Offroad-Express

Hi, removed my egr valve & throttle butterfly today and thought i would share my findings on the effects . it was on a flat road approx 30min apart once engine was warm.

before/after(deg C)

idle = 150/95 = 37% cooler
3rd gear 2000rpm = 250/175 = 30% cooler
4th gear 2000rpm = 340/250 = 26% cooler
100kph = 450/375 = 16% cooler

works out to about 75 deg c cooler temps on average which has to be better for the engine.
full throttle acceleration stayed the same at 500 deg c. and less engine braking. both of which i expected but didn't expect to see such a large difference in exhaust temps

this is a 1kz-te engine installed in my double cab hilux.

next hoping to install intercooler to see if that makes any diff then wind the boost & fuel up .

Was it exactly the same piece of road going in the same direction with the wind exactly the same ?

The reason I ask is that, what appears to be a flat piece of road can give that difference when going in the other direction on my pyrometer.

cheers Richard

yep exactly same piece of road in same direction tried to get it as identical as possible so as to remove the likely hood of any false readings hence i had mods completed asap (tops 30min) so as weather didn't change.

I've noticed differences in EGT too when I add morey's additive to my fuel, it increases the cetane rating (by about 5) which appears to increase temperature (not conclusive). This makes me wonder what the differences are in cetane rating of the fuels is between retailers? I always try to buy from Gull so I don't really have experience first hand on fuel cetane differences or their impacts. Also noticed small headwinds and tailwinds can cause as much as a 150 Deg C change in EGT (land rovers are aerodynamically challenged). Drafting behind a truck the other day decreased EGT by 70 Deg C at 90kph and 2900rpm.

Conclusion I have drawn since installing the gauge is that relatively small changes in driving environment can have a disproportionately large impact on EGTs.

Always good to read of others experiences.

Good results.
Just a pity you couldn't have done it in two stages, first with the EGR disabled, then with the butterfly.

I think the butterfly going would have made the biggest difference of the two. It'll be interesting to see if warm up times change in cold weather.
My work car has a warm up mode which is high idle and (I think) shutting the intake butterfly. Without it in traffic in a frost you never get the heater working.

could be a issue i'll let you know as time goes on. although it's not very often i'm in traffic and usually doin 80-100ks so may not be as much of a issue for me as it would be for others.

1rugger wrote:could be a issue i'll let you know as time goes on. although it's not very often i'm in traffic and usually doin 80-100ks so may not be as much of a issue for me as it would be for others.

Try driving across Chch on a frosty morning at 8am, then you'll find out.

Apparently the new diesel cars run the aircon backwards (heat pump mode) to get passenger heat in cold conditions with low load on the motor.
Some cars use electric, but you can only get soo much electrical power from a 12v system and AC systems can shift heaps more.

1rugger wrote:before/after(deg C)

idle = 150/95 = 37% cooler
3rd gear 2000rpm = 250/175 = 30% cooler
4th gear 2000rpm = 340/250 = 26% cooler
100kph = 450/375 = 16% cooler

with EGR blocked without butterfly disabled would have been interesting to compare. but otherwise temp difference looks fairly normal.
typical EGR is off at full throttle hence no change in EGT's.
however most of the older systems have EGR off at idle to, so i'm not sure why the temp difference unless the EGR valve is stuck open a bit which is a typical problem they get.

tweake wrote:i'm not sure why the temp difference unless the EGR valve is stuck open a bit which is a typical problem they get.

It'll be the butterfly gone/disabled.
The butterfly on those is mostly closed at idle, keeps the engine quieter, reduces NOx and gives you faster warmup. But yes higher EGT's too.

yes, could well be. i think the earlier toyotas had the butterfly open at idle. not sure with those ones.

certainly without the butterfly choking the motor performance just off idle will be improved.

on the 1kz-te motor at idle the main throttle is fully closed but the small ecu controlled butterfly is fully open. so far i haven't noticed any difference in warm up times but prob won't till i try it in a good frost. and agree that the main diff would be caused by the removal of the throttle body as i believe the egr valve is only open when engine is at idle so it could only effect idle egts.

1rugger wrote:........... i believe the egr valve is only open when engine is at idle so it could only effect idle egts.

egr valve is open at part throttle right up to almost full throttle. hence why the drop in egt's except for full throttle.
butterfly system is there to draw in more egr when there is little exhaust backpressure.
some of the newer motors use EGR all the time

tweake wrote:

1rugger wrote:........... i believe the egr valve is only open when engine is at idle so it could only effect idle egts.

egr valve is open at part throttle right up to almost full throttle. hence why the drop in egt's except for full throttle.
butterfly system is there to draw in more egr when there is little exhaust backpressure.
some of the newer motors use EGR all the time

that does make sence now that i think about it. but wouldn't that also affect turbo spool up/ boost pressure due to loss of air flow when egr valve is open

yes, thats partly why you get a boost in part throttle performance with egr being blocked.

the only downside is you use more air, so airfilters can get clogged up quicker.

tweake wrote:........ so airfilters can get clogged up quicker.

would rather change a few air filters than a cracked head