1JZ vvti - VVT solenoid question Rough idle

**pales** · 18-05-2011, 10:33 AM

Hi guys/Experts

I have a 1jzgte vvti in a JZA80. There is an issue with the idle, its rough at times, not all the time, but mainly at traffic lights when I'm creeping forward. Under load on the freeway, on boost etc its fine, runs beautifully. Its no

When it happens it sounds like a rotor, very rough, unstable idle sometimes has stalled if the revs aren't kept up.

Thoughts:
-Plugs - Changed them, still happens
-Bad Fuel - Running new fuel through, still about 1/4 tank of the old stuff, no noticable change
-AFM - Will be cleaning that today/tomorrow
-Coilpacks - Wouldn't clear with revs, would only get worse.. correct?

After some reading I'm also now thinking
ISCV playing up
VVT solenoid playing up

My question is:
Where is the VVT solenoid located on my engine? Is it aslo known as the OCV which would be near the cam gear?
By disconnecting this when its running rough, will this help to isolate the issue? i.e if it gets worse when disconnected then its not that.

Any other thoughts are most welcome.
the motor has been in the car and running beautifully for 10 months now, so I'm confident that its not part of the conversion thats causing the issue.

Also, it doesnt happen when its cold, which is making me lean more towards a stuck ICSV.

Cheers Mike

**George** · 23-05-2011, 08:22 AM

When you stay in front of the car, the valve is on the right edge of the engine right before you. These valves sometimes get "almost stuck", that is they sometimes work ok and sometimes don't. In the later case it's 50/50 that ECU will "collect" appropriate error code, so that in several days after resetting the codes you will eventually read VVTI error.

So what I would suggest is
1 Check and write down the error codes
2 Reset them and read again after one day of driving. If VVTI error is present in both cases then it should be considered as true

There's also a rough way to judge if your valve is true crap or not yet. If you disconnect a good valve when engine idles nothing should happen. If you then apply 12v from battery to valve terminals (any polarity) your engine should stall, the faster the better (then your valve is rather ok than crappy). If the engine keeps running, no matter how bad, then your valve is to be replaced.

**pales** · 23-05-2011, 08:38 AM

Hi George,
Thanks for the reply.
I ended up finding it, just wanted some confirmation. Thanks.

I have actually done that exact process, i checked the error codes and got a handful of them (some were from when i did the conversion im sure), i recoreded them, cleared the ecu and drove for a day of two until it happened again. I then checked the error codes and got a error 59 which points to VVT-i solenoid, so I figure I'm on the right track.

I have currently disconnected it and amy effectively driving around without VVT-i as a test, so far the idle has been perfect so I'm confident that its the cause.
I will use your method of checking though to confirm.

Would you suggest buying a new one or trying to clean it up? I have to remove the throttle body to get it out so I am leaning towards buying a new one so its done once.

Also, I have noticed that sometimes the gearbox is in the wrong gear, its an automatic. Sometimes when I pull up to lights it seems to change down late, I think this might be speed sensor related... if there is an issue with the speed sensor, would that cause issues that "Appear" to come from the VVT-I valve? i.e. when i pull up to lights the ecu still thinks i'm going fast so the vvt-i solenoid isnt adjusting... so the vvt-i solenoid might actually be funuctioning properly but its just getting the wrong data, does that make sense?

Thanks again
Mike

**George** · 23-05-2011, 02:12 PM

Glad that this helps!

Given that you are 100% confident that the VVTI valve is to be replaced - buy a new one. Otherwise you may lose lots of time for nothing. There are though some web guides (with photos sic) explaining how to return VVTI valves to life, but they are all related to disassembling them. Among the most popular reasons of malfunction listed (as I can remember) was too weak spring inside.

As for the auto, if you don't read a speed sensor error then the problem must be somewhere else. Low line pressure may be the case as well.

**pales** · 23-05-2011, 02:27 PM

Hi George,
Thanks again for the help, much appreciated

I'll order a new one and fit it up.

Thats a good point about the error code from the speed sensor, I didnt even think about that throwing up a code, so given there is no error code it must be ok.

Can you explain a little more about the low line pressure? and how to troubleshoot/check that?

Thanks Mike

**George** · 24-05-2011, 03:27 PM

The easiest test for pressure is to check "on" times for D and R. When the auto is warm enough (travel 10km) and engine idles for a minute or more, switch from N to D and see how much time it takes to make a kick. Wait a minute, then write down the time it takes to engage R. Manual says that for D, 1.2sec is ok and for the R the time should be around 1.5 sec. You generally worry about it only if you get something above 2-3 seconds.

Another quick test is the stall test. With initial conditions as above, step on the brake, switch to D and give it full throttle. Don't do so for more than 5 seconds. Write down maximum RPM you reach within this time. for 1jz-gte 2950-3250 is listed as normal. Higher revs indicate low pressure.

**George** · 26-05-2011, 07:09 PM

any updates so far?

**sundee86** · 07-03-2014, 09:25 AM

Just digging up an old thread because I can't find much on testing the vvti solenoid.

I tested it as per above, so engine running, unplug, no idle change, 12v to the solenoid, held there for 1 minute, no change, switch polarity, 1min again, no change.

Is this the only way to test the vvti solenoid?

Engine has a low idle and rough idle... And has a constant pulse beat thru the exhaust.. Throughout the rev range.

Was really odd, 1st start (jzx73 conversion) all was sweet, 2nd start I have this problem..

Any help would be great!

**1JZ-Rolla** · 07-03-2014, 12:30 PM

If it's the VVTi solenoid, it shouldn't run rough right through the revs, only at idle where the valve overlap affects running the most.

Strange that you couldn't get any change in running at idle with the test procedure though? That still points to a solenoid issue.

Do you have another solenoid available to you that you can swap out to test?

**JSF** · 07-03-2014, 08:04 PM

Not sure if this will help you out at all, but i had a idle issue as well, For the first 10 - 20 minutes the car would run great, i could thrash it etc and nothing would happen. When it got hot, the car would start having a really bad idle through decel and also whilst at the lights. I think the only reason it didn't stall was because my idle screw was turned up a little so it idle'd higher. If it's an on/off issue i'd recommend changing the solenoid, it's a $90 fix. You can try and test the vvti solenoid, but it won't give you much idea if it's that or not because people told me to chuck a 12v to it and if it stalls then your solenoid is fine, mine stalled, but when i put in a friend's solenoid the issue completely went away.

It's been a week now and I have a new solenoid and the car is running great!

**slide86** · 08-03-2014, 06:58 PM

Had the exact symptoms described with my jzx100........It was the vvti solenoid. Got a new OEM one from Toyota for $100. Half hour to fit, never saw an issue again.