Random Bucking

[boost92]

92 Talon TSI
I have a strange problem. To start things off I will fill you in on the events that led up to the problem. I built a boost leak tester on day just to see if I had any leaks. Car was running fine then. I found a huge hole in my intercooler so I took it off for reapair (jb weld) I had to drive my car to work that day so I used to some pipe laying around to fab up a hot pipe (bypassing the intercooler). I kept it on waste gate boost. It ran fine for a few days until one day comming home i down shifted into third to pass someone and it started to stutter a little but. Its not a constant stutter but a just a ever few seconds kinda burp or buck. I got home and replaced the intercooler and drove it again and it still does it.
I have drove on it like that for a few days now as im trying to find out what the problem is withouth spending all my money buying parts I dont need. It has a brand new fuel filter on it, that I know. I did another BLT and I have leaks around my throttle body and Im seeing a wet spot around a injector or two. Would these leaks cuase a random buck like that. Im just trying to narrow down my possibility's. Also I know my alternator broke a bolt off and wiggles a round a little bit.
I thought mabey it was turn sensitive but im not quite sure. I took a sharp left turn while on throttle and it bucked again but I havent had the same outcome since then. It also seems to be worse when I just barley give it a little throttle like when I first touch the gas. The tach jumps about 200-300 rpm when it does this and it occurs on deceleration as well. Only seems to do it above 1800-2000 rpms. and I dont think it does it at first startup or first few minutes of drive. Thanks for all your help and sorry for the long description, just trying to give you a good scenario to help you diagnose! thanks again

 

[babyviper]

How much boost were you running without an intercooler?

 

[boost92]

about 10psi, with a few leaks. When I did the BLT at first it would not hold any pressure on in car gauge. After I put the hot pipe in it would hold 13psi leak out in about 2 seconds. But to answer your question, it was running 10-11 psi. But I also was not getting in it very hard. When i went to pass the person I wasent watching the gauge so it may have built a little more than that. But it was on straight wastegate

 

[babyviper]

It's probably spark plugs replace them with some NGK bpr7es and give it a try.

 

[boost92]

I just replaced them about 2 weeks ago with BPR6ES's gapped at .026-.027. I will post a pic of the plugs tomorrow If that will do any justice.

 

[babyviper]

When you ran without an intercooler your plugs got fouled, you need new ones now. Your have been diagnosed, take 4 NGK's and call me in the morning.

 

[boost92]

The plugs are not fouled. I have seen many fouled plugs and am not a beginner. Need another recomendation

 

[boost92]

I meant to say in the description that I had pulled plugs to see if they were fouled. They were very clean. Porcelain is light brown closer to white. Only indication I have of running rich the thicker carbon around last thread of plug. Ground strap is light brown and the timing indicator strip on strap is at exactly the bend (indication very close if not exactly correct timing)

 

[babyviper]

I've seen the same thing before too, my cousin put in some fresh 6's drove don the street and by the time he came back the car was bucking. If you have a cat-back and an intake you need 7's. Can you please replace those plugs, just give it a try it is only 10 dollars. Replacing the plugs is the first step, if that doesn't work we will go from there.

 

[boost92]

ok I wil give it a try.

 

[boost92]

I pulled the plugs again today to change and here are pics of each one.
Talon Stuff pictures by boarding_wolf_1259 - Photobucket

Take a look and let me know what you think. Thanks

 

[boost92]

Great, now either I have a new problem or the old one got worse. All I did was replace leaking intercooler with a new one. I had to remove coolant over-flow tank to route lower IC piping. Heres a video that shows whats happening.

<embed width="448" height="361" type="application/x-shockwave-flash" wmode="transparent" src="http://s579.photobucket.com/flash/player.swf?file=http://vid579.photobucket.com/albums/ss237/boarding_wolf_1259/VIDEO_046.flv"></embed>

 

[boost92]

I also noticed today that my coil pack bracket is broken and it slides around a bit.

 

[boost92]

replaced plugs and made no difference

 

[babyviper]

Is the tachometer the only thing jumping or does the car also buck when driving the vehicle.

 

[boost92]

I solved my problem today. Replaced the ignition coilpack for one off ebay (35 bucks) Runs awesome. The accual bracket that holds the coilpack down had broken in two places. and the terminal for the number 4 cyl had burn spots and black inside it. Thanks to everyone for the help!