I was wondering how to adjust the idle on a 3.4 V6. I just swapped one into my truck, and its running fine, but seems to idle a bit high. On my 3.0 you would just adjust the distributor, but the 3.4 is distributorless, and is timed by the position of the timing belt, which cannot be adjusted. Is it computer controlled and cant be changed?

 

If I remember correctly the adjustment screw is on the throttlebody.

 

Yes. There is likely a reason for it idling high, but it will take a bit of work to find the cause.

 

A couple ideas to check since this is a computer controlled feature:

1. Idle-up feature of the A/C when engaged.
2. Throttle cable

Jamie's right though, this is going to take some time to track down.

 

Just to clarify, there is NO mechanical idle adjustment on the 3.4. It is a computer controled function.

 

Ditto to what AK9 said. There is no adjustment.

 

So there is no screw on the throttlebody like DavidA said?

 

I thought there was a screw adjustment on the throttlebody spring?

 

On a 3VZ (3.0L), yes, there is one.
On a 5VZ (3.4L), no there isn't one.

The ECU uses the IAC valve to control idle on the 3.4L
.....which might be something to look at for this high idle condition.

 

check for vacuum hoses.

 

May I ask where is the IAC valve? sometimes, my truck is idling around 600 rpm on drive with my foot on the brake, i can feel vibrations on the seat. I have to put it in neutral as it gets annoying sitting on the traffic. once in a while it idles at 750 rpm, which is the desirable engine idle speed.

 

Also, the idle surges. It will be running a little high, then for a split second drops to a lower rpm (one that is a little more desireable) then back to the higher rpm. I havnt done the resistor mod to my tach yet, so im not sure of the actual RPM as of yet.

 

You probably just need to give your throttle body a good cleaning to get it back to idling well again. I don't know what kind of maintenance you have done, but you should also change the air and fuel filters, plugs (OEM Densos or NGKs) and clean the MAF while you are in there. The IAC can be cleaned but it is a bit of a pain to do and most of the time the other items are the ones causing the low idle.

http://www.4x4wire.com/toyota/mainte...tenancep5.html

 

This is what my 2001 is doing, I posted about this but and have changed the spark plugs and fuel filter with no change.

 

Did you clean the throttle body yet?

 

I sure did, I used FI Throttle Body cleaner from Napa.

 

Ok, then if you are still having issues with the idle dropping too low then you might want to try cleaning the IAC valve too.
Keep in mind the idle will drop by about 100 rpm when the AC (or windshield defrost) comes on.