M5 poor performance and missing - The Unofficial BMW M5 Messageboard (m5board.com)

AustralianM5 · 9th March 2006, 05:10

I have been reading threads here for weeks now but am not sure the problem with my car has been described exactly. It accelerates OK up 3000 rpm or so and then there is a sudden jerk and loss of power where the engine appears to be missing, there is no check light coming on and the car will not accelerate very well, it will however cruise perfectly well. The induction roar changes during this phase of WOT but with little acceleration. This behaviour is worse with high ambient temperatures, its possible to get to 7000 rpm in first and second it just won’t do it very quickly, in cool weather it almost seems like a fast car.

At the local dealer they changed a cam position sensor but said that it was otherwise OK. I later changed the spark plugs also. The car has done 145,000km/90,000 miles, we have 98 octane fuel which I exclusively use. I did the MAF test described on this forum and it only gets to about 90 L/H but am not yet convinced that it is the MAFs yet. MAFs here are $890 each but there are none available right now.

I have had this car for 3 months now and have yet to experience the power everyone raves about, it will be great when I get it running right.

Jayson · 9th March 2006, 05:20

Turn off the traction control.

AustralianM5 · 9th March 2006, 05:26

Jayson

Yep thanks but I do already religously turn off the traction control every time I get in the car.

Thanks Anyway

Jayson · 9th March 2006, 05:51

Quote:

Originally Posted by AustralianM5

Jayson

Yep thanks but I do already religously turn off the traction control every time I get in the car.

Thanks Anyway

Alright sorry, I have seen that a few times though. If you did plugs mafs and all I"m not real sure.

silver00 · 9th March 2006, 06:06

You couldn't get in on DavidS's group buy for MAFs? On the surface, it does seem like a MAF issue to me if you're not getting any other SES faults.

How about the rest of Inspection II items? Did you change air filters? Fuel Filter? etc?

I'm sorry your car is running poorly. But the first things I'd do is make sure it's up to date on maintenance (including fresh MAFs and maybe even O2, and Cam Position Sensors).

gsfent · 9th March 2006, 06:18

Quote:

Originally Posted by AustralianM5

I did the MAF test described on this forum and it only gets to about 90 L/H but am not yet convinced that it is the MAFs yet.

That number is not even close to healthy MAF. 120 or so is considered a good working MAF depending on temp, humidity, altitude. I have seen 142, others have seen as high as 160.

Quote:

MAFs here are $890 each but there are none available right now.

DavidS has a group by at $115 and you can pick up a vW MAF for around $60-$65. Not sure about shipping. You do have to swap the MAF out of the housing, you will need a 5 or 6 point torx bit. Some people have been able to undo the torx with a pliers.

Given the cost of the MAFs, you definitely need to replace yours. A very cheap investment. It will be a different car.
Regards,
Jerry

rigsby · 11th March 2006, 00:02

Hi
I had a very similar problem to you, but it seem intermittent, in the end changed the 02 sensors (didnt seem to make much difference), the MAFs (seemed to make a big difference) and a camshaft position sensor (again big difference). Still not sure its a 100% but can live with it.

aaronmiles · 12th March 2006, 09:43

Quote:

Originally Posted by AustralianM5

I have been reading threads here for weeks now but am not sure the problem with my car has been described exactly. It accelerates OK up 3000 rpm or so and then there is a sudden jerk and loss of power where the engine appears to be missing, there is no check light coming on and the car will not accelerate very well, it will however cruise perfectly well. The induction roar changes during this phase of WOT but with little acceleration. This behaviour is worse with high ambient temperatures, its possible to get to 7000 rpm in first and second it just won’t do it very quickly, in cool weather it almost seems like a fast car.

At the local dealer they changed a cam position sensor but said that it was otherwise OK. I later changed the spark plugs also. The car has done 145,000km/90,000 miles, we have 98 octane fuel which I exclusively use. I did the MAF test described on this forum and it only gets to about 90 L/H but am not yet convinced that it is the MAFs yet. MAFs here are $890 each but there are none available right now.

I have had this car for 3 months now and have yet to experience the power everyone raves about, it will be great when I get it running right.

Hey mate ... im in Melbourne, if you are too we can catch up and do some testing.

You have some different options for MAFS in Australia.

