severe bucking problem

[mikeylighter]

I have been trying to figure this out for a few days, but I had a previous post about high rpm missing and loss of power, but it turned into every time I hit between 45 and 5000, the car tries to shoot me out the window. It was initially throwing a maf code, tracked that down to a broke wire, but it still didn't fix it. Hooked up dsm link tonight, and the front o2 is completely dead, would that cause the bucking? I'm hoping that's all it is. And do o2's generally die instantly, or slowly just get worse?

 

[gofer]

Attach the log. The o2 might not be dead, it might not be cycling because it's locked in open loop for a different reason.

By looking at a log we can see EVERYTHING rather than just guessing at whats going on.

 

[mikeylighter]

It's on my buddies laptop, I'll try and attach it tomorrow. It started throwing the o2 code, and voltage stayed at 0.0.

 

[Turbosnatch]

My Evo did this a while back.

I replaced the CAS and it's been fine ever since. Can you get a spare CAS to try?

 

[mikeylighter]

I can probably steal one off my buddies car to try, but that wouldnt affect the o2 sensor would it?

 

[Turbosnatch]

I wouldnt know, however pull te o2 out and clean it

 

[rixcidia]

I have that same prob I'm thinking I have a major boost leak

 

[kqodprez]

I was going to say check for boost leaks. I don't see any mods in your profile. Are you still on the stock ic piping? I sprung a leak in mines back in the day under that plastic mesh.

 

[mikeylighter]

here is the log. Changed the o2 and it started reading again. Car has an aftermarket sidemount and is hard piped. Let me know if there is anything that needs to be logged. Car has been boost leak tested and it was fine. The pull where the issue is happens towards the end of the log.

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[ChrisMgst]

I looked at your log and you should upload an updated idle log with CombinedFT, Closedloop, and AEMwbgauger1, and WBfactor. Do you have an AEM wideband? Your front o2 is cycling now. I am very much a newbie when it comes to ecmLink learning myself. I have v3 which seems more user friendly. If I was you go on ECMTuning, Inc. website watch there tutorials and dont go over 30% throttle until you've watched and verified that everything is up to par. Also you might want to edit your profile with current mods listed that would help the Wisemen on here to better serve you.

 

[primo513]

I looked at your profile and it doesn't look like you have a wideband o2. Its pretty difficult to tune with ecmlink without a wideband. If you do have a wideband or plan on one in the near future, you can simulate the front o2 sensor in ecmlink and see if that can fix your "dead" front o2 sensor

 

[LGOMEZ90]

I had similar issues and it turned out to be my crank sensor.

 

[mikeylighter]

To clear things up, other than the intake and turbo back exhaust, the car is stock, so I haven't put a wideband in, I didn't think it was a necessity. It has gotten worse. After I replaced the front o2 sensor it spits and sputters at low rpms now, If I give it more than half throttle it runs aweful, until it gets to about 2500 and it clears up, boost gauge spikes up to the full 12 lbs, and it runs awesome, until about 4500 and cuts.
I did do another boost leak test tonight, and noticed air coming out of a tiny hole on the nut that is attached to the part where you attach the vacuum line to the turbo. It had that hole from the factory, but I don't understand why since it seems like that would just act like a boost leak. I removed the MBC and the car seemed to straighten up a small amount. I also found a leak in between the ic piping, but it doesn't really seem to appear until about 15lbs of boost and I dont see how that could affect it in the low rpms that much. If I drive without hitting boost (which is hard, that t25 spools quick) it runs okay, but the second I try to build boost it sputters and bogs down then clears up, boost jumps up, and it takes off.
My last question is, if the problems continues after I fix the small boost leak, could it be the CAS? If you look at the log you can see when the cut off happens, the ignition timing jumps to 30*, but its difficult to see if that happens right before the buck, or during. I am really trying to avoid the "keep throwing parts at it until its fixed" route as much as possible. Also, I am new to dsm's, but my friend who knows a bit more about these things told me I need the black top cas, would either a faulty cas, or the fact that i'm not running the black top cas cause issues similar to this? Sorry for the long winded post, just trying to get all the info I can for you guys so we can figure this thing out. Thanks for all the help