Moarpower

A little worn but obvious. Doubt the caps and rotors are the issue.

Moarpower

OK so, new capacitors on ecu, new ect sensor, new rotors, caps, coils and plugs. New 02 sensors.

same issue is present, inconsistent idle, rough after driving.

leads need to be replaced they are original. And that timing is certainly off a tooth on the right cam.

Moarpower

Any other ideas??

TO clarify the issue, It starts fine, drives okay too. It is just running rough, but not as though its not firing on a cylinder. Just a random an unpredictable stutter during the revs which gets a little worse as the car is warmed up and driven. I believe this killed the original o2 sensors. Each lead, when pulled alters the idle so they are all firing, how efficiently I do not know.

deanshark

I'd say the timing being off is 99% your problem. My 93 was off by a tooth and ran ok when it was cold but after it warmed up it ran like crap.Most people, when they have a problem, always think the ECU is bad when it's not. Granted, some do go bad, but not every one. You threw alot of parts at the car but most of them should have been changed anyway with a timing belt job. Should be all set after the belt is changed, good luck.

Moarpower

thanks mate. The timing belt and leads are ordered but aren't going to be here for quite a while. The of living in Australia. I found a very good price on the kit but it is on back-order til November, so I either wait, or pay OEM price at the dealer.
Is there any way to just loosen the belt tension and correct that cam while I wait?

Moarpower

Managed to get the timing set back. It was certainly off. But the issue still appears to be there. I will try to post a video

Moarpower

https://www.youtube.com/watch?v=szOMjg2lm7Y&feature=youtu.be

I sat the phone on the steering wheel as the vibrations can be heard and they coincide with the idle pattern

Here is the video. Reset the timing, still happening. Also managed to headbutt the underside of the car and split my forehead. Some blood to go with the sweat and tears I guess.

Im guessing the next thing to do in check the leads, I have some ordered but they are weeks away, and do a compression test. Any help is as always, greatly appreciated.

Moarpower

Any other ideas guys? Have I missed anything ?

Yamae

At first I'd try the injector balance test. Other than this, there are some other methods to check the balance. One is to check the driving time differences of each injector using a current prove and an oscilloscope. The primitive method is to measure the amount of injected fuel each but this requires you to remove all 8 injectors from the engine and drive them using a jig.

Moarpower

Thanks. I have never really messed with injectors before so it will be new territory for me.

Moarpower

Can't find a way to test the injectors without special tools. my tips on how to do this cheaply? I'm not spending too much more money on this car.

Moarpower

Could this be a cam sensor ?

Moarpower

Still looking for help here, I had the injectors checked bvy a shop and they said they were fine they cleaned them for me and the issue is still present. Any other ideas besides leads which I have ordered? I was wondering if it could be another sensor? No codes or CEL

Amskeptic

Well, I am coming in cold here, but I did listen to your video. Way more exhaust note than I was expecting . . . do you have any exhaust leaks on a stock system or do you have aftermarket headers/exhaust components further back? Are they separately plumbed down the car?

Point one: I believe Lexus did some exhaust tuning to make sure that the engine had equal scavenging from each cylinder. If you look at that firing order, it would have to burble like an outboard without the top-drawer cancelling that Lexus did pull off nicely with the stock exhaust system.

Point two: if you feel a misfire, you must find the offender. I would use the injector plugs to kill each cylinder briefly until you have determined which cylinder is participating less than the others (and if you feel absolutely no change in idle rpm when you pull an injector plug, that is your culprit). Once you have determined the culprit, a compression test would tell you if it is due to mechanical damage.

Colin

Moarpower

Thanks Colin. This only issue with this engine is that to get to the right injectors and leads I need to remove the intake tubes and maf assembly. Once there it is almost impossible to diagnose as the idle is pretty much completely screwed without the vaccum and air intake running right. I've done a compression test and it's all fine.
This is a real pain.

OH the car has an aftermarket exhaust fitted now but the issue was present before the change.