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Corsa Sport » Message Board » Tutorials & FAQ » Diesel Tuning » Engine Tuning » Post Reply
||posted on 18th Nov 02 at 16:54|
Increasing boost on a 1.5TD Izuzu engine as found in the Corsa and Nova up to about 97
Look down the back of the inlet manifold, you will see the injection pump, on the top of it is a cover held on by 4 x 10mm bolts which has a rubber hose attached to it.
you can pull the hose off by hand, undo the back two bolts with the socket, the front two can be reached with the 10mm spanner, once you have loosened the bolts you can undo them with your fingers.
a fuel pipe bracket is attached to one of the back bolts, gently bend it up about 5-10mm, it is then possible to twist the cover round slightly and pull it off.
Once the cover is off look at the inside of it and you will see a dimple in the middle, just rest the cover on a vice or something flat and hard and hammer the dimple until it is flat, it takes a few hits with the hammer to achieve this.
Back to the car now, look at were the cover came off and you will see a rubber diaphram, gently push a small screwdrive down the side of it and you will find it is possible to lift it up until it hits the bottom of the inlet manifold, if you get a torch and shine it through the gaps between the inlet manifold from the front looking through the gaps you will see the small white ring that sits below the diaphram, just hold the diaphram up with one hand and with the other take the stanley knife and reaching over the manifold you can get to the white ring and cut through the side of it, take the pliers and pull the ring off.
Put the cover back on and re-attach the pipe.
Looking down the back of the inlet manifold again look at the injection pump and on the right as you look at it there is a cover (anti-tamper cover) which on my car was a gold/silver colour, under it is the max fuel screw, you can tell by the shape that it could have a nut and screw under it, on mine it was possible to turn it around with a pair of mole grips.
This was the hardest bit getting the cover off, it is designed to just be pushed on and never come off, it took about 15 minutes with a hammer, screwdriver and pliers to get it off, don't hit it to hard as the screw is under it (well don't go to nutty but you have to hit it pretty hard) I ended up knocking it out of shape so I could get a small screwdriver down the back of it and lever it off.
Once it is off look were the slot in the screw is pointing and mark the pump with tippex or white paint so that you know the original position of the screw (just a safety precaution) loosen the lock nut while holding the screw still with a short screwdriver, once the lock nut is loose turn the screw 1/2 turn clockwise and lock up the nut.
Nearly there now.
Next the actuator, look at the front of the engine find the exhaust and turbo, on the right of the turbo you will see a rubber pipe, get the pliers and release the clips on each end and remove the pipe (one end of the pipe can be reached from the top the other end from under the car.
As I mentioned on the message board I just blocked the pipe up, if you want to do the same just find a bolt that is a good tight fit into the pipe, cut the head off of it, saw a slot in one end and screw it into the pipe so that it is possible to push the pipe back on,
I did it that way as I thought it would be good because it would not be possible to tell that the engine had been messed with, but now I think that my car is boosting to much at 1.2 bar and I have ordered a bleed valve (£17.50 from Larkspeed), I intend running 1 bar of boost, I will try to fit the bleed valve as far under the car as possible so that it cannot be seen from the engine bay.
I have a boost gauge so I could check the before and after boost pressure, one thing I found is the safety valve on the front left of the inlet manifold pops off at around 1.1 bar, that is why I have decided to limit the boost to 1 bar.
before boost pressure was 1/2 bar (7psi), after mods 1.2 bar (nearly 17psi).
Now get in the car and drive around the block and be amazed at the difference.
Like I said on the message board the car is greatly improved, smoother reving, seems quieter to me, less smoke and boy does she go, at 2500 rpm it just revs up so fast, 2nd and 3rd gear is amazing, motorway acceleration is also much improved.
The idle speed will need lowering as the extra fuelling will cause it to be high, there are two things that need doing, it is easy to see were the idle screw is, this is just a lock nut and screw on a bracket that the throttle arms rests on, there is also a cold start high idle (bit like a petrol choke) which raises the idle speed when the engine is cold, it is a linkage just behind were the idle screw is, it is also a locknut and screw, just adjust the screw so that there is about 2-3 mm gap between it and the throttle arm.
Suggestion Submitted by Kris TD
[Edited on 29-04-2006 by FAQ]