Small gurgle on downshifts?

[bbiess]

I'm having a few of (related?) issues with my '04 3.0i that I'm hoping to get some suggestions on.

Disclaimer - I've only owned the car for a couple of years, so I have never experienced what it felt like new, so it may turn-out that everything it's doing is 'normai', but thats what I want to verify. It by the way has 31K miles on it and was maintained to the letter by the previous owner.

I was experiencing some ignition misses and some low speed bucking, so I took it to my local dealer who diagnosed the issue as a misfire on a single cylinder. A new coil and 6 new spark plugs (I decided to just get the other five plugs replaced as well) later and they reassured me that the issue was taken care of.

On my drive home I noticed none of the severe bucking, however, I still have the following happening, which I frankly thought would have been ignition-related as well.

1. Second gear, low RPM, throttle down - still some minor chugging that seems to clear up as revs increase.

2. Approaching a stop light, car in 2nd/3rd/4th gear, under power- very faint popping from the tailpipe, not really a backfire, more like a gurgle.

3. At said stop light, revving the engine - I get kind of a 'Shhhhhh' sound from under the hood (driver's side) then a after a very short delay the 'vroooooom' exhaust note. Is this throttle response delay normal?

I ran a bottle of fuel treatment in early spring and have only ever used premium no-lead fuel.

Normal? Abnormal? Common issues? No issues at all? Any insight, comments, suggestions and/or recommendations are much appreciated!

[bbiess]

Bump for 123 looks and no replies????

[Asianoak]

Well I'll reply just so it's not 124 views with 0 replies. Honestly can't give any feedback since I have a 3.0si with magnaflow exhaust so I always get some burbles and pops on downshifts although much less so since changing out my sparkplugs. Good luck on determining if it's normal for your model.

[bbiess]

Yay! A response!! Thank you.

[midlo]

Totally normal. These engines are a dog under 2000 RPM and trying to pop a downshift from down there will result in a big gasp and another second or two before it picks up. Try pulling all your downshifts earlier (2500 or higher) and you will no longer be mashing the brakes trying to get ahead of the slow response. Popping the throttle from idle does nothing but foul your plugs. If you want to hear it while stopped, ease it up to at least 1500 before romping it. Who does that anyway? Although BMW has done a pretty good job of giving us the best of both worlds, no performance engine runs well at low rpm.

Also on my 3.0i 60K, new plugs smoothed out the idle, new AF cut some of the gasping at low rpm, but I think the best overall performance bump I got was using Mobil 1 0w-40 over RL 5w-30 euro. Good luck!

[bbiess]

Thanks Midlo! This helps a lot!!

[Arsonism]

All I can say is that for me this was a desired aspect of an exhaust. Regardless it sounds pretty common to me and others have lent more insight than I could possibly.