acceleration problems!!! Fuel Cut?? Boost Leak?

[turbodsm_125]

I have a 90' eclipse GSX. I have spent a fortune on this car as i built it from a bare shell. THe car has a fully rebuilt motor, FMIC, K&N filter, BESK, full 2 1/2 exhaust and a few other things done to it. My problem is that once i get the car started it idles fine but if you give it any gas it wants to stall for a second then acclerates. I am not sure what does this. THen today i was driving down my road and every time the car startyed to build up boost(3000-3500rpm) the car would spit and spudder and would want to quit. Not he car wont idle at all and just wantsw to quit unless you give it gas constantly. Any help you could give would be much apprciated!

 

[romeen]

Most likely a boost leak. Build yourself a leak tester as shown in the tech section. It will prove invaluable in keeping your car running strong. BTW, how much vacuum are you showing at idle? It could be other things of course but this is a good place to start.

It doesn't sound like fuel cut. Fuel cut is violent.....most guys describe it as feeling like you hit an invisible brick wall. Scared the crap out of me first time it happened.

Let me know the results of your boost leak test. If you need any help let me know.

 

[dsmer1G]

Check your intake pipe after the MAF, if it has come loose it will run like that and not want to idle.

 

[appeartobelosin]

im having the same problem with my 1997 GSX....the turbo builds up and it just doesnt pull like it should....then when i get to about 4000rpm the motor jolts and wants to stop but it will keep going after that....what do i do if it is a boost leak? help me out PLEASE!!!!

 

[numlock666]

sounds like the maf to me. Its going to take a big boost leak to make it buck like that.

 

[96_charcoal_tsi]

Also check your plugs. Kinda sounds like it's getting to much fuel and that could be a reason as to why it is hessitating. Also do a boost leak test.

 

[appeartobelosin]

whats the best way to do a boost leak test? why is the turbo not pulling the car like it should? i just put a mbc on it and ever since then it has been jolting when i hit around 4000rpm....can the maf really make that big of difference???? makes me wanna drive this POS off a cliff....i have put a Godspeed FMIC on it. a turbo xs mbc. greddy bov. and thats bout it....what would make it jolt and want to stop? it feels like its just getting cut off....idk what to do? what can i do bout my MAF? not going to sound big and bad....im kinda new at this and im lost.

 

[turbosax2]

http://www.dsmtuners.com/forums/art...-boost-leak-test-how-boostpro-net-tester.html

 

[tsiawd3]

get new plugs and wires also use a bottle of injector cleaner
hope this helps
worked for me

 

[appeartobelosin]

so i connected my boost controler between only my turbo and the wastegate. this helped the jolting for the most part. i think that i am getting to much compression in my motor and think the timing might be off. i also think that it is sparking to soon so it exploding to early....before the cylinder if all the way at the top???? just thinkin. i took it out during my lunch break on a open road and played with the mbc. if i turn it up to far then the jolting comes back into play when i hit around 4000rpm's.....so i dialed it down and it seems to be running ok now....just think the timing is off and maybe the gap between my plugs is off....there is prob a boost leak somewhere in my fmic piping cause i can hear a loud whistling noise when the turbo builds up..........ill try timing and check the plugs.....i let ya know what happens after i make thos adjustments.....thanks everyone for your help

 

[appeartobelosin]

i have a boost leak somewhere on my car....i havent performed a boost leak test yet....but when the turbo gets fully built up there is a high pitched whine coming from somewhere....any thoughts?

 

[16g-2ndgen]

It doesn't sound like fuel cut. Fuel cut is violent.....most guys describe it as feeling like you hit an invisible brick wall. Scared the crap out of me first time it happened.

true story, especially when safcII dont want to freakin work

 

[TurboDSM610]

Well that whining nosie you hear is probably your j-pipe. A friend of mine was having that same problem just check the gasket, as for the fuel cut part definetly a boost leak and hitting fuel cut is bad for your engine so try to be easy on the throttle.

 

[appeartobelosin]

i fixed the fuel cut....the engine was getting to much compression....i ordered a new MAF kit that i can connect into my upper pipe on my FMIC....cant seem to still find that high pitched whine....f**kin pos....hahaa

well nevermind bout the boost leak. one of my bolts that hold down the bov came loose. now i feel dumb. oh well it gone now. thanks everyone. i still have a problem with my fuel cut tho. when i mess with my mbc and turn up the boost i hit around 4000rpm @ full boost and it jolts real bad....any thoughts???? thanks

 

[turbosax2]

well nevermind bout the boost leak. one of my bolts that hold down the bov came loose. now i feel dumb. oh well it gone now. thanks everyone. i still have a problem with my fuel cut tho. when i mess with my mbc and turn up the boost i hit around 4000rpm @ full boost and it jolts real bad....any thoughts???? thanks

Do a proper boost leak test.

