no power when accelerating
 

hey guys so I'm away on business and I drove her for over 2 hrs with no problem. I was an hour early so I just sat in it for 45 mins with it running and then decided to hit a gas station real quick. she had no power meaning acted like it was a small 4 banger instead of a 4.4 v8. the fan is really loud seemingly audible based on rpm level. no over heating, no smoke, no smell, no obd2 codes, no check engine light, no creamy color in oil, oil level coolant level and transmission fluids all check good. no leaks that i can tell, idles fine, transmission shifts at correct rpm and smoothly, once at desired speed the fan gets quieter and she rides normal. JUST NO POWER! tomorrow a coworker is going to stop by the hotel and scan it with his bmw software. I'm not sure what version or program he is using. Please help!

oh and it is a 2000 4.4 sport package now at 101k. relatively recent work done includes new spark plugs, new valve cover gaskets, both rear air bags on suspension, new tires, laser alignment.

when you say no power, what do you mean? you say the idle is normal, shifting is normal, no codes, no external symptoms... what makes you feel that the power is lost?

you press on the pedal, does the engine react? the RPMs go up with the pedal? or, you floor it, but the RPMs are barely going up to 1500-2000? could it be the air supply is compromized? check the MAF, the air hoses, the throttle butterfly...

how about a vacuum leak? when you pop the hood, any strange noises?

no strange noises. no power meaning it reacts like a slow hybrid, rpm climbs but forward movement and rpm are not matched as normal acceleration for it. it's about half of regular performance. i put it in neutral and floored it the fan was so loud it sounded like a tornado and rpm increase wasn't quite as fast. sorry it is hard to describe other than saying half performance and extremely loud fan when increasing rpm level.

Hopefully there will be some codes to help pinpoint the problem. Sounds like everything was fine and all of a sudden it isn't? Terminator has asked the key question without a scan, how the engine reacts to peddle pressure both driving and in neutral? I have seen your symptoms when a cat crashed and that happens without any warning. If it started directly after taking on fuel, was it from a 1st. rate name brand source?

I actually didn't put any fuel in. after noticing the problem I drove drove it for a few miles and returned to work. thanks for helping guys. and yes everything was fine before the 45 idle in the parking lot. the car was never turned off.

My experience with MAF going bad was that it first caused a rough idle, it gave you warning. That said, to test the MAF, unplug the connection. If the condition improves or disappears the MAF is the culprit. I can't think of air blockage that would come on that fast, or spark. I suppose fuel could but not likely in your case unless you were sucking the tank dry. The long idle time has me leaning toward a cat or something in the emission system but I would think it would light up the dash with warning.

fuel lines clogged? fuel filter?

how about taking a short video for us?

pulled the maf, problem still persists. tomorrow I might be able to snag a quick video on my way to work. I'm trying not to drive it but tomorrow I have to drive it to work so that I end up within a hundred miles of home so AAA will tow it.

check engine light just came on. probably because I pulled the MAF. two videos. the first is in neutral the second in drive.

In neutral - YouTube

In drive - YouTube

yes I know my brakes are squeezing...

it seems that the engine responded fine while in neutral... but when i gear - the RPMs went high, the speed did not... wonder if it has to do with the tranny???

the fan was still crazy loud in neutral

sounds like you have a bad clutch fan .Was your CEL on before your issues ?

fuel filter?

my filter was clogged and got the loss of power symtoms, slow rpm gain, no power

it threw no codes

Only concurrent symptom with the loss of power appears to be the engine fan on more than usual. That indicates high temperature. High temperature could be related to a failure of a catalytic converter. Symptom would be reduced power. Worth checking anyway.

Don't understand why OP would idle for 45 minutes. Not good for the engine.

Not exactly ideal as fan will run constantly, but not a problem as long as your cooling system is functioning. Why do you say not good?

OP - I'd guess you have a fan clutch issue after that long idle. I'm not familiar enough with the e53, but this isn't uncommon on some other chassis models. May be locked up and/or binding, which also explains the noise. The drag can lead to a feel of sluggish acceleration.

I'd start with the fan clutch. With the engine warm, you should be able to hold the fan still or slow it down greatly (use a cloth to rub lightly against the blade tips) with the engine idling. If it resists strongly and will not slow, the clutch is bad. An engine fan running at 4000 RPM can easily pull 15 horsepower off the engine which will slow your acceleration, but not necessarily diminish your cruising speed.

