Acceleration Hesitating

[Daportugeezer]

I have a 2001 x5 4.4i e53 with lpg

The problem I have is that it is lacking/hesitating on acceleration whilst using petrol until the lpg kicks in and then it's fine...even when switching over to petrol again it fine

I've been to a few bmw specialists but they keep giving me different diagnosis...one says it's the timing chain..another says the fuel pump and filter...

I have recently changed the cats and two oxygen sensors...and diagnostics have no oxygen sensor errors...

Only error I get is FUNCTION INLET CAMSHAFT SENSOR BANK 1....

I am waiting on oem new sensor from Germany to arrive

Any help would be appreciated

Quote

MultiQuote

Edit

Re

[Greydog]

From your description it sound s like the hesitation only occurs when the engine is cold as LPG only activates after a set engine temperature is reached. You say once on LPG it runs fine with no hesitation? Then if you switch back to petrol its still fine?

How much fuel is in the tank? Do you know when the fuel filter was last changed? Try taking off the fuel cap sound s daft but if its vent is blocked it can cause issues

[Daportugeezer]

Thanks for reply....I've always got a full tank of fuel as fuel gauge doesn't go below half way mark since lpg fitted...so paranoid..haven't changed fuel filter since I got the car three years ago..

[Daportugeezer]

I'll change the fuel filter weekend and update...hopefully it's the case...

Just to add it does run slightly erratically for a while then as lpg kicks in it smooths out...

[Greydog]

Sounds like a fuel delivery problem or injectors. As it only happens before the engine is fully warm does the emission air pump run?

[Daportugeezer]

Cheers greydog...ill check those things and update

[Daportugeezer]

Ok...fuel. Filter changed....I now have continuous hesitation on fuel only, even when warmed up car still hesitates....but does not when lpg kicks in.

..I'm getting several diagnosis from different mechanics....so at a loss and none of them seem to be 100% on fault....

[Greydog]

You need either someone with BMW 1.4.0 software on a laptop or get a copy yourself (Ebay) you will be able to read the codes and see what the issue is.

As the car runs smoothly on Gas but not on petrol it points to be something on the fuel delivery side. Fuel filter is OK so next likely suspects in no particular order, Fuel Pump, MAF, excess fuel return system, Injectors, fuel rail pressure.

[Daportugeezer]

Got no codes what so ever...I've got a delphi diagnostics...only errors I have are oil level sensor faulty and front right parking sensor inactive...dme has no codes...ill go through the fuel system...cheers for heads up..

[Greydog]

Got to be something in the fuel system?

Fingers crossed its a simple cheap fix.

[Daportugeezer]

Ok..fuel pump changed, fuel filter changed and injectors cleaned......still hesitates....at a loss now....

[Greydog]

Bummer

Does the emissions pump run on start up? It is designed to push extra air in to balance rich mixture when the engine is cold, normally only runs for 3 or 4 mins (on mine anyway) Probably going over old ground but thinking out loud. Have you checked the MAF, check the plug clean the contacts, have you isolated the LPG system pulled the fuse to make sure its not part of the problem? When were the plugs last changed? Check the Vanos solenoid plugs.

Sorry I cant be more help other than throw in my thoughts on where I would look

[Daportugeezer]

Maf sensor fine...not showing codes.....did full service last month....I do think that the vanos is not good...as it's noisy...was thinking of replacing vanos...but not urgent....didn't think that would cause problem....I may have to remove lpg system to investigate further...thanks...will update...weekend

[Greydog]

Have you tried unplugging the Vanos solenoids I had a sticky one, if I started cold it gave a 5 sec rattle but if I turned on the ignition let all the lights cycle out on the dash no rattle. Changed the drivers bank solenoid and no issue for the last 18 months (that's tempting fate)

[Daportugeezer]

I get the rattle on cold start....if I let it cycle

.I get nothing...ill give your idea a try....thanks mate

[Daportugeezer]

Hey greydog..

Thanks for all the pointers.

Update....New symptoms...

If I accelerate hard it sounds like a bang coming from underneath of car..more of a loud popping sound...sounds and feels like a missfire but not from rear of exhaust more to the front

At my wits end...

Now being told by garages thats it..cat converter, oxygen sensors, egr valve.

I have noticed oil leak from valve cover..but dont think thats it..

