full bosst back firing

[onelowgst98]

i just realized i spelled boost wrong sorry guys its 3am here hey i know you guys are gonna tell me to search but i already did and cant realyy find the problem. Im tryna find out whats going on with my car its a 1998 eclipse gst automatic with a rebuilt engine with about 20,000 miles on it and a new evo 16g. i dont have a boost guage im just going off of the stock one when my boost guage is topped it my car like kinda back fires for some reason....i didnt upgrade my injectors or fuel pump could that be the problem? it feels like the car wants to keep pulling but the backfire stops it im just tryna see what this 16g can do. oh and i dont have a mbc either so i guess the car is at stock boost

 

[98spydereugene]

you shouldn't be backfiring on stock wastegate pressure on a big 16g, I'm running one right now on stock wastegate til motor breaks in, and have ran two previously, its definitely backfire and not fuel cut right?

 

[onelowgst98]

it more like a stutter so it maybe fuel cut? how do i prevent that? as soon as the guage tops out it does it everytime

 

[98spydereugene]

fuel cut is abrupt and it'd feel like your tranny is laying 100yds back, so I doubt it's that..have you checked tps, cam positioning sensor, or maybe bad plugs. Using bpr7es I hope?Does it happen in every gear or just high gears at full boost?

also have you done fuel filter change?could be something as easy as that...

 

[onelowgst98]

it only does it when im in high rpms i know i didnt change my plug wires when i put the motor im so maybe ill try that out. i have a lil exhaust leak to that would be a problem would it?

i was told i have to get it tuned? im just taking one step at a time i dont want to up the boost yet

 

[Tre3zy]

they might be rite since you dotn have fuel support for the 16g then your hitting fuel cut.... this happened to me when i got a full 3" exhaust on my 14b boosting 15psi.... i hit fuel cut at around 4-5k RPM's

 

[98spydereugene]

you shouldn't need a tune at all with just those mods, sounds like to me to be an ignition problem, wires, plugs, something in that direction. replace wires with ngk blues and get bpr7es plugs if you don't know what's in there or how long its been..good start and good thing to have anyway..

you shouldn't be hitting fuel cut even with a 16g, especially at stock wastegate pressure

how long ago have you changed fuel filter?could be something as simple as that

 

[t-rexn8]

I agree...

New BPR6ES plugs at .028 & some NGK wires is a perfect place to start.

All the heat and especially the high boost are really hard on wires and plugs.

 

[dsmtun3r98gst]

Hey you may be overboosting man. I had the exact same problem you did right after I upgraded to a VRSF FMIC for some reason after the upgrade I was boosting all the way up to 22psi . IDK why it didn't happen when I had my stock sidemount. I installed a boost gauge just to see exactly what my boost was and took it for a test drive; I floor it a bit and when I looked a my boost gauge it went up all the way to 22 psi and I wasn't even at WOT .

All I did was connect a second vacuum source into the waste gate and boost went down to 12 and the problem was solved. I thought it was funny/weird how I didn't overboost when I had my stock side mount, and with the FMIC it did . Must have had some serious leaks .

How many vacuum lines are feeding the 16g wastegate you have? the T25 has 2, one coming from the boost solenoid and the other coming from the niple of the t25. If you deleted the one coming from the turbo that can be your problem since the 16g doesn't have one and needs to have one made.

When I installed my 16g I just had one vaccum source running towards the wastegate thinking I wasn't going to have any problems. Didn't have any issues up until a new fmic

 

[onelowgst98]

im gonna replace the fuel filter and plugs and wires today and see if that works. the car pulls like a champ but as soon as that guage tops out it sputters. i dont even think i gapped the plugs when i put the motor in

 

[Swish]

i had the stutter problem at high RPMs, threw in a new fuel filer and all of it went away , i also had to throw in some cheap Bosch Copper Plus since auto parts stores don't carry NGKs for our car any more.. pfft! NGKs are on the way!!

 

[nek]

fuel cut. a non ported 16g will boost creep up around 19psi with stock boost. Stock fuel system can only handle around 16psi. The cpu cuts fuel to protect the system when your maf detects to much air which is what your feeling.