Loss of power under load...
 

Hey guys first off let me say hi, and thanks to all the members on here for all the great information you guys post! I've actually solved all problems so far just by reading here even when shops were stumped..(ended up being vanos seals).

So quick info about the car and the issue:
Car is a 2002 x5 3.0i automatic. 200k miles. Got it recently, on the way home I got a CEL, and noticed significant power loss, misfires, no stalling. Noticed that it would barely go uphill and the more you gave it gas the less power it seemed to had. So I got home, and did the basic maintanance, replaced air filter, oil filter, oil, spark plugs(ngk), coolant. It ran a little better, but still had slight misfires sometimes, CEL, ran fine in the city, but any hard accelaration would make the car fall flat on its face, and heavy misfire. Did some research, checked the DISA valve, it was broke so I replaced that. Also cleaned ICV, and replaced the CCV. Car was completely different, felt more responsive, more power, still had CEL, still had slight misfires sometimes, agravated by heavy throttle, and still no power under load. Put it on a tester all it said was random cylinder misfires, sometimes cyl 1, sometime 3, etc.. so as a last resort, I kept seeing about the vanos seals, and saw that it could make you have all my symptoms, so I figured heck surely no one replaced them and at this mileage they're toast, so I replaced those as well and NOW.. car runs smooth, no misfire, no CEL, it feels like it should...UNTIL you press the gas about halfway or more... then again you feel the extreme power loss... motor revs but it doesn't pull... if you feather the gas it feels so good, responsive.. and feels like it has power, but if you wanted to pass somebody you would have a hard time.. also going uphill is also a hard time for this X... any ideas what this could be? It's driving me crazy that I've solved everything and it runs smooth, and no CEL, but it has no real power :(

Thanks in advance for any suggestions !

Also going up hill the car has a hard time revving up and pulling, its not revving up like crazy and the car not going anywhere so trans is not slipping

If you have a misfire have you checked the condition of the coils and then the injectors?

After replacing the vanos seals all misfires went away, under load and normal driving... as far as I got into checking the coils was unplugging each one and listening for a difference witch there was significantly for each one when unplugged.. so I figure they are ok..

So quick recap, replaced spark plugs, air filter, vanos seals, ccv, disa valve, car runs great under normal conditions, no misfires, no CEL's. Under heavy load..ex: uphill or accelarating hard the car just has no steam, feels like its being held back...

Btw guys would a video help?

The coil still can be defective especially becomes intermittent under a load. With the miles on the vehicle you may want to recheck the coils. I have seen two cases where the coil only fails under load and is intermittent. You may also have a bad injector. You need a proper diagnosis.

So time to go to the dealer I guess... something I wanted to avoid since I've had bad experience with them. Went with a 325ci, with ssg trans, with a defective slave cylinder for the clutch and they tried to tell me it was the whole gearbox :))

Sounds like a bad MAF. Suggest you try cleaning it with MAF cleaner. Doesn't always work and even if it does it is time to replace it.

Sounds more like bad fuel pressure under heavy load. Check the fuel pressure at the rail under heavy acceleration

Already tried cleaning it, no change. Tried driving a little without it.. its no better no worse.

I don't have any gauge for this.. would any shop be able to check this or dealer only? I will be replacing the fuel filter as I'm sure its probably never been changed unfortunatley, could a soft failing fuel pump also be the culprit?

The Fuel Pressure Regulator is part of the fuel filter. I would replace it soon and see before paying someone to check it out. If you don't know it has been done then expect it hasn't. Glad to see you are getting her back to life. (and not complaining about it!) :thumbup:

Ill be replacing within a day or two. I love the car, wife hates it.. probably cause I put everything from door handles(none of the doors opened from the outside) :)), bushings, a wheel bearing, and the parts mentioned in the OP and it obviously still needs some TLC

If you have a bluetooth scanner you can look at live data and see. What the 02 sensor is showing at wide open throttle under load or going up a hill. Stft should be at a positive value.

I agree with fuel pressure problem and to replace filter as first step. Sounds like it would be a good idea to replace filter regardless if you might need a fuel pump or something else. And I agree that after replacing the filter the next step should be measuring the rail pressure. No money wasted by replacing the fuel filter especially if it's never been done but going any further without checking the fuel pressure might not be a good idea.

I got a fuel filter on the way, I'll be replacing tommorrow and posting the results..

So changed fuel filter and no change.. all though it seems to be a little better.. maybe its just me. Guess a full diagnostics is in order?

With 200K miles on the vehicle you may want to put a new set of coil packs in the vehicle.

200k

I would still look at the fuel pressure at the rail before throwing parts at iit.

True could have a weak fuel pump under heavier loads/demands

:iagree:

Got an appt. on Friday at the local dealer.. will post an update for anyone else having the same problem..

Partially collapsed catalytic convertor? Need those O2 readings.

2002 X5 3.0 314,600 miles
2014 4281 24,300 miles

2004 325i sold at 123,600 miles
2001 325i sold at 66,000 miles

1970 Firebird - Under restoration

A fuel pressure gauge is cheap quick tester.
Example: https://www.amazon.com/OTC-5630-Fuel...ressure+tester

Or a block exhaust system could also be the problem. In my younger day, I had an OPEL 1900 that couldn't get out of the way of a bicyclist until one day I removed the exhaust. What a different that made. It felt like I dropped a V8 in that 4 bangers.

Remember an engine is nothing but an air pump. It can only breathe as much air as it exhaust.

Some auto parts store rent fuel pressure gauges, rent fee is returned when gauge is returned. Some will test it for you.

FYI, cleaning doesn't eliminate MAF, doesn't always work and problem could be connector. Did you use MAF cleaner, spray liberally, in particular the wires that are not readily visible in the sensor?

Have you checked for error codes?

:iagree:

Air in, Air out. It has to have somewhere to go :rofl:

So dealer diagnosis is: bank 2 pre cat o2 sensor, vanos solenoid... they also said to replace spark plugs but they are new ngk's, and coils as well. Not sure how good their diagnosis is.. regarding the plugs...dont even think they removed them.

Question: where is this vanos solenoid?

Nobody knows what these guys are talking about?

Also, can a bad o2 sensor affect performance that bad?

Most of the long time posters on this forum know what it is and where it is located.

http://cdn4.pelicanparts.com/BMW/tec...ne/Pic2-01.jpg

The silver thingy with the wrench on it is the vanos solenoid.

Depending if it a precat or post cat 02 sensor. Post cat sensors don't affect the engine mixture. Precat changes the fuel trim which can have an effect on the engine's mixture.

Plenty of discussions about this on this forum as long as you are willing to use the search feature instead of just posting the same old questions.

The first step the BMW tech would do is check for OBC error codes and from there likely do some other troubleshooting to verify the codes were not a symptom rather than the cause. The might also look at realtime information while the engine is running. It could have a vanos code and misfires info on different cylinders traced back to plugs. Usually that is enough info to know what needs to be done but the information can be interpreted incorrectly.

UPDATE! Changed O2 sensor, no difference in performance. Car died half way home.. ended up being the fuel pump. So now I got a new fuel pump and O2 sensor in and it still doesn't pull. Only difference is decreased fuel consumption from.. 22l/100km to 17l/100km, probably from the O2 sensor.

Only stored code is 68 DME, vanos exhaust camshaft, end position not reached. There is no CEL, vanos has seals done.

What else can it be?.. timing is off? ANY help is greatly appreciated!

Check out that valve spool that is in the bottom right hand corner of upallnights picture, it might be sticky in it's bore especially at the bottom where it's hard to clean.

Will do tommorrow! :)

Did you just purchase the X or did this problem suddenly appeared?

Check the compression in all the cylinders. If the disa valve was broken the pin that holds the flap in place could have gotten suckered into a cylinder and wreck havoc with the valves.

Recently purchased, on the way home it started having problems. Disa valve was one of the first things checked, the flap was broken and replaced with a brand new one.

Pin was not loose, and the flap was intact but loose from the shaft that moves it.

SOLVED!!!
 

UPDATE! SOLVED!!!

Removed both PRE CAT O2 sensors and took her for a spin... BIG BIG DIFFERENCE! Looks like my cats are plugged...

So again.. SOLVED. Thank you all for helping!

To confirm your cats are PLUGGED up. Tap into a good source of intake manifold vacuum and insert a Vacuum gauge.

• Read engine vac at idle
• Read at 1500 RPM (no load required)
• Read at 2500 RPM again no load required

If you vac number drop as RPM increases, your down stream exhaust is indeed blocked. Drop the cats and see if the number change, because a collapsed pipe and or muffler further down stream will give you similar results.

If you are really ambitious, there are pressure gauges and lines that can be screwed into the O2 ports upstream and downstream of the cats to see the drop live.

Where is a good place to tap manifold vacuum with a normal pressure gauge? I think I have the same problem and just happen to have a boost/vac gauge lying around.

Instead of a vacuum gauge, I would tap in a compression pressure gauge at the 02 sensor.

See this video at 3:56

https://www.youtube.com/watch?v=9TlygJMxTps

If you have the app Torque I believe there is a PID that measure manifold vacuum.

Looks like this guy nailed the problem.

https://xoutpost.com/1097105-post26.html

I do have pro version. Hadn't put it on X5 yet, only cheaply built MKV Jetta and in-need-of-tune-up Navigator. Video was on point. I'll be doing that next time X5 leaves the garage. Thanks.

I don't think Srmmmm cares if he is right, if he does, he should know helping someone is not a contest.

It's not a contest, but people should be aware as to who have knowledge as to how to fix these cars.

Much of the time incorrect contributions here are not an indication of lack of knowledge. If that were the case none of use are knowledgable as to how to fix these cars.