Car jerks at 15psi

[negativezero27]

gah i put my new boost controller back on (turboxs). Took us forever to figure out that we had it backwards. The website said the wrong thing. But not my car is set for 15 and spikes to 17psi. but like when i hit 15 my car starts to jerk. it only does it like 3 times but it jerks when it hits 15psi then the boost drops when it does this. Then when i shift my bov flutters. Also when my car doesn't jerk my bov doesn't flutter. its really weird. I have to vent without the MAFT, because the tube that my intake from my bov has this really bad bend in it. That might be the problem I don't know. Almost fills like a fuel cut or something. I bought a MAFT but it wont be on until next week, have to wait for shipping.

 

[playitlouddsm]

Boost leak bro..

 

[dsmsucks]

Boost leak bro..

I can be a boost leak(most likely) or plugs and wires

 

[redfury]

Do a leak down test, spots the boost leak quick.

 

[negativezero27]

boost leaks will make my car jerk like that? Because it was at 14psi and it would never do that. The reason why i got my car to go up to 15 is because of a bad actuator. It was bent and would only let my car go to 14. But my TB leaks and my car would boost just fine with 14. Hits 15 psi at 3k and then past that it will jerk a couples from 3k to redline. Could it also be that im using cheap gas from 7-11, 91 oct?

This is what my actuator looked like.

You must be logged in to view this image or video.

 

[2gGSX]

Definitely check your plugs.

 

[95blackGsTurbo]

Sounds like a fuel-cut issue if it does it at 15psi and not 14psi. Boost leak would cause it at any psi depending on size and the plugs would do it at any psi too. Just to be sure I would get a set of NGK BPR7ES plugs and gap them at .028''. If that doesn't help you are looking at hitting fuel cut. Actually reading the rest of your post now hook that damn BOV back up. If you know it could be the problem why not try to fix it. That will cause problems if the BOV is leaking and especially when shifting. Get that recirc. tube back on there and let us know what happens then.

 

[Fabian972]

Same problem i had when i floor it .....took it to dealer had a boost leak so tighten up your braces and you should be alright if not new hose time

 

[zatomz]

I've been having the same problem. I'm running 16 psi and when it gets really cold out my car has been spiking to 19 and almost 20 psi which I'm not set up for, fuel wise. It would start jerking at about 4000 rpm until I shifted. Also it would leap forward if i had any load on it what-so-ever and then let it off. Now I also discovered that I had the same recirc tube that you mentioned (bent almost in half and cracked on the sides). I said theres got to be a better recirc tube, went everywhere to try and find one but no one carried anything like it. I knew the guys at advanced auto (go figure) and they let me browse all of their radiator tubes and i actually found one that was pre-bent and fit my bov to intake setup perfectly with out creasing the hose( I had to cut a 1/4 inch off). I just did this today so I do not know if this will fix this problem or not but i will post up an a day or two and tell you how it went. Also it sounds better as well, more distinct. Good luck

 

[negativezero27]

I figured i would bump my old thread then to start a new one. My car is still doing this jerking thing. I recently just put my evo3 16g, 680cc injectors, fpr, 3-inch turbo back exhaust, new BPR7ES plugs and brand new wires. I did a boost leak test and have a leak on the throttle body. I replaced the gaskets and put some rtv on it aswell. Then i did another boost leak test and it went to 20psi stopped and then held it for a second then, slowly dropped. I hit full 12 psi somewhere in low 3k's and higher 2k's. Then i hold full boost until i get into the 4500rpm range. But now, sense i recently put all of this new stuff on my car doesn't jerk any more. it backfires when it hits full boost, and then feels like my car is chained to a tree. I have my maft set on stock injectors sizes because, when i had the maft set on 680's, it was running horrible.

Do i need a dyno tune or is there anything else i should trouble shoot?

 

[GVR4592]

Do you guys have dataloggers?

 

[TSi Fury]

If you're running your BOV vented, and you keep the gas at a certain point other than WOT, once the car has been at that point for an amount of time, the BOV will start to open and it will cause your cark to jerk pretty bad, and loose boost. Does it jerk at all under WOT?

 

[majik2k5]

If you're running your BOV vented, and you keep the gas at a certain point other than WOT, once the car has been at that point for an amount of time, the BOV will start to open and it will cause your cark to jerk pretty bad, and loose boost. Does it jerk at all under WOT?

Actually, I had this problem when I ran mine vented a few times before my MAFT setup. It would begin to open up slightly and cause some pretty harsh jerking and backfiring. Sounds like a good possibility.

 

[91turbotalon]

Definately fuel cutting and it would help to reciculate the bov. some cars run fine and some dont vented without a maf-t

 

[negativezero27]

well it use to jerk when i floored it. to answer your question, no it doesn't jerk at all under WOT. i can get a little bit of most with half throttle. Which the car does not jerk at all when i do this. the only time the car jerks is when it hits full boost (12psi) then when i get to 4500ish rpm my car backfires and i then have the diamond symbol on my forehead from the steering wheel after it makes a dramatic hault. But i boost leak tested my car and my bov didn't leak at 20psi and my car does all of this at 12psi. i also vent because i have a maf-t. I might turn up the boost and see what else happens. might make something stick out like a swore thumb.

any more things i should test?

 

[ILLiCliPSE]

could it be your boost controller realizing there's a drop in psi, then try to actually gain back the 15 psi from a boost leak...as in constantly dropping and gaining boost?

 

[negativezero27]

i don't think its my boost controller. Its brand new and this is the second boost controller i have tried. when my car hits 12psi it stays there. my gauge does not sway back and forth.