Why is the engine hunting

[pmessling]

After the rolling road day the other week the car hasn't been right, i have tried resetting the idle but can't get the car to idle at all, its all over the place and hunts constantly, and cuts out too.

Any thing i should look at before sending the car away?

I have plugged it in to the laptop, and have a bad air fuel ratio on one of the banks. but everything else other than the adaptive's are okay.

I'm stuck at the minute as i can't get it to idle steady to see if the idle is set properly or not, although have set the TP's to 14.8, then the idle stop to get the 19%

SO HELP ME PLEASE

Peter

[spongy]

Check your vacumn pipes sir,and all the sensors sounds like an air issue

[Tanguero]

The only vacuum lines are for the fuel cannister purge and you should clamp that when you are setting the throttle pots. It might just be worth loosening the fuel cap and various people have reported a stuck rollover valve or clogged carbon canister causing idling problems.

Is the software showing wild swings in ignition timing at idle?

Does it still hunt on part throttle?

[pmessling]

I've been reading up on the rollover valve when I did some searching so is definitely one I can look at.

As for partial throttle is stays steady. But when off throttle it hunts then goes to about 1500rpm stays there then fulls right of to stalling point

[C3BER]

Lambda sensor would be a good bet. You can look at the pc and see everything is fine with your sensors but it's not always the case. I had a temp sensor look perfect on the pc but was totally shot and caused all sorts of problems with boiling water.

[Tanguero]

Lambda sensor wiring crossed is another favourite - but you can probably rule this out unless you have had them disconnected for any reason.

[C3BER]

If the lambda sensors are shot then they will give the hunting effect along with stalling. They don't last forever and after a blast at charlies they may now be on their way out. It is possible they don't even show a fault on the pc.

[pmessling]

Yeah the lamba aren't showing up at all as faulty on the pc. Will take a look there as well. Guess no harm in changing them out even if they aren't.

[a1rak]

You shoulld be able to see on the laptop if the Lamda's are trying to work,They normally will flick between 0 to 1 and 1 to 0 when the fuelling is being controlled under lamda, so if they are staying static its a good bet something is wrong. Try taking the car for long blast down the motorway as this will burn off any deposits on the sensors that may be causing trouble. It will not effect the fueling during higher speeds as the lamda's only work i think at low engine speeds and small throttle openings.

[pmessling]

i've found some good threads posted by other people in the past about similar symptoms, and solutions so when the weather brightens up i can have another go before ordering some new lambdas. hopefully tomorrow, try a few things.

[Tanguero]

Before you fork out for new lambdas its always worth pulling them out and blowtorching the end until they are as hot as you can get them, then sticking them back in.

[pmessling]

Screen shots start from the bottom.

I left the fuel cap off for most of this, i checked the lambda plugs and all seems good, also the throttle pots and purge pipe. i started the car as normal, got it to running temp, and still was idling badly, although better but would not hold the rev's and stalling. I unplugged the passenger side TP ODD according to the wire is that correct? and the car ran better, and tried it the other way round and both ran better, also swapped on plug to the other side, and the car is running much better. i also reset the adaptive's, as you can see they improved alot, put the TP back and the car is running much better, strange, however the lambda1 was constant 0 where as the other was cycling as it should, lambda 1 would go shot up to 1.3 if the throttle was blipped, but would go back to 0, where as the other would continue to cycle.

Does this suggest that lambda1 is faulty, so which side is lambda one, and is the odd bank the passenger side

[C3BER]

If you pull a lambda will it not show left or right not working.

I'm still going for one lambda being shot.

[pmessling]

that is very true, i should have done that. i'm going to say from looking at the screen shots its the passengers side since its the odd backs that's misbehaving lambda one.

[C3BER]

Fingers crossed all will show daylight soon.

[pmessling]

Yeah, might be able to get some more driving in. haven't done that much this year, although have managed to upgrade all the suspension, few winter jobs lined up.

[pmessling]

sensor ordered. hopefully come soon and may change it whilst at work and drive the car over the pit, although its a train pit, should be find,

[pmessling]

Have managed to change the sensor at work, and all seem's much better, adaptives are much better, and runs well, idle is a little low so will sort that out next as well as balancing the banks up now i know that the problem has been sorted.

On the live data the lambda's are looking good with a nice range of movement.

Managed to drive the car over the pits at work, sounds easier than it is as they are train pits.

Lambda come out pretty easy, although cut the old one out as i couldn't get to the cable ties holding the old one on, which is a shame as i wanted to test it, although cut at the plug so guess still could if i wanted.

My hands look like i've tried slashing myself, as do my arms, but never mind.

Successful so far, just need to drive home now and see how it does, driving to work idle was about 1600rpm

[pmessling]

[C3BER]

So good they wrote a song:

La la lambda la la lambda