1JZ Idle issues - weird ISCV behaviour.

[Aether]

Ain't getting anywhere with this issue and it is driving me f&$^ing insane...

Have changed the ECU to a third one...same issue.
Removed the aftermarket EMU and when back to stock factory ECU and 380cc injectors...same issue...so it ain't the aftermarket EMU or tune.
Have replaced the CTS sensor, the IAT sensor, the MAP sensor, the ISCV valve, the TPS sensor...have checked the Crank and CAM sensors and they are all fine...have also re-adjusted the TPS sensor.

Start the car, it will not idle...after the car stalls, I can hear the ISCV valve open. Disconnect the ISCV connector, start the car and it idles high to around 2000rpm and begins idle hunting.
Read on a supra forum that if the 1JZ begins to idle hunt then it is seeing the IDL signal from the TPS and a fuel cut map is executed, thus why the idle hunting occurs, as the ISCV is stuck open and unable to adjust the intake air at idle.
Checked the throttle valve and it is 100% closed at idle.
Whilst the car is idle hunting, reconnect the ISCV connector...it idle hunts for 2-3 times and then begins to lower the RPM to a steady and perfect 800rpm. No fluctuation or hunting at idle, rock steady and perfect smooth idle. What the $^%.

What the hell is causing the car not to idle, as mentioned I have disconnected the ISCV connector when the car was not idling properly and removed the ISCV valve and noticed that is 100% closed which it should not be at idle, as with 100% throttle valve closed the only way for the car to get air and idle is through the ISCV valve.

I also have noticed that when the car is not idling properly I can hear a slight knocking sound form the engine every couple of revolutions which goes away with accelerating...and the idle feels a little rough with some fluctuation in RPM (50rpm or so).
If I do the above where the connector is removed, start the car, it idle hunts, reconnect the connector, RPM lowers to a steady 800rpm, there is no knocking whatsoever, smooth idle and no fluctuation in RPM...

[Mundoolun]

Get a ob11 scan tool. Sounds like a bad oxygen sensor. Will causes car to run poorly and go into limp home mode.

[bk_]

Software-based Toyota OBD scanner - http://www.clublexus.com/forums/perf...ger-found.html

Looks like the russians kinda based it on my reverse engineering that I did years ago but atleast they extended more of the work and made something out of it

[Aether]

Thanks heaps bk_ for taking the time to post that tool up here!

Have built the COM->USB connector, connected it to the ECU and have got the laptop logging data from the ODB1 port...whooooo!

From the quick test I did, it seems as though the ECU is seeing the temp signal, and looking into it further I was running the wrong system diagnostics...

The JZZ30 has a multitude of diagnostic options, and I was using TC/TS/E1, which was running diagnostics for the ABS/TRC system and not the EFI, funny thing is that looking into the workshop manual, error codes 21 & 22 exist for both ABS/TRC and EFI tests...kinda misleading if you are running the wrong diag test...

Anyway after running the TE1/E1 diagnostics there was no EFI/ECT errors...to confirm the ECT/IAT sensors were working fine, I removed the connectors on them, ran the TE1/E1 diag and got errors 22 & 24 back, reconnected them, and errors went...so sensors are fine and that doesn't seem to be the problem. From that ODB1 tool, I can see that the TPS is 'Closed', that the Neutral Park switch is 'On', and the A/C switch is 'Off'...timing is jumping between 10 degrees to 18 degrees at idle, O2 is showing it as being RICH at idle. Injector time is between 2.5 - 3.0 ms.

But please take note that the test I did was connecting the ISCV connector after the car has started...which seems to idle fine, it is when I start the car with it connected that it causes idle issues, and I will post those results soon...just wanted to get a feel for the program and confirm that the cable was working

[bk_]

What about IAV valve duty rate?

it should be 125 steps when IGSW=on, engine=off
then it should be around 100 steps on cold start (around 10-15C)
and it should be around 40 steps on hot idle.

