[Mk2] [Turbo] 90mm throttle body idle speed control

[mr2c8cya]

have a 90mm throttle body to put on my two was wondering how i will be able to set idle speed as there is no place for isc vavle?

[Vampire]

Iv just fitted an 80mm throttle body and have the same problem

the car idles, but Has no boost, i dont know if its being caused because the ecu realises there is no IDle control valve and puts it in limp home mode?????/

[adam3442]

From memory you the idle control valve works off coolant temperature and unbolts off the stock TB.

You could unbolt it and mount it to the car and run the coolant pipes to it to reinstate idle control via the ECU.

Disclaimer - I think!!

How did you get on mounting the TPS, are you sure high idling isn't a TPS issue?

What TB are you using?

[mr2c8cya]

mine runs fine without it, you can buy a bosch or like one and do it with one of them

[Vampire]

have you totally removed your idle control valve? iv done that and my ecu is throwing a wobbly, any info on what you have done would be much appreciated!!!

[mr2c8cya]

yes completley gone, just adjusted the idle screw, what state of tune is your car at? my standard throttle body was no restriction until i went over 500 bhp

[Vampire]

you running a fancy ecu? im running standard rev 2.

what screw did you turned to adjust?

[raptor95GTS]

check your other thread - no wonder the search doesn't bloody work

[mr2c8cya]

yes a link g4 and there a screw on side of it to adjust the butterfly which will let more air in on idle

[RyanRs]

The IACV is on the bottom of the stock throttle body. you will need to either remove this and custom mount it so as its still functional Or alter the idle maps to allow for an IACV-less idle.

If you adjust the idle stop screw on the butterfly you will be keeping the TPS from giving the ECU a Zero voltage reading as the TB is never fully shut, this will cause over fuelling on decel and lead to poor running and bad fuel consumption, unless the TPS is re-calibrated.

Also take note... any throttlebody larger than the stock one on a stock motor will do nothing other than upset the way it drives.

[jimGTS]

sounds like a mod you should have asked about before fitting, especially if trying to run it with a stock ecu!

[mr2c8cya]

i dont see what gain you would have on this what inlet manifold do you have?

[Vampire]

THE CAR IDLES FINE, just alot of lag before the turbo boost comes in, there is litrally no power from 3k - 4k. i would have thought that boost would be related to air being passed, surely as iv not chnaged my pipe work then thats the same restriction on air flow as before?

also, iv found a snapped plug on back of engine, which i though was oil pressure sender but now think it could be knock sensor? need to get hold of a new plug to see if thats casuing any problems

[RyanRs]

The plug on the back of the motor, below the plenum is the knock sensor, im sure that with this unplugged the ecu will think that the sensor is faulty and will activate safe mode. Do you have an EBC fitted? if so then the ECU will not be able to cut the boost pressure like it does on a stock mr2 but it will still retard the ignition timing, this will increase lag and kill off the power at lower revs -like whats happening to yours.

What manifold have you got? Airflow with throttle bodies, plenums and runners is a bit of a dark art. its not just a case of 'bigger flows better', you need the correct sized components for the engine its running on.

[Vampire]

the differnce in size from a 65mm throttlebody to a 70mm throttle body is hardly massive, i didnt think it would upset the ecu to much.

Its defo the Knock sensor thats not plugged in then, but the plug for it is damaged, any1 have a rev2 knock sensor plug(the bit on the engine loom) going cheap?

and how do i clear fault codes?

[mr2c8cya]

if you disconnect the battery and leave for half a hour reconnect and the ecu will re learn the engine and may do so to acomadate the throttle body

[Vampire]

Its done exactly that!

Attatched a new plug onto the Knock sensor, unplugged battery for an hour, started up and let it find itself, warmed up, took it for a spin using all gears, Car is happy bunny! so you can ryn a slightly larger throttle body with No Idle valve on a rev2 ECU