HELP, annoying slight misfire!!!!!!

[stevebigo]

Hi all,
can somebody help with my problem, i am the very proud owner of a 91 525se
24v with manual trans, i have owned for about four months, although it has 180,000 it is in great condition and has full beemer history, i have always loved the straight six engines and the noise it produces , the problem is although it does drive beautifully and very smooth, it feels very slightly like it is holding back when excelerating hard,i just get the feeling that it is not 100% i have changed the plugs and checked all connections, is it possible that it has one of the coil packs breaking down??? i.e being the six cylinder not that noticable like the fours!!!! also the tick over sometime climb's to 1100 then back to 800, i love the beemer very much and so want to solve this problem to make it perfect, any help or advise would be appreciated,
thanks
steve

[winfred]

look for vacuum leaks in the air boot and the two hoses comming from the valve cover to the intake, the small one hides way back under the intake and connects to the fitting that the idle control valve uses to connect to the intake

[Steve525]

You dont describe your misfire very well. Does it happen when you are pulling away at lowish revs "under load". I had this problem and solved it by replacing the coil packs with a set of used newer ones. Reply if this sounds like your problem and I will get you more details re brands etc.

[stevebigo]

look for vacuum leaks in the air boot and the two hoses comming from the valve cover to the intake, the small one hides way back under the intake and connects to the fitting that the idle control valve uses to connect to the intake

Thanks winfred, i shall take a closer look tomorrow, its not much of a misfire, just enough to annoy, and i know that its big engine but seems to be thirsty too, i.e about 15-20 miles to the gallon, might be my keen right foot though!!!!!
thanks steve

[stevebigo]

You dont describe your misfire very well. Does it happen when you are pulling away at lowish revs "under load". I had this problem and solved it by replacing the coil packs with a set of used newer ones. Reply if this sounds like your problem and I will get you more details re brands etc.

Hi steve525, no it doesnt seem to misfire at low revs, will cruise around lovely but as soon as you excelerate its as if it holds back,about mid rev range under load!also it does pull through it, its not a great deal but just a bit hesitant!! i had a 12v 525 before this one and seemed a lot faster and responsive which i'm sure is the wrong way round!
i'm thankfull for any ideas,
steve

[dacoyote]

Steve,

Just something to look at on that M50 (I think).

Pull the coil packs and see if there is oil in the bottom of the well, if there is you got a value cover gasket leak... easy fix... expensive if you put off.

Just something easy to to check

[stevebigo]

Steve,

Just something to look at on that M50 (I think).

Pull the coil packs and see if there is oil in the bottom of the well, if there is you got a value cover gasket leak... easy fix... expensive if you put off.

Just something easy to to check

excellent thanks dacoyote, i shall check,
many thanks, steve