redtop, rough idle and misfiring/studdering under boost!!

[mayorquimby]

OK, I've seen about 50 people with almost the same thread. After reading the threads and trouble shooting my car, I have had not luck fixing the problem.

I have a '90 S13 couple, had a ka24E was swapped for a sr20 REDTOP!!
Normal upgrades:

FMIC
SAFC NEO
BLITZ AIR FILTER
BUDDY CLUB SPEC 2 EXHAUST (LOUD AS HELL) (MANY TICKETS)
AEM TRU BOOST RUNNING 10 LBS. (+/- 200 whp)
SILVIA FRONT END
300zx FUEL FILTER
STOCK INJECTORS
HIGH FLOW CAT. CONVERTER (HAD TO PASS INSPECTION)
NISMO THERMOSTAT
HKS CIRCLE GROUND KIT
ATTAIN SHORT SHIFTER
STOCK BOV

Alright, now that's out of the way.

When I first got my swap done, the car idled and ran pretty well. Except when I built up boost. IT would misfire and studder. I take my foot off the gas and it will run normal (but at low boost).

Also, starting the car when its cold...It will misfire and studder, until I get on the gas!! If I keep the engine at about 1500 or 2000 it will idle fine. Or if the car has been running for along time.

I have changed spark plugs many times and the normal R NGK'S and irdium's work the best. TO be honest my car runs perfect for about 3 days with these plugs and then starts acting up again. I pull the plugs and the arm is WHITE. IRdium I have no break ups until they break up!!


What is causing my plugs to burn up so fast!! because its not burning rich and my injectors and coils are working fine!!

HEY ANY INFO WOULD HELP! SINCE HAVING THE CAR I HAVEN'T HAD IT 100%

[Sil180]

Its feels like your O2 sensor is not working or not connected. The car runs rich and retarded when come on boost and cold start. So the car misfire. Also could be your AFM is dirty or faulty.

[Z33dori]

i to am having thins problem... minus the burning though spark plugs...

but as soon as my car starts to build boost it will stutter. But it only does it after the 1st 5-10 mins of driving. but then i keeps going. and after a while the car will try and stall it self out and die. and it will Mis fire at idle.

[Z33dori]

Bump....any One

[SHIFT_*grind*]

The O2 sensor shouldn't cause a misfire. The ECU only uses feedback from the O2 sensor under cruise and idle (closed loop), not when you're accelerating.

Check very carefully for boost leaks.
Clean your MAF.
White spark plugs are indