Hunting issue

[kazi]

Me.... again.

Ok so I was getting a code 6 (no RPM signal) tested everything and now it's gone. But I now have code 3&4. Something about igniter and coolent temp sensor.

Car on cold start was horrible to star. 3/4 turns of the key. I thought that static timing was out but that's all fine. Changed igniter and car started much better. But the car is still hunting between 1400-2000rpm. Have bled the coolant system and still hunting. Someone sujested the MAP sensor so I unplugged the vacuum pipe that goes into the inlet and the car stopped hunting and ran better although more lumpy.

Throttle body and gaskets around throttle body are fine.

TPS has been replaced and set up. Stop screws where all loose as well for some reason.

Anyone any ideas before I burn the car?

[jondee86]

Let me see if I have this right.... you get the engine started and leave
it idling at around 2000rpm. Its not hunting, but after a few minutes of
warming up it starts to hunt.... drops to 1400 and then climbs back to
2000... drops to 1400 and then climbs back to 2000... over and over like
you were gently pressing and releasing the throttle.

You reach under and feel the two little hoses that bring water to the
throttlebody... one of them is a little bit warm and the other one is cold.
You pull the hose off the MAP sensor and the hunting stops but the engine
runs rich and rough. You take the intake ducting off the front of the
throttle while the engine is running and block the AAV port with your finger
and the engine stops hunting and idles normally.

Fuck me !!! You'd almost think that the AAV was stuck open

Cheers... jondee86

[kazi]

No. The huntings starts immediately from cold. Car won't idle unless you sit on the gas for first 20 seconds or so. I took the vacuum off from the MAP and it calmed down when I blocked the hole on the inlet.

I've blocked the AAV port and idle air bypass valve and hunting stopped. Blocked just AAV and it dropped but still hunting. I then screwed the air bypass down with the AAV still blocked and hunting stopped. Opened the AAV port and started hunting although it was very minimal.

[totta Crolla]

Can you do another error code check but this time with the throttle pressed to the floor. Please report any codes.

[kazi]

(04-30-2017 08:52 AM)totta Crolla Wrote:  Can you do another error code check but this time with the throttle pressed to the floor. Please report any codes.

I will give that a go.

I have swapped over the throttle body with one that I know works but still doing the same thing.

[totta Crolla]

Sorry that should have read, go from completely off throttle to some throttle and off again. Check codes while doing this.
It should go from no code to code 11 and back to no code.

[kazi]

(04-30-2017 06:59 PM)totta Crolla Wrote:  Sorry that should have read, go from completely off throttle to some throttle and off again. Check codes while doing this.
It should go from no code to code 11 and back to no code.

no error codes buy doing this.

So this is what I've done. So far I've changed, igniter, throttle body, every vacuum pipe, bled the cooling system, drained the cooling system and refilled, reset TPS, replaced the TPS and it still hunts!

When you plug the AAV port in the TB the hunting stops.

When you unplug the TPS the hunting stops.

I'm just not convinced that the AAV is stuck open as both throttle bodies worked fine and so did both TPS before removal/fitting so I just can't buy that both TB & TPS have gone bad when they worked only a few weeks ago.

next port of call? radiator?

[totta Crolla]

Ok you can eliminate TPS idle problems by adjusting it with engine running, mark the current setting with some paint or other marker and the turn the TPS slowly and listen to the engine. You are looking for a drop in idle speed and no hunting, this should now be idling with the IDL switch activated in the TPS. In order for the engine to idle correctly the IDL switch in the TPS must be activated and in your case, no code 11 with the throttle pressed suggests that the ecu is not going into idle mode.

[jondee86]

(05-02-2017 03:18 PM)totta Crolla Wrote:  ... no code 11 with the throttle pressed suggests that the ecu is not going into idle mode.

Interesting !! IIRC having the IDL switch closed is necessary before
setting base timing as well as for pulling codes. The most obvious check
is the engine rpm dropping when shorting the plug and the timing jumping
when the shorting wire was removed.

Having the IDL switch closed is also a requirement for overrun fuel cut to
occur... that plus high engine vacuum and engine speed above 1800rpm

So possible explanation of no code 11 is that the replacement throttlebody
has not had the TPS adjusted correctly as you suggest. But if that was
the case, cycling on fuel cut should not be happening ? Engine rpm would
just stay high on cold start until the engine begins to warm up and the AAV
gradually closes to bring the rpm down to normal idle.

Cheers... jondee86

[totta Crolla]

Is there also a correction for stabilising the idle using ignition timing ?
A higher "idle" timing from the ignition timing map, not the pre-set 16° IDL timing, would ensure the engine runs faster, the MAP value is higher and the fueling would increase to match ?
When the AAV closes the MAP value drops but the ignition timing stays higher than 16° IDL, using the 'off idle ignition map'
This is exactly how the Freedom ecu works and the Freedom is basically a fully programmable stock ecu.
Dunno, just a thought really.