BMW 318i losing power - SOS

bluebubbles

Bought a 318i 2003 automatic petrol import recently. Driving fine for the last month but took it for a drive today and its lacking poke. Basically, when I put the boot down at lower speeds it noticeably takes quiet a bit of time to go up the gears and the engine revs. When it gets to a speed for a minute or so we'll then the revs ease and it settles until you press on the gas again. The manual option is slightly better but its still lacking power. I havn't really serviced it since I bought it but am about to. Any ideas really appreciated???

AzureAuto

Sounds like a misfire alright, possibly a coil pack is breaking down. Needs to be checked out. Even a good service could make a difference. Pm me for contact details of a good bmw mechanic...

bluebubbles

AzureAuto wrote: »

Sounds like a misfire alright, possibly a coil pack is breaking down. Needs to be checked out. Even a good service could make a difference. Pm me for contact details of a good bmw mechanic...

Thanks Azure Auto, your very good to respond. C'ant really get it looked at until Monday but do you know if its a big job....

beam99

Try disconnecting the air flow meter and drive it then, if the performance has inproved then thats your problem. The air flows do give trouble

dudara

The mass airflow sensor is often a culprit when there is a shortage of power. A good clean with an electronic cleaner, or a new MAF unit can help sort it.

Disconnect the sensor and drive without it hooked up. If things are smoother without it, then it needs looking at.

bluebubbles

dudara wrote: »

The mass airflow sensor is often a culprit when there is a shortage of power. A good clean with an electronic cleaner, or a new MAF unit can help sort it.

Disconnect the sensor and drive without it hooked up. If things are smoother without it, then it needs looking at.

Hi guys, seems like great advice. Can you explain how to disconnect or might there be a link on how to do this? thanks

dudara

Here's a link on cleaning the MAF - to disconnect it, you just need to pop out the electrical connector.

The MAF sits in the pipe leading out of the box where your air filter is located.

Muckie

Your Maf sensor is on the air intake pipe, little black flat box.
Its close to where you put the air filter in, standard press and release
clip holds electric cable to the sensor.



Hope it helps.(this isnt the BMW, just similar)

bluebubbles

dudara wrote: »

Here's a link on cleaning the MAF - to disconnect it, you just need to pop out the electrical connector.

The MAF sits in the pipe leading out of the box where your air filter is located.

Thanks guys, I done that there and drove it. It appears to be much better. Not perfect but far more power when say I get to kpm. Seens to be the problem I think but slightly concerned that the power isnt as prominent though still better from the off....

JHMEG

AzureAuto wrote: »

Sounds like a misfire alright, possibly a coil pack is breaking down.

318 is a 4 cylinder. Running on 3 cylinders means dog rough and engine will vibrate quite a lot. OP only mentions lack of power.

Checking for mis/non-firing: engine running pull a pack off a plug, one at a time. If there is *no* change to the way the engine is running then something's up with that one. Swap pack to another plug... does problem follow the pack?

dudara

bluebubbles wrote: »

Thanks guys, I done that there and drove it. It appears to be much better. Not perfect but far more power when say I get to kpm. Seens to be the problem I think but slightly concerned that the power isnt as prominent though still better from the off....

I know that when the ABS is engaged on mine, it doesn't accelerate as quickly. Turning off the ABS gives better acceleration.

bluebubbles

JHMEG wrote: »

318 is a 4 cylinder. Running on 3 cylinders means dog rough and engine will vibrate quite a lot. OP only mentions lack of power.

Checking for mis/non-firing: engine running pull a pack off a plug, one at a time. If there is *no* change to the way the engine is running then something's up with that one. Swap pack to another plug... does problem follow the pack?

Hi there,
Worth a go aswell. Any chance you would be able to send me a link to where the plugs would be? Handy with my hands but not to knowledgeable on cars and less so on Bmw's

Fishtits

dudara wrote: »

I know that when the ABS is engaged on mine, it doesn't accelerate as quickly. Turning off the ABS gives better acceleration.

dudara, I think you're mixing up ABS (anti lock braking) with something else - traction control maybe? ABS is not switchable. (assuming you're driving a BMW as per the OP)

A misfire would give you a warning lamp - OBDII mandates a warning lamp for any emissions related problem. The MAF sensor could in theory fail and remain under the radar.

Get it plugged in and analyse the fault codes would be my advise, auto trans can throw a curve ball.

Cheers.

JHMEG

bluebubbles wrote: »

Hi there,
Worth a go aswell. Any chance you would be able to send me a link to where the plugs would be? Handy with my hands but not to knowledgeable on cars and less so on Bmw's

Plugs = spark plugs. On the top of the engine, probably under a plastic cover. Here's another BMW (no idea which one), 6 cyl, coil packs labelled. Your's will look similar, but you'll only have 4.

http://home.earthlink.net/~frankie66/images/bmw_diy/valvecover/valvecover_coils.jpg

Like I said in my earlier post tho, if it aint dog rough you're probably looking in the wrong place.

dudara

Fishtits wrote: »

dudara, I think you're mixing up ABS (anti lock braking) with something else - traction control maybe? ABS is not switchable. (assuming you're driving a BMW as per the OP)

You're right - I was actually trying to remember if it was the traction control or ABS while I was typing it.

