s14 sr studdering backfiring problem

[black240sx96]

ok so i just finished checking for vac leaks...nothing! i used 2 cans of carb cleaner all over every hose clamps intake..etc... nothing...i think it has to be an electrical problem because its not constant but almost completely random. no matter if i drive hard or crusing it happens at any rpms any speed at any time....but if it is electrical where the hell do i start....

[mexicanracer03]

dame this is a difficult on to diagnos

ok umm have you checked all the wires ?? one of them might be causeing a short.

Check your wires then. I'm almost out if ideas

[mexicanracer03]

same goes for the plugs, maybe the wires going into the plug is loose, Just trying to eliminate all the posible causes.

LMK how it goes

[black240sx96]

ok and as far as the wiring goes thats where i get a bit messed up on because everything looks fin under the hood. all plugs are connected all wires seem intacked...except of the harness for the coil packs. theres one where that looks like its a gound so i bolted it down in the back of the engine. in the FSM theres a "loop" wire which i dont have and i think its the one i grounded. now to the ECU....have no idea...cuz theres some wires connected some arent some are tied together and some arent. the only way i might beable to figure the ecu part out might be to see another SR s14 zenki but god knows your the only one answering my post and your car looks like it has a s13 sr.

[mexicanracer03]

where the wires look cut or damaged wrap electrical tape and where the coil wires exposed just splice them back together.

[black240sx96]

in the pink thats the wire i grounded under the hood. the red circles are the ones that arent connected to anything also theres 2 wires that are connected together circled in pink which i dont know why that is...

[black240sx96]

anyone??

[mexicanracer03]

on the wires in Red do you see the other end of the wires ?? if so conect them to see if it changes.

did you check the harness where the firewall is ? perhaps a wire is causeing a short. Not sure what your problem is but Man I'm just trying to help you out the best I can since No one else knows anything.

[black240sx96]

on the wires in Red do you see the other end of the wires ?? if so conect them to see if it changes.

did you check the harness where the firewall is ? perhaps a wire is causeing a short. Not sure what your problem is but Man I'm just trying to help you out the best I can since No one else knows anything.

no i didnt see anyother ends that might connect to it. and as far as the wiring at the firewall its all protected and i dont see any cuts or anything...i know man ive been on this for a while but i cant seem to figure out the problem and no one knows anything about it...and whats also killing me is that the check engine light will blink when this "misfiring" happens but it doesnt stay on so i can get the code. it just blinks and goes away. i tried getting the code anyway and it gives me a 55...so

[mexicanracer03]

have you posted this on http://www.Zilvia.net they have a sr tech section aswell and have alot more exp. with sr's

[mexicanracer03]

just a though have you changed your O2sensor ?? if that doesn't do it try another MAF sensor perhaps you can barrow one from your buddy.

[black240sx96]

i changed my o2 sensor twice and since i am pretty cool with a guy that sold me the engine he owns the company so he helped me out switching mafs and ignitor chip coil packs and all that...honestly i did almost everything i knew and what was on these post before i posted this. and nothing this is crap! and i am 99% sure that it is not the long block or anything internal or else it would happen more offten than not.

[clovers525e]

what maf are you running? i'm using a sohc s13 ka maf on mine and it runs super rich and at about 5 or 6 grand it will just kinda bounce like its on a rev limiter, with only a little gas it will clear it fine but under anything more then half throttle it just gets stuck. if this sounds anything like what your experiencing you may want to check the maf voltage on the signal wire. mine read like 6v's at idle, s14 fsm stated like 4.5 but you better double check that, its been a while.

p.s. i loved when i had this motor (kouki s14sr) in my s14, it ran great once i tuned down the maf with my emanage like 50%, i think im going drop in resistors this time .20$ vs $200+

[black240sx96]

what maf are you running? i'm using a sohc s13 ka maf on mine and it runs super rich and at about 5 or 6 grand it will just kinda bounce like its on a rev limiter, with only a little gas it will clear it fine but under anything more then half throttle it just gets stuck. if this sounds anything like what your experiencing you may want to check the maf voltage on the signal wire. mine read like 6v's at idle, s14 fsm stated like 4.5 but you better double check that, its been a while.

p.s. i loved when i had this motor (kouki s14sr) in my s14, it ran great once i tuned down the maf with my emanage like 50%, i think im going drop in resistors this time .20$ vs $200+

awsome. i havent tried that. im going to check right now. just quick question before i do. does the engine need to be warm or can i do it cold. also you said you have an emange? anything under the hood ?? because if you dont i would like (if its not too much to ask) if you can take pictures of vac line from the throttle body to see where they are going to also i would ask for pics of your ecu wiring but you have an emange no nvm about that. lmk. THANKS

[clovers525e]

ok, so i pulled the fsm for a 2000 s15, so numbers may still not be correct and mine were most certainly not lol, so ignore the insanly high voltage numbers i posted earler, the s15 fsm stats that the maf should read .8 to 1.5v under no load and at idle, 1.4v to 2.0v around 3000 rpms in Neutral. ac switch off and after warm up.

i no longer have my emanage (used it when i has a s14 chassi) but now i run a s13 chassi and switched from the zenki (red WC ecu and blue ecu clip) to the kouki (black NA ecu and white ecu clip) wiring harness and ecu.

i got the harness new from nissan though, so if there is a section your unsure about (eccs relay for instance) i can help you out, but our f4 plugs are slightly different and i have no clue on how i did my s14 swap .

as far as the vac lines under the throttle body goes, most get capped off. youll need to run your waist gate off the hot side of the intercooler piping, your iacv off the cold side intercooler piping, your bov off one of the nipples under the throttle body and for this you need to take vacume line and blow to make sure it runs to the middle of the plennum. there are two (maby more) you can look under and see were they run into the intake. some of the nipples open up before the throttle body and some are after (or directly inside) so you have to check which ever you use. the fuel pressure regulator has a nipple conviently located across from it. all the other lines around the trottle body get capped off. one can be used as a boost gauge signal, infact you should never use or need to use a t line because there are so many open vacume lines for god knows what.

[black240sx96]

ok. so im pretty sure all my vac lines are fine..jjust always been worried about it. i actually bought the harness from nissan also brand new and the shop i took it to did all the work for me. just about a month after this problem started happening str8 out of no where. one day i got off work turned on the car and wham this problem. i never took it back to the shop because theyve been tring to screw me for a long time. it took them 7 months to do my swap correctly. (and they have the highest rep in miami) anyway i really think this has to do with an electrical problem simply because it doesnt happen often just very random. i have a link up to a you tube video i posted and you can hear the engine studdering and what not. so now im here. btw if you need the FSM for the s14 i have it just give me your email and i will send it to you. but thanks for the idea im going to look into it now

[black240sx96]

at idle maf signal was between 1.25 and 1.28v

[black240sx96]

also all 4 of my injectors and vtc solenoid valve are reading at the ecu about 23 v and it should be at 11 - 14v (bat v) while idle. just in the on possition it reads fine.

[black240sx96]

anyone know about this ??

[black240sx96]

WELL I FINALLY FIGURED IT OUT!!! so i got home yesterday and decided to attack this problem again before i call it quits and take it to a shop in orlando. so i took out the spark plugs and the coil packs and inspected them for the 450th time. all of them are good. then i took of the sub harness for the coil packs. they looked fine (From what i could see) all the original heat srink and tape looked in good condition. so i said what the hell let me take all this appart and inspect every wire one by one. first thing i noticed was that the wires that led to coil pack number 1 (number 1 piston) was actually tied into the main plug not on its own set of lines. and that was taped off. so i took that tape off and low and behold CORROSION. this is was so corroded that it was white. so i got some corrosion sprey and cleaned it good. sanded it just to get that copper look back to it and good to go. then i started to see some little nicks in the wires that was causing the copper wires to be exposed. so i taped that up and re heat wraped the sub harness. took it for a test drive and BAM no more studdering or breaking up. runs like a champ should. so the problem was the factory taping failed and the wires had corrosion and exposed wiring which would cause the electricity to just to the nearest metal instead of going through the coil pack and into the spark plugs. (monitors i guess you can lock this thread up now) Problem Solved. untill next time.