BMW E30 320i Engine Shuddering

Hi

I have very recently bought myself my first car, a 1987 E30 BMW 320i. I have had to repair a few things along the way costing me a couple of loans from my dad. However the current problem Iam having, I cannot seem to fix. So here goes,

When Iam accelerating from idle (+-800RPM) to about 3000RPM the car performs brilliantly. The problem starts at about 3200RPM to 4000RPM when the car starts to shudder violently. It however does not seem to lose any revs but does cause a loss in power. I was told by a friend that I should replace the rotor arm and the distributor cap which I have done. This looked like it had fixed the problem but It now seems to have come back. This problem has started since I bought the vehicle as it was fine for the first 3 months of ownership!

Does anybody have any suggestions at allbecause Iam afraid that this shuddering is causing undue engine wear which I cannot afford to repair. Iam currently thinking of replacing the HT Leads, the Coil and the Spark Plugs.

Any suggestions would be greatly appreciated

Thanks

Hi Dergside

I have already put in a new clutch and a new master clutch cylinder so it cannot be that. It could possible be the drivetrain which I do think is slightly unbalanced as I get a slight vibration through the car at about 50 MPH. Allthough would this really cause the engine to 'missfire' (for lack of another word). Rather than a shudder I could describe it like when you are accelerating and at about 3600RPM suddenly pulling your foot totally off the accelerator and the immediately putting your foot flat on it again. You get a sudden jerk. Also, forgot to mention that this happens about 3 times between 3000 and 4000RPM. And even stranger, the engine works fine above 4000RPM all the way to the highest I ever pushed it at about 5700RPM.

BeemaBoy

I used to have a 3.0i 24v Vx Senator that had a violent hicup in the rev range.  This turned out to be the distributor.  Previously I was getting a screach from the dizzy which tuirned out to be a worn/dry bearing.

It came to a conclusion while doing 80mph in lane 2 on the M1 when the dizzy bearings finalied failed so the shaft was able to whip and pushed the rotor arm into the side of the dizzy cap and shattered it into a million little pieces, shuddering and a noise like timing chains leaving the block and being trailed on the tarmac below.  You could actually wobble the dizzy shaft in the bearings.  1 No. new dizzy please.

As the shaft whipped the timming of the spark was interrupted so you get the hicup.

New dizzy cured all the problems.

Take the dizzy cap and rotor arm back off and try and move the dizzy shaft, if you can wobble it, you need a new one like mine!

About 9 months before the above I had replaced the dizzy cap which seemed to help but it gave out eventually.

By the way when did you last change the sparkers on it?  What are the HT leads like too?

Sounds like an electrical fault.

Andrew

Hi

Thanks very much to all of you for your suggestions.

Firstly I will talk to my mechanic about that 'Dounut Coupling' and see what he thinks about servicing or replacing it. I actually thought that the distributor shaft could be at fault and I initially tried to move it, but it is rock solid in its mounting. To recall to when I last changed the spark plugs or HT leads is impossible, because I have only bought this car about 6 months ago and have not got the miles needed to replace these items.

An interesting thing though, when I actually had a closer look at the HT Leads, the one on the sixth cylinder has some black electrical tape on the join between the cable and the connector(where it fits ontop of the spark plug). Could this have been used to cover up a hole or cut in the cable and it has just recently got worse, so the tape no longer keeps the spark in, and therefore the problem now occurs?

To answer b318isp question. The economy guage does 'flutter' back towards the middle and then back to the right hand side again, but I dont seem to lose any revs at all, only speed. And no, it does not do this when it is stationary and even worse ,when I rev it to the problem range in neutral, there is no 'hicup'. So figure that!It only seems to give trouble when it is under load!

Iam actually thinking or replacing the spark plugs as they a pretty cheap, but the HT leads are a bit more pricey. I was quoted about 36 pounds excluding the plastic HT rail and the rubber cover that all lie in. Is this a good price? I will only go a head if you guys think it is worth it .

Thanks

What concerns me is that it only happens between a certain narrow rev band. A failing plug lead should cause a problem over a greater (and higher) rev band than that.

Try driving along in 4th or 5th car. When the splutter occurs, vary the position of the accelerator pedal (incl. putting it to the floor). Try an see if the postion of the pedal affects it (this is to see if the Air Flow Meter is a potential cause).

A spark lead fault also would not explain the fluttering of the econometer. This is suggesting that the ECU is receiving information that is causing the flutter, e.g. the Air Flow Meter or the crank sensor.

Can you borrow one plug lead to replace the one with tape as it will quickly prove (or not) its causation before you spend money?

Does this car have sequential injection?

Yes you can use a bit of WD on a flap meter.

The crank sensor, senses the crank timing.

Girlfriend had a Metro with a cracked plug that only gave a 'chug' at about 3,000rpm and only once!! Starnge as to why iit only did it then - replaced it and it was fine.

If you have a small black box on the inside of the nearside wing replace the relays under it, these would be your DME and fuel pump relays on a Motronic car but i'm not all that on the old Ljet.  On the Motronic these relays failing cause exactly the symptoms you desribe.

AFM shouldn't need cleaning with WD40, thats the wrong stuff to use, you ideally want to clean it with carb cleaner as this doesn't leave a residue and allow dust etc to stick to it.  I doubt the AFM is sticking they tend to be pretty good, if it was the AFM then it's more likely to be a worn out track in the top.

Edited by paul325i

I know, but you shouldn't need to lube it for it to work smoothly.

Hi Guys

I have eventually got around to getting to the Parts Centre and I managed to get the sales clerk to score me only one HT lead to replace the faulty one, and guess what, the problem still occurs. Will be replacing the spark plugs tomorrow to se if that gives any joy.

On a different note, I got this response from a memeber of another forum I posted the same question at. Does this sound right?

------------------------------------------------------------ -------

I had a hunch it could be the catalytic converter so I looked up a little info for you as reference.

These are all signs that your catalyst is clogged going.
I think the excess exhaust dispensed at higher speeds is choking up your engines and giving you some of these symptoms if not all. As the MAF's were pretty solid on here, and if a clogged fuel filter will usually affect performance more noticeable at other times as well, like no starting, or clean itself out with gas detergents.

Markedly decreased low rpm power,
Engine runs a little hotter than normal at constant cruising speeds,
Exhaust leaks near header that won't seal in spite of new gaskets,
Bucking or hesitation while accelerating,
Cat's exterior surface temp cooler near outlet.

------------------------------------------------------------ -------

I also funnily enough remember my father telling me that we do not have Catylictic Converters (excuse the spelling!) fitted to our cars in South Africa. Is this correct or have I been drinking too much again???

Thanks

BeemaBoy wrote: These are all signs that your catalyst is clogged going.I think the excess exhaust dispensed at higher speeds is choking up your engines and giving you some of these symptoms if not all. As the MAF's were pretty solid on here, and if a clogged fuel filter will usually affect performance more noticeable at other times as well, like no starting, or clean itself out with gas detergents. Markedly decreased low rpm power, Engine runs a little hotter than normal at constant cruising speeds, Exhaust leaks near header that won't seal in spite of new gaskets, Bucking or hesitation while accelerating, Cat's exterior surface temp cooler near outlet.

You probably don't have a cat and certainly don't have a MAF. The solutions mentioned do not explain why the problem occurs in a limited range.