To De-cat or not to De-cat that is the ?

Hi all had a few discos now and been lurking about on here but thought time to put a question out there. I have a 98 300Tdi Auto jap import that I NEED to get more ooomph out of. I know the route to go, however on consulting my mechanic, he seems to think if the cat is ok there is no need to remove it as it shouldn't be restrictive. So my good friends the question is over to you lot, is he correct or will there definitely be a difference without. I will be removing the centre box and even the back box(as long as the noise is acceptable for Mrs W).

I'll be doing the EGR as well though mine has the water heated/cooled egr system so not sure whether o blank off at exhaust manifold as per normal or the bit where it would have gone into the intake pipe(being replaced).

ta

EGR is not just about restriction, it's about mixing exhaust gas with clean air... which is not good for the engine(it's like somebody puts a pipe into the arse and inhales his flatulence just to not disturb the "environment")

Get rid of it, blank the exhaust, bypass the EGR cooler(connect the coolant pipes together) and sell it to someone who thinks that EGR is good and wants to keep it working

the problem is now that its an mot fail, so you need to blank the EGR without the MOT tester knowing its been done.

or find the sort of MOT tester that you go down the pub with

same applies for Cat btw regards MOT afaik, but like you say it is probably over specced for the engine so might not be a problem. speak to a diesel eggspurt

Nah the cat law was bull…..thats only for petrols according to the last thing I read on here



As to the EGR just play dumb or make something up about it being an optional pipe for a second turbo…….

Mines passed the MOT last week with the egr valve removed

Cat and egr will make no odds for mot if it turns out to fail on the egr just put it back on and go back for the retest the cat wont count for mot take off your inlet manifold after blanking the egr and clean the **** out of it as it will be full of gunk, the same goes for the intercooler soak it in petrol and then give it a few hours to dry out will make a noticible difference afterwards decat helps too but not a huge amount

Thanks for the replies, I'm certainly going to clean the intercooler out in fact i have a spare one soaking as we speak, the inlet manifold I'm a bit cautious about doing only because I've read differing accounts about gaskets combined with exhaust gaskets etc..

As for the Cat, If i just remove both silencers wont that have the same effect, as i said I'm pretty sure the cat is not restrictive unless it is breaking down..

EGR wise I'll remove completely might even utilise the redundant pipes to make a water heater for a shower system or heated windscreen washers

Take the inlet off that where you will recover most power i had no probs with the gasket

Water heating sounds good. Not sure how much instant heat you could get for a shower though?

Don't wish to spoil your fun and I know everyone likes to have a play about using something for something else, but it's an EGR cooler circuit so may well be designed to flow cool water, whereas the heater circuit for your cabin heat is part of the hot circuit so if you wanted to make a heated water tank or instant heat type shower you'd probably be better coming off that circuit.

your main problem is your disco is or will be a EDC (fly by wire)one
so you cant alter the pump it's got the dreaded ECU that controls it
you cant remap you used to be able to get the chip replaced cant remember who used to go but long gone now

mine is the same 97 disco 1 auto EDC de catted and de EGR ed still a gutless wonder de catting and removing egr made little difference to mine also mine have a has a new head and all has been cleaned
only way to go is retro fit a manual injector pump and injectors EDC injectors are not the same

fitting manual injection would be top on my list of mods if i had an auto.

a highly tuned auto 300tdi would be a nice thing to have

octo0072000 said:

your main problem is your disco is or will be a EDC (fly by wire)one
so you cant alter the pump it's got the dreaded ECU that controls it
you cant remap you used to be able to get the chip replaced cant remember who used to go but long gone now

mine is the same 97 disco 1 auto EDC de catted and de EGR ed still a gutless wonder de catting and removing egr made little difference to mine also mine have a has a new head and all has been cleaned
only way to go is retro fit a manual injector pump and injectors EDC injectors are not the same

Click to expand...

to quote Allisport "Our electronic option can be used on it’s own to provide 15-20% more power and torque for £325+vat or we can adjust the fuelling to suit our uprated intercoolers." it would be interesting to see how that compares to a tuned manual pump.

Though if consensus is that I can get more from a non edc pump setup then I know where I can get one and the injectors

wylie_eyed said:

to quote Allisport "Our electronic option can be used on it’s own to provide 15-20% more power and torque for £325+vat or we can adjust the fuelling to suit our uprated intercoolers." it would be interesting to see how that compares to a tuned manual pump.

Though if consensus is that I can get more from a non edc pump setup then I know where I can get one and the injectors

Click to expand...

from allisport web page EDC disco has non flashable ECU re chip only
is the £325 plus vat to remap not rechip

if you go pump route you need injecter pump/pipes /injectors throttle cable set up and the auto kickdown set up for manual pump and a live feed from the wires but you leave the ecu in place by all accounts it's to do with central locking aircon cruse etc are all linked in
have fun

Each vehicle is tuned individually to take into account the many factors that need to be considered when remapping and chipping.
Some vehicles with earlier, non flashable ECU systems need to be re-chipped rather than remapped, but we also offer a full range of plug-in tuning units to suit 99% of modern turbo diesel cars, trucks and even tractors.

that quote from allisport was in an e-mail after i posed the question directly as in this is my vehicle what are my options.. obviously new intercooler was mentioned

Ok this is the plan, once the weather stops raining and the missus goes "shopping" , I will leave the cat for now, just remove middle box which is very restrictive by all accounts and the rear if it's not too loud. At the same time I will do the EGR mod put the cleaned Intercooler in, and clean the inlet manifold.
Question is the inlet manifold easy to get off on its own? I thought you had to remove the exhaust as well because they share the same gasket!!
I will then see how that is before deciding on any other mods however I have "sourced" a non edc auto that can donate all the bits

They do share the same gasket but its a tough one and should be ok only two bolts and tow nut hole the inlet on easy job