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Discussion Starter · #1 ·
Here we go again, my car recently got a new problem. I was driving my car, came to a turn, shifted down to 2nd, when I hit the gas, the car bucked hard, the rpms dropped, then went up again and bucked again, I clutched, and shifted to 3rd. A few miles down the road I floor it in 2nd, to see if it would happen again, nothing. So today I am driving with my girlfriend, and everything seems fine. I pull out of a gas station, hit 2800 rpm in 1st (no real throttle just light acceleration), and it proceeds to buck hard again, I shift to 2nd and try to rev passed 2800, it bucks hard again. I then tried it further down the road in 3rd gear, and it again bucked around 2800rpm. So I drove around the rest of the night under 2800, and it bucked a few times in 2nd randomly.

It feels as if it is a fuel cut... It goes from having power to having none at all, and the rpms fall quickly. I have not tried to accelerate through the bucking to reach higher rpms. I am going to replace the DIC with the spare tomorrow hoping it is just spark related, but no codes have been thrown.

Any ideas?
 

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Discussion Starter · #2 ·
Alright what the fuck. I replace the DIC, take it for a drive, flooring it in 2nd, doing everything to get it to replicate the bucking. Nothing. The ends of the old DI were white, and there is black oilish shit in the area down by the plugs. Just now while driving home, I pull onto a pretty busy road, a car is coming up on me, so I get on it in 2nd, and the car says "nope", and bucks like nothing I have ever experienced. It bucked so hard it reset my iPod... so the whole way home I try to replicate it again, flooring it in 2nd, 3rd, passing the rpms where it usually happens, nothing. At one point I went all out and floored it in 2nd spinning my tires through 2nd.

I don't understand this car, it's in time out right now, thinking about what its done.

I am going to try new spark plugs next, to me it feels like fuel cut / something cut off completely for a split second.

Any help?
 

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replace your bpc. my fathers car had this issue for about two years lol. We went crazy replacing everything, started with a bpc, then a di then the map sebnsor and tps, turns out it was the bpc after all and we had replaced it with a bad one, when i got my ng, on a hunch i slapped my bpc in and sure enough the bucking dissapeared and the car ran like a champ!
 

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That cut hits effing hard too. Like a goddamn brick wall.

edit- my car had a similar issue when the vac line to the wastegate actuator was ruptured, however that was consistent whereas dad's bpc issue was intermittent,
 

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Discussion Starter · #5 ·
I have a T7 bpc I believe, so isn't that less likely to go bad? I will also check the vac line on the WG, but it seemed intact when I checked earlier.

And yeah its a fucking brick wall for sure.
 

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Discussion Starter · #8 ·
I ordered a T7 boost control valve, since my car was converted to one. Also ordered new plugs for the hell of it.

Hopefully this BCV fixes this shit.
 

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Discussion Starter · #9 ·
Okay new BCV is in, took it for a drive today, 40 mins to an hour or so, ran it through its paces and it seems to be solved (knock on wood). Now I have a new problem, when you floor it and hit peak boost, the cars front end shakes heavily. I believe it is due to the pass side axle + axle bearing. It was bad before all of this, would spit oil and was clearly gone, just never got around to it. I am guessing the bucking finally did her in, as the car makes a clear whining sound from the front end now at low speeds.

Add it to the list of winter things to do before Carlisle!
 

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Discussion Starter · #10 ·
Ignore my last post, car is still messed up. Turns out now in addition to bucking (still does it apparently), it now misfires upon acceleration. At idle the engine runs perfect, give it throttle, and it misses like a bitch. Even in neutral it will miss.

Already tried:
Brand new plugs
Brand new BCV
Spare DIC
Spare ECU tune

It seems fuel related to me, but perhaps CPS? Any ideas on what to try?
 

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Discussion Starter · #12 ·
Fuel pump ?

Occams razor, try the little simpler things first, but maybe it's that?
Fuel pump is pretty simple actually seeing how I have a spare from a 99 9-3. Last time I checked the records the fuel pump was replaced about 10 years ago I think.

This car just pisses me off, love-hate.
 

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Why don't you find someone who has a known working DI cassette and try that. You can also put your DI cassette on their car and see if they have the same problems.

I'm sick of people trying a used DI cassette with an unknown history. How is that any form of troubleshooting?
If the car is still missing the DI cassette is still suspect.
 

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Discussion Starter · #16 ·
Why don't you find someone who has a known working DI cassette and try that. You can also put your DI cassette on their car and see if they have the same problems.

I'm sick of people trying a used DI cassette with an unknown history. How is that any form of troubleshooting?
If the car is still missing the DI cassette is still suspect.
Well my spare DIC was used on my car for around 2 weeks with no problem, that was about 2 months or so ago. So unless that DI died within the last 2 months, and this one died as well...

Not to mention, the car did not miss before the new BCV (with my spare DIC on), then after swapping back to my original DI, which the car never missed with, it still missed, leading me to think it is not spark related but fuel.

However, the only things that changed were NEW plugs (which my dad says he gapped correctly), and a new exhaust manny gasket.

PS - Is there anyone that lives near me willing to let me test my DI on their car?
 

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Fuel pump ?

Occams razor, try the little simpler things first, but maybe it's that?
This is what I was thinking from the begining - those pumps do strange shit when they are failing at times - I would start here since the BPC and plugs didn't clear it up. Again - like WyldSaabMan said - a new DI would be the best route to go in this department, but chances are it's the FP anyways.

Not sure if a FPR could do this too - but if the pump does't correct - that's the next place I'd look.

Do you have a Fuel Pressure Tester? Would be nice to see what your values are at start up, idle and under a load while driving.... this would clearly show you that it's a fuel pressure issue (pump).
 

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What is the date code on both of your DI cassettes?
 
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