Acceleration issues have returned to haunt me

[sytrus]

Now I'm not necessarily a newbie, but I couldn't think of anywhere else to put this.

My issue is one that was solved on these forums a few months back where I was stepping on the gas and going nowhere. Now the problem that I believe I had solved has returned and it's pissed off.


Basically what happens (in any gear) is I will stomp on the gas, to the floor, now acceleration feels strong for a few seconds until suddenly at about 4.5-5 grand I all of a sudden get a jump and loud popping noises out of my engine bay and exhaust.

Now the exhaust sounds like backfire, but no modification to my boost, air, or fuel has been done to the car (I do have a turbo back and 02 dump).. but the only way I can describe the feeling of the car when this occurs is by comparing it to hitting fuel cut. It feels EXACTLY like it with the exception of the motor slowing down after it hits, the motor is still roaring on but it keeps jumping and making the noises. (I'm gonna try to upload a video somewhere).

Now, this has happened before as I mentioned earlier (of course not to this extent of the problem) and I was told to do several things including; run a boost leak test and check the spark plugs. Before the problem was a faulty plug.. this time it is not and the boost is still fine (although I do get spikes up to 20lbs due to my turbo back and no boost control). The one thing I did notice however were white lines on my exhaust manifold throwing a red flag up to me that it is cracked in these two places. That is the only problem I know of that needs fixing, but other than that I really have no other clue as to what could be the cause of this problem.

So my question(s) are...

Does anyone have any similiar experiences or solutions?

and

Could the cracked manifold be a contributor to this problem?

 

[95blackGsTurbo]

Since you didn't fill out your profile I'm gonna assume you have the stock turbo and injectors. 20lbs is gonna cause lots of problems. Probably have another boost leak. And with no boost control you are just running your car into the ground. Just because your boost gauge reads good doesn't mean there isn't a leak. Do another test, http://www.vfaq.com/mods/ICtester.html. The manifold cracking would cause a laggy turbo because of escaping exhaust gases. Do the boost leak test, get some sort of boost controller and get back to us. Run a compression test too because with no boost control and A/F ratio's all over the place you are probably lacking in that area as well.