No acceleration hesitation when starting cold

[robert740il]

gentlemen, i have a 1999 740il E38 V8 M62tu ME7.2, its beautiful. i have been getting P0171 and P0174 codes for about 2 months and the problem is getting worse. on cold start, high pitch whine and after about a minute it sounds like a phaser from star trek goes off and the engine idles down. acceleration is spotty, shifting is rough especially on low gear deceleration to accelerate to second gear i get a clunk. so far i've only disconnected maf while running the engine stumbles but continues to idle at a slightly higher speed, which i think is correct. i cannot find any cracks/leaks in the main intake system and the idle control i think is electronic in the throttle body. there is no hose to it. i'm thinking cam positioning sensors or O2 sensors. i've looked at other threads but none for this engine. how to proceed ??? thanks, this forum is great! robert740il

[Timm]

You have perfect symptoms of a failed PCV valve (called OSV on here). Have a look at the DIY section and Bob's yer Uncle....

[Edwin NL]

Also check for vacuum leaks, also in the DIY section

[dafi740]

The high pitch on start up [ while running on choke] could be an air hose under MAF
which became undone..I had this a couple of weeks ago...put it back in and sorted for the noise...for the rest , looks like you need a new MAF...:)

[robert740il]

auto parts store computer says pcv not needed for this vehicle.?

[darkstarmedia]

auto parts store computer says pcv not needed for this vehicle.?

get it from a dealer.... it's not a normal valve like you are used to seeing....


http://www.realoem.com/bmw/diagrams/j/f/79.png (http://www.realoem.com/bmw/diagrams/j/f/79.png)

Part #2

Richard

[robert740il]

i cannot find the pcv(osv) in my bentleys 7 series manual. can you provide part no. and where to find this part.? also i do not have a link to the DIY section on this bimmerforum page. where to find?

[darkstarmedia]

e38.org

look for OSV....

Richard

http://www.oembimmerparts.com/catalog/item/4550551/4616509.htm

less than $80.

It'll take you less than an hour to change it.

Richard

[robert740il]

thanks for your help. i found it in the book(thanks darkstar) it is listed as the crankcase breather valve. it says to use a slack tube manometer to check for 4-6 inches water column. the book says if the crankcase vacuum exceeds the specs. the breather valve should be replaced. i already bought one. i hooked my manometer to the oil cap and did not get any reading at all. the manometer is old but i didn't think they can go bad. any thoughts? robert740il

[Timm]

If the PCV valve gets gummed up, the crankcase vacuum can increase. If the diaphragm is torn (as they usually are), then the vacuum decreases as there is no connection between the inlet manifold and the crankcase. This is the document you were referring to:

http://www.meeknet.co.uk/e38/pdf/BMWCrankVentSys.pdf

PCV is an acronym for Pressure Control Valve, and that's just what it does. When it goes wrong, it doesn't control the pressure correctly.

[robert740il]

ok, once again i appreciate your help. the new crankcase breather valve took me 4 hours,3 1/2 hours out and 1/2 hour in. you were right, sludge and a coating of oil on the inside. i'm now holding exactly 5" of water column. i erased the codes w/obd II and drove on and off 2 hours. codes p0171 and p0174 came back. ran much better but still no acceration when i step hard on the gas. if i take it easy its slow acceleration. took out Maf cleaned it and looked alright put on new O ring. so far no more whistling. pulled out maf while idling and engine quit. robert740il

[Timm]

If you just had the codes and good acceleration, then I would suggest manifold gaskets (inlet, throttle body etc). But as you have poor acceleration then it really points to a faulty MAF, especially if the tick-over is OK. I know you have replaced this a while ago, but are you absolutely sure that it was a genuine part.

P.S. Well done for replacing the PCV valve!

[robert740il]

ok, just recieved and replaced new maf. pgautoparts.com http://www.pgautoparts.com/index.php?main_page=product_info&cPath=1&products_id=56&zenid=k7dms5r7lblb9v0bjc8h70e253
$68.95 plus shipping. exact match. car started after 1 min. cranking and idled rough with a tick for awile. warmed up and seemed to be alright. took for test drive, good acceleration but car died halfmile away when i slowed for turn. started right up, took it easy back to shop. car died again as i slowed to pull in. shot me a new code of P0112(intake air temperature sensor 1 low) i am researching. hope the link helps

wondering could the harness, x6217, be faulty.

[Timm]

Sorry, but that's not a Bosch part, it is a copy. I know the OEM parts are expensive - but at least you are sure that they are going to work.

I purchased one of those cheap ones once, and the car didn't want to start properly or tick-over. When it went to BMW they just laughed at how far out it was!

[Edwin NL]

Thats not going to work, you need Bosch, these cars are very picky on brands

[robert740il]

thanks timm and edmond, you guys know your stuff. it really galls me to pay over $100.00 more for the same part. i'm calling bosch to find out why. alot of good that will do. i'll let you know when the copy stops working.

[IcemanBHE]

Sounds like its already not working.....

Bosch only for engine electrical components.

[bmwbob89]

Who said they could replace the OSV in an hour? Maybe swap the guts but not the whole thing. Or maybe if the torx bolts were replaced with hex bolts.

[7partsonly]

Well just unplug the mas and see how it drives, if its better then you know the issuie.