hunting at idle

[Paul C]

My car has just started hutning at idle,only by about 50 to 100rpm.I have a map ecu2 fitted so no maf to worry about and at present dont have O2 sensor connected. Recalibrated tps sensor and since then this has happend. Do you think that without the O2 sensor the car is hunting to find idle afr.

[Nutter_John]

do you still have the stock o2 sensor connected to the stock ecu , if so it could be the mapecu2 and stock ecu fighting over the idle control

You really should be tunning with a senson in for monitoring the afr's

[Paul C]

Stock ecu sensor removed,using wide band o2 sensor but at present no o2 sensor is feeding back to stock ecu

[Nutter_John]

ah ok makes sense - what does the log look like when this happens , is it just hunting between cells

[Paul C]

to be honest never thought to do log. From what i remember i think it just sits in the one cell.

[Paul C]

just to add noticed that the afr jumps around between 14.1-14.7

[Nutter_John]

sounds like it is hunting between cells - for instance it see's a value at 800 rpm and one at 600 rpm - but the idle is between that value so it interpolates the vlues to get a reading etc etc

hope that makes sense

[Paul C]

so what do you think put them vslues the same to see if it stops the hunting as i think there isnt much in it with fuel between 600-800 or alter idle screw to see if it settles

[Nutter_John]

i would record ( on paper what the values are ) and then adjust the 600 and the 800 to be the same that way you should get the same fueling if it sits between those cells

or turn the idle up to be always above 800 rpm

Your call really

[Paul C]

Do you think this could be the sign of the idle stepper motor starting to give up on life? I will start by altering fuel cells and if no joy will alter idle screw and maybe give stock ecu its o2 signal back. But that will be tomorrow can't be ar*ed now, need to rest after a hard day on the tools.

[Nutter_John]

problem when you give the ecu back it's signal it will hunt more as the fuel trim tables come into effect as both the stock and map fight to balance out the idle

don't think it is the sign of a problem just normal , mine hunts around a bit at idle somewhere between 800 and 500 ish depending on temp etc etc

[stuartturbo]

mine use to hunt but seem so much better since i gave the inlet a good clean out care of the amsoil foam cleaner and since then it also has not stalled coming of throttle as it did do before

[Eurospec]

John is pretty much on it with this.

If the idle is sitting between two cells (or 4!), it will still highlight the one it is closest to. If you simply map that cell as the idle moves naturaly as the stepper motor moves it, it will move off the sweet spot more toward one of the other 3 cells. You need to map all to get it perfect.

However sice the afr is only moving a little, my guess is your stepper motor is a bit gummed up, or you are very very close to getting it spot on.

The off boost stuff is by far the hardest to get right.

Cheers,

Ben.

[Paul C]

Thanks for all the replies will get cracking on solving it tomorrow.

[Eurospec]

By the way Paul. Boost solenoids and harnesses are here. You want me to post it, or take it to TOTB?

Cheers,

Ben.

[Paul C]

I'll get it off you at totb i am eager to fit but will just have to wait

[Paul C]

Haven't altered anything as i havent had time to give full attention but managed to stall.Was about to pull onto a round about using light throttle and the revs dipped and stalled. Hopefully benh will have time to shed some light on the tuning sides of things at totb. If he can fit me in.

[Eurospec]

That is either a lean tip (wierd that you have not had before though) or a stepper motor issue.

A fragged stepper will will make it do all sorts, including (eventually!) kangeroo down the road like your worst 'driving test' nightmare.:speechles

One of us will take a look at it for you on sunday:scholar:

Cheers,

Ben.

[Paul C]

That is either a lean tip (wierd that you have not had before though) or a stepper motor issue.

A fragged stepper will will make it do all sorts, including (eventually!) kangeroo down the road like your worst 'driving test' nightmare.:speechles

One of us will take a look at it for you on sunday:scholar:

Cheers,

Ben.

I've changed map since installing intercooler so probably need to address that.Also cleaned stepper motor and that made no difference.
I appreciate that you will be busy on sunday plus i will have the family in tow, so if it doesnt happen then no probs as you've already helped a great deal.

[Gowf]

One of us will take a look at it for you on sunday:scholar:




Well if we get a brake from pushing your car about we will!!

Did you get that ait issue sorted? I have been meaning to get back to you, but has completely slipped my mind.

[g6acb]

but has completely slipped my mind.


Knocked out by 3 litres of buckfast more like :thinking:

[Paul C]

ordred new stepper motor from cam skill will fit tommorrow if it gets delivered.hopefully this will fix the problem

[Paul C]

Typical now that i have ordered a new stepper motor i decide to look at a thread in the members section to do with tps

http://www.clubvr4.com/forum/showthread.php?t=12295

The symtoms i have are the same as indicated in the thread.i guess some tps adjustment is required.£85 well spent i think not.

[Nick Mann]

Bugger. I don't remember that info. I guess at least its good you found it now. I hope you get it working one way or the other.

[Paul C]

is the tps sensor definitley at the front of the throttle body as tps guide above suggests that it has 4 pin connections when mine only has 2?

[Wodjno]

is the tps sensor definitley at the front of the throttle body as tps guide above suggests that it has 4 pin connections when mine only has 2?

TPS is at the rear of the throttle body! Nearest the Bulkhead!

[Paul C]

glad to hear what is the front one for? Although gowf was looking at vr4 that didn't have a rear tps sensor.now i'm confused either way i need to set up the back one. I have found that if it isn't in the right position it drops back to idle control very early and it feels like power loss

Front sensor

18681

Rear Sensor

18682

[Wodjno]

what is the front one for?


Stepper Motor, Idle Control Valve !

[Paul C]

Does it work with stepper motor?

Today i replaced stepper motor re setup tps and sprayed a can of 10k boost in the throttle body.So far every thing seems ok. The big test will be tomorrow when i go to ten of the best. car idles smooth not driving problems other than gearbox relearning but nothing else. Will post any further problems tomorrow.

Thanks for all advice

Paul

[Wodjno]

Does it work with stepper motor?

Today i replaced stepper motor re setup tps and sprayed a can of 10k boost in the throttle body.So far every thing seems ok. The big test will be tomorrow when i go to ten of the best. car idles smooth not driving problems other than gearbox relearning but nothing else. Will post any further problems tomorrow.

Thanks for all advice

Paul

As far as i know.? Once the TPS senses theres no throttle, the Idle control valve takes over and takes care of the idling process..