 

[Eclipsegst2312]

I had a similar stuttering problem. I changed my spark plugs and wires and it cleared right up. Hope that helps you.

 

[AlphaAssault]

well nevermind bout the boost leak. one of my bolts that hold down the bov came loose. now i feel dumb. oh well it gone now. thanks everyone. i still have a problem with my fuel cut tho. when i mess with my mbc and turn up the boost i hit around 4000rpm @ full boost and it jolts real bad....any thoughts???? thanks

I have this problem now. There is only one thing that I messed with before developing this problem, and that is the BOV. The BOV was venting strait into the atmosphere. so over the weekend, I reconnected the BOV back to the intake. Now, I get the lurch you are referring to at 4k rpms. From what I can tell, its one of 2 things:

1) The clamp for securing the hose to the BOV was completely missing. I need to find a new one, and when i do Ill throw it on the hose and hopefully that will seal up the boost leak, if that turns out to be the problem.

2) Now that I am venting correctly, the air-fuel ratio might be messed up in my engine. I have a manual boost controller, but I havnt messed with that since I bought the car. Now that there is more air in the system, I could be running lean if the ECU has already compensated for the air being vented out of the system. To compound the issue, my MAS has been hacked, and Im sure isnt functioning as well as it should. SO, is this making since to anyone? Which way should I turn the dial on my MBC so as to reduce the level of boost?

 

[neoviper]

Alpha, recirculating your BOV and making your car run leaner shouldnt do this to your car. If I'm wrong on this someone correct me ( and please be gentle ) but im gonna give it a shot.

If you recirculate your BOV after your car is already tuned for an externally vented BOV, the extra air going into you intake can cause a slight increase in boost your car is producing, or so i've read. How much boost are you running right now? because if this is true, than that combined with the slight increase in boost can give you fuel cut.

Try venting the BOV again to see if the problem lingers, or just turn the Boost down

 

[neoviper]

But first I would put that clamp on the BOV hose as that is most likely the source of your problem.

 

[AlphaAssault]

Ok, the hose clamp at the BOV wasnt the problem. I reconnected everything, and went for a test drive. Again, I heard the boost spool up, but I wasnt feeling the power of the boost. I pulled it into neutral before the engine had a chance to lurch like it did yesterday. Next, which was should i turn the knob on the MBC to get the boost down a bit? Im thinking I should turn it clockwise. I dont have a boost gauge, so Im shooting in the dark here.

 

[GVR4592]

This is a perfect example of how NOT to build a dsm. Take boost controller off of the car, connect the wastegate to a vaccum/boost source(intake manifold, not the throttle body). Wait until you can afford to get a datalogger, fuel system upgrades, and a tuning device. Then you can put the boost controller back on your car. If you keep screwing around with it the way it is know, you're not going to have a car to drive.

 

[AlphaAssault]

This is a perfect example of how NOT to build a dsm. Take boost controller off of the car, connect the wastegate to a vaccum/boost source(intake manifold, not the throttle body). Wait until you can afford to get a datalogger, fuel system upgrades, and a tuning device. Then you can put the boost controller back on your car. If you keep screwing around with it the way it is know, you're not going to have a car to drive.

Hey! I bought the car like this. Im still learning, so some creative criticism would be appreciated, get it? When I bought it, it was running fine, though the BOV was venting into the atmosphere. I route it back into the intake, and now Im getting a lurch and no power when under heavy boost. I havnt touched the boost controller at all, and I will gladly turn it down if it fixes the problem. Unless you have another idea of how to fix this issue, which way should I turn the MBC to reduce the boost?

 

[neoviper]

If you can post a picture of it im sure someone would be able to identify it and tell you which way to turn it.

 

[AlphaAssault]

Its basically a black box with the dimensions: Length-1.5inch, width-1.5inch, height-.5inch, with a round brass knob at the top, and with the hoses connected at opposite ends of the box. Its very simple.

EDIT: Heres a useful tidbit. I turned the boost down with the controller, and it took longer for the engine to start lurching under the boost. While it took longer for the engine to lurch, because the boost was lowered, it also took longer for the engine to reach higher rpms. So, um... what does this mean exactly?

 

[neoviper]

Your gonna need to do a boost leak test as that is ### the problem seems to be