. as far as can work out it is only there to make the erg system work and send throttle position to the ecu so i am wondering if you block off the egr system if you can also remove the throttle body & move throttle pos sensor to throttle pedal? which i believe would give more air flow at idle resulting in better cooling and better throttle response? any feedback/info would be great.diesel throttle body purpose?
diesel throttle body purpose?
Hi, can anyone tell me the purpose of a throttle body on a diesel eng? thinking of the 1kz-te engine but I'm sure the Principal is the same on other diesel engines . as far as can work out it is only there to make the erg system work and send throttle position to the ecu so i am wondering if you block off the egr system if you can also remove the throttle body & move throttle pos sensor to throttle pedal? which i believe would give more air flow at idle resulting in better cooling and better throttle response? any feedback/info would be great.
. as far as can work out it is only there to make the erg system work and send throttle position to the ecu so i am wondering if you block off the egr system if you can also remove the throttle body & move throttle pos sensor to throttle pedal? which i believe would give more air flow at idle resulting in better cooling and better throttle response? any feedback/info would be great.
Re: diesel throttle body purpose?
Yes it's primary purpose is to provide an appropriate amount of vacuum for the EGR to operate I believe. As a side effect you get a bit more engine braking, though of course you get the part throttle pumping losses that having a throttle brings.
In the 2L-TE you can just remove the two butterflies (provided you've blocked off the EGR) leaving the throttle body and position sensor undisturbed, not sure about the 1KZ.
In the 2L-TE you can just remove the two butterflies (provided you've blocked off the EGR) leaving the throttle body and position sensor undisturbed, not sure about the 1KZ.
Re: diesel throttle body purpose?
butterlys is for EGR and to smoothen shutoff. 1kzte has interesting butterfly setup, i think one is actually contolled by the throttle cable. so to disable it you need to actually remove it fully. part of the ecu operate butterfly is mounted off to the side for some reason on those, yet to work out why.
if you block off EGR you realy do need to disable the butterfly otherwise they create a restriction.
if you block off EGR you realy do need to disable the butterfly otherwise they create a restriction.
Re: diesel throttle body purpose?
I believe the ecu controlled butterfly is for the idle up control but could be wrong
89 LN106 Hilux 3.0L turbo,2" bodylift 50mm suspension lift, lockrite rear, lsd front & 33" wranglers & winch
Re: diesel throttle body purpose?
nope, its a diesel not a petrol. all fueling is ECU controled and from injection pump directly.
Re: diesel throttle body purpose?
yes but you can't add fuel with out air so i believe the ecu opens the throttle to let air in then adds fuel to lift the idle up. as the ecu throttle is very small from memory about 15mm in dia.
89 LN106 Hilux 3.0L turbo,2" bodylift 50mm suspension lift, lockrite rear, lsd front & 33" wranglers & winch
Re: diesel throttle body purpose?
good point.
i'm not 100% sure on the setup but i understand that small butterfly is open at idle anyway. its not a progresive opening either, it open or its shut which would make it useless for rpm control.
i have my doubt the the boost sensor can read the small amount of pressure change it would make, mainly because of the filter thingy in the sensor line. that tends to dampen out any presure changes.
the amount of air at idle is more than enough for it to be able to add extra fuel to centrol idle without going to rich.
to date everyone i know that has disabled the butterfly has not had an idle problem.
i'm not 100% sure on the setup but i understand that small butterfly is open at idle anyway. its not a progresive opening either, it open or its shut which would make it useless for rpm control.
i have my doubt the the boost sensor can read the small amount of pressure change it would make, mainly because of the filter thingy in the sensor line. that tends to dampen out any presure changes.
the amount of air at idle is more than enough for it to be able to add extra fuel to centrol idle without going to rich.
to date everyone i know that has disabled the butterfly has not had an idle problem.
Re: diesel throttle body purpose?
sounds logical. will have a play with it tomorrow if i have time and let you know what i find. thanks for the info 
89 LN106 Hilux 3.0L turbo,2" bodylift 50mm suspension lift, lockrite rear, lsd front & 33" wranglers & winch
Re: diesel throttle body purpose?
The old pneumatic governers used to sense the pressure difference across the butterfly and use that to provide fuelling control. Why toyota kept using a variant of the system on the electronic engines like the KZ I have no idea.
My electronically controlled nissan (which had EGR) had a single pneumatic controlled throttle valve on the intake, this helped the EGR and also restricts engine airflow for faster warmup. It's a very different (and simpler) system than the toyota with no direct link to the throttle.
My electronically controlled nissan (which had EGR) had a single pneumatic controlled throttle valve on the intake, this helped the EGR and also restricts engine airflow for faster warmup. It's a very different (and simpler) system than the toyota with no direct link to the throttle.
Re: diesel throttle body purpose?
i'm not sure if its related to the old style system. the 2lte motors runs the same system as the 1kz as above, however the earlier 2lt runs a system more like what your nissan does with a butterfly that ecu controlled not throttle control.
maybe its there in case of engine run away.
maybe its there in case of engine run away.
Re: diesel throttle body purpose?
Had a play with it today and the ecu valve is a three position valve (open,1/2open&closed) the valve rests in the open position and is 1/2 open for initial engine start and open once engine is running and is fully closed while the engine shuts down. so my thoughts are that it is 1/2 open to let the starter to turn over easier(lower compression). and similar to allow for smooth shut down. 
. but i started my engine and shut it down with the throttle wide open and it made no difference so correct me if I'm wrong but i'm thinking it is a design that is good in theory but doesn't do much/anything in practice.
. but i started my engine and shut it down with the throttle wide open and it made no difference so correct me if I'm wrong but i'm thinking it is a design that is good in theory but doesn't do much/anything in practice.89 LN106 Hilux 3.0L turbo,2" bodylift 50mm suspension lift, lockrite rear, lsd front & 33" wranglers & winch
Re: diesel throttle body purpose?
the valve closing at shotoff simply makes the engine shutoff smoother. with it not operateing the engine shuts off with the normal shake a lot of motors get. usually with working valve the motor barly even moves on shutoff.