We’re covering this topic because it concerns many Saab owners who drive diesel-powered models. Whether it’s the TiD or TTiD engines, the question of disabling or removing the DPF (Diesel Particulate Filter) and EGR (Exhaust Gas Recirculation) systems—both electronically and physically—comes up frequently. Below is a full overview based on forum discussions and shared experiences.
Table of Contents
Performance and Fuel Consumption Improvements
Many Saab 9-3 TTiD and TiD owners (1.9 Twin-Turbo diesel and 1.9 Turbo) who removed the DPF (Diesel Particulate Filter) and disabled or removed the EGR report specific improvements in engine operation. Removing a clogged DPF eliminates its restriction, which can improve throttle response and engine power. One enthusiast noted that after a software DPF delete with a remap, the car achieved performance comparable to a tuning kit (BSR box): “I got exactly what I was supposed to get with a BSR kit, but without the DPF hassle and at two-thirds the cost. Result!”
He also reported a slight fuel economy benefit: fuel efficiency “improved slightly,” reaching around 40 MPG (≈7.1 L/100 km), which he considered excellent given the added power. Similarly, a user on another forum (focused on Škoda but referencing the similar 1.9 TDI engine) reported that after a DPF delete, average consumption improved from ~6.4 to ~5.9 L/100km (44 to 48 MPG) with a Stage 1 remap. Most enthusiasts agree that removing a clogged DPF eliminates symptoms of power loss and “turbo lag” caused by regenerations, letting the engine breathe more freely and respond better, especially at higher RPMs.
The Problem of Black Smoke and Emissions
The most common side effect of physically removing the DPF is increased soot (black smoke) through the exhaust, since there’s no filter to trap it. Users report very noticeable smoke immediately after a DPF delete when flooring the accelerator. One Saab TTiD owner vividly described: “When you floor it on the highway, there’s enough smoke behind you to completely block the view for the car behind”.
However, this was an extreme case—it turned out the EGR cooler housing was cracked, allowing hot exhaust to leak under the hood and disrupt combustion. After fixing the fault, “the excessive smoke disappeared overnight,” with only a small puff of soot during sudden acceleration, “nothing like before”.
Because of issues like this, forum members often discuss disabling the EGR system alongside the DPF. EGR valves left active can introduce soot into the intake and contribute to smoke. Some recommend physically blanking the EGR and disabling it in the ECU remap to reduce smoke clouds. One owner described his process: he installed a blanking plate and disabled EGR flow monitoring in the ECU maps, so the ECU doesn’t throw an error because of a blocked EGR. Effectively, this means the EGR is no longer operational, which reduces soot buildup and potential smoking.
It’s important to note that excessive smoke after DPF/EGR removal may also indicate other problems. Forum users suggest checking fuel injectors—faulty or imprecise injectors can also cause excessive smoke. Under normal circumstances, a properly tuned remap after a DPF/EGR delete should limit smoke to acceptable levels (a little puff during sudden acceleration, not a continuous cloud). Some tuning services even claim that properly done DPF removal should not cause persistent smoke. If it does, it usually indicates incorrect mapping or a mechanical issue.
Technical Inspection and Legality
DPF removal is officially illegal in many countries and grounds for failing technical inspection. For example, in the UK, since 2014, vehicles originally equipped with a DPF automatically fail the MOT test if it is found missing or disabled. The same applies to the EGR if its removal affects emissions.
In practice, however, owners have found ways to pass the test despite removing the filter. The key is to ensure it looks like the DPF is still present and that smoke emissions stay within limits. A common approach is removing the internal ceramic core of the DPF while keeping the original housing in place—visually, it appears the filter is still installed. A proper remap after removal should also ensure the engine doesn’t produce heavy smoke.
UK-based TTiD and TiD owners confirm that passing inspection is possible. One owner reported: “My 9-3 1.9 TTiD (2008) passed MOT smoothly today—no complaints and no problems with the smoke test. This is with the DPF removed and EGR blocked” (uksaabs.co.uk). He even asked the inspector for the soot test result and concluded that EGR blanking was “the lesser of two evils” compared to a clogged DPF causing faults and smoke.
Still, there is risk—if inspections become stricter or if future testing includes particle count measurements or ECU parameter scans, a car without a DPF could be rejected. Some suggest using tools like the eSID unit to monitor DPF saturation and perform forced regeneration as needed, thereby avoiding problems while keeping the car legal . This is a more conservative approach for those who want peace of mind and a clear conscience regarding emissions.
Potential Issues After Removal
Aside from the smoke already mentioned, owners report several other possible side effects after DPF/EGR removal. Mechanical failures in the EGR system may surface—such as cracked EGR coolers (accordion-style pipes), which are common on 1.9 TiD/TTiD engines. One forum user experienced this shortly after his DPF delete. While likely unrelated, long-term heat exposure may have contributed. He noticed exhaust gas entering the cabin and had to replace the part. Afterward, the smoke issue improved significantly.
Software errors can also occur if the remap is not done correctly. DPF removal requires disabling all ECU monitoring parameters (differential pressure sensors, regeneration triggers, etc.), while EGR blanking requires turning off flow detection. A poorly done remap might leave some parameters active, resulting in check engine lights (e.g., codes for low EGR flow or high exhaust pressure). However, experience shows that trusted Saab tuners in the UK typically handle these changes routinely, and there have been no reports of ECU errors after a properly executed DPF/EGR delete package.
Some users have also reported improved long-term reliability: with the DPF gone, there are no more frequent regenerations that dilute oil with fuel, nor the risk of a clogged filter causing limp mode. This also avoids expensive DPF replacement procedures. On the downside, the engine emits more soot into the environment, and if the catalytic converter remains, it may be exposed to higher soot loads.
Swirl flaps (butterfly valves in the intake manifold) in the TTiD engine are a separate topic—some advise leaving them alone, as their removal can affect engine behavior. Most discussions remain focused on the DPF/EGR systems.
Enthusiast Opinions and Overall Consensus
Across Saab forums and enthusiast communities, the overall sentiment about DPF removal (with a proper remap) is positive among those who had issues with the system. Owners who performed the procedure are mostly satisfied: their cars no longer enter limp mode unexpectedly, there’s no worry about regenerations every few hundred kilometers, and throttle response is subjectively improved.
Many emphasize that a good remap doesn’t significantly increase fuel consumption—in fact, it may slightly improve—and that smoke levels are kept within acceptable limits. One member noted that after his DPF/EGR delete, “smoking was much better (reduced), and fuel economy slightly improved,” maintaining about 7 L/100km, which he found reasonable for the available power.
In short, most who’ve done it don’t regret it, calling it a permanent solution to diesel soot problems—“no more DPF hassle – result!”.
Still, the consensus isn’t unanimous. Some veteran Saab enthusiasts warn about environmental and legal implications: removing factory emissions systems means the car emits more pollutants than intended. Members stress that DPF removal shouldn’t be done “just to make the car run better” on a properly functioning vehicle, but mainly when the filter is causing problems or for track use. In some discussions, comments like: “You can remove the DPF if you want to pollute the air we all breathe” underline the moral responsibility.
Some advise solving the root cause of DPF clogging (e.g., longer trips, cleaning, or filter replacement) instead of removing it, to keep the car compliant.
In conclusion, most Saab owners who’ve done a DPF/EGR delete report positive experiences in performance and reliability, with only minor negative effects (a bit more smoke). However, everyone acknowledges that the procedure is illegal on public roads in many countries. Thus, enthusiasts are divided: some believe the gains outweigh the risks (especially with proper visual disguise during inspection), while others oppose removal due to principles or fear of penalties.
As one member advised his father, also a TTiD owner: it’s better to keep the DPF and EGR if they’re working and maintain them—because that way, “MOT stays happy”.
In summary, the improvement in engine behavior is confirmed, but every owner must decide whether the potential legal consequences and ethical dilemma around emissions are worth it.
