More BOOST does NOT = more power 05 Rodeo 4JH1 TD

[TheStitt]

Hi all just wanted to help a mate out, he has a 05 Rodeo with the 4JH1 TD in it
Its got a 3 inch exhaust, aftermarket cooler and runs a Safari Dtronic piggy back chip.

Now he went out and bought a Boost Controller, Gauge and EGT sensor with the aim of upping boost on the run to help with towing etc.

This is the Dyno graph



The top runs are with the chip installed lower runs aren't, dotted lines are boost.

The reason for the question is the 3-5kw gain all that can be expected from the extra boost. My mate was hoping for a little more. The tuner was stumped he has never seen so little gains. Even on the turbo diesel. My mate used the tuner I used for the wagon and he is a smart cluey guy.

Just looking for experiences of people that have played with Turbo Diesels

thanks Stitt

[trdee]

are these electronic fuel injection? loz's landcruiser is mechanical and all we did was turn up the fuel metering screw and let it freeboost. makes shitloads more power lol

not exactly the most technical help... but yeah

[mattysshop]

what was the torque increase?

usually more fuel = more boost = more power from the deseisels i've seen... as this has a chip on it, and was tuned properly this should have been sorted... but yeh most of them seem to double in power (to equal a normal petrol engine) but make insane amounts of torque...

was a hi-flow particulate filter used?

[fixeruperer]

ive only played with the common rail diesels, like the gl mercs, when i chipped them, they cheat the rail voltage and it ups the boost and pumps more fuel in, i never put them on the dyno but the seat dyno, was impressed, made a big difference.

as matt said, what about the particulate filter ?, even just removing them, there is good gains.

[boxh34d]

Yeah, if the fuelling is not adjusted, then it might not increase in power at all.
Also, there is a reasonable chance that the turbo may not be able to push more air either. I've seen a couple of factory TD's that after the basics were done, they just could not make any more power due to the small (factory responsive) turbo not supplying any more air as the boost was wound up. Once they changed to a slightly larger turbo, run at the same boost, power was increased.
Check the fuelling as the first point though.

[MRMOPARMAN]

+1 on what the others have said. was it a plug in chip, or a tunable chip? as the others have said diesels dont increase power unless you put the fuel into it.

also what the others said.. did the exhaust system include the cat.. or was it a cat back? these things are infamous for melting cats and restricting power. if you pull it off and find it buggered, replace/block the EGR valve assy also, as the blacked cat buggers these aswell.

[CELICASUPRA7M]

yeah, ive seen a few rodeos that had blocked cats, also one that went back to the dealership over and over for no power. they couldn't fix it lol.

My advice, get a ford ranger 3.0 td, they chirp 2nd on dry bitumen lol

[dangdang]

Diesels like to run lean and too make big power...massively lean.

It's a different fuel chemically and needs to be treated differently in regards to air fuel ratios compared to petrol engines.

Perhaps the tuner doesn't fully understand stoichiometric ratio's regarding these engines.

[dnegative]

Diesels like to run lean and too make big power...massively lean.

Its not really an issue to run a diesel engine lean, its part and parcel of controlling the fuel not the air. They are the complete opposite of petrol engines, run them too rich and they go pop
Sounds to me like its not getting extra fuel for the added boost, being common rail means its an ECU issue and not a simple (but dodgy) method of having a fiddle with a mechanical injection pump to add more juice. Chances are the added boost is outside whatever parameter the ECU considers safe and wont come to the party, piggyback might be able to fix it.


Most piggy back diesel chips are fairly simple, increase the rail pressure, more injection timing, more boost. None of it is great for engine longevity, especially when you start playing with more fuel and timing.

[fixeruperer]

hmmm, i never seen a drag/race diesel look like its running lean.. those things chuff like a mofo.

[boxh34d]

Dangdang:
Diesels don't make the most amount of power when running lean at all. No fuel means no power. They run smoothly and economically when running lean - up to around 35 and 40:1 is not that unusual for low load work.
Stoic for diesels is around 14.5:1 - not all that different from petrols, and they will often make max power when running slightly rich. Problem is however, that soot is rediculous, and EGT's are hugely difficult to control. Drag type trucks will often run their AFR's down around here to try and extract every last pony out of the engine, kicking and screaming.
Most normal diesels I've seen are tuned 'lean' to around 18 to 22:1 AFR as this seems to be the best compromise between reasonable power, good reliability, fuel consumption, low smoke and controllable EGT's.

[dnegative]

hmmm, i never seen a drag/race diesel look like its running lean.. those things chuff like a mofo.

That's because they don't have to last or meet emissions

Do the same to your landcruiser and if you don't melt a piston or two first you will get pulled over for blowing more smoke than Thomas the tank.

[fixeruperer]

yeh but did you see how happy thomas was most of the time

i thought we were talking about power anyway

[CELICASUPRA7M]

most diesels will run on petrol and most petrols will sort of run on diesels lol.
We had a current model hilux come into work lacking power, took it for a drive and it still got on boost ok, just a bit gutless, turned out it was full of unleaded lol.

[fixeruperer]

no they wont.