HELP BIG PROBLEM

[Hessom]

Okay, so I was out last night and I drove and parked the car. When I got back in the car and turned it on, it started, then I just watched the rpm's die down and the car shut off. I turned the car on again, and this time, I held down the gas a little after I turned it on. The car stayed on this time, however, the check engine light also stayed on. So i drove for literally like 20 metres, then turned the car off. When I went to turn the car on again, it would do the same thing. Even after holding down the gas, as soon as I let go of the gas, the rpm's would drop and the car would again shut off.
Does anyone know what could be wrong? The engine on my car only has 150,000 km which is approx. 90k miles and it runs very strong.
There is no problem starting the car, but it will not stay on.
ANOTHER problem that might be tied into this, I have noticed that my temperature gauge sometimes drops a little while i'm driving. It has never gone past the half way point, but after it is completely warm and I'm driving, it sometimes starts to say that the engine is getting colder and colder, which makes no sense (to me, atleast).
Could it perhaps be some sort of sensor that is broken causing my car to just shut off.
Again, the car has no problem turning on, and once it is on, if I hold down the gas it can stay on for as long as I hold it down. But as soon as I let go of the gas it shuts off.
The car cannot idle on its own? Any help would be greatly appreciate. Thanks.

[J!m]

I would check the MAP (Manifold Absolute Presure) sensor. Most likeley this is the first problem. The code reader will tell you for sure.

The second problem is likely the temp sender, which is on the side of the radiator. This is unless ALL the gages are dropping slightly, in whch case you have a bad instrument cluster.

[cdonahue]

clogged fuel filter? when was the last time you changed yours? mine got so bad the car wouldn't idle, and when i pushed in the clutch (driving) the rpms would drop a lot faster than normal. my engine code, however, said that it was the knock sensors... which it wasn't.
good luck

[DustenT]

I would check the MAP (Manifold Absolute Presure) sensor. Most likeley this is the first problem. The code reader will tell you for sure.

The second problem is likely the temp sender, which is on the side of the radiator. This is unless ALL the gages are dropping slightly, in whch case you have a bad instrument cluster.

As far as I know, we don't have a MAP sensor. The m44 uses a MAF (mass air flow) sensor.

[Hessom]

I have the M42 engine, does that have the MAP sensor?
About the fuel filter, I had an oil service done less than 600miles ago. Fuel filter is almost brand new.
The M42 has the OBD 1, so as far as checking why the engine light is on, do I just follow the procedures that include pumping the gas pedal five times, etc.? Again, any help would be greatly appreciated. Thanks.

[DustenT]

I have the M42 engine, does that have the MAP sensor?


No.

[Hessom]

Okay, so any ideas as to what the problem can be?

[J!m]

As far as I know, we don't have a MAP sensor. The m44 uses a MAF (mass air flow) sensor.

The MAF (Mass Air Flow METER) has nothing to do with Manifold absolute presure. MAF is the measurement devise for air volume entering the engine for fuel regulation purposes. The MAP sensor senses the absolute pressure (or manifold vacuum if you want to think of it that way) in the intake manifold for determining engine vacuum for the fuel economy calculations, among several others.

Who told you a MAF could replace a MAP? That's just silly...

I think you are confusing the hot-film air mass meter with the heated wire air mass meeter and the earlier 'barn-door' air mass meter. The later wire and film types are far more accurate than the barn door type as they also use ambient temperature to more accurately calculate the volume of oxygen entering the engine, rather than just the volume of air.

[Hessom]

Okay, so if the car has a broken MAP sensor, it is able to fire up, but not able to idle and stay on, right?
Jim, are there possibly any other things you can think of that might be the problem?
Thanks again.

[b.u.ti-ful]

Check to see if your oil fill cover is screwed tight. These engines don't idle if they're loose.

Also, make sure the plastic idle adjust screw on the manifold hasn't slipped out of adjustment.

Good luck

[DustenT]

Who told you a MAF could replace a MAP? That's just silly...


I'm pretty sure we don't have MAP sensors on our cars. I had one installed when I was running a datalogger (PLX R-500) and I know how they work. :)

When converting a car over to stand alone engine management, a MAP sensor will replace a MAF sensor. Any car that runs a blow off valve to atmosphere is most likely running a MAP sensor.

[Hessom]

Okay, so I went to where I parked the car, started it up and it was able to idle. I started driving it to the mechanic and the check engine light even disappeared. I dont know what is going on now, but I left it at the mechanics and they will deal with it some time this week. If you guys think of something in the mean time, please let me know. Thanks again.

[b.u.ti-ful]

So, what was the problem?

[Hessom]

I had the wrong spark plugs, and my wires needed to be replaced. Cost me $108cdn including labour (at a BMW dealership), but everything is fine now.

[hubrisin]

How difficult is it to replace a knock sensor? Does the intake manifold need to be removed? I need to replace my knock sensor on my 98ti.
Thanks

[mooseheadm5]

I'm pretty sure we don't have MAP sensors on our cars. I had one installed when I was running a datalogger (PLX R-500) and I know how they work. :)

When converting a car over to stand alone engine management, a MAP sensor will replace a MAF sensor. Any car that runs a blow off valve to atmosphere is most likely running a MAP sensor.

Just stumbled onto this one. No, J!M, no MAP sensor on these cars M42 or M44. M42 uses the VAF (vane air flow) to sense the amount of air and M44 uses MAF (mass air flow) to sense the mass of air entering the engine. Jap and American cars usually use a MAP sensor to sense the amount of air entering the engine. You can use a MAP sensor to run aftermarket fuel injection like Megasquirt (my favorite!) or you can use MAF. MAP is easier but less accurate, does not easily adapt for add-on components because you have to feed the computer approximate engine efficiency values for every load/rpm combination and air filters and exhausts change that, but works great for boost as you can build in boost pressure enrichment without extra sensors. BMWs calculate fuel economy based on requested injection pulse width (known fueling rate for requsted pulse width) and MPH, no vacuum sensors on a BMW engine whatsoever. As you can see, though, this system can be thrown off by wrong tires, different injectors, incorrect fuel pressure, etc.
-Paul