Infrequent stutter at lower rpm

[dudecati]

Hi All - I've had my 91 318is for about 2 months now. In that short period of time it has always run very smoothly. In the last day or two I've noticed an infrequent (but becoming more frequent) stutter or stumble. Just quick jerks or uneven spots.

From what I can tell it happens between 2500-3200 rpm, it appears from having almost no throttle to giving it gas, also SEEMS to be as I feather on the gas - I'll have to try getting on the gas harder to see if I can replicate it there.

Any thoughts? I plan on putting new plugs in this week. I also plan to replace the fuel filter. Pointers and ideas are much appreciated!

[roguetoaster]

Sounds like a classic vacuum leak to me. Start with the intake boot and work your way down from there.

Are you sure it only happens from 2500-3200, not off idle too?

[dudecati]

Not 100% sure on that off idle question but I believe you are onto something - I've just not really felt it there so much. I have noticed that it can occur when I've been off the gas (like shifting) and then reapplying the gas - which really is off idle.

Thanks for pointing me in the vacuum leak direction. I already replaced the intake boot as it was cracked but have not gone into the rest of the vacuum possibilities. It was next on my LONG list of things to do!

Sounds like a classic vacuum leak to me. Start with the intake boot and work your way down from there.

Are you sure it only happens from 2500-3200, not off idle too?