General Maintenance & Repairs - Total loss of power, especially at WOT

Alright so I've been paying my TA a lot more attention lately. Didn't drive it for a very long time and noticed some power loss initially but after driving it around for a while the power seemed to return. I have recently been upgrading the stereo and installing some sound deadening, but I believe that to be unrelated to my problem. Suddenly when starting it up last weekend the car barely turned over. I could hear the car struggle to start. At WOT in first gear the car drags badly, and barely reached redline. In any other gear at WOT my engine seems to bog down badly around 3k RPMs, and barely climbs if it climbs at all after that. Occationally I get spurts of power in second gear, the car will launch then die down, then launch again, all in WOT. Even without WOT the car seems to be having some major power loss and I can hear the engine struggling. I don't believe its a bad plug or anything else because the loss of power should be more consistant if it was.

After doing much searching on the forums the common theory for my issue seems to be the MAF. My issue seems slightly unique to the ones I have read however, since the car is having issues starting and issues while not at WOT. Most of the issues I have read involving the MAF only occured at WOT. I've checked the car multiple times for codes and have received nothing, though I'm uncertain I'd even get a code because the computer is restarting nearly every time I start the car (as indicated by the trip meter being set to 0 and the swooping of my guages). Now, I could take this to a mechanic and have it diagnosed but it seems if the likely conclusion is the MAF I may do better to spend my money upgrading the MAF and airlid (my airlid has some cracks in the seal that have caused some particles to get sucked in and stuck in my MAF screen).

So I'm wondering, should I go ahead and replace the MAF and lid and see if that fixes my problem, or are there any other theories floating around as to what my problem is? Or am I simply better off taking this thing to a mechanic?



On an added note: I replaced the fuel filter about 2 years ago and have only put about 3k miles on the car since then. Car was running fine with the replaced filter.

Easy way to check the MAF is to unplug it and see how it runs at WOT. Should force it to rely on the O2's and take the MAF out of the loop, if it runs pretty good then your MAF may need some cleaning.

Also you need to figure out what is killing your voltage and resetting everything, check the alternator and the battery. I've heard of electrical issues causing wierd engine problems like this. Also it will allow you to pull codes, which helps alot.

After that you may need to start looking into other issues like your fuel pump and injectors IE a fuel pressure check. If you can get a wideband on it, it would make things easier.

Is it a M6. It sounds like the problem I have. Like to a T. My clutch just slips and "looses power" around 3k RPM's. My battery dies to but I just bought a new battery. It still starts hard sometimes though. I just figured it was two different problems. Interested to hear what your problem is. Hope you can get it figured out.

My battery seems to have a slow drain someplace. If I don't drive the car for a few months the battery is always dead. I think the recent resets are just from my battery being very low due to all the stereo work I've been doing. I'll try the tip about disconnecting the MAF, I'm hoping it's that easy. I wouldn't mind upgrading the MAF. The car is an M6 but the clutch isn't slipping, that wouldn't cause my RPMs to bog down. I'd like to find my knock sensors but I have no clue where they are.

Knock sensors are under the intake manifold.

Easy way to check the MAF is to unplug it and see how it runs at WOT. Should force it to rely on the O2's and take the MAF out of the loop, if it runs pretty good then your MAF may need some cleaning.

Also you need to figure out what is killing your voltage and resetting everything, check the alternator and the battery. I've heard of electrical issues causing wierd engine problems like this. Also it will allow you to pull codes, which helps alot.

After that you may need to start looking into other issues like your fuel pump and injectors IE a fuel pressure check. If you can get a wideband on it, it would make things easier.



:cheers: :cheers: :cheers:

Thanks a million. Unplugged the MAF and the car ran fine. Problem seems pretty obvious at this point. I have a bit of a policy about repairing things in my car. The MAF screen is pretty messed up and the cut before the airlid is obviously allowing particles in since there's some stuff stuck on the MAF screen. As a result, I'm just going to upgrade both the factory lid (and get rid of those obnoxious baffles) and the MAF as well. Could I probably get away with some repair work on the lid seal and a cleaning of the MAF? Of course. Am I making excuses to upgrade stuff? Absolutely. Better not ever bend a rod, I'll need a new (bigger) engine... Thanks again.

A lot of your problems could be due to your PCM resetting! You should get that fixed first and then check for codes. (Your PCM has to re-learn engine settings when it looses power and will run rough until then.)

If your MAF was damaged and needs replacing you should get a code. Otherwise, it may be worthwhile to just try a cleaning first.

Temporary fix for airbox cracks = duct tape. If you want to get classy, there's even black duct tape widely available now.

No problem OP.

I would tape up the cracks in the lid and get another STOCK MAF or simliar like a vett MAF. I don't like playing around with aftermarket MAF's I think that SLP or someone makes one with a resistor in it and it SUCKS to tune with (I'm an HP Tuners junkie so it drives me nuts). I ended up tuning my MAF completely out, no because of issues, but I really like SD tune better, it's a little snappier with my tune.

Try a good electrical cleaner on the MAF first and see if it helps at all, it's like a $8 can instead of some bucks for a new MAF.