I have had an intermittent problem for a while now. Between 2 & 3krpm's I will get a very short (but not slight) power loss. It's kinda like the car hiccups then it will pull through the rest of the gear fine.

Recently I have notied an occasional crack noise right as the power cuts (sharp, metallic sounding). usually in the morning, right when pulling out of the driveway, but then the sound will not happen again that day.

This is not like a misfire, it's like it starts to boost then the boost is dumped for a 1/2 second, then everythings back to normal. No cel's before, during, and after. I'm also chasing a boost leak, but this car had this problem before the leak.

I have replaced all the 4mm vacuum lines and the DV hoping to resolve this issue, I'm hoping there is not a problem with the wastegate?

 

I'm guessing you have tip trans? A short dip in engine speed/rpms between 2 and 3k at part-throtle..? Most noticeable in 2nd gear? This seems to be a common trait on B5's with tip trans. Probably has to do with the tq. converter, but I'm not an expert on this. My 2000 is tip, and I've noticed what you describe for about 30k miles.

Crack noise as the power cuts? If you have a 2000/01 -A metalic noise on a cold start is very likely a noisy combi-valve (located on passenger firewall side of engine.) That valve is only in action on a cold start while the 2ndary air pump is running (the pump itself may also be noisy) and turns off after about 45 seconds. Pop the hood next cold start and listen for it. The air pump and combi valve is what accomplishes the same thing as older EGR systems. If the engine is warm most of the day, you wouldn't hear this again. Or does the crack noise sound like it comes from the suspension? Could be a noisy control arm as you pull out of the driveway.

 

Forgive me for not giving spec's, more details...explaining things are not my forte!

It's a 2001 1.8tfwd 5sp 134k

The noise is definately not suspension, it happens when im already on the road, during a second gear pull. The noise has a very short duration ~.5 sec, which coencides with the power loss. It is a hard noise to describe, and i really have no way to record it. Maybe it could be more like a pop kind of sound. This is why I was wondering if it might be the wastegate? Maybe somehow actuating when it shouldn't be?

The sound is what get's me, the car will have the power problem 75% of the daily driving, but this sound will happen 10% of mornings.

The vehicle also isn't boosting anything like it used to, but as I said I have been attempting to track down a boost leak....not sure if this is related.

The intermittent deal has been there since I bought the vehicle, but the noise hasn't, it was more of just a little annoyance but now im gettin a little concerned.

 

Does this power loss / hiccup only happen during a hard pull in any gear above 1st as opposed to casual driving? You might be going lean and detonating. Detonation sounds like a metalic tapping noise. I also dealt with this intermitently until I figured out my MAF was bad. A bad maf will cause you to be in limp mode (low boost) as well. Pull the seal ontop of the airbox and unplug the maf. See if it improves. If it does you know thats the problem, but don't drive with the maf disconnected for too long- you'll be running a little rich.

 

It does hiccup in higher gears, but it is much harder to detect. I will run with MAF unplugged for a while and see what happens. I'm pretty sure the MAF was replaced when my father had the car for a little while. Who knows, maybe it's gone again.

Is there a vac line that goes to the turbo? Maybe for the wastegate? The stock ones i've been replacing were disintegrating, maybe this could be an issue?

 

Yeah the braided vac lines usualy get crispy like that. There are beefier rubber lines used for the wastegate and N75 (boost controler). They should be fine but you could always check.

Detonation is more likely to happen or be noticeable under heavy load in 2nd or 3rd gear.

 

So I did as ya said and disconnected the MAF...the car wouldn't idle for crap, had to tripple toe it everywhere I drove. Seemed to help with the problem, so I'll be cleaning/looking for a new MAF.

Should the idle be hunting really bad with the MAF unplugged?