MAS Sensor?

[GregE240]

Help - I think I've fallen foul.

Started car earlier, pulled out of road - absolutely NO power or torque - if I managed 40 up the hill near us I was lucky. Car has no "go" at all, and feels very sluggish.

Got car back home, and on drive it won't rev past 4000rpm.

I've got a horrid feeling I know what the problem is....can someone confirm the bad news for me?

Just got paid - how ironic.

Thanks,

Greg

 

[GregE240]

Well, thanks for the overwhelming number of replies

Car seems okay now, no idea what it was. Running on Optimax for a while now for cleaning purposes.

 

[Ian B Walker]

Originally posted by GregE240
Well, thanks for the overwhelming number of replies

Give us a chance eh, not everyone lives on here. Sometimes you can wait for ages before getting a reply to a question. Just depends if the relevant guru logs on, on the particular day you have the problem. But anyway glad to know that you have a result. I am using Optimax for a while too to clean up my lump, dont notice any difference as yet, but early days.

Ian

 

[GregE240]

Fair point Ian, and taken.

I'm also running a dose of Comma's "D-TOX" through the first tank of Optimax. It is recommended by BMW, even has a part number on it.

Did a quick search of the BMW GB forums and a number of people on there seem to rate it.

I'll report back.

Cheers,

Greg

 

[Ian B Walker]

That will be interesting Greg, what is this D-Tox? can you give us a run down on it or a link to the manufacturers web site if they have one. I am doing a booze cruise at the end of Nov and want max peformance and reliability out of my car, seing as how we are going to do Preston-Dover-Calais and Belgium and back in one day. The engine has a lot of miles on it so I need to ensure that everything is spot on. Doing an oil / filtre change during the week and am considering a synthetic oil after a real good flush out. Anyone out there with advise on oil brand?

 

[Dieselman]

Originally posted by Ian B Walker
Doing an oil / filtre change during the week and am considering a synthetic oil after a real good flush out. Anyone out there with advise on oil brand?

I like Millers oils because they are good and inexpensive. MB approval as well.

Did anybody else notice that PTS at Luton were using Millers products in their cars? These are monster machines so 'Nuff said.

 

[Ian B Walker]

Thanks for the tip Dieselman, will check them out tomorrow at my local motorfactors. Have a nana :bannana:

 

[GregE240]

Originally posted by Ian B Walker
That will be interesting Greg, what is this D-Tox? can you give us a run down on it or a link to the manufacturers web site if they have one. I am doing a booze cruise at the end of Nov and want max peformance and reliability out of my car, seing as how we are going to do Preston-Dover-Calais and Belgium and back in one day. The engine has a lot of miles on it so I need to ensure that everything is spot on. Doing an oil / filtre change during the week and am considering a synthetic oil after a real good flush out. Anyone out there with advise on oil brand?

Hi Ian,

More info to be found at:

http://www.commaoil.com/News/newsdtox.htm

I looked long and hard at the additives for sale in Hellfrauds yesterday and this seemed like a good 'un. It is recommended by BMW as I said - even has a BMW part number on it - so I have high hopes. A couple of people on BMW GB's forums said it made a difference to their respective cars so we'll see. As well as this i shall run Optimax through the next couple of tankfuls so the top end should get a good clean too.

In terms of oil brands, I used Halfords own synthetic (in the grey bottle) on my wife's MX-5 for a while as the garage would not supply synthetic oil. The Merc and her Boxster now run on Mobil 1.

ATB,

Greg

 

[Ian B Walker]

Thanks Greg / Dieselman, going to look and try, will let everyone know the outcome, how much did you say a new engine was??? ha ha

 

[Steve_Perry]

In response to your original question Greg, it does sound like the MAS could be at fault. The first step is to hook up to STAR diagnostics and see if the fault logs give any clue, then blame the MAS

Out of interest does the problem disappear if you switch off, remove key and switch back on again?

I'm currently having the same issues as you, only it's intermittent and the dealer says they can't find anything wrong with the car, grrr. No power and car doesn't want to rev past 3,500 to 4k rpm. For me, the problem usually occurs after I've hit full throttle with kick down, ease off to cruise then the next time I want to accelerate, the car doesn't. I then pull over, switch off/on and the problem is gone. The only big trouble for me is that I had a new MAS back in June.

It's happened about 6 or 7 times in the last two months but it happened 4 times last week and 3 of those were on a trip to Manchester and back.

Click here for more on my observations.

S.

 

[GregE240]

Originally posted by Steve_Perry
In response to your original question Greg, it does sound like the MAS could be at fault. The first step is to hook up to STAR diagnostics and see if the fault logs give any clue, then blame the MAS

Out of interest does the problem disappear if you switch off, remove key and switch back on again?

I'm currently having the same issues as you, only it's intermittent and the dealer says they can't find anything wrong with the car, grrr. No power and car doesn't want to rev past 3,500 to 4k rpm. For me, the problem usually occurs after I've hit full throttle with kick down, ease off to cruise then the next time I want to accelerate, the car doesn't. I then pull over, switch off/on and the problem is gone. The only big trouble for me is that I had a new MAS back in June.

It's happened about 6 or 7 times in the last two months but it happened 4 times last week and 3 of those were on a trip to Manchester and back.

S.

Hi Steve, good to hear from you mate!

