major juddering at 2000 rpm cruise!!! help dammit!!!!

[hairypete]

ok, this is drivin me loopy! drive it hard, and there is no problem, but try and cruise at 2000 rpm and she starts juddering very violently, i have done the 2 to 2.5 litre conversion and since then it is just getting worse and worse. i am almost sure its not bushes, and the prop is well tight and where it should be. the clutch was replaced when the engine was swapped and as far as i know everything is as it should be...well nothing is hanging off!

someone mentioned it might be something to do with the little box on top of the air filter, but its sealed up good and tight and i dont wanna make things worse before i know for sure!

and before someone thinks it would be funny to say keep drivin it hard then...i would but i can only get 180 miles out of a tank when i do that, so its not a real option!

hope someone can shed some light in my hour of need!

[16azev_needed_for_my_e30]

Have u checked your leads/ spark plugs - start with the simple - cheap things first

[billgatese30]

mine started doing this when the inlet manifold went. does it sound like there is air leaking from somewhere when the bonnet is up and the engine is on tickover?

[Andy_magic]

I've had this, it was down to a weak mixture caused by a vacuum leak.

[Martinaston]

As you started refering to prop shaft and clutch i take it its not the engine playing up.
If the car feels like it's bouncing backwards and forwards below 2k revs in any gear it's wear in the drivetrain driveshafts/diff/gearbox.
Jack one wheel up and if you can spin it slightly with it in gear then crawl under it and see if the prop shaft is turning as well, if it is it's the gearbox (rebuild)
If its just the one wheel that moves its the diff
If the shaft on the other side moves a bit as well it's the shafts (Ԛ£200)
Knackerd car?

[Pete159]

I had this problem on my 325. I had a spare one to fit which cured the problem. The box on top of the airflow meter I replaced had been opened before so I opened it again, cleaned the carbon track and carefully bent the wiper to increase its contact pressure. Seal the box again with a suitable sealant (silicone sealant as used in DIY). This fault is probaly caused by cruising for long periods at 50 mph (aproximately 2000 rpm).

[Andy_magic]

I hadn't thought of the AFM. Good point

[hairypete]

cheers guys, will check the diff out martin, it could be tht on its way out, its still the two litre kit runnin under there so it might be gettin a hammerin from the 2.5 engine.

i know its not the ignition side of things, i have replaced it all a few months ago, from the coil to the leads, dizzy, rotor arm, plugs and even a new bit of trunking above the exhaust manifold! been very definate in checking it all over again and again.
and thanks to pete, will rip the airflow box apart aswell and have a nosey. i take it blue tack isnt the recommended sealant???

ok once again thanks guys, will let you know what i find out after the weekend.

[Martinaston]

I'll be absolutely clear just in case your not the sharpest tool in the box (no offence) but when i said try turning the wheel i was refering to turning it by hand with the engine OFF (don't mean to be patronising but you never know with some people)

I take it you have an open diff? As it is a little trickier to tell with a limited slip.

If it's wear in the gearbox and only slight you may get lucky and get away with changing the oil to a thicker grade to take out the slack but that can sometimes lead to problems with the gear change especially when cold.
(if it's a realy worn gearbox fill it with sawdust and sell it )
Only kidding (but i have seen it done)

[hairypete]

ah bugger, you could have told me that earlier, i had the back jacked up with the engine going and wheels spinnin lovely in fourth, ...

well i dunno about the sharpest in the box, but i managed to swap the engine in one long day, the only snag the two of us had was with a leaking engine hoist that we had to keep puoring in oil as we pumped! lol, all good fun, but yeah i got what you meant! cheers for the concern...awww you care! lmao!!!!

once again, cheers, and will let you know after the weekend. cant wait! oh, and anyone live up near stafford or alton towers and fancy meetin up for a pint and a chat, be good to meet some fellow zoners...

[Martinaston]

I had the same problem with a crap halfords jack and thought it was stange when i couldn't get the wheel back on