Could it be MAF sensor?

[jeegnesh]

Current mileage 71k, the MAF sensor was changed in April 2007 at 37k was from Euro Car Parts Part No: 434330250 Bosch: BCH 02802170 07 for £149+VAT

Problem: For a long while now, when I start the car from cold it idles up and down if I try to pull off it most likely to stall unless I over rev it, it settles down after a few minutes. Sunday night when i was slowing down the engine just cut out, this happened twice, both times the car started back straight away. A couple of times over the last year or so I have noticed that when I am driving it it suddenly starts to choke so you I am acelerating but it doesn't want to go and sort of misfires, but then its all good again a minute later, this has only happened twice, sometime ago and not seen this again. No warning lights are on. The other symtom I have noticed mainly happens during summer, sometimes during a hot start it struggles to start but always does eventually.

So would these symtoms hint at MAF sensor? I have read people cleaning the sensor is that worth a shot, and how do you clean it? And any instructions on where and how to take the MAF sensor out? Also the best price for a new sensor and where?

Off course if I am going the wrong route and should look at something else would love to know?

 

[Nick_USA]

Your original problem could be a range of things including your MAF and you could try cleaning it first, see the link below (about half way down the page):

http://sites.google.com/site/mikefocke2/checkenginelightcausedbymassairflowsensor

For 'MAF cleaner' use isopropyl alcohol you can get it from Maplins etc.

But don't try to touch the sensing surfaces with anything.

 

[jeegnesh]

I have never opened the engine cover, anyone in the West London area fancy showing me the way really don't want to be doing it on my own for the first time. Bit of a big ask I know.

 

[GOOFY]

Hi Jegneesh

The cold start problem is exactly what I experience on very cold mornings, and have done since I purchased the car. I have mentioned it on the forum before - some mentioned the MAF, ignition coils etc. I do not think it was the MAF as I cleaned it out on mine (car had only 18k on clock ) and from what you are saying it seems it made no difference to your car. All I can think of is that it could be the coils and HT leads. However I never get any vibration, hesitancy , or misfires etc. It only happens when car is very cold, and is reminiscent of not using the choke (remember those things before fuel injection) - the engine stalls below 2k rpm until warmed up.

I think its just a sensor (cold enrichment valve connected) that is not putting more fuel into the engine when cold or allowing more air (air bypass valve). What I do is when its cold is hold the revs at 2-3k rpm for about a 1/2 minute before setting off,. This always works and it drives smoothly after that.

 

[jeegnesh]

To be fair that would work for the cold start issue, even without rev it for 30 seconds, if I leave it for around 2 minutes it is fine. I guess the cut outs I had on Sunday was what concerned me more, but I think I would need to get it on the road a little more to tell if there really is an issue. Might check my indy and see if they are willing to test the MAF sensor for me.

 

[jeegnesh]

My Indy took a look at the codes and suggested that Variocam solenoid is sticking as its shows Cylinder 1,2,3 misfires and also a possible Air leak which they would need to investigate further.

The problem is the car actually feels fine and the above would cost a fair old amount, I feel to leave it longer, also read on the Variocam solenoid sometimes more driving and alot of thrashing helps. Regards the the cold start apparently its a common 2.5 trait so nothing to worry about there at least.

Not sure on my next move here :-(

 

[Steve Brookes]

Your air leak could be caused by a split in the air oil separator. This is very common. About £200 all in for an indy to change it.

It can be a real problem for indy's to absolutely diagnose a problem which is related to the air/fuel system because the basic diagnostic system that most have can't pin point that a fault code is caused by one of the oxygen sensors, the MAF, the air oil separator or another leak, which are common reasons for poor cold starting and an initial lumpy idle. Most indy's can't afford the latest Porsche diagnostic system because it is horrendously expensive for them.

From experience a MAF should be good for 4 or 5 years and then it wears out. A Bosch technician who came to one of our regional meetings informed me that the constant heating of the wire means that it will eventually fail. He also said they are self cleaning (because of the heating of the wire) so there is no point trying to clean them. Taking it out and disconnecting it and the battery leads to a basic reset which may make it feel like the cleaning worked but the smoother running will deteriorate again after a couple of days use.

My own recent poor starting and idling in the first couple of minutes was cured by a new MAF. However, I had already had a new air oil separator, coil packs and oxygen sensors, so I knew that they were unlikely to be the problem.

BTW what is your model year and type because the Bosch part number for the MAF you quote above is not the correct one for a post 2000 year 2.7 or 3.2?