Well, as I posted, I took the car straight back home and left it for about 7-8 hours before moving it. Immediately the car felt normal so I took it out for a run around the block. All 100%.

So I've no idea what it was

As I said, I put some of this D-TOX stuff in the tank and I'll be using Optimax for a while. The car seems fine now.

I spoke with Andy Gayle at some length on Saturday after it happened and he said the only solution as you say is to hook it up to the computer and see what the ECU says.

For the moment I'm prepared to think it was a one off, damp possibly? We had a heck of a lot of rain that night and the car was facing into it. But, its never happened before.

The problem did NOT disappear if I turned the ignotion off and on, the other thing I found in the process is that if the car is in P, it only revs to about 4500rpm? I'm not sure if thats normal, if you're moving and you select N, you can rev it to the redline no problem.

The only other thing I can think it could be is that the plugs are up for replacing soon, could be related?

Thanks for your thoughts Steve. Much appreciated.

ATB,

Greg

 

[Steve_Perry]

Originally posted by GregE240
The only other thing I can think it could be is that the plugs are up for replacing soon, could be related?

Could be related to that. Remember you have 12 of the little blighters though Other ideas that occured to me whilst stabbing in the dark were: MAS? Lambda Sensor? fuel injectors? spark plugs? accelerator resistor? ECU?

What really gets my goat is the fact that my problems occured within a month of my car having a major service... am I justified in thinking the timing is more than coincidence? Service - 15Aug03 Problems started - 17Sep03

Hope you get yours sorted soon Greg, don't be surprised if it does come back though. Heh and if you get your problem sorted before me, let me know what it was please mate

S.

 

[Dieselman]

Greg and Steve.
Both of your problems sound like the MAF sensor is at fault. They can give intermittant problems and just because it's new doesn't make it exempt.

It is possible that they can be damaged at service due to baging the air trunking around.

I've been out and metered my own MAF tonight just for comparison.

Readings as follows car in P.

All readings in Volts DC.

Revs-700-1000-1500--2000-2500--3000--3500--4000--4500--5000

-----1.96--2.18--2.35---2.6---2.74---2.82---2.93---3.07---3.08---3.08


Get some readings when it works and when it doesn't just to see if there is any change.

Can anyone (Ron) with a 300 turbo take some readings as a comparison for me as I think my MAF may not be working fully?

 

[Steve_Perry]

Just an update guys...

Today the dealer pinned my problem down to a faulty pedal value sensor. That's the variable resistor that turns the accelerator pedal position into an electrical input signal for the ECU.

Anyone have an idea on cost? I am waiting for the dealer to get back to me with a price. I know how much variable resistors go for in RS catalogue, who wants to bet that the MB version might be more than a few pounds than a standard potentiometer?

S.

 

[DavidG]

The Engine Management Unit might need changing.............like mine did.

David

 

[GrahamC230K]

Originally posted by DavidG
The Engine Management Unit might need changing.............like mine did.

David

I feel for you. Just had mine done too. £770 + vat for part alone.

 

[mapleleaf]

Originally posted by Steve_Perry

I'm currently having the same issues as you, only it's intermittent and the dealer says they can't find anything wrong with the car, grrr. No power and car doesn't want to rev past 3,500 to 4k rpm. For me, the problem usually occurs after I've hit full throttle with kick down, ease off to cruise then the next time I want to accelerate, the car doesn't. I then pull over, switch off/on and the problem is gone.
S.

Just had the same happen to me on the E55


Kicked down at 80 it dropped 2 cogs then wouldnt pull past 4000 rpm and wouldnt change up , had to ease off the gas to force a change of gear - well scary !

dealer has car today for a service - diagnostics showed the engine misfiring on all banks so they changed the spark plugs (£200's worth) and only later did a test drive with the diagnostics hooked up & whilst this is an intermiitant fault it happened for them - (a rare event ) - upshot is that the loss of power/misfirig is a faulty MAS sensor - only another £194 sir plus labour! shall be we book it back in ?

So they are fitting the MAS sensor on Monday.

hey ho!

 

[GrahamC230K]

Originally posted by steve_bcs
upshot is that the loss of power/misfirig is a faulty MAS sensor - only another £194 sir plus labour!

Just my luck the MAS is cheaper on an E55 AMG than it is my car.

 

[mapleleaf]

Hey graham - sorry to hear that !

just a thought but now that i've spent a few bob fixing up the car it must be a bargain now ! glad it didnt sell really as these faults would have come up and i would imagine a new owner would be well unhappy!

 

[GregE240]

Same problem as original reared its ugly head yet again yesterday, much to my annoyance.

As follows: started car, going up the hill out of my road no power at all, car very very hesitant and no picking up speed. If I got above 40 I'd be amazed. Luckily no traffic about. Pulled off the main road into a side road and opened bonnet. At tickover the car was all but stalling, very very lumpy, like it was only firin g on 5 cylinders.

Stopped engine (it had all but warmed up). Checked spark plug connections, all seemd to be fine, visual check showed up no visible problems.

Restarted car and guess what? All back to normal, tickover back as it should be OK for the rest of yesterday, and fine this morning?

The only bit f information I have is that the spark plugs are nearly 50,000 miles old. My service book doesn't exactly make it clear how often they should be changed. Probably a good place to start I suppose.

Any ideasss gratefully received!

Thanks,

Greg