E46 330ci trembles at idle and engine light on, no smoke, no oil leaks..

"Brian Lam" wrote

There are so many causes of engine light on that it's useless to even try to diagnose it without READING THE F#$%^ CODES.

FloydR

Low fuel; wrong fuel, contaminated fuel, clogged lines..

Faulty ignition, disconnected / broken spark plug leads, oiled plugs.

Machanical failure, broken ring / burnt valve in one cylinder, slipped valve or ignition timing belts.

ECU fried.

What piece of over enthusiastic driving brought this condition on?

O2 sensor on the way out?

How old is the car and what milage has it done?

Had a similar problem two months ago (also 330ci e46) and it cost an arm and a leg to fix - throttle control wiring had a high resistance.

Hope it's the sensor!

Ranger

I had a similar problem on my E46 325i. The problem was the ignition coils. They were replaced under warranty. I had the car towed to the dealer back then, but was told it was OK to drive (although there would be significant loss of power).

Of course, that may not be the problem in this case.

Anoop

The possibilities are endless. What you need to do is pull the trouble codes. This is easy and free at Autozone. If you are in California, you can visit an Autozone store, where they will put the scan tool on your credit card and you take the tool home with you. After pulling the codes, you return the scan tool and Autozone puts a Full Credit for the previous "purchase" back onto your card, making the tool free to use.

There is a data port along the bottom edge of the dashboard that you plug the scan tool into. Once the scan tool is connected, set the Igniton Switch to ON but not START, and the codes that are stored will be displayed. Come back here with the code list and we should be able to help you determine what the repairs needed will be.

I like this link for diagnosing the codes ...

Once you pull the codes and jot down the list, you can reset them -- directions are on the scan tool. After you start the car and it runs poorly and the Check light comes on again, yuou can repeat pulling the codes, and this will tell you what the actual problem is. (Codes can be stored from months ago that are truely transient problems that have nothing to do with the price of beans today, so the second pull of codes will give a code that matches one from the first list, this will be the actual problem and all of the others are likely to be old and of no consequence.)

If you are outside of California, I do not know if Autozone will do the same -- allow you to leave the store with the scan tool. You can purchase a scan tool for less than BMW charges for the service to extract the codes though. And, if the problem is one that you can fix at home, the scan tool is a good buy, but if the problem requires dealer service (or equivelent), the education is probably worth the cost of the tool. The scan tool is not unique to your car, you can use it on any 1996 or later make or model automobile or light truck.

By your description -- runs rough at idle -- my money is on a bad ignition coil. Your car uses a separate ignition coil for each spark plug. Along the top of the motor you will see two round plastic plugs, pop these out with a small screwdriver -- be careful to not brake them. This allows the entire top cover of the motor to be lifted out. Under this cover, you will find the coil packs with the spark plugs immediately below them. The coil packs are held on with two 10mm nuts, and the spark plugs take the standard 5/8" (15mm?) Spark Plug socket.

If this is the problem, the cost of the scan tool and a coil pack will be less than the cost of the service call at the dealership.

If you are new to this sort of thing, I suggest you get a friend that is not new to it to help guide. Reward the friend with a 6-pack after the job is done. There are common things -- anti-sieze compound -- that should be done with installing plugs that one familiar with this sort of thing should already know, and which if you are not aware of can create problems down the road. The work is easy if it is what I suspect is true, but if not done right, you can shoot yourself in the foot.

None of these will turn the Check Engine light on.

There are no spark plug leads.

It is probably not safe (for the car) to drive. Surely, it will be no fun to drive.

Don't know about the E46, but there was a coil recall for my 3 liter Z4 (same engine as the 330i) in late 2005. So if that's the problem, a dealer should fix it at no cost.

Tom K.

Just a guess (with the same engine in my E39 and having the experience twice), but BMW's supplier provided a large batch of bad coils which have failed regularly. Only cure is to go to a dealer (preferred ... I think they should replace as a good will fix, it was a recall item) or indy mechanic to read the codes and replace the coils. Even if its not coils, the only way to diagnose is through an OBD code dump.

If it is a coil, you can just replace the effected coil(s), but the latest bulletin is to replace all six. Of course, if its your nickel, you might want to just go after the bad one and spread the cost of replacement over time. OBTW, if you determine which coil, it's about a 15 minute DIY.

R / John

There are, but they might not be HT, unless the 330Ci is really a diesel...

Okay, but the "leads" are part of the coil pack, they are not wires. They can not be not connected, but they can be physically broken/burned to a crisp. If this is the case, one must remove the coil to find out.

I meant the wires going to the coils, which might well be subject to damage.

The "control wires" leading to the coils are not bullet proof, but they are protected. I seriously doubt any damage to these wires, especially on an E46. I'm not sure the first year of the 330, but my recollection is around

2005. This makes the car about 3 years old at this point. Surely the wires will survive 3 years.

But still, one must pull the plastic cover off the top of the motor and get close to the coil pack(s) to investigate this.

There is nothing the OP can do from here without pulling codes first. Well, there is nothing he can do with any degree of certainty ... He can poke around and hope, I suppose.

Just talked to a BMW master tech on a forum, he also reckons the coil pack as he has done quite a few with similar symptoms. Let's see what code he'll get when he visit the dealership coming Thursday (earliest). He's in London so he has to book the car in and pays a premium just for pulling the code.

For less than the cost ot pay the dealer to pull codes, you can buy the scan tool and pull codes yourself. TYhen, you will have the scan tool and can pull codes on any '96 and later car or truck. (Since you said you are in London, you may have different rules as they apply to the OBD II specification.)

In any case, this is data that should be available to you from the OBD (On Board Diagnostic) system, you can buy the tool that pulls the data for less than it costs to pay the stealership to pull it.

I just bought my second vehicle that is a post-'96 model, I will be buying the scan tool from my local auto parts store as soon as either of them turn the Check Engine light on.

You may have seen another on this thread that said there was a recall on your coil packs. Be sure to investigate this before you pay for these parts. His car is the Z4, but the motor is the same and the recall ought to apply ...

I'm with the above - I had this symptom with my E46 325i and the coil recall solved the problem. epbrown