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Car Forum / BMW Cars / May 2008E30 325i engine shudder
Hi all, I have just recently bought another E30, a 1991 325 convertible to replace the 320 i already have. The new car runs perfectly when driven but at idle there's a bit of a shudder from the engine every now and then. You can feel it shaking the car a bit when sat in a traffic jam for example, not constantly, just a few shudders every 10 seconds or so. I replaced the rubber engine mounts to see if they were to blame but it made no difference. The idle speed stays totally constant even when it shudders. With the engine running and the bonnet up, you can feel and see the shudder while at idle although you can't really hear it, no change of engine note or anything. Once driving the engine runs perfectly. The car's done 97000 miles and had a full service/inspection 2 just before I took ownership. Has anyone experienced a similar problem with M20s or have an idea what it could be? Thanks Mark > Hi all, I have just recently bought another E30, a 1991 325 > convertible to replace the 320 i already have. The new car runs [quoted text clipped - 7 lines] > you can't really hear it, no change of engine note or anything. Once > driving the engine runs perfectly. I'd try cleaning the idle control valve and checking the rotor arm / distributor isn't worn out. I'd also check for air leaks in the intake hoses.  SignatureWho needs a life when you've got Unix? :-) Email: john@unixnerd.demon.co.uk, John G.Burns B.Eng, Bonny Scotland Web : http://www.unixnerd.demon.co.uk - The Ultimate BMW Homepage! Need Sun or HP Unix kit? http://www.unixnerd.demon.co.uk/unix.html www.Strathspey.co.uk - Quality Binoculars at a Sensible price > > Hi all, I have just recently bought another E30, a 1991 325 > > convertible to replace the 320 i already have. The new car runs [quoted text clipped - 11 lines] > distributor isn't worn out. I'd also check for air leaks in the intake > hoses. Thanks John, I might try spraying some carb cleaner around the hoses then. The main intake boot that normally fails on these seems to be quite new looking at it, so I suspect that's been replaced recently already. Good idea on the distributor too, hadn't thought of that, although you'd think that it would cause problems at higher revs too wouldn't it? > already. Good idea on the distributor too, hadn't thought of that, > although you'd think that it would cause problems at higher revs too > wouldn't it? Maybe it is. It'll wear gradually so all you'll notice is a slow decline in high end power and fuel economy. SignatureWho needs a life when you've got Unix? :-) Email: john@unixnerd.demon.co.uk, John G.Burns B.Eng, Bonny Scotland Web : http://www.unixnerd.demon.co.uk - The Ultimate BMW Homepage! Need Sun or HP Unix kit? http://www.unixnerd.demon.co.uk/unix.html www.Strathspey.co.uk - Quality Binoculars at a Sensible price In article <1d47205a-dd80-4c0b-badb-e224f7aaad45@l64g2000hse.googlegroups.com>, > Hi all, I have just recently bought another E30, a 1991 325 > convertible to replace the 320 i already have. The new car runs [quoted text clipped - 7 lines] > you can't really hear it, no change of engine note or anything. Once > driving the engine runs perfectly. Idle misfire is often down to a poor spark - for whatever reason. The mixture is at its weakest and that needs the best spark. Check the usual things - especially plug leads. Signature*Is it true that cannibals don't eat clowns because they taste funny? Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound. On May 16, 3:56 pm, "Dave Plowman (News)" <d...@davenoise.co.uk> wrote: > In article > <1d47205a-dd80-4c0b-badb-e224f7aaa...@l64g2000hse.googlegroups.com>, [quoted text clipped - 14 lines] > mixture is at its weakest and that needs the best spark. Check the usual > things - especially plug leads. Right, thanks. Tonight I had a quick look and have more or less discounted a vacuum leak (spraying carb cleaner around didn't have any affect and all the hoses look good) so I think it's definitely ignition. I have also noticed another symptom which I'm hoping will be part of the same problem: with the engine at idle (hot or cold), if I blip the throttle on and off quickly (most noticeable if done by hand under the bonnet) there's a definite hestitation/flatspot before the engine revs freely. In fact if you watch the needle the revs seem to even drop a fraction before it picks up. To eliminate the plugs themselves I replaced them with a newer set from my 320 and this made no difference so I'm thinking about swapping the distributor cap, rotor and ht leads next. Does that sound sensible for the symptoms? Thanks again Rev it to 3000 rpm and then light your foot off totally. If it dips below idle and almost stalls that's a sign of a vacuum leak. > Right, thanks. Tonight I had a quick look and have more or less > discounted a vacuum leak (spraying carb cleaner around didn't have any [quoted text clipped - 9 lines] > rotor and ht leads next. Does that sound sensible for the symptoms? > Thanks again SignatureWho needs a life when you've got Unix? :-) Email: john@unixnerd.demon.co.uk, John G.Burns B.Eng, Bonny Scotland Web : http://www.unixnerd.demon.co.uk - The Ultimate BMW Homepage! Need Sun or HP Unix kit? http://www.unixnerd.demon.co.uk/unix.html www.Strathspey.co.uk - Quality Binoculars at a Sensible price >> discounted a vacuum leak (spraying carb cleaner around didn't have any >> affect and all the hoses look good) so I think it's definitely >> ignition. Never, never discount a vacuum leak. Go ahead and check the ignition but realize that there are many subtle ways for vacuum leaks to occur that are pretty damn hard to detect. Not as bad as with a carb, though, thankfully. --scott Signature"C'est un Nagra. C'est suisse, et tres, tres precis." Hi John, dropping down from 3000 to idle is fine, it doesn't dip below. Thanks. > Rev it to 3000 rpm and then light your foot off totally. If it dips > below idle and almost stalls that's a sign of a vacuum leak. [quoted text clipped - 12 lines] > > rotor and ht leads next. Does that sound sensible for the symptoms? > > Thanks again
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