Boggin and Jerking sr

[staygold24]

Setup: redtop sr, fmic, custom turboback, stock 7 psi, fuel pump and hks bov

I have been having an reoccuring problem with the car boggin down and revving slow then jerking when letting of the throttle under boost. It also is not a constant problem but maybe happens once a week. It will also start while driving but not upon startup but if it occured while driving and I start it up again soon after it occurs it will continue. I have searched and saw cas, maf or boost leak. I didnt know if these possible solutions would be a constant problem or intermittent like mine. Dont flame, I did try to search but if I missed something or if yall could point me in the right direction.

Thanks guys

[HellonFire]

Does it bog at any RPM? Only High, or Low?

Have you pressure tested to see if there are any leaks?

You said it happens only after you let off? It could be that you are going extremely rich after you let off the gas becuase of your atmospheric BOV.

Answer some more questions, be a little more specific, and you will get more help.

Tyler

[staygold24]

Sorry bout that, the bov is recirculated so that shouldnt be the cause of the problem and it is through all rpm and I can go up in the rpm just gets there so like something is holding it back. It happened yesterday again and let it sit for a while then started it up and drove around fine again. Could it be from a leak in the intake tube? I have a shoddy rig to recirculate the bov.

[Duzzes_Wild]

leak in ic piping

check all piping, i had a boosted ls that did this when i let off first i thought it was something else cuz it wasnt jerking on throttle but sure enough it was just a crappy weld

[staygold24]

wouldnt a boost leak be constant all the time though? and not just go away over time? im just trying to eliminate some possible things

[GSXRJJordan]

wouldnt a boost leak be constant all the time though? and not just go away over time? im just trying to eliminate some possible things

lol, not a flame, just a jab... a boost leak leaks MORE when you boost more. At vacuum, a leak actually sucks air IN to the FMIC piping, just generally not enough to make anything crap out. As soon as you boost, that air runs out of the hole rather than making that long ass journey around to the TB... lazy laws of physics...

I've seen this one problem cause more symptoms than anything else. Boost leaks screw up your partial throttle and full throttle A/Fs, mess with your partial throttle and full throttle response, and cause this damn surging that makes you want to "drive though" the problem (give it more gas to get it to stop surging). Check all your rubber elbows (I assume you dont have all silicone, because you're leaking somewhere) by jiggling them and looking for something obvious, then have someone peg the throttle while you have your hand over each joint, from the turbo to the throttle body - it's not the most elequent method, but has helped me find culprits in the past. If all that fails, it's time to check your BOV for leaks (esp if it's a knockoff).

[staygold24]

no offense taken, but you see I can boost all day hard up to redline then something just happens, not neccessarily right after that but can be at low throttle also that feels like its hesitating really badly. I just dont see why a boost leak would occur once a week when I drive it the same everday and boost it pretty hard at times.

[Duzzes_Wild]

have u checked your little maint. items such as fuel filter, plugs, and fuel injectors

[staygold24]

plugs are new but i will replace all those items pretty soon but check them when i get a chance. it also usually starts if im in too high of a gear when i should be in a lower one causing it to bog down some then it just keeps happening through all gears

[staygold24]

bump.........

[GSXRJJordan]

Your boost level is measured at the throttle body, which is futher down the pipe than the leak - that's why when you're boosting "high", the turbo might be creating X amount of air, but leaking Y amount, and by the time it gets to your throttle body, it's at whatever pressure you have your boost controller set at. When you stop boosting, there's enough of a difference in the amount of air metered to the amount getting to the intake mani for the engine to bog... It may be one "remote" possibility, but I think many would agree it's the most likely.

As you said earlier, CAS and TPS are also probabilities, and lower down the line, FPR (too high?) and o2 sensor (but you'd see other problems also if it were o2 sensor)

[1eightySX]

I am in the exact same boat, I have a redtop sr20det barely modified and it does the same thing. I have changed my Maf and that seemed to help for a bit. Than I found my car was leaking gas and the same problem started up again. I fixed my leaking gas problem and then it stopped again. Now the temperature outside has dropped and my car is doing the eaxct same thing as staygold24's. Is there a possiblity that this problem could be caused by a bad fuel filter or bad fuel pump. I find my fuel pump is super loud. Maybe we can kill two birds with one stone here.

[nisans13turbo]

I am in the exact same boat, I have a redtop sr20det barely modified and it does the same thing. I have changed my Maf and that seemed to help for a bit. Than I found my car was leaking gas and the same problem started up again. I fixed my leaking gas problem and then it stopped again. Now the temperature outside has dropped and my car is doing the eaxct same thing as staygold24's. Is there a possiblity that this problem could be caused by a bad fuel filter or bad fuel pump. I find my fuel pump is super loud. Maybe we can kill two birds with one stone here.

My fuel pump primes really load usaully after hard driving, that shouldnt be the problem because my car drives fine. Maf, cas, fuel, bov, injectors, intercooler pipings are still not the problem then its a hard call, maybe you should double check it, sometime you can overlook on something.

I had the bogging issue when I installed a MBC and it'll bog at high rpm at 12psi then I tape it off my hotpipe and it solved he problem. Hope this helps.

[staygold24]

Allright it hasnt done it in a while but I installed a boost controller and boost gauge and rearranged the vacuum lines. I really have no idea what it is and it hasnt caused a problem lately and I daily my car.

[ladiesman8527]

my car does this every once in a while. im just puttin up with it until i can buy a fmic kit. im positive its a boost leak.

[koukidough]

^^ same here

[nismoman]

+1 FOR BOOST LEAK, I had an intermitent problem like this that was driving me nuts. Made a boost leak tester and found a huge leak at the pipe coming out of my side mount. Fixed it and all my problems went away, it was missing at idle, bogging randomly, and running great sometimes. Now it runs great all the time.

[GR8WHITE]

i had a similar problem and what my problem was that when i went to change the fuel pump to a walbro pump i noticed that the pickup filter attached to the pump in the tand was filled with crap and gunk, replaced the pump and strainer and it ran like a champ, just my two cents.

[staygold24]

Ill test for leaks again, I also change the fuel pump recently and everything looked good.