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Forum name4G63 Tech
Topic subjectstill sputtering 3/4-wot
Topic URLhttps://forums.2gnt.com/dcboard.php?az=show_topic&forum=i67&topic_id=9486
9486, still sputtering 3/4-wot
Posted by kelvinb1, Nov-06-04 05:54 AM
so i changed out the injectors (factory 450cc blue tops), rewired the fuel pump (possible fuel shortage at high throttle) and still sputtering??? it does not miss anymore, but still having issues. any other ideas? possible o2 sensor? there is a crack in the exhaust manifold, but when revved there is no air that comes through.
9487, RE: still sputtering 3/4-wot
Posted by eclipzGST, Nov-06-04 11:35 AM
Have you checked for boost leaks?
9488, RE: still sputtering 3/4-wot
Posted by kelvinb1, Nov-06-04 11:41 AM
i have not done a leak test. i guess i have a question on that. i cap off one side (say it be the turbo-out side) and i hook the other side up to the air compressor, say at 10psi, is that basically what i should be doing?
9489, RE: still sputtering 3/4-wot
Posted by Diceman19, Nov-06-04 12:01 PM
just build a boost leak tester as per vfaq.com directions. pull off intake snorkle (if your stock, intake pipe if not) and put the tester on the cold side of turbo. flip on compressor and start pumping. dont turn up the psi on the compressor too high though or you might "spool up" too quick and risk breaking something. ;-) you will have a very very slight drain in the intake piping. that will be normal. you will know if there is a leak. it will be hissing like a pissed off snake.
9490, RE: still sputtering 3/4-wot
Posted by kelvinb1, Nov-06-04 12:04 PM
Originally posted by Diceman19
just build a boost leak tester as per vfaq.com directions. pull off intake snorkle (if your stock, intake pipe if not) and put the tester on the cold side of turbo. flip on compressor and start pumping. dont turn up the psi on the compressor too high though or you might "spool up" too quick and risk breaking something. ;-) you will have a very very slight drain in the intake piping. that will be normal. you will know if there is a leak. it will be hissing like a pissed off snake.


awesome thanks for the info! the only thing i can of possibly wrong is the ic is tilted backm like the guy hit something. ill check it out though. thanks gst also! :D
9491, RE: still sputtering 3/4-wot
Posted by Jeff_99gs, Nov-08-04 06:46 AM
You are probably running too rich. Also what spark plugs are you running and what gap?
9492, RE: still sputtering 3/4-wot
Posted by eclipzGST, Nov-08-04 11:37 AM
Originally posted by Jeff_99gs
You are probably running too rich. Also what spark plugs are you running and what gap?


posting your mod list will make it easier to pinpoint what your problem may be.


9493, RE: still sputtering 3/4-wot
Posted by kelvinb1, Nov-09-04 12:59 PM
its basically stock. ive only done the bcs mod and taken that restriction out. thats it. it was sputtering before but i did change the plugs (ngk v-power and i know it has a 6 in it, likes 6es) stock air filter, stock wires, it looks like the stock fuel filter. that will be next to change out along with the wires, and maybe a k&n chopped air can
9494, RE: still sputtering 3/4-wot
Posted by eclipzGST, Nov-09-04 03:02 PM
Originally posted by kelvinb1
its basically stock. ive only done the bcs mod and taken that restriction out. thats it. it was sputtering before but i did change the plugs (ngk v-power and i know it has a 6 in it, likes 6es) stock air filter, stock wires, it looks like the stock fuel filter. that will be next to change out along with the wires, and maybe a k&n chopped air can

Originally posted by kelvinb1
so i changed out the injectors (factory 450cc blue tops), rewired the fuel pump (possible fuel shortage at high throttle) and still sputtering??? it does not miss anymore, but still having issues. any other ideas? possible o2 sensor? there is a crack in the exhaust manifold, but when revved there is no air that comes through.


do you have a 5-speed or A/T?
Why did you change the injectors? If you had an A/T with the smaller turbo/injectors, I could see swapping them if you bolted on a 14B...
Also, you shouldn't have needed to do the re-wire either unless you are running more boost and/or bigger injectors. I don't think the re-wire would hurt anything though.
Now, if you still have the 13B and are running 450's with a re-wired pump, that MAY cause you to run a little rich although I had 14B/450's in my 1G and it ran fine. :shrug Got me man...

9495, RE: still sputtering 3/4-wot
Posted by kelvinb1, Nov-10-04 06:36 AM
injectors were changed because one was bad. (resistance for injector 1 was 4.8 the others were 2.5) i only swapped one, but it still did it, so i swapped all 4 in because someone said to, i forget his name but he has a 1g on here too. i rewired the pump because i read on vfaq that on higher rpm's sometimes the fuel pump wouldnt get enough power to give enough fuel, so i said what the hell and tried it, since this is really only happening at 3/4-wot. i have yet to do a boost leak test. ill get back with you on that.
9496, RE: still sputtering 3/4-wot
Posted by eclipzGST, Nov-10-04 07:18 AM
Originally posted by kelvinb1
injectors were changed because one was bad. (resistance for injector 1 was 4.8 the others were 2.5) i only swapped one, but it still did it, so i swapped all 4 in because someone said to, i forget his name but he has a 1g on here too. i rewired the pump because i read on vfaq that on higher rpm's sometimes the fuel pump wouldnt get enough power to give enough fuel, so i said what the hell and tried it, since this is really only happening at 3/4-wot. i have yet to do a boost leak test. ill get back with you on that.


Yeah, if you have no fuel/boost control, chances are there's a leak somewhere. Sometimes the stock intercoolers get some corrosion on the top near the outlet that will cause it to rot out and you'll get pinholes that turn into bigger holes.
Do a boost leak and get back to us.
What year is the car? Could be ECU related also...
9497, RE: still sputtering 3/4-wot
Posted by kelvinb1, Nov-10-04 01:17 PM
its a 1991 talon. ill check out the intercooler
9498, RE: still sputtering 3/4-wot
Posted by Vandy420a, Nov-10-04 04:16 PM
It really does sound like a major air leak somewhere. Another issue could be one or more of the new injectors aren't working right, i.e. giving too much fuel or a crappy spray...
9499, RE: still sputtering 3/4-wot
Posted by kelvinb1, Nov-12-04 12:26 PM
Originally posted by Vandy420a
It really does sound like a major air leak somewhere. Another issue could be one or more of the new injectors aren't working right, i.e. giving too much fuel or a crappy spray...


i put in some of that lucas fuel stabalizer, its really thick, so maybe it will do something? i have yet to check for a boost leak yet. my weekend is over, so im out of time :(. i did make a gauge pod though :D