[RESOLVED] 2g bucks hard under heavy acceleration

[miller97tsi]

i have read all of the threads posted about this and stilll havent gathered enough to narrow what my problem can be. when i am driving regular i have no problems but when i put it to the floor about 4500 to 5000 rpm the car takes a hard nose dive, it makes a loud thud noise let off the gas and everything is fine. what could be the problem? i have little mods and i am confused. could the fact that i have an after market bov not recircted or what?

 

[jrohner]

That sounds like fuel cut to me. How much boost are you running and have you done a boost leak test?

 

[dave99gst]

Sounds like spark issues, proper plugs ? proper gap ?

 

[No_Skillz]

A BLT is in order.

 

[miller97tsi]

running stock boost, aftermarket bov and intake thats it. havent done a boost leak test the plugs are new i just bought them but i guess that i should check the gap size. how would i get rid of the fuel cut with out me running very many aftermarket parts.

 

[No_Skillz]

Because you have many boost leaks. Your MAF is seeing much more air than is actually reaching your cylinders. The ECU thinks you are running too much boost and kills the fuel supply to save your motor.

 

[miller97tsi]

so a blt is more than likely in oreder to fix this problem.

 

[No_Skillz]

Yes. You want to pressurize the system to 20PSI and achieve a leak back to 10PSI in no less than 20 seconds.

Also, since you've been running rich for a long period of time, it's a good idea to change the spark plugs. NGK BPR6ES gapped at 0.028". While you're at it, might as well do the wires, too.

 

[miller97tsi]

would a big boost leak make car buck that hard? also it doesnt do it all the time but most of the time. but the times that it doesnt do it you can feel little what seems to be surges under heavy accel. now regular driving not hard at all car runs great just these little things is whats troubling me. also is there really any spots in particular to pay close mind to when running a boost leak test?

 

[habitatguy187]

Yes, a non recirculated BOV is in essence a boost leak. Because the maf is counting the air that the BOV vents to the atmosphere, therefore you have a "leak" in your turbo system. If you recirculate it your problem should go away, if not, then you have more than just one problem.

 

[miller97tsi]

the thing it is that i have capped off the return port for bov. is there anyway around not recircing the bov. what else can i do? any other spots that i can check?

 

[gage333]

thats fuel cut. i was testing my mbc and accidentaly turned up to 22psi, with only an intake, hks bov. NOT A GOOD IDEA. But i turned it down to 15psi and it pulls pretty good and doesnt cut off fuel, so thats probably your problem. TONE IT DOWN ON THE BOOST BUDDY

 

[habitatguy187]

Don't listen to that guy above me, what he's talking about is right but it doesn't pertain to your problem. The only way to no recirculate your bov is to get a gm maf, aka, a maf that reads the air after the bov. Since yours reads it before, it's counting all the air that's not getting to the engine, causing fuel cut. Figure out a way to recirculate it.

 

[miller97tsi]

is there a way to recirc the turbo xs rfl

 

[habitatguy187]

is there a way to recirc the turbo xs rfl

I'm not sure I've never seen one. Do a search on it and see what you can find, let us know how it goes.

 

[bpk1337]

is there a way to recirc the turbo xs rfl

http://www.dsmtuners.com/forums/newbie-forum/156855-how-recirculate-your-rfl.html
heres one. I would definitely recirc. I have a blitz and my car randomly would stall while down shifting and bucks hard when in high RPMs and letting go of the gas. Recirculated and it all went away it also saves gas

oh yeah theres also this one
http://www.dsmtuners.com/forums/turbo-system-tech/182340-rfl-recirculating-i-did-pics.html

 

[markdr7]

I'm glad that someone asked this question. I just bought a 95 Tsi and I'm having the same problem. I think that mine is getting fuel cut from the fake greddy ebay bov. I'm gonna swap it out with a 1g bov and see what that does.

 

[miller97tsi]

i dont know if i can unscrew the horn it is on there real good but i am going to try and go to homew depot and take care of this problem. then i will try and do a blt and see were that gets me. but the one thing i dont understand is that the inatke is capped off. so why would that make my car buck that hard

 

[No_Skillz]

A vented BOV will cause you to run rich whenever it blows off since that should be recirculated into your intake system but is instead lost. It won't contribute to your fuel cut.

However, since turbo xs is notorious for producing poor quality BOVs, it could be leaking under boost. As covered before, if you have enough boost leaks, you will fuel cut.

To markdr7, just changing a BOV is inadequate. You are only patching one leak hoping that it is enough to compensate when you most likely have lots of other leaks. While you MIGHT avoid fuel cut, your car will still be running extremely rich and as your other boost leaks grow with time, you will eventually be back with the same issues. A full BLT is recommended.

 

[habitatguy187]

A vented BOV will cause you to run rich whenever it blows off since that should be recirculated into your intake system but is instead lost. It won't contribute to your fuel cut.

Why wouldn't it contribute to fuel cut? I've had someone tell me something similar but I don't understand??? How is it different than a boost leak since it's lost air counted by the maf?

 

[miller97tsi]

ok i just made my recirc pipe, it looks good i will op test it tomorrow i will update you guys tomorrow i hope that this will fix the problem, do you also think that this was the main problem? i will try and get a blt done soon.

 

[gage333]

Don't listen to that guy above me, what he's talking about is right but it doesn't pertain to your problem. The only way to no recirculate your bov is to get a gm maf, aka, a maf that reads the air after the bov. Since yours reads it before, it's counting all the air that's not getting to the engine, causing fuel cut. Figure out a way to recirculate it.

thanks for making me feel like a dumba**... but you are right though, i forgot to mention that. when i wasnt recirculating my bov was when it was when the cut was happening

 

[jrohner]

It is a boost leak contributing to fuel cut only if the valve is leaking. Usually they seem to seep a little bit of air, but if it leaks quite a bit, there's your fuel cut issue. When you do the boost leak test, that will tell you if it's just the BOV or something else.

 

[habitatguy187]

It is a boost leak contributing to fuel cut only if the valve is leaking. Usually they seem to seep a little bit of air, but if it leaks quite a bit, there's your fuel cut issue. When you do the boost leak test, that will tell you if it's just the BOV or something else.

Again why is this so? Wouldn't it also be a boost leak if it wasn't recirculated?

 

[miller97tsi]

ok so good news i recirced it and it doesnt buck hard anymore. but it is still kinda surging in 2nd gear. it is kinda hesitating a bit but then it will seem to kick back and take off. is this why you guys recommend a blt. if so i will take care of that this weekend. so one problem down now it is just trying to figure out the little hesitation. any suggestions where to look. maybe intercooler piping and couplers. one last question if my bov is leaking by will it need to be replaced or is there some way to fix it.