*HOW TO* Tune your TD
ILL JUST START BY SAYING THE CREDIT FOR THIS GOES TO sir_bombalong ON cavweb
How to tune your turbo diesel Isuzu engine
Anyone thinking of carrying out these modifications please note that no one at PNG can be held responsible for you breaking your car (though if done correctly your car will be just as reliable and even as fuel efficient)
The Isuzu td engine was used in the following models ? though different displacements:
1.7 ? Cavalier mk3 turbo diesel
1.7 ? Astra mk3 turbo diesel (note, some Astra?s had the GM turbo diesel ? do not tune it! It will blow up, plus there is no guide as such to tuning it that I know about it)
1.7 - early vectra B's
1.5 ? Nova turbo diesel
1.5 ? Corsa B turbo diesel
1.5 ? Corsa B Diesel (not possible to tune this)
How much will this cost me??
boost gauge - recomended ?25-50
cone air filter - recomended ?25>
boost control valve - mandatory if you are going to turn up the boost ?15-40
The white ring modification
This is a white washer in the fuel pump diaphragm, which you can remove to increase fuelling whilst on boost. Makes a rather large difference, plus it is fairly mandatory if you are serious about playing with your engine.
A very very good guide on tuning the Isuzu:
http://www.corsasport.co.uk/board/vi....php?tid=35931
How to do this on your 1.7L cavalier??? SAME FOR A 1.5TD
Well the cavalier has a different inlet manifold so you will need to remove it completely, which is a pain. To do this you will need a 12-point 8mm long socket. As you will need to remove a couple of very awkward nuts and loosen off the injector nuts. Make sure you buy a new inlet gasket as the old one is bound to break plus its good practice to. Once off, the white ring is under the fuel pump casing with four bolts on it, you will see a black rubber diaphragm as per Corsa instructions, instead of using your Stanley knife, you can just pull the diaphragm and plunger up and out, making note of there position in comparison to the fuel pump casing, its important as the plunger is eccentric and controls the entire fuelling of the car, you can turn this plunger to increase fuelling throughout the rev range but I wouldn?t recommend it, stick to standard as its plenty for the average owner. Also should you lose position, pull out the plunger, if you look carefully there is a worn line down the plunger, look into the whole that the plunger came from note a pin sticking out from the side of the whole? Line them up.
A note on turning the fuel screw up, easiest done whilst inlet manifold is off especially getting that ******* cap off!
Taken from diesel tuning supreme Rich C
Quote:
Originally Posted by Rich C
Right first off, you either need to buy a boost gauge, as I did, or borrow (if your not bothered about having a boost gauge) to set up the bleed valve. The first picture shows where I mounted it. It's there because I don't look at it that often and I didn't think was quite right on the A pillar (The cars not fast enough to pull that sorta thing off...)
The next picture shows where I put the bleed valve and where to put the pipes linking it in.
To start with there is a strait piece of pipe linking the turbo compressor outlet to the wastegate actuator, remove this. You'll need to get hold of some extra pipe to plumb in the bleed valve, I used some fuel line I had at work, but almost anything will do, as long as its a good fit on the turbo outlet and bleed valve.
Fit the bleed valve in between the turbo outlet and actuator, I suggest fitting it somewhere you can adjust it without having to remove anything, to make it easier to set the boost pressure you want to run.
Sorry about the poor picture, but I didn't have time to remove the inlet hose to show it better, I'll take another one tomorrow when I have time.
When you've got that fitted, keep the bleed valve fully closed and go out for a run. The max boost you should see is about 0.7 bar. Open the bleed valve a bit at a time until you are running 1 bar of boost, then lock the bleed valve off (it should have a little locking grub screw or something to stop it moving.)
Note; the engine won't produce full boost just revving it, you have to go drive it a full throttle in at least 2nd gear.
Now you've got your boost sorted, you just have to turn the fuel up a bit.
The next picture shows the max fuel screw. To begin with, there is a anti tamper cover over it, remove this, its awkward, side cutters and cut it off is probably best.
Mark the start position of the screw, then undo the lock nut (while hold the screw) now turn the screw 90degress (quarter of a turn) clockwise. This will increase the fuelling. Then nip the locknut backup (while holding the screw in its new position)
Now, start it up, the idle speed will be a bit high due to the extra fuel. Make sure the temp gauge is above 90, locate the accelerator lever (with the accelerator cable attached) At idle, this lever rests against the stop nearest the O/S wing, undo the locknut and undo this stop until you get the idle back down again. Should be idling ~800RPM.
Sorted. Go for a blast and see what you think.
I know that some of this overlaps with what Corsa sport say?s, however think of the Corsa sport guide just for white ring modification, rich c? comments are far more relevant to us cavalier owners. oh just to mention, rich c' piece there doesnt mention the white ring mod just turning up the fuel and boost i'm sure you can work out how to do the white ring mod with the info given on this page
Some images courtesy of Rich C showing where the bleed valve should go
fitting a boost guage and the location of the fuel screw:
Further tuning:
induction kits: some info on sucking! - the cars come standard with a collection box and a airfilter box (on top of the inlet manifold) the collection box is not meant to have a element in it just the airbox is. as for induction kits:
no off the shelf kits available so anything will do really, i have a pipercross that i picked up in the sales for ?35, originaly meant for a c2vts, if you are turning your fuel up i have heard that using a cone filter reduces the likely hood of smoking at low revs (still to be expected when you are on boost) i also found an extra 50 miles per tank that way - dont ask why! relocation of the airfilter is popular ussually to under the headlamp on the near side, the off side is in theory better as its more of a straight line but from experiance i found it tricky to do in reality. if you are lazy (like me) then you will probably want to just remove the element from the airbox, remove the collection box, get a cold air feed and plonk the cone filter on the end of the rubber pipe that comes from the collection box to the airbox. this is fine but consider the air flow over a hot engine and around a lot on unecsary corners. if you can be bothered take it straight from the turbo to the near side light. the breather off the rocker should either be vented through a breather filter or fitting it into your new induction system. all this will add up to a not so fantastic gain of power but no more droping off of torque, power and eagerness when the engine gets hot.
Exhaust system: a decat, and maybe an sri system from the cat back, would free it up, not all that expensive either.
Intercoolers: intercoolers can be easily mounted as per cav turbo petrol. Most common is the frontera 2.8 one. Obviously anything will fit if you can make it. Make sure you have alloy tanks as you would be supprised at how much pressure the turbos can produce, dont want the tanks popping off now!
Turbo?s: an early 90?s 3.1td Isuzu trooper turbo will fit, and line up correctly so we hear, its the easiset upgrade as its bigger and you can use the standard manifold. however no one I know of has done this. I suspect a better route is to go with something like a t3 turbo complete with a custom manifold,
Laughing gas: big and easy gains,
Engine work, the usual headwork, balanced, lightened flywheels, etc etc
the purpose of this thread is to compile a thorough guide for anyone wanting to tune up there isuzu. I know there are people who know a shed load more then me so Please!!! Feel free to add to this thread, also if there are any discrepancies please post them up as well i dont pretend to know everything on the subject, i just compiled all the info which i have found on here plus personal experiance from my own fiddling. hope it was useful
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Originally Posted by Xen0phobiak
