engine shudder / vibration moticeable at low RPM

Hi all, I am a new member from Johannesburg, up until now my 2003 M3 has been great but last week while driving in heavy rain at low speeds, I noticed a shudder or vibration between 1500-3500 RPM. Even at startup, as you turn the key the engine feels uneven, but it idles ok and there is no noise to speak of. Between 1500-and 3500 RPM there is no noise just an engine unevenness / slight vibration or shudder, that the best way I can explain it.

I took the vehicle to the dealership, it is under warranty, they did a range of tests and gave me a 5 page printout to show all is in order, no misfire etc, etc. I asked about the spark plugs and they said they only change the at 100 000km.

What could the rain moisture have afffected?

I would really appreciate any comments or suggestions do you may have.

Thanks

Warren

It could possibly be one of the coils going out. It will run badly. Any loss of power?

Hi Jim,

I am still trying to determine if there is any loss of power, there may be some loss at the lower rev range but I cant say for sure whether there is any loss over 5000 RPM?

I was speaking to someone just now and they mentioned engine mountings

What do you think?

Thanks

Warren

I have never heard of an engine mount ever going in any E36 BMWs or E46 BMW's. I would highly doubt that is the problem.

When you went through heavy rains, did you also go through deep puddles? There is a "snorkle" from the airbox to the driver side brake duct. You can easily check to see if there is any moisure in the airbox that could be messing up the Mass Air Flow....just pull the 2 snaps on the airbox and lift out the filter. One side of the airbox has slots/hinges that half of the airbox hooks into. It will be a tight squeeze to get the air filter out without unscrewing all the hoses. Check under the filter to see if there is any moisture. If there is, it could be messing up the MAF, causing the uneveness.

Usually with the E46 M3's only two things will cause the engine roughness....MAF and Coils. If it's the coils, they will get worse and eventually you will have almost no power or the car will not start. There was a service action to replace all the coils (6) with a better brand for free and they were warrantied for 6 years/100K miles.

I'm thinking it's the MAF as it started after running in heavy rains. Do you have an aftermarket intake on your car?

When I was driving in the rain I did not go through any puddles, I first noticed the engine roughness in the rain while stuck in heavy traffic, at first I thought it was the air conditioner compressor kicking in as the uneveness reminded me of other vehicles I had driven and a similar roughness could be noticed when the air conditioner compressor had just began functioning.

After I while I turned the aircon off but the roughness was still there, thats when I started to suspect something else.

I have already taken out the air filter and there was no moisture to speak of just a lot of dust and debris ( I was suprised by the amount of debris as I had the 50 000KM service 2 months ago).

The air intake is standard as is everything else

I'm guessing the MAF. It could just be dirty. That would easily give you the rough idle and slight shudder. If the coils were bad, the engine would really be cutting out on you with possible stalling and a very noticeable loss of power.

You can easily pull out the MAF and clean it yourself. You need to first get a spray can of electronics cleaner. Something similar to this.................

http://www.defender.com/product.jsp?...0903&id=536256

When you say MAF do you mean the actual paper air filter? if not what is the MAF and how should I access it to clean it?

The MAF (mass air flow) is an electrical piece just past the airbox. Be very careful removing it as it is one big thin metal piece inside. Spray it down with electrical cleaner, let it dry, and then replace. If you bend it or drop it, it may never work again and it's about $250 USD replacement part. If you're not comfortable with this, let the dealer do it.

Thanks for the info Jim, I will get back to you in a week or so

Jim, I have booked my vehicle in at the dealership but I wanted to ask your opinon regarding something I noticed today.

While driving, the shudder / roughness is still there even if you take your foot off the gas and decelerate, as you go from 4000 rpm down, at approx 2000 rpm the shudder appears even with your foot completely off the accelerator pedal.

Also, if you put the vehicle in neutral , at a complete standstill and step on the accelerator pedal, as the revs get to 2000 rpm the shudder appears and then when you take your foot of the pedal and the engine revs come down again, the shudder appears again at approx 2000 rpm.