 

[jeegnesh]

mine is a 1998 2.5

Still confused as hell whether I really need to do something right now or wait for something more substantial to suggest I have a problem to fix, but then I am scared the waiting could cause other issues.

 

[Steve Brookes]

ORIGINAL: jeegnesh

mine is a 1998 2.5

Still confused as hell whether I really need to do something right now or wait for something more substantial to suggest I have a problem to fix, but then I am scared the waiting could cause other issues.

OK it sounds like you have the right MAF because the part for the 2.5 is different to the 2.7/3.2 and since you only got it in 2007, it should be well within it's life span. I think your indy has already given you some good information....it might be worth asking them to check the air oil separator for the air leak they suspect. If it has a bad leak you'll be able to hear a hissing noise coming from the drivers side vent near the door.

 

[jeegnesh]

OK no more confusion my emissions warning light came on today, so guess its time to take her in and get this and the air leak sorted out. Oh this is gonna hurt I feel []

 

[Steve Brookes]

ORIGINAL: jeegnesh

OK no more confusion my emissions warning light came on today, so guess its time to take her in and get this and the air leak sorted out. Oh this is gonna hurt I feel []

My own experience was that the light came on and the garage read a fault code that indicated it was the O2 sensors. Two were replaced at great cost. Two weeks later the light came back. Therefore the O2 sensors weren't the problem. It was only at my insistence that I could hear an air leak that they found the leaking air oil separator. This was replaced and the problem was resolved - the light has never come back on since. Therefore I think you would be wise to ask them to specifically check the air oil separator.

 

[jeegnesh]

Did you have the same light light come on the emissions one? (orange)

the oxygen sensors are registering a fault as u mentioned but the good news is they were not thinking it is those due to the other faults. But I will definetly be asking them to check the air oil separator out. Thanks for that.

 

[Steve Brookes]

ORIGINAL: jeegnesh

Did you have the same light light come on the emissions one? (orange)

I know it as the check engine light (CEL) but yes, we're talking about the same one.

 

[jeegnesh]

Thanks Steve sure enough the air oil separator was busted, ordering a new one now. Now to see how many of the 13 faults that will get rid off (oxygen sensors and cylinder misfires, bank adjustment)

 

[jeegnesh]

AOS replaced, new spark plugs still warning light and errors, now Bank 1 Camshaft Sensor is being replaced, on order.

This is getting ugly, although I was told it driving so nice now, some consolation

 

[Steve Brookes]

Sounds like you're getting there. Here's hoping that the sensor will be the last thing that needs doing and you can just get out and drive it []

 

[jeegnesh]

Have the same hopes myself.

 

[jeegnesh]

UPDATE: So Air Oil Separator, Spark Plugs, Bleeder/Breather Pipe (O-rings), Oil Bleeder/Breather Pipe, Connector and O-Ring was changed all seemed fine. I picked it up and drove in 20 minutes of solid traffic before the engine light was back on. Only sympton was idle being a bit low, else running fine.

Took it back the computer now read cylinder 4,5,6 misfire and Oxygen sensors, cleared the faults. Drove nearly 300 miles including a long drive to Bristol and back, no light, however issues:
1. After a good thrash when you coasting to a stop the engine would cut out, but turns on straight away happened 4-5 times.
2. In traffic and also other times, the idle is low a little shaky and occasionally bounces a little.

Took it back today no engine light on, however the reading shows cylinder misfire 1,2,3,4,5,6, bank sensor 1 needs adjustment, Oxygen sesnors and fuel ventilation

What the hell is going on.

By the way other then the 2 issues mentions, it drives fine.

 

[Steve Brookes]

A few posts above your indy had read a fault about a camshaft sensor and one was on order to replace it but you've not mentioned if they've replaced that aswell?

They're reading misfires on all cylinders....any idea if your car has had new coil packs at any point?

Before you spend any more money try this little trick first:

1. Put key in ignition and turn it so the lights are on.
2. Disconnect earth lead from battery for 1 minute and then replace.
3. Don't touch anything for a further minute i.e. leave the dash lights on
4. Start car without touching the accelerator and let it idle for about 10 minutes
5. Go for a good drive and see if the idle settles down

 

[jeegnesh]

Missed that yes bank 1 camshaft sensor was changed.

Looking at the history of invoices I don't see any coil packs mentioned. Should they?

The procedure above what does it do?

I take it when earth is disconnected the lights would no longer be on in the dash?