Engine Problem - Help Please

[juser]

Hi,

Second issue of the night!

So I read earlier on about the OBC Code... Typically, I set a code and couldn't remember it! It was only the last 2 numbers, so I kept on trying to start it by entering a code and then failing!

So basically, I tried and tried and tried several times, until I'd had enough and unplugged the battery!

The car starts fine now, however, I've noticed that the car idle is jumping slightly! If I rev the car, as soon as it hits the bottom it stalls... Further more, if I press the gas very slightly, it almost hesitates!

When driving, so long I put enough gas, the car goes forward, but again, if only a light amount of throttle, it almost stutters and nearly cuts out!

The oil light has come up, I'm not sure whether this has anything to do with it!

Has anyone had this sort of problem before? This is on a 325i SE Auto

[Brianmoooore]

If disconnect the battery is ALL that you did, then hopefully the problem is that the ECU has lost its idle settings. Continue to drive the car and it will soon learn them again.
Oil light? The oil service light on the service indicator panel? Unless it's just a coincidence, this could be a sign of duff SI board batteries which couldn't do their job with the main battery disconnected. Worth changing them before they leak over the circuit board and destroying it.

[juser]

If disconnect the battery is ALL that you did, then hopefully the problem is that the ECU has lost its idle settings. Continue to drive the car and it will soon learn them again.
Oil light? The oil service light on the service indicator panel? Unless it's just a coincidence, this could be a sign of duff SI board batteries which couldn't do their job with the main battery disconnected. Worth changing them before they leak over the circuit board and destroying it.

Brian, I think it may be fair to say, you've been my knight in shining armour! Disconnecting the battery is definitely ALL that I did and that was purely to reset that bloody OBC code which i programmed wrong!

Speaking of the SI Board... It appears that sometimes it fancies telling me my brake lights aren't working, I have a look and everything is in tip top condition!

I'll keep driving the car as I did subtlety notice an improvement! Cars that learn huh... Now that's new to me!

[Brianmoooore]

Whatever the SI board does, it makes no comment on the brake lights. The SI display is concerned only with the annual inspection and service intervals for the oily bits.
Are you referring to the Check control mounted near the mirror? This should always indicate a brake light problem after starting the car until the brake pedal is first pushed, but if it comes on after that, there is probably an intermittent fault with the brake light circuit. Only has to occur for a fraction of a second for the light to come on and stay on until reset by switching off the ignition.
The most common cause in my experience is that the pull rod that goes across the car behind the heater box needs adjustment to take up 20 years of wear in the linkage. The brake pedal should only be able to be lifted a very small amount from its rest position. If it's sitting to low, the brake light switch might be switching on occasionally. If left too long, the switch will be damaged.
The pull rod has a normal thread at one end and a LH thread at the other end, so loosening the locknuts and turning it will either raise or lower the brake pedal.

[juser]

Whatever the SI board does, it makes no comment on the brake lights. The SI display is concerned only with the annual inspection and service intervals for the oily bits.
Are you referring to the Check control mounted near the mirror? This should always indicate a brake light problem after starting the car until the brake pedal is first pushed, but if it comes on after that, there is probably an intermittent fault with the brake light circuit. Only has to occur for a fraction of a second for the light to come on and stay on until reset by switching off the ignition.
The most common cause in my experience is that the pull rod that goes across the car behind the heater box needs adjustment to take up 20 years of wear in the linkage. The brake pedal should only be able to be lifted a very small amount from its rest position. If it's sitting to low, the brake light switch might be switching on occasionally. If left too long, the switch will be damaged.
The pull rod has a normal thread at one end and a LH thread at the other end, so loosening the locknuts and turning it will either raise or lower the brake pedal.

I think I may have identified the problem! I posted another issue and was advised that my water problem may come from a damaged tail light gasket! I've looked in the boot and guess what... There's water coming through and only on that side!

With regards to SI, i think I may have got confused with the check control and relating to another minor issue... I think the brake light coming up is related to the water.

By the way, when I said the oil light came up, I meant on the check control! I'm guessing I better add some oil?

[Brianmoooore]

The oil light on the check panel is set to be very pessimistic. It comes on when the oil level is still well above the minimum level on the dipstick, and will come on earlier still if the car is parked uphill or with the LH side higher than the right.
The water itself won't cause the brake 'check' light to come on, (water has no effect on low impedance, low voltage electrics) but if it has caused any corrosion it might.

[juser]

Stop tinkering for a while and enjoy the car.

Valid point, but water coming in to the boot isn't cool... Not on the long term

[Speedtouch]

You may need to disconnect the battery again, leave it for an hour or so to reset the ECU, reconnect, let the engine idle for at least 10 minutes to enable base idle settings to be learnt, switch off, then go for a drive throughout the rev range in all gears.

This ensures full data transfer from the EPROM to the processor.

[juser]

You may need to disconnect the battery again, leave it for an hour or so to reset the ECU, reconnect, let the engine idle for at least 10 minutes to enable base idle settings to be learnt, switch off, then go for a drive throughout the rev range in all gears.

This ensures full data transfer from the EPROM to the processor.

OK - Thanks, I'll give this a go when I get home later - Thanks

[juser]

You may need to disconnect the battery again, leave it for an hour or so to reset the ECU, reconnect, let the engine idle for at least 10 minutes to enable base idle settings to be learnt, switch off, then go for a drive throughout the rev range in all gears.

This ensures full data transfer from the EPROM to the processor.

Gave that a go, still didn't work! Still drives fine, but again, becomes a bit hesitant before going if i don't put enough gas and when the car is in neutral if I rev it, as soon as it drops back down, it just cuts off... This is on an auto, so I'm not sure whether that makes a lot of difference.

[Brianmoooore]

If it doesn't sort itself out on its own, start looking for air leaks between the air flow meter and the inlet manifold. The large convoluted hose can split, there's a rubber cap blanking off a small stub pipe under the throttle body (if your car doesn't have a cat., etc.) that rots and falls off, there's a metal elbow (or two) that goes into the RH side of the throttle body that can come loose, etc., and then check out the throttle position switch for correct operation.

[juser]

If it doesn't sort itself out on its own, start looking for air leaks between the air flow meter and the inlet manifold. The large convoluted hose can split, there's a rubber cap blanking off a small stub pipe under the throttle body (if your car doesn't have a cat., etc.) that rots and falls off, there's a metal elbow (or two) that goes into the RH side of the throttle body that can come loose, etc., and then check out the throttle position switch for correct operation.

One of my friends is a mechanic! I'll flag this to him and pass on your comments as being very honest, I know cars, but this is slightly too technical form me and I'd rather someone better qualified to look at stuff like that - Thanks again for your advice Brian