420A Random power loss, idle drop an sputtering. Help plz!

[2GNT_RS-T]

Whats up everyone. Just wanna start out saying sorry if this has been posted before This is my second time making a thread so im really new. Im just have an annoying issue ive been trying to figure out for awhile now. My car is having this strange issue when driving. About after the 3rd-4th time stopping (mostly when the car is already warmed up) the idle will drop slighty to about 500rpms an it will start to misfire an sputter alittle bit. Once i start driving, it will accerate decently but then it will kinda break up/bog lightly until i get to about 3000-3500rpms then it will clear up an pull smooth when i get into boost. After that pull it starts to run good an smooth til the next 2 or 3 times i stop an it will start doing the same thing again. When its not doing all that, it starts perfect everytime, it drives good, pulls decent an idles at about 800 rpms. Even when its in its good phase an idling good an smooth there feels like a little power loss overall. This is gonna be hard to explain but When i do a WOT pull it usually pulls good all the way through til i switch gears an it will fall on its face an loses boost or something instead of staying in boost an pulling all the way through. Hope that all makes sense. Heres some of the new parts i put in if this helps: legit Walbro fp 255, fuel tank, fuel filter, plug wires, spark plugs gapped at .30, turbo mani gasket, seafoam, WG gasket, VC gasket set, cam and crank sensor with new harnesses an i did a smoke vacuum test an the only smoke i saw coming from the hole from my fmu. I would REALLY appreciate any kind of feedback. I just want my baby running the way it should be. Thanks

 

[Murdertalon]

Is this a N/T that has had a turbo added?

First thing I would suspect is you need to check grounding to engine. I had similar issues with a Neon that ended up being the ground strap to block broke and the ground to the head was super high resistance. It caused sensors that rely on grounding to start freaking out basically. After I added a couple ground wires (chassis and block) everything was normal.

 

[2GNT_RS-T]

Is this a N/T that has had a turbo added?

First thing I would suspect is you need to check grounding to engine. I had similar issues with a Neon that ended up being the ground strap to block broke and the ground to the head was super high resistance. It caused sensors that rely on grounding to start freaking out basically. After I added a couple ground wires (chassis and block) everything was normal.

Yes its the n/t with a 14b turbo added on. As far as i know the grounds are good. Ill check them all an report back. Would you know how many ground points the are on the n/t?

 

[Murdertalon]

not completely sure, if I remember correctly there was a mesh ground strap wire from frame to block and a wire from the chassis to battery. literally take a multimeter and touch the negative battery terminal and the block/ head and if you get any resistance add a ground wire to the block and or head. I remember I had high resistance to the head (where sensors bolt to) and then dug around and found that mesh ground strap had broke.

also check out the cam position sensor and spark plug wires for 2 things 1 make sure they aren't jumping spark anywhere (look at the engine running in the dark) 2 check resistance of. plug wires and end connection inspection

my 2g was missing randomly (no codes) and one of the plug wires had a broken clip that locks it into the coil pack

 

[2GNT_RS-T]

not completely sure, if I remember correctly there was a mesh ground strap wire from frame to block and a wire from the chassis to battery. literally take a multimeter and touch the negative battery terminal and the block/ head and if you get any resistance add a ground wire to the block and or head. I remember I had high resistance to the head (where sensors bolt to) and then dug around and found that mesh ground strap had broke.

also check out the cam position sensor and spark plug wires for 2 things 1 make sure they aren't jumping spark anywhere (look at the engine running in the dark) 2 check resistance of. plug wires and end connection inspection

my 2g was missing randomly (no codes) and one of the plug wires had a broken clip that locks it into the coil pack

Sorry if this sounds stupid but what do you exactly mean if i get a resistance? If i do get a resistance, what number would show up?

 

[Murdertalon]

if you check continuity and it's anything other than 0 ohm from battery terminal to block resistance then you need to address some things.

 

[1990TSIAWDTALON]

Sounds like it is loading up on fuel and then you "clean" it out by driving and after 3-4 stoplights it is misfiring. Can you be over fueling it at idle or have an injector hanging open a bit, fouling a plug slightly and then after you drive a bit it burns the fouling off and it starts all over again, but this is just a random guess in the dark.

 

[2GNT_RS-T]

if you check continuity and it's anything other than 0 ohm from battery terminal to block resistance then you need to address some things.

Ok cool so if i check resistance between the negative terminal an block/head an it shows anything other then 0, then i need a ground put on? Sorry im kinda new to all this stuff

 

[2GNT_RS-T]

Sounds like it is loading up on fuel and then you "clean" it out by driving and after 3-4 stoplights it is misfiring. Can you be over fueling it at idle or have an injector hanging open a bit, fouling a plug slightly and then after you drive a bit it burns the fouling off and it starts all over again, but this is just a random guess in the dark.