DubTony

I'd a similar problem recently. Disconnected the MAF and all was well. Put on a new one and the problem was back. Turned out it was a "bellows and a hole in a hose" (his words not mine). Nobody could tell me why disconnecting the MAF made it drive ok.

To the OP, don't drive for any length of time with the MAF disconnected. That'll cause more problems.

Myrddin

It really is adviseable to get the cars fault read FIRST, before going fault finding. At least then you have a frame of referance, and can identify which faults you have induced yourself. All thats going to happen now is that if the OP cant fix the car, she will bring it to someone who will read out the faults, sport the open circuit on the MAF sensor and charge her accordingly to replace it.

It may very well be the fault, and with the MAF disconnected, the car will run on preset values, which may explain why the OP feels the car is still not 100%. If the OP goes messing with coils now too, she will induce open circuit faults on all four cylinders, meaning whoever diagnoses the car will see euro signs (MAF & 4 Coils).

There are a few things which can cause these symptoms, Ive seen everything from a blocked up crank case vent valve, breather pipes perished, oil caps not sitting correctly, dip-sticks not seated correctly. It could have been an easy fix, but may well cost the OP more now in the long run.

DublinDilbert

DubTony wrote: »

Nobody could tell me why disconnecting the MAF made it drive ok.

With the MAF disconnected it will estimate the mass flow and default the mixture to "rich", which will compensate for the additional air getting taken in via the vacuum leaks, and make the engine run a bit better.

JHMEG

EnterNow wrote: »

If the OP goes messing with coils now too, she will induce open circuit faults on all four cylinders, meaning whoever diagnoses the car will see euro signs (MAF & 4 Coils).

Pulling a coil off a plug with the engine running will throw up a misfire at most, and will not do any damage or leave any codes that cannot be cleared by disconnecting the battery.

Myrddin

JHMEG wrote: »

Pulling a coil off a plug with the engine running will throw up a misfire at most, and will not do any damage or leave any codes that cannot be cleared by disconnecting the battery.

I didnt say it would cause any damage, it will however induce a fault code which might confuse the issue.

If the car has to go to a mechanic, he will surely see this fault as well as the MAF fault and think to himself sure enough these must be the faults, and qoute accordingly. The OP may advise the mechanic that the MAF and coils were disconnected, but whos to say they wernt the fault all along. Im simply saying its good practice to get a diagnostic done initially, in order to have a frame of reference, as disconnecting batteries to clear faults, isnt always 100% successful.

JHMEG

The OP didn't say the CEL was on, so there are no faults stored by the sounds of it.

Any decent mechanic will clear all faults first, as the conditions that trigger one fault can lead to spurious faults be triggered and stored (ie false positives). Eg a misfire can lead to a knock sensor fault being falsely triggered. Starting with a clean slate then the mechanic can identify which fault(s) is/are persistent.

Myrddin

JHMEG wrote: »

The OP didn't say the CEL was on, so there are no faults stored by the sounds of it.

Any decent mechanic will clear all faults first, as the conditions that trigger one fault can lead to spurious faults be triggered and stored (ie false positives). Eg a misfire can lead to a knock sensor fault being falsely triggered. Starting with a clean slate then the mechanic can identify which fault(s) is/are persistent.

Not all OBD faults will trigger an EML, there very well be faults stored but not deemed critical enough to alert the driver. Sometimes certain faults are required to endure multiple drive-cycles by the DME, before the EML is triggered, so your reasoning is flawed there.

I've seen "decent" mechanics clearing all faults before, and arrogantly assuming they will manifest again immediately, and many times Ive seen them biting nails and getting nowhere. A good tech will be aware of chain-reaction faults, and will often fault find back to source. By all means clear all faults to begin the process, but not before you have read them out before pulling connectors off. Im not posting to "prove Im right/your wrong" etc, Im simply saying its good practice to get a readout on the car, BEFORE diving in fault finding. Taking in a customers car and mindlessly wiping the fault memory will only lead to time-wasting.

JHMEG

EnterNow wrote: »

Not all OBD faults will trigger an

I thought the purpose of the light was to indicate a stored fault?

My post is from my own experiences. A customer bringing in a car with a CEL turned on can have a pile of unrelated codes stored. Of course a note is made before they're all cleared.

Myrddin

JHMEG wrote: »

I thought the purpose of the light was to indicate a stored fault?

My post is from my own experiences. A customer bringing in a car with a CEL turned on can have a pile of unrelated codes stored. Of course a note is made before they're all cleared.

If a an intermittent misfire is detected, a fault is stored but once the current drive cycle ends, the EML will go out if the misfire doesnt reoccur upon startup. Same goes for mixture faults, knock faults, map faults, voltage faults and various others.

Im posting from my own experiences too, 5 years as a bmw tech will teach you things the hard way sometimes

My god we dargged this thread off topic JHMEG Do you think anyone noticed?? Back on topic, OP let us know how your getting on...