AC Idle up issue - 1NZ-FE

[NiGhTShAdE]

Yeah i meant maf ....wrongly written map....
btw it should have been asked before anything....What are the rpms on a/c when idling?

Sent from LG Optimus LTE LU-6200 using PW forums mobile app

[OwaisYunus1]

Currently, I have the rpm adjusted manually at 1k without ac so that it stays at around 750-800 when the ac is turned on. If I keep the idle at 900, with the ac on, it goes to around 650-700 at which, the idle becomes a little jittery.

Sent from my HTC One S using PW Forums mobile app

[SER_GTR]

If Nothing Works...Try That Valve ....It May Resolve Your Issue W.o Bashing Much Of Your Head ....! Its Very Popular Among Mechanics

[afnan.bashir]

do resistance check on your IACV solenoid and check if its clogged. If there is no change on idle this can mean few things

1. Your ECU is not controling it
2. Your ECU says it to control but it does not control by adjusting valve
3. it adjusts the valve but no effect on rpm

if nothing works i would do one thing i would remove the compressor relay and then turn on the ac. if idle rises i would know it is working saying it because may be compressor is kicking in and taking a bit load so instead of increasing it decreases. but i doubt that. make sure your ecu is wired properly. how do you know that compressor is controlled by ecu? did you checked the wire

[OwaisYunus1]

The ecu is controlling the ac, I know this because most of the wiring is stock and like I said earlier, it has not been touched by local ustaads and any changes required in the wiring for the swap were done by me and no corners have been cut.
I've removed the ac relay to check if its increasing idle, it does not and it wouldnt because its designed in a way that as soon as it detects any load, then only it increases idle. Without the compressor working, there's no load on the engine.

The iacv, like i mentioned earlier is fluidy smooth and its not clogged at all. The idle increases at cold start and then comes back to normal once the engine is at operating temperature, which shows that the iacv is working fine.

Now the issue is, either the ecu is not registering load for some reason or its trying to increase idle but is not able to for some reason.

Sent from my HTC One S using PW Forums mobile app

[OwaisYunus1]

I've found a solution for the problem. The idle control valve like I said earlier, has 3 wires, one is +12v, the other ground and the third one is the signal wire from the ecu. With the ac running, the signal wire should get a little under -6v for the idle to increase which for some reason was not being given to it by the ecu while the ac is running (it was getting around 6.8v from the ecu) though its functioning totally fine with cold idle. So I made a small circuit that gives it around -5.8v when the ac turns on and bypasses the signal coming from the ecu while the ac stays on. With that, the issue has been resolved and running fine now alhamdulillah.

Sent from my HTC One S using PW Forums mobile app

[stranger729]

@owais_yunus

What (which device) is the source of the negative power supply rail? Is it the ECU?

[kkoool]

check for air leakage, An idle not getting adjusted can be due to air leakage from the intake manifold.
Also check the throttle shutter for any leakages, Is it allowing air to pass through IACV at close position.

[pradeepbuss]

old thread but important one.@OwaisYunus1 >> can you share your circuite diagram please. thanks

[pwuser160126557421]

Hello. My premio is facing the same problem. Can you please explain the solution in more detail? Also, is it possible to get the circuit diagram?

[jdolondriz]

@OwaisYunus1 can you share the diagram of the circuit you added?

[OwaisYunus1]

Apologies for not replying earlier. I was away for a few days. It was a long time ago, I dont think I have the diagram any more. The circuit did not last long though so I wouldnt recommend it. I later found out that some electrician had worked on the car at some point and short circuited some of the wires around the ecu connectors. While the car was running, this is one of the features that wasnt working. So I replaced the whole of the wiring inside the dashboard from a Luxel as I was also shifting to a climate control ac unit. This fixed the idle up issue for me as well.

[jdolondriz]

Thank you for the reply @OwaisYunus1