Injection time at hot idle should be 1.4 + 0.7 (dead time) = 2.0 msec
Upon cold start, injection may be up to 3.0 msec, then tapers off to 2.5 msec then slowly goes towards 2.0 msec.

Timing should be around 10 degrees on hot idle. Not sure how much it should be on cold idle... around 15? Not sure if it should be different on auto/manual. I know it is for other engines (eg: nissan)

I wouldn't worry about O2 when it's cold. When it's hot, it will bounce between rich and lean. As long as injection doesn't deviate much (5%) from 2.0 msec it's OK.

[Aether]

Will grab those details for you tomorrow with a full log from cold start through to hot as I am currently at work, going to have to keep foot on accelerator thou in order to keep it from stalling.

Thanks heaps for you time on this and also the link to the ODB1 tool...hoping it can shed some light on what is causing the idle issues.

[Aether]

Problem fixed!!!

Thanks goes to you bk_ with the link for that ODB1 tool, it helped me to diagnose the TPS as being the problem and was caused by the TPS sensor and the throttle stop screws which must have been adjusted from the factory settings.

Adjusted the throttle stop screws to factory specs, adjusted the TPS to set IDL to closed and VTA to 0% when throttle is closed and car idles perfectly now at cold start (1500-1600rpm)

The ODB1 tool, now shows cold start idle at 100 steps, and hot idle at 40 steps as you said, spot on!

Once again, thanks heaps mate...without your help I would have been trying to resolve this for a much longer and stressful period...

[Daddio]

Good to hear its fixed (and points out that setting TPS correctly was in my second reply )

[Aether]

Indeed you did point to that, but had no real way of setting it as all the throttle body stop screws had been messed with and had no starting reference to set the TPS...but all good now with the idle...perfect cold start and stable idle!

One other thing which I have noticed now that the idle is stable is that I am getting a slight knocking/tapping sound which I can feel on the timing plate behind the cam gears...
I have taken a stethoscope to the engine and can only really hear the problem from the timing plate itself, no where else in the engine is the knocking/tapping so predominant.

The car is running Brian Crower 264 cams/valves/springs with a set of CP pistons/rings and custom made gudgeon pins. It also has a set of Jun adjustable cam gears, with stock OEM belt, new idler bearing, new tensioner, ACL Race main/rod bearings.

Have checked all cylinder compression and they are fine at about 190PSI.
Have removed coil pack connectors one at a time whilst the car is idling and knocking/tapping is still present.
Under acceleration the knocking/tapping seems to go away.
Upon cold start can feel absolutely no tapping, but as it slowly warms up the tapping gets more predominant where it becomes audible.
Have checked the cam gear bolts and they are not fouling up against the timing back plate.

You guys have any ideas?

[Aether]

Update:

Changed the CAM gears back to factory ones...same issue with the knocking.
Checked the cam lobe to shim clearance, all good, also checked cam cap bolts, all to correct torque specs.
Checked tensioner and all good, as mentioned it is brand new.

Any chance that it could be the flex plate causing the knocking?
Would a cracked or loose flex plate bolts, transfer all the noise/knock all the way to the front of the car to the timing cover back plate?

I tried to listen to the knock on the sump, but couldn't hear the knocking...probably being drowned out by the oil in the sump...

Video of the knocking, sorry about the audio at the beginning, fan killing the sound, but it can be clearly heard from 40 secs onward.

http://www.youtube.com/watch?v=ICKPH...ature=youtu.be

[sundee86]

Having this exact same problem with my 1jz vvti (jzx100) conversion in mx73.
anyone got a link to a 1jzgte vvti diagnostic manual or FSM?
would like to get the specs to run through some tests and to check/re set the TPS and throttle stop

[bk_]

For JZ vvti OBD, see http://www.2jzgarage.com/2013/01/2jz...d-information/

[sundee86]

Thanks for that BK_ ive found the Russian service manual, is that all there is out there?
nothing in english?