4age Idle Problems.

[Hibba]

I havening this annoying as fuck issue.

It was doing it before i replaced the loom and ecu, and it stopped for awhile and now its doing it pretty much all the time at idle.

No matter what temp the car is at the idle will jump by 900~rpm then go back down, and back up then back down it keeps repeating.

When the car is under load and driving its fine, its just at idle.

Does anyone have any ideas?

[Cuzzo]

Usually when it does that it indicates air in the coolant or the water sensors are fuked(or wiring issue with them) However usually it will do it all the time.

[bmak]

I'd say air lock in the water lines at the throttle body

[Hibba]

My finger is pointing towards the Auxiliary Air Valve on the T/B, If it block the airport for it it dies down to 800-700rpm but it sits there quite happily.

I think my job for this weekend will be to take the Auxiliary air valve off and put a plate over it and just use a little throttle to start the car.

[parrot]

I reckon you have an airlock at the back of the head, not the throttle body. You need to bleed it out with some vigorous hose squeezing once the thermostat opens with the radiator cap off. Even try parking on an incline (nose up and do it there.

[kickn5k]

Webers4x48 had same issue with his ae82 twin cam and it was solved by unblocking the coolant channels through throttle body. There was also a thread on rolla club and am led to belive even old coolant can be your fault. We unpluged each sensor while it was running to eliminate that issue.

stu.

[parrot]

No, I still reckon it is at the back of the head. The EFI water temp sensor in the sensor block at the back gets a lock and this results in a rythmic surging idle, drop off, surge and so on.

[sanchez]

i've had similar issues and it was caused the AAV not working correctly due to the thermostat being faulty. i hope this helps

[kickn5k]

No, I still reckon it is at the back of the head. The EFI water temp sensor in the sensor block at the back gets a lock and this results in a rythmic surging idle, drop off, surge and so on.

I think you are pretty right there as that problem was the most preached to us
as i have been informed on that issue the cheapest way to fix it is to change the coolant and bleed it properly. In saying that we found a heap of posibilities on what it could be and they all rely on the cooling system in one way or another.
hope its sorted soon.

stu.

[webers4x48]

hi there. I hav a 4age big port in a ae82 seca that had the same problem. It first did it on a cruise and a few days later it came good again. A month later and it came back but to stay this time. I racked my brain and checked out alot of threads of different forums and got alot of advice. I fixed mine with a process of elimination and found it to be blocked coolant lines that go to the aav on the t/b. I did a thorough clean out, put new coolant in and blead the system (a must!!!) do this by squeezing the front radiator hose till know more air bubbles appear.

I hope this helps in some way cause I know how f@#king annoying it is....

Leigh

[parrot]

Wherever it is, clearly you need to thoroughly bleed you cooling system and you should be right.

[JP]

also note if your TPS is set wrong, it could be in the "fuel cut RPM" region, causing the idle to bounce. You can check this by simply unplugging the TPS connector while the car is running. If it stops bouncing, grab a feeler guage and multimeter and set the TPS correctly.

The 4age engine manual goes into detail about the fuel cut RPM etc.

[Hibba]

Well i dont think anyone grabbed it, But it looks like the manifold gasket is shagged and has a leak