Does this change your view or advice at all on what I should tell the dealership to look for?

I'd still have the dealer look at the MAF and have them check all the coils. If it turns out to be one bad coil, they should change ALL 6 coils to the newer brand which comes with a 6yr/100K warranty.

I'm still guessing the MAF....it would give you a shudder as you stated at certain rpms. They should easily replace that part to check if the shudder goes away.

Let us know what the dealer finds. Their electronic equipment should be able to pinpoint the problem. If it were a bad spark plug, the "check engine" light would come on. It won't trip for bad coils for sure but I'm not sure about the MAF. Either way, let the dealer work on it.

Ok, I will let you know what they say

Hi Jim,

Just got my car back form the dealership, they reckon the problem is the flywheel, they have ordered a new one and it will will take 10 days to arrive.

They are also going to replaced the clutch for good measure

What do you think? Can the flywheel cause a vibration / shudder at low revs?

The flywheel could cause a vibration but I don't think if the car is in neutral that it would vibrate as you reved the engine. At least you'll get a new clutch out of it, even if that's not the problem. Keep us posted.

Hi Jim,

I just got my vehicle , it is sorted out 100%, they replaced the flywheel and the clutch.

They found one of the bolts in the flywheel had come out and was lodged somewhere and this unbalanced the flywheel at low revs!!!!!!

can you believe it?

Anyway it is like a new car, clutch as smooth as silk

thanks, and tell me what you think

cheers

Warren

Hey Warren. I am from JHB to man. Have a 04 SMG. I had the same issue on the E90 330i i had. They replaced the flywheel and clutch and all was better in the world.

Motorplan is an amazing thing isnt it

Motorplan is lovely but it took the dealer in Sandton 3 weeks of the vcar being in and out of the dealership for them to correctly diagnose the problem

anyway, nice to hear from you boet

cheers

how ironic. My car is doing the same thing. In 1st in low rpm's it shudders when i apply pressure to the accel. I also think ive lost power. Im calling the dealer now to take it in.

Does it also vibrate / shudder when it is in neutral? (approx 1500-2500 rpm)

No. And actually i didnt notice it yesterday. Im wondering if it is because of recent cold temps.

Originally Posted by Warren O

Does it also vibrate / shudder when it is in neutral? (approx 1500-2500 rpm)

Originally Posted by Ventoux

No. And actually i didnt notice it yesterday. Im wondering if it is because of recent cold temps.

same here....ugh

it could be a numerous things to do with your sensors ... the MAF sends voltages to the ecm to let it know the temperature and amount of air being induced if the voltages are incorrect you will recieve a hesitation or shutter in various rpm ranges ...sometimes temperature related ...the AIC or ACV air idler valve could be sticking ...this device controls most of teh lower rpms and idle it has a motor and they do go bad that causes a shutter.....bad coils cause a constant shutter or misfire.... bad camshaft sensor causes increased fuel usage with loss of power ....usually a shutter due to a sensor driven that way to long ruins actually working parts then it becomes more costly and or causes you to fail smog (like me) the TPS throttle position sensor sends voltages the the computer to corrilate the amount of throttle possition it is ...closed open sortive open ....the three wire tps's have alot of points of reading....if the tps is going bad it will act like a missfire or shutter at random times at certain rpms ...out of all these sensors the MAF and the AIC are the most exspensive i hope this helps

I had the same problem with my 540, infact i have changed a couple of coils and spark plugs but the problems keeps resurfacing. finally my mech-tech agrees its the MAF all the way.

MAF's are expensive hence searching for a cheaper alternative made for VW from Bosch.

He did a simple check, he applied the brakes and revved the engine at the same time, it never went beyond 1500 revs. he says, it should ideally pass the 2000 mark .

Wow, a loose bolt from the flywheel is a heck of a find. I would have never have guessed that.

question.. I am experiancing the SAMME vibrations in my 1984 bmw e30. Im gathering its probley the bolt on the flywheel as I dont think the 318i m10 has whatever MAF is. though is it alright to drive on for a week ? as its my only means of transportation.