Any more suggestions please...

 

[Greydog]

Sounds like a pre-cat back fire 

There are EGR breather tubes that run at the back of the engine above the gearbox if one is split or perished it could cause issues? Blocked CAT will cause to much back pressure never experienced it myself but I have read symptoms are poor performance hesitation etc. It may also cause misfire in the exhaust due to trapped un-burnt fuel?

Oil leaks on the valve covers are almost mandatory on the BMW V8 !!!

I don't know if you are aware of www.realoem.com enter the site put in the last 7 digits of your VIN and it will bring up your cars build spec, then search the EGR drawings it will give you an idea how they are routed. Same for all the systems on the car, as far as the CAT goes other than change I don't know what to suggest 2nd hand maybe?

 

[Daportugeezer]

Thanks once again...looks more than likely im going to have a week off work and going to do a complete strip down of fuel and exhaust..before it gets worse..

Thanks again mate..

.

 

 

[Daportugeezer]

Hey..greydog..

Need your help yet again.

Ok..fuel filter charged,fuel pump changed, changed all coils and plugs..valve cover gasket also done, new maf sensor..

Ok..ongoing problem....i removed the maf and air filter intake...And whilst car was cold...IT shot off like a rocket....memories......pointing that its not the injectors or the cat...(thank god)...only when it reached normal operating temperature it lost power to the point that it had no power whatsoever..that I had to switch over to lpg...im now worse than being at a loss..saying this only thing I have not changed is the egr valve...

Can it simply be that or something else..

Any help please mate

Thanks

[Greydog]

Morning Alan

Have you read the OBD for codes? I know originally you said you had a Cam sensor Fault.

From the symptoms my instinct says the fault is on the inlet side somewhere. Just a re-run of what you have done fuel pump, Filter, MAF. Coils and plugs That leaves the vacuum system and emission control.

Vacuum system, on the back of the inlet manifold is the vacuum control valve that can cause issues if the diaphragm is split or sticking or any of the vacuum hoses are collapsed internally. It is linked to the oil separator but this is a votex type and don't normally give to many problems themselves. However the vacuum system can upset its operation.

Remember the cats will be free when cold but not when up to temp

Fingers crossed

Dave

 

[Daportugeezer]

This is a big issue to me mate

If I start car...when cold and then remove maf sensor connector...IT becomes speedy González...then when warm it has no power..If i leave connector off overnight and Start car in the morning car it has no power at all...confused.com

I have no blowing or suction at the air filter pump or the egr...im gonna strip it all down

[Greydog]

Having problems replying for some reason???

Do you have a code reader? I use BMW 1.4.0 cheap and cheerful but works really well for me give fault descriptions in English not just numbers.

The MAF is it the right one for the engine or is faulty (if its second hand it maybe? even new not unheard of) 

The emissions pump is under the air filter housing mine runs for about 2 mins or so on cold start.The vacuum control is on the back of the inlet manifold if its US then it can cause all sorts of issues.

Just spoke with the guy who services mine (ex BMW Tech) and he said have a look at www.meeknet.co.uk then click Tim's BMW loads of stuff on the V8's (I just looked wish he had told me about it sooner) 

I also use www.realoem.com a lot for drawings and part numbers

[Daportugeezer]

Ok..ive ordered new maf...bosch...!Removed! expensive..

I got a UK model

I think im gonna spend some money and replace the whole air system..

Ill update...And Thanks for info

[Daportugeezer]

Thought id give you an update..After all the sweat and tears of buying and changing parts....IT turned out to be a faulty maf sensor ( brand new from dealership) was faulty...my mate did voltage test on maf....dead as a dodo...money returned as was not willing to wait 3 days for another...ended up buying second hand bosch maf from breakers £26.10....And michael knight eat you heart out...running perfect 1000% better and much smoother...

Wont have to service car now...New plugs, coils, egr valve, oil change and filter (magnatec), fuel filter, fuel pump, valve cover gaskets...£620 spent...when it could have been only £26:10...

Story of my life...

Thanks for the help mate...i learnt a few things along the way...valve covers were the worst job of all.

Cheers 

 

[Greydog]

Woo Hoo well done Matey perseverance pays off 

At least you know just about everything under the bonnet is good, now enjoy your X