356083&jsn=366

PauleyH

So the rough idle continues even after the new O rings have been put in around the injectors. It only does it when the engine is up to temperature . Any thoughts guys . The best way to say it is the idle throttle hunts when up to temperature

RA40

iTrader: (6)

Did the car have this prior to the TB change service? My thought is one of the wiring harness wires has an intermittent connection but enough to arc across to run after being moved in the process. One of the items to check would be Yamae's ripple test for the ECU.

The other thread that comes to mind is this one but we don't know the outcome for that car:
https://www.clublexus.com/forums/ls-...seconds-6.html