DaivdS's group buy is the one that I took. US$115. You can get the VW part and just change over the sensor, but from other board members testing, they are 'close but not close enough' and does not have the temperature sensor, which is a problem if you are using a standard intake. If you are using an IATS kit then it may work just fine

If you really want the BMW ones and they are ex-germany, then I suggest you try Imparts (www.imparts.com.au) and hanvic (www.hsy.com.au) which will probably have them in stock even if BMW does not. When I last checked they were $550 or so. There is a good bloke at BOSCH in Melbourne called 'ARN' (03) 9543 5283 who actually has an M5. The Bosch part number is
0280-217-533 "Air Mass Meter". Now that is for the entire assembley rather than just the sensor.

Here are my notes for when I was looking

Hanvic - 631.95+ inc

Imparts - Ed: 9417-4857 $520 (inc) in stock

AustralianM5 · 14th March 2006, 08:37

Aaron
G’day I thought I was the only skip on here! Thanks for the very kind offer to test with your MAFS but a mate of mine just bought an E39 M5 front cut to convert his E34 M5 to an E39 engine. I have borrowed his MAFS and sent those and my car to a non-dealer BM specialist to sort out. Testing has again revealed the VANOS is OK and the car is running lean which could be fuel flow or pressure as well.

Are you sure that the separate temperature sensor is needed, only 4 pins of the MAF plug has a contact in them I assumed that it was the separate temp sensor that was not used. I do have a standard intake system, what is the IATS kit?

Thanks also for the other leads I will wait and see what advice I get from the bloke looking at my car today before I buy any more bits, the VW parts seem so cheap they may be worth a try.

I will be at the next BMW Club Victoria meeting, first Monday in April it would be good to talk with another owner of this car. The car club details are at: http://bmwccv.bmwclubs.asn.au/

aaronmiles · 14th March 2006, 09:14

Quote:

Originally Posted by AustralianM5

Aaron
G’day I thought I was the only skip on here! Thanks for the very kind offer to test with your MAFS but a mate of mine just bought an E39 M5 front cut to convert his E34 M5 to an E39 engine. I have borrowed his MAFS and sent those and my car to a non-dealer BM specialist to sort out. Testing has again revealed the VANOS is OK and the car is running lean which could be fuel flow or pressure as well.

Are you sure that the separate temperature sensor is needed, only 4 pins of the MAF plug has a contact in them I assumed that it was the separate temp sensor that was not used. I do have a standard intake system, what is the IATS kit?

Thanks also for the other leads I will wait and see what advice I get from the bloke looking at my car today before I buy any more bits, the VW parts seem so cheap they may be worth a try.

I will be at the next BMW Club Victoria meeting, first Monday in April it would be good to talk with another owner of this car. The car club details are at: http://bmwccv.bmwclubs.asn.au/

The system running lean will be your MAFS I would think, get those working properly, and you will see the mixture return to normal. A bit more likely than fuel pressure related, especially since you are having MAF problems. If you were having lean issues with perfect MAFS Then it would point to fuel. Check your O2 sensors also. You can replace these easily yourself. I got a set from Bursons next day delivery and I think they were about $120 each or something. NTK (NGK) make them and they are a direct fit and have been good for me.

Get them to check the diagnostic voltage (pin 3 and 5 I 'think') to see how fouled the MAFS are. 1.00v is perfect.. 1.01 -> 1.03 is 'normal'. For example, my original MAFS were 1.12 which flowed about 120lt p/h. Got my new set and the flowed about 160 until they settled back to about 140 and have a diag voltage of about 1.02.

Both MAFS have a temp sensor but only one is used. They are 4 wire on one side and 5 wire on the other side.

If you want the long version of what an IATS is, there are many articles about it, just do a quick search for it. The quick and nasty explanation is that the temp sensor in the MAF suffers from heat soak and sends figures to the DME that are higher than the actual air coming in. The IATS is a temp sensor that you put where the heat of the radiator and such like is not going to inflate its figures. board member Elevens ( I think it was him) mounted his on the entry to the airbox, and I have done the same thing which I think is the easiest position to do it.

http://www.beastpower.com/Merchant2/...Store_Code=BMI

They are worth the money as the most accurate the figures coming in the better the car will be able to adapt to the ACTUAL conditions rather than PERCEIVED.

Cheers,
Aaron