Beyond the fan clutch, I would look to a restriction in the air intake, then the fuel filter or fuel pump as the next possible issues. If any of these were bad though, it's unlikely you could reach maximum shift point RPM levels. Will the engine go over 4000 RPM on a full throttle upshift?

My experience with a bad catalytic converter on other vehicles was such a severe restriction in the exhaust system that the vehicle would not exceed 30 MPH, so I doubt that is your situation.

I suspect that your extended idle period encountered a failure point in your fan clutch. Good luck.

Because IMO you experience additional (and unnecessary) engine wear compared to shutting it off. Manufacturers know this, and those owner's manuals that list the conditions that qualify as Severe Service, thus requiring more frequent oil changes, include vehicles subject to extended idling. Idling means less efficient combustion, thus more unburned fuel. That results in more combustion chamber deposits. The exhaust catalyst will clean up the tailpipe, but that unburned fuel can wash down the cylinder walls, even with EFI. Some vehicles will have an idle speed increase circuit just to avoid extended low speed idle.

I think that engines are happiest when they are run at varying speeds, at varying loads. I have had to leave a vehicle idling for extended periods in extremely cold climate conditions, so you can't always avoid it, and at normal temperatures occasional idling isn't a problem. But extended idling of an engine designed to run up to 6000 rpm is bad practice, IMO.

Apart from the accelerated engine wear, why waste the fuel and pollute more? My idle limit is about 1 minute when parked.

In initial post Mad Mike writes that there is no overheating or smell associated with the loss of power. I keep coming back to the 45 minutes of idling and the sudden onset. I have never had a fan clutch drag an engine down that much and I have taken a clutch fan off cars in the past and replaced them with non-electric no clutch fan. Never had a transmission, maybe a torque convertor act like that. Per my post and JCL's I can't think of anything other than a cat.

Ok, we're on the same page then. It's just semantics. I take 'bad' to mean something that will cause harm to a car. I wouldn't consider normal wear and even sporadic periods of extended idling bad, guess I'd call it 'not ideal.'

Are clogged cats common on these things? In my experience they aren't on most, and very uncommon without first having O2 or related CELs. I agree though; while fan clutch can cause some drag, it's usually not as extreme as is described here. I've also run cars without mech. fans.

I wouldn't say common but have seen it happen well under 100,000 miles.

Forgot to ask: Do you run a lot of fuel additives as they can contribute to early converter failure.

2002 X5 3.0
2004 325i

Mad Mike,

What did you find was wrong?

Hey just as an update, I am still working on the problem. and no I don't run any fuel additives. I should know more as far as a solution to my problem goes tomorrow.

ok so I took it to a bmw mechanic who scanned it and the only problem was the mass air flow sensor so I went and bought one and put it on. no result with my current issue. does it take a certain amount of miles or time to learn the new sensor?

Nope, should be better immediately.

If it was MAF disconnecting the power to the old one should have improved idle. Same goes for new one.

what were the actual codes that he pulled?

status update. clutch fan needs replacing (it's almost seized) however they still can't figure out my power loss. luckily e mechanic has one so he knows what it should feel like vs mine. Currently it is not throwing any codes at all and idles great no sputtering, normal temp range, shifts fine, no smoke or smell, just lacking a roughly 40% performance amount. I have an appointment for July 10th for some down time in the shop for repairs. I will keep you posted.

Your Tech didn't notice a bad clutch fan when he was scanning it? I would stay away from him and go somewhere else.Remove or replace the fan 1st then see how it runs

WTF, went to go to work this morning and compressor kept raising the car so now I have a foot or more between the tire and wheel well! I just had those bags replaced a few weeks ago. bmw checked out everything with the compressor etc and said it was good to go. now I have to figure out how to let the air out and get it to where I can drive it until the 10th when I can fix the other problems. since November. valve cover gaskets, coolant expansion tank and hoses. spark plugs and boots, air filter, new tires, laser alignment, both air bags for suspension, drivers side door handle, and within the last two weeks the original problems as noted in the first post, the key battery has died and the lift gate shocks have gone bad....

Alternator or battery

update. I deflated the bags so it sits about normal. pulled the fuses so the compressor won't jack it way up again. as per my original problem need a clutch fan and awaiting a diagnosis on performance loss. I should find out on the 10th.

I would almost bet on the fan causing the drag on the motor . Very easy to remove reverse thread tho

update. after a new fan clutch, relays, fuses, and resetting/training the throttle she seems almost back to normal. also did a re-sync on the key and replaced the lift gate struts.