sr20det high end missing or hesitation

[White Comet]

just started having an interesting problem. i have a 93 hb w/ an sr20det blacktop swapped in and minor bolt on mods. teh mbc is set to 11 psi but will spike to 14 pis occasionally if it is cold. the other day i stepped on it and boost gauge read 14psi and dropped to 11 but it sputtered and misfired almost. the air/fuel gauge read lean. but i'm wondering what exactly is going on. teh gauge normally reads rich and it only started doing it just the other day. i'm thinking its not getting enough fuel is what it sounds like, but shouldn't it be fine on the stock fuel system fro up to that boost. i'm pretty sure injectors are fine but i will check, replaced the fuel filter w/ a z32 one just a few weeks ago, the rest of the system is stock except for a walborro 255 lph fp. could it also be spark, i'm not sure what state the plugs and wires are in. i wanted to upgrade but its still running on what it came w/. could the cold be effecting it? i'm kicking around different ideas but would like some input. today i will change the oil and filter and maybe do plugs and wires. i also thought it could be detonation but i'm running 93 octane so i dont think thats it. the tank was very low so could it have been sputtering cuz it needed gas? i filled up to the top w/ 93 so we'll see how the ride home is. thank you for your help.

[karmakaze]

because of the fuel sock on the walbro units not being very long they do have issues with running on a low tank. Its a good idea not to let it get under 1/4 tank.

also, if your air/fuel gauge is not a wideband i would not trust anything that it says. its just a light show, not a diagnostic tool.

[S13FASTBACKSR]

true that the narrowbands are not nearly as good as wideband or who knows how good they truely even work but none the less i wouldnt look past it..check your fuel injectors to make sure they are spraying fuel out correctly..one or two of them might be shot..pull the fuel rail off with the injectors in and crank the engine over (pull your coilpacks) this way you can see if the injectors are working properly

[White Comet]

sounds good, i figured i should check the injectors. the gauge is a narrowband, it was there when i got the car. it gets annoying cuz even at steady throttle its all over the place. i filled up w/ 94 and it still did it but not nearly as bad. is there anything to do about the fuel sock, or just deal w/ it. thanks for all your help. it also seems to do it worse when the car has been on longer. any more advice would be great thanks

[karmakaze]

it could also be your fuel filter.

[S13FASTBACKSR]

ya could be a clogged filter..check that and the other things out and let us know

[NY S13 SR]

"even at steady throttle its all over the place"

AFR gauge will jump back and forth at steady throttle. That shows it is working, as the ECU reads the O2 sensor it adjusts the fuel one way then the other.

It can show if you have a bad MAF or O2 sensor so it is not useless. I use it to test Z32 MAF's, I can spot a bad one is 3 seconds.

_________________________Jeff Hhttp://www.heavythrottle.com

[ILikeMy240sx]

Sounds like your sparks getting blown out.

Gap your plugs to .028check your ignitorcheck your coil pakcscheck your ignition harness

[White Comet]

i was thinking plugs too. i'll check 2marrow. lol its prolly not the fuel filter cuz i just replaced it. i wrote that in the original thread but that is a lot to read so it could have been missed. any reccomendations for spark plugs

[ILikeMy240sx]

NGK BKR7EIX gapped to .028

or BKR6EIX depending on how much power you are making.

[SlowS13Silvia]

NGK BKR7EIX gapped to .028

or BKR6EIX depending on how much power you are making.

yes yes

and also check your timing with a timing light i think stock its suposed to be 15degrees and mines set at 19 with bkr6eix plugs... just my 2 cents

[S13FASTBACKSR]

yes ngk iridiums ftw..the gap size depends on how much boost you are running..the lower the boost the more of a gap, the higher the boost the less of a gap..also the stage you get depends on how much HP you are putting out..stage 6 is lower hp #'s 7 is mid and 8 is high hp #'s

[White Comet]

sounds good, im picking up the plugs tonight, ngk was my first choice anyways. the only mods are large fmic, 3" turbo back, intake and 12 psi of boost. which of those plugs would be best? thank you all for your help and input. def less sputtering on full tank. i'm still gonna change the plugs but i think gas was the prob. is there anything that can be done aobut that or just deal w/ it

[S13FASTBACKSR]

i'd go with heat range 6 gap them to 28-30...what can be done about what? the gas you have in there right now? drain it

[White Comet]

thanks, no i meant about the shotness of the fuel sock. thanks for the help on spark plugs. hopefully they will fix the problem. one slightly off topic question: how do you read an air/fuel ratio gauge?

[480sx]

Depending on what type of gauge you have, usually 18 leds and the middle one should be stoich (usually at top of gauge) But just reiderating what everyone else has said, the only time a narrowband afr gauge is even moderatly on target with its measurments is when your on the throttle, so do not try and tune or get too worried about what the gauge is saying, its really just for show.

[White Comet]

huh, ok thanks for the help. im not tuning by it i just wanteed to know how to read it. its a faze btw. thank you on my way to get spark plugs