2004 isuzu npr 200 sitec 140 engine mods.

[simcoe]

Hi guys, its been a while since ive been on here.
ive got my self a 2010 fuso dual cab work truck which goes quite well, bigger exhaust and remap etc.
I just bought my guys at work a single owner 190k old 2004 npr 200 single cab with steel tray and racks all set up for work, it has the sitec 140 motor. Mannnnnnnnn its slow compared to the fuso, i get the fuso runs 22 psi of boost stupidly low in the rev range, where as the npr is only 6/8 ish at 2200 and max at 2500 of 13. i put a boost gauge on it to see what it was doing then wacked a boost t on it to have a trickle. I also took off the tamper cap on the max throttle adjustment which helped.
These are common rail by the look of the pump, which basically leaves me to think its a remap and manual boost adjustment.
On the wknd im going to tap another barb into the turbo outlet to see what boost it makes there in case there is a leak. Its just so lazy until 2500 which is not ideal when lugging gear around as it borders on dangerously slow.
I have read that you can swap the ecu out from one of the bigger rigs that run the same motor ie 185hp, 205hp etc.
Just curious if anyone out there has had a tickle up of theirs.
cheers

 

[simcoe]

so did a bit more testing, and results are pure lazy and pathetic for a turbo diesel.
5psi by 2000 and 14 by 2500.
only good thing with it it does return 13 ish lph where as the fuso is 17. weight wise thought the fuso is 4.3t and suZi is 3.75, fuzi still flogs it.
going to pull the inlet manifold off on the wknd and clean it and then block the egr.
failing that its most certainly tune time and give it some fuel.
ill also track down a 3' exhaust brake flange set up and build 3' exhaust and dump, for now ill be removing the muffler.

 

[Andy Hino]

I had two NPR 300's of the same vintage and they were totally different vehicles to drive (both bought new for a business)
One was lazy as you described and the power delivery was very linear and it felt decidedly naturally aspirated
The other one would get up and really go as soon as the boost started to build and you could hear this angry growl from the intake

I questioned the head mechanic at the dealer and he had no idea why they were so different and I still dont know why.
Im betting one was either over boosted (but we never had any issues with it in more than 400,000 km) or the other was down on boost (but it still seemed to have plenty of torque, it just didn't feel like it)
Id be checking everything to see if you have a boost leak or there are any other issues

 

[simcoe]

I had two NPR 300's of the same vintage and they were totally different vehicles to drive (both bought new for a business)
One was lazy as you described and the power delivery was very linear and it felt decidedly naturally aspirated
The other one would get up and really go as soon as the boost started to build and you could hear this angry growl from the intake

I questioned the head mechanic at the dealer and he had no idea why they were so different and I still dont know why.
Im betting one was either over boosted (but we never had any issues with it in more than 400,000 km) or the other was down on boost (but it still seemed to have plenty of torque, it just didn't feel like it)
Id be checking everything to see if you have a boost leak or there are any other issues

yeah wow, thats interesting regarding your experience.
I have not had much time to have a look at it, its my workers truck and we rarely have time to play cars. It drives ok in the flat, just dies hard when hitting any sort of gradient.
I did find that the waste gate was stuck shut when i put compressed air into it, i was hoping that it was stuck open causing a lack of boost build not stuck shut,it now moves freely.
There is no boost leak as i have the same pressure at the turbo as i do in the manifold.
I plan to pull the turbo to see if the blades are pitted or is the waste gate flapper is corroded.
I have a water injection kit on my fuso, i might take it off and put it on suzi to give the intake a good warm water wash in case there is excessive carbon.

ill report back.

 

[Curtis in Texas]

I'd bet the turbo is toast! You aren't getting any boost. And since you say the plumbing is solid & the waste gate is stuck I'd say it's been like that for a while. I think that if it had boost, that waste gate should have hade to operate enough that it wouldn't be stuck.
The 4JB2-TC's are so much like the Cummins 4B's not funny. Also check the intercooler for air restrictions!

Your motor should be seeing 21:1 compression ratio. Also change out the fuel filter as it may be chocking the fuel delivery and not letting it get enough fuel to wind up. (HAd that happen on my 2.2L Isuzu TD Trooper.) And then the air filter needs to be checked too! Well , hack let's just show what Isuzu recommends checking.
Here's a picture of the Factory Manual that covers those issues. Taken from the Factory Manual.

I'm looking at a 2002 FSR with the 6 cyl to build into an Off Road RV. I'll boost it up just like I did with my 5.9L Cummins I built and put in my Class A Motorcoach. 450 Hp and an Alilison 1000 5 speed replaced the 460 Ford and C6 tranny. Even regear the Dana 70 and installed a Limited slip.

 

[simcoe]

its not long had a full service and blocked the egr while i was at it.still slowwwwww.
intake manifold looked and feels clean.
didnt take the turbo off but just looked at the front wheel and its fine, no pitting and spins freely.
intercooler is clean.
ill wack a spare egt gauge on the dump and see how much fuel this this is actually getting.


i spoke with a mechanic mate heavy diesel mechanic other mate and by chance he has the same year model truck and motor combo, he said the exact same thing. slowwwwwww.
round town on the flat i can sort of live with, it just hates hills and has no urge, literally like an na td42 or 1hz.
remap time