Ignition breakup/Bogging/Backfiring

First the specs and info.
1993 240sx - 97 S13 Blacktop (type x)
- Walbro ? 190/255
- OEM injectors
- OEM Coil packs
- New NGK spark plugs
- New Z32 Fuel filter
- Stock T25 Turbo
- Apexi intake
- OEM MAF
- FMIC
- 3" meagan dp and catback w/ magnaflow hi flow cat
That should be everything… Let me know if anything else could apply to this situation
With WOT under load from mid to high RPM the car sounds like its backfiring and it loses almost all power. Under partial throttle the car drives normally. Coming down from mid to high rpm to a stop if i do not rev the car slightly it will 75% of the time stall out on me. If i leave the car over night or for a long period of time when i go to start it next it has a significant amount of trouble and takes a while to start as if not getting fuel, but then when it fires up (or at least last time when it fired up) there is gas splashed out of the muffler on the ground behind it. Sometimes the car runs like it has absolutly no issue at all but 90% of the time its pretty weak sauce. Im lost at this point, i have a new walbro to put in it (thought it was being starved until the other day i saw the fuel on the ground after start up) but i need a new sending unit in good shape first.

Im looking for technical help, not just a try changing this because im in school for another 6 weeks and dont want to just buy shit and cross my fingers.

Thanks

Jeff.

backfiring under load could be a small boost leak. and for the stopping problem im guessing your bov is not recirculated. so to solve that problem recirculate it, or tighten the spring a little till u can drive without stalling. or just up the idle rpm a little bit. and are u sure its gas spalletered out of the muffler or are u just guessing its gas. put that warlbro in itll take u like 20 min max.

^ Im guessing its gas because i couldnt smell it over the exhaust fumes. It shouldnt be the BOV as the car drove fine for a couple months.

Ignition break-up? You need the splitfire coilpacks I’m just about to pull out of my car.

^ PM me a price, im looking for a set of those… Also does this problem sound like low compression could be the culprit? The more i think about it the more i think of other possibilities.

Check yo PM

could be the idle air control vavle then. pull it off and try cleaning it.

Update: Did compression test on the weekend, 140psi across all 4 cyl. That’s a relief!

well, there’s no way it’s compression…you have an intermittent problem. Compression isn’t intermittent. :slight_smile:

I’m gonna go with possible intake leak or MAF.

try NGK BKR7E @ 0.026 gap, clean the maf sensor wire with abs sensor safe brake cleaner and a q tip

I use those plugs at that gap :slight_smile: going to clean the MAF sunday and hopefully check my O2 sensor tomorrow with a friends fancy thing that checks o2 sensors

don’t use brake cleaner, spend a few $$ on some electrical contact cleaner from crappy tire, and just spray the crap outta it without touching the wire. get the little red extension as close as you can to it, but don’t touch it.

its the abs sensor safe brake cleaner, people use it and it works, if you use contact cleaner, that actually could eat away at the metal since its supposed to eat away corrosion, trust me, dont put the red straw with high pressure near it either, your more likely to break it with the pressure then to lightly skim it with a q tip

just my two cents, no hard feelings, its all up to you in the end

you can open the gap on the plugs, your car is a coil on plug setup therefore you can run .32 gap.

also what boost are you running while this problem occours, if the problem is with raised boost, lower and see what happens.

do you have a fuel pressure gauge?

and how old are the spark plugs,

The plugs are about 3 weeks old, my gap is about .29 the boost was at 10psi when the problem arouse because of this i have decreased it back to stock 7psi and its not AS bad. My MAF looks good as new i took it out today. Im thinking its the coilpacks. Car is off the road for winter now so ill work on it here and there on weekends not too worried about it since im not driving it, Ill be pickin up U2N’s set of coilpacks hope that fixes me up.