I kinda thought the same thing. What can cause it to load up on fuel or over fuel at idle besides for a hanging open injector?

 

[2GNT_RS-T]

Sounds like it is loading up on fuel and then you "clean" it out by driving and after 3-4 stoplights it is misfiring. Can you be over fueling it at idle or have an injector hanging open a bit, fouling a plug slightly and then after you drive a bit it burns the fouling off and it starts all over again, but this is just a random guess in the dark.

What do you exactly mean by injector hanging open? Like its spraying fuel continually?

 

[Murdertalon]

What do you exactly mean by injector hanging open? Like its spraying fuel continually?

Also I take it you run an aftermarket fuel pressure regulator? I mean you probably should have one from the sounds of it. You might want to verify what your fuel pressure is set at do you monitor AFR air fuel ratio? If its showing excessivly rich then too much fuel- and could be a stuck injector or your over running your injectors with too much fuel pressure.

 

[1990TSIAWDTALON]

Yes, like maybe it has a little debris in one letting it "leak" constantly. Just seems weird that it misfires (I think it is trying to foul a plug) then it will clear up after a constant drive. Is it spewing any black smoke out the tail pipe?

 

[2GNT_RS-T]

if you check continuity and it's anything other than 0 ohm from battery terminal to block resistance then you need to address some things.

I checked the head continuity an it was 0 but then i checked thw block an it went crazy showing high numbers

 

[2GNT_RS-T]

Yes, like maybe it has a little debris in one letting it "leak" constantly. Just seems weird that it misfires (I think it is trying to foul a plug) then it will clear up after a constant drive. Is it spewing any black smoke out the tail pipe?

No i don't see any smoke from what i can tell. Ive always wondered if i had a bad fuel injector(s) cause a gew months ago i had to change my gas tank cause it was completely covered in rust an fuel injectors was one of the things i never changed

 

[2GNT_RS-T]

Also I take it you run an aftermarket fuel pressure regulator? I mean you probably should have one from the sounds of it. You might want to verify what your fuel pressure is set at do you monitor AFR air fuel ratio? If its showing excessivly rich then too much fuel- and could be a stuck injector or your over running your injectors with too much fuel pressure.

No its the stock fuel regulator. I know i was about to go buy a fuel pressure gauge cause right i cant afford a wideband/afr gauge but its definitely next on the list

 

[2GNT_RS-T]

I checked the head continuity an it was 0 but then i checked thw block an it went crazy showing high numbers

The continuity from the battery to the block was going crazy, it wouldbt stay on a number. So whats some of the the things i should address? Btw the continuity from the battery to head was 0 same with battery to tranny

 

[Murdertalon]

The continuity from the battery to the block was going crazy, it wouldbt stay on a number. So whats some of the the things i should address? Btw the continuity from the battery to head was 0 same with battery to tranny

Add a ground cable to block, I would run it from battery terminal to a bolt on the block. If you saw resistance its not grounded properly, that can cause sensors to go nuts. I think factory location for ground to block is an o ring electrical connector on one of the starter bolts. If this fixes it likely it was sensors having issues because they need to be grounded.

You can look in scrap yards for the part or go to any battery store / one that replaces terminals ect and let them know you want a hefty ground ran from battery terminal to block.

When I had my neon this literally took me months to diagnose and pin down I was having random loss of power but it was so inconsistent that I was still able to use it as a DD.

Also consider an improperly grounded block can get shocked from your spark plugs firing and then who knows what charge your block can hold and then mess with sensors. I had this exact thing happen- not saying this is your main cause of issue but its one you can check off the list.

 

[2GNT_RS-T]

Add a ground cable to block, I would run it from battery terminal to a bolt on the block. If you saw resistance its not grounded properly, that can cause sensors to go nuts. I think factory location for ground to block is an o ring electrical connector on one of the starter bolts. If this fixes it likely it was sensors having issues because they need to be grounded.

You can look in scrap yards for the part or go to any battery store / one that replaces terminals ect and let them know you want a hefty ground ran from battery terminal to block.

When I had my neon this literally took me months to diagnose and pin down I was having random loss of power but it was so inconsistent that I was still able to use it as a DD.

Also consider an improperly grounded block can get shocked from your spark plugs firing and then who knows what charge your block can hold and then mess with sensors. I had this exact thing happen- not saying this is your main cause of issue but its one you can check off the list.

Awesome man i appreciate your help. Im gonna do all that today an ill let you know how it goes. It definitely sounds like it could be my problem