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Bad fuel economy 84 MKSD33T
Posted: Mon Jun 05, 2006 3:08 pm
by 84mksd33t
hey guys,
im getting pretty bad economy from my 84 swb sd33t
From a full 60l i struggle to get 420kms - I shift at around 1900rpm
So no thrashing
I noticed that the pressure release plug on the inlet manifold is very easy to pull out (fingers can pull it out with ease) Is this normal? or could i be losing boost because of this? (boost gauge reads 4-5psi - stock is 8?)
I have a friend with an aftermarket turbod sd33 - he gets 550ks to the tank thrashing the pants off it :(
What are some things i can check?
- Fuel filter (where is it located?)
- Do they have a TPS?
- Do they have a thimble like on the TD42?
Any suggestions or help is much appreciated as Going through 100$ of fuel in 4 days isnt fun :(
Cheers,
Cody
Posted: Mon Jun 05, 2006 3:59 pm
by NZ4x4
I get about the same as you but drive it a bit harder.
If you are running bigger tires or carrying heavy loads it could hurt your economy.
Posted: Mon Jun 05, 2006 4:03 pm
by pongo
Maybe your injector pump needs some adjusting. Check air filters,etc. Mine might get close to your figures, but im running 4.6 centres. You will be able to hear your pressure release working if its letting out air. Mine is bloody loud.
Cheers
sd33
Posted: Mon Jun 05, 2006 5:20 pm
by badger
mates mq runs a huge after market turbo and 35's get better econamy than that and enuf power to spin em in third
mab needs a tune up or injector clean
Posted: Mon Jun 05, 2006 6:06 pm
by zer0
try putting a bottle of diesel power into it next time you fill up (its and additive that cleans and makes things run better its preety much the diesel version of spitfire for petrol engines) you can get it from pretty much every store like auto barn supercheap etc etc
Heath
mk
Posted: Mon Jun 05, 2006 6:41 pm
by DR Frankenstine
If your changing at 1900 rpm your turbo would only be just starting to come in. At least rev the thing to 2800 rpm get the thing working.
Turbo diesels hate being laboured.
Posted: Mon Jun 05, 2006 7:24 pm
by gurumon
that's only about 15l / 100 klm.
my na sd33 chews about 18 or so per 100klm on the highway (much worse off road).... i don't have a tacho so i rev it till it stops accelerating
i also use about 1 litre of oil every 400k's

sd33
Posted: Mon Jun 05, 2006 8:21 pm
by badger
you will get that when u rev it till it stops thru each gear lol
Posted: Mon Jun 05, 2006 8:24 pm
by 84mksd33t
So you think i should hold gears until 2600-2800RPM?
I dont like the amount of noise the engine produces ay...
Too loud
Ill trry it and see how i go!!
Re: Bad fuel economy 84 MKSD33T
Posted: Tue Jun 06, 2006 9:14 am
by festy
84mksd33t wrote:hey guys,
im getting pretty bad economy from my 84 swb sd33t
From a full 60l i struggle to get 420kms - I shift at around 1900rpm
So no thrashing
Me too. I used to get better than 12l/100km, now only just managing 15l/100km
I noticed that the pressure release plug on the inlet manifold is very easy to pull out (fingers can pull it out with ease) Is this normal? or could i be losing boost because of this? (boost gauge reads 4-5psi - stock is 8?)
4-5 is stock. You'd know if you were losing pressure via the pressure relief valve, there's a big 'sneeze' and you lose *all* boost. If you keep your foot into it, it sounds like a steam train tshhh-tshhh-tshhh-tshhh
What are some things i can check?
- Fuel filter (where is it located?)
- Do they have a TPS?
- Do they have a thimble like on the TD42?
Fuel filter - there's one on the firewall behind the injector pump, and there's another filter in a banjo joint on the injector pump itself.
TPS - I don't think so
and no idea what a thimble is.
Check compression? Fuel pump timing? Have you had the injectors serviced?
TD
Posted: Tue Jun 06, 2006 5:17 pm
by Patroldude
Stock boost is like 9psi according to Nissan.... we cranked it up to like 13pound - never cooled one, got the cooler sitting there but never got around to it hey.
Your economy sounds like crap but... NA diesel used to use less than 3/4 of tank to get from Sydney to Cooma and TD uses just over 3/4 on highway - this is on stock 4.33 diffs with good 31 inch rubber. Sutherland to Cooma about 500kms I think.... 68 litre tank... so we be doing like 10l/100kms off road only chew little bit more....
My 5 litre though..... different story!
Mk
Posted: Tue Jun 06, 2006 5:54 pm
by 84mksd33t
Well when i increase the boost - max i get is 6psi and then the pressure release goes off.l
The car feels very slow - and doesnt pull likea turbo diesel :(
can someone post pics of where the filters are please?