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(Post Link) post #1 of 11 Old 28-04-15 Thread Starter
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DPF Removal help

I know I have a thread in the Giulietta section relating to this but no one who's had a DPF removal and can answer some questions have come forward yet and I reckon this section may have more people who have removed their DPF.

So I have Spider Performance Tuning Box currently and I'm thinking about removing the DPF but I want some better understanding on how it affects these before deciding:
  • Smoke
  • Possible Engine issues
  • MOTs (I am aware its unlikely to be seen that its missing due to its hidden position in the engine compartment but will it affect its CO2 results)
  • Tax
  • Acceleration/Delay

I really want to remove the hesitation/delay you feel when you ask for power and you get it.
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MOT - According to the Telegraph, as of last year the removal of a DPF is an instant MOT failure. So I guess you could be lucky and they don't notice, but if they do, no MOT for you.

Smoke - Regarding smoke, you should see an increase (how dramatic I couldn't say) in soot/smoke blowing out through the exhaust as you might see on older diesel cars. Given that its a relatively modern engine, it probably wouldn't be too bad but without actually deleting the DPF and finding out, its hard to really gauge just how much of an impact it will have.

Possible engine issues - Shouldn't really have any impact on the engine. If anything, it could actually make the engine less prone to issues given that you no longer have a DPF getting full of crap.

Tax - no idea

Acceleration/Delay - You should get a minor boost to performance and MPG given that you are no longer using fuel to burn the particulates in the filter and you are removing some restriction in the exhaust system. But not too sure exactly just how much more improved the performance would be. I wouldn't imagine it would be a huge different but it might rev up a little quicker given the lower restriction?

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(Post Link) post #3 of 11 Old 29-04-15 Thread Starter
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Thanks for the reply, I intended to bypass the dpf as that's the method I'd heard of but some have mentioned hollowing it as an alternative so the dpf isn't removed from the car.

I can deal with some black smoke as long as its not embarrassing and its good to know it won't have damaging affects on the engine.

I believe its worth getting the egr removed as well?

I'm really not bothered if there's no performance or economy increase as I'm happy with this car now for that (I wouldn't moan about having more of course) my main aim is to get rid of the delay you feel sometimes.

Its like sometimes you'll be cruising in 4th at 40 (probably about 1700rpm) then you think right I want to overtake quickly, you put your foot down you get a puff as if it's going to do something then a delay like the power is getting blocked somewhere and then after that delay the power kicks in, its no where near as bad as before the tuning box was fitted but you feel it. I don't know if my description is making any sense but that's what I'm trying to alleviate.

Last edited by Chobbito; 29-04-15 at 15:05.
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Smoke - if you just get rid of the DPF then it will not increase the smoke - if you go for performance remap at the same time then it depends who you go to - good remap will not increase smoke
Engine issues - none, DPF is an afterthought added to reduce particulate emissions and getting rid of it will improve things.
MOT - if they find out it's a failure
Tax - tax is based on CO2 emissions and therefore should be lower for a car without the DPF - however DPF removal is illegal so you can't really declare it so your tax will stay the same
Acceleration/Delay - no DPF means less backpressure and more efficient engine and better turbo spool up - so everything will improve here

if the EGR is working correctly it will not have major effect on anything - however EGR will fail sooner or later.
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Quote:
Originally Posted by jacekowski View Post
Smoke - if you just get rid of the DPF then it will not increase the smoke
Not true completely, because if you see smoke map, it's really low afr at high revs/load and rely on the DPFs ability to reduce smoke. This is eventually partially supressed by overboosting which comes after common dpf removal.
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Don't bother removing the EGR if its in working order. It has no impact on performance and is simply there to assist the AFR when you are using no/low throttle as it pumps exhaust gases back into cylinders that are starving for air due to the lack of throttle. At high throttle/load the EGR valves close and thus, won't impact your performance and if anything, help at low load.

Regarding your issue, you are describing turbo lag. So yes, as Jacekowski said, removing the DPF will help in this regard as the lower back-pressure will allow the turbo to spool at lower rpm, thus reducing the lag.

Just make sure if you do remove the DPF that you get it tuned properly by someone who knows that they are doing. Otherwise you can have all sorts of issues!
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Originally Posted by yan.ko View Post
Not true completely, because if you see smoke map, it's really low afr at high revs/load and rely on the DPFs ability to reduce smoke. This is eventually partially supressed by overboosting which comes after common dpf removal.
Like I mentioned I'm fine with a bit of smoke as I get none at the moment, I get a DPF regen probably only once a month or two (never got the light but you can tell when its doing a regen as the car goes sluggish and the instant MPG is halved for 5-10 mins).

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Originally Posted by Vengeance View Post
Don't bother removing the EGR if its in working order. It has no impact on performance and is simply there to assist the AFR when you are using no/low throttle as it pumps exhaust gases back into cylinders that are starving for air due to the lack of throttle. At high throttle/load the EGR valves close and thus, won't impact your performance and if anything, help at low load.

Regarding your issue, you are describing turbo lag. So yes, as Jacekowski said, removing the DPF will help in this regard as the lower back-pressure will allow the turbo to spool at lower rpm, thus reducing the lag.

Just make sure if you do remove the DPF that you get it tuned properly by someone who knows that they are doing. Otherwise you can have all sorts of issues!
Ah right I'll leave the EGR as it wasn't my intention to touch this originally but it was mentioned that it might be worth doing at the same time.

That's really great to know that I'm looking in the right area and this will help, I'm swaying towards getting it done and I'll likely be going to Gus, when you say get it tuned properly do you mean getting the DPF removal done? or do you mean getting a remap done too? as I don't want a remap as I like the box and its ability to remove it if I want to take the car in for anything or selling it so its back to standard.

I've also thought about adding one of These Pedal Boxes to work along side my Spider Performance Box what do you think, will this help further?
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There is a lot of people around that will do exactly same work as gus for a lot less (200-300).
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There is a lot of people around that will do exactly same work as gus for a lot less (200-300).
I certainly don't want a 'what you pay for' job done on my car and Gus has a good reputation but who would you suggest alternatively?
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Not many tuning places actually understand how the ECU works and how diesel engine works, the maps i've had a chance to see from celtic tuning, angel tuning and gus are modified in exactly the same way (values differ slightly between them, but not in any major way).
Here someone did reasonably good write up on how does one of those maps look like (missed out few things) https://www.alfaowner.com/Forum/tunin...l#post11294842 (this one was about map from gus specifically).
All of them also disable a lot of DTCs (that is in top of the ones that relate to DPF) like low oil pressure, too high/low boost pressure, fuel rail pressure too low/high, they also disable a lot more of engine protection maps (not really doing anything until things go wrong).
They also modify injector calibration map (map that ecu uses to work out how long to open the injector for if it wants to inject specific amount of fuel) this has the effect of making the trip computer read a lot better MPG than the car is really doing (this is where most reports about improved fuel consumption after remap comes from - most of those remaps do not change anything that would improve engine efficiency in any way - real mpg gain comes from removing the dpf).

So who would i actually recommend - any place that will actually show you what they are doing and can explain what they are doing and why.
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You will need to get a remap after removing the DPF as the car can (pretty much will) eventually go into limp mode and throw up all sorts of warnings etc. as the DPF is no longer there. This will obviously cause catastrophic performance issues and basically render the car useless. You can also suffer from over-boosting issues which can damage the engine pretty quickly (in some instances completely kill it). So yes, if you delete the DPF get a remap! Otherwise you are just playing with fire and will get burned pretty quickly.

As jacekowski said, make sure you get it done by someone who knows what they are doing. As there aren't many good diesel tuners out there and they will need to have a pretty good understanding of what is required to get you the most out of your DPF removal.
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