Spongy Brake Pedal in My 996 ? Air in ABS Lines?

Looking for some input. Ever since I got my 996, the brake pedal has felt spongy. Last year I had the brakes flushed as part of a track inspection, but the feel didn�t change at all. I recently drove another 996 (a Turbo) and the pedal feel was totally different�much firmer. A tech mentioned there might be air trapped in the ABS system. I�ve also heard that without properly cycling the ABS pump, normal bleeding won�t get all the air out. I talked to a friend at a Indy Shop and he thinks there�s still air in the lines. I�m hesitant to pay another $200 for a full bleed just to end up with the same result again. Has anyone had success with specifically bleeding the ABS module on these cars? Did it make a noticeable difference? Also, does anyone know if there�s a DIY way to trigger the ABS pump without dealer-level tools? Any advice or shared experiences would be super appreciated

A normal brake fluid flush does not require an ABS bleed. PIWIS and some other scan tools have the ABS brake bleed. I'd find an independent with a PIWIS and discuss your problem. The last place you want to be is on the track with air in the brake lines.

Food for thought. Have had numerous BMW X5. The biggest PIA to bleed brakes! Took me a week. Had to use a Foxwell scanner that had the brake bleed function. I have no idea whether P cars need that, but might want to look into it.

Use your scan tool to activate the ABS while bleeding. You should be able activate each individual wheel.

Early 996 don't need anything special to bleed brakes, later cars need a PIWIS or similar (Look at Porschetech's thread for buying a cheap one). I know my 98 doesn't. As well as air in the lines, could be signs of a failing master cylinder or servo...

I have not had any trouble with air trapped in the ABS. That said a quick way to bleed it is to make some ABS assisted stops on a dirt road.

Maybe you have soft pads? My 996 Akebono pads are very soft compared to the pads I had prior. Just a thought.

@nhpstudio , sorry to hear about your spongy brake pedal. Assuming the flush was done properly with high quality fluid, and assuming your calipers and brake lines are in good working order, and your pads and rotors have sufficient life left in them, you can consider replacing your 996 master cylinder with a 997 GT3 master cylinder which will help to firm up the pedal feel. Its a relatively cheap part which was ~$200 before the new tariff policy.

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^^^^ This. Gravel works too in case it�s mud, not dirt.

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Have heard others talk about doing this. But, I don't get it. If there is air in the lines, you get the ABS to activate(mini pumps of brakes), where does the "air" go??? It is a sealed system. When you bleed them normally, you open the bleeder and give the trapped air somewhere to go. Just wondering if this slamming of the brakes on a slick surface is internet lore or can someone explain why it should work.

The ABS activation, either by diagnostic tools or braking, 'washes' the air inside the ABS unit into the brake lines from where it can be bled by a the conventional brake bleeding routine. So a single ABS activation alone won't solve it because, as you said it is a closed system, and must therefore be followed by a final bleeding of the brakes. The ABS doesn't do 'little pumps of the brakes' only but does 3 different steps: First it holds the brake pressure and prevents it from rising should the brake pedal be pushed harder. 2. It can reduce brake pressure by releasing fluid from the caliper (actually the brake line running to it) back into the reservoir 3. It can pump brake fluid from the reservoir into the master cilinder (this is what causes the vibration in the brake pedal) and when opening the passage to a caliper increase the brake pressure to the level dictated by the force applied to the brake pedal by the driver (and not more). Now there could be a scenario where air is trapped inside the ABS that upon activation through hard braking, the air is washed into the reservoir by step 2. Then a final brake bleeding would not be required. If you activate the ABS often enough,step 2 will be repeated enough times that eventually all air inside the ABS (mind you, only the air inside the ABS) will be washed into the reservoir, where it then rises to the top and is out of the fluid. No final bleeding required. Bosch 5.3 as fitted to 996.1 (with F/R circuit instead of diagonal split in the hyundai case) explained: https://en.ppt-online.org/361816

That�s a great breakdown, hardtailer. Thank you!

Should also be pointed out - stock 996 brakes have a �soft� pedal feel by default. Many posts going back to the aughts attest to owners struggling with this even after multiple rounds of brake bleeding. GT3 MC upgrade seems to make people happy. It�s also been suggested to undergo a full caliper rebuild.