my s14 rb25det has been bogging down lately. when i start to accelerate ill get a bogging down feeling like its missing so to speak. i just changed the plugs recently and my car is running rich. i think it might be the gapping, i think i should bring em in to around .030. i was just wanting an opinion of other possibilities. i thought maybe i need to clean my mafs also.

 

does anyone have any ideas?

 

I know it sound retarded, but my HONDA(yes i said honda, get over it everyone) did the same thing. I replaced EVERYTHING from plugs, wires, cap, rotor, fuel filter, EVERYTHING.

Turned out to be the 02 sensor. IT also will make your car run ritch if it's in limp mode.

I know it's a long shot, but just thought i'd throw it out there.


BTW- didn't you gap the plugs when you put them in?

 

moved to "Engine Swaps"

 

hmm I would guess a leak in the intercooler piping, bad 02 sensor, or failing MAFS/mafs wiring. Try unpluging the O2 and MAFS(one at a time) while the car is running, if nothing changes in the way it runs, there is your problem. A bad TPS could cause this too, that will have to be checked with a voltmeter. If you just put in new plugs it shouldn't be the plugs, my RB20 fowled a couple of plugs because it was really rich on start up, and they would not clean out I had to replace them. I think spec gap on the plugs is 1.1mm(.044), I've narrowed mine to about .034 to handle increased boost.

 

i just took the plugs out and re-gapped down to .030 and it still did it. im also gonna replace the fuel filter. i was thinking it could be mafs or fuel pump, but i didnt think about the o2 thanks guys ill check them also.

 

rkcarugy i pm'ed you

 

Sounds like a boost leak to me also!

 

bottumbunk you say you have 780cc injectors. What time of fuel management system do you have to control these huge injectors. the only reason i ask is becuase maybe they r dumping too much fuel and u r not able to slow them down enough

 

i'd say it would be ur O2 sensor or tps (throttle position sensor) because if your tps is spiking/dropping off it can cause what some people call hesitation or a bogging same for your O2 sensor.

How much hp are u making with that motor that u need 780CC injectors? lol

 

i have two cars one s13 with an sr20, gt25r, 870cc inj. and i have a s14 rb25det pretty much just bolt ons. the s14 im having a prob with. the sr i have no probs whatsoever its running smooth. i noticed today after the car is running at normal temp it runs fine at least for now. so this sputter is only while the engine is apparently cold. the temps around here are cold right now but i think it did this on adecent day to.

 

psileighty: i havent dynoed the sr yet ill be doing that when it gets warmer. if i had to guess 350+whp but like i said no hard numbers yet. it days make my rb s14 feel like a grandma car.lol

 

i learned that its now idling at around 2000 rpm now. so im thinking maybe it is a tps sensor. if so does anyone know how to check it.

 

MAF, check the wiring

Who did your wiring and what did you do?

Email me or look for me on AIM tomorrow "jonpowellsrb25" and I will try to trouble shoot it with you.

 

i wired it. but its been a while. ive been wiring (soldering) for years. not saying it still wont come apart. so you think it might just be the mafs wiring. or do you think the unit possibly failed. i have a spare z32 mafs ill try if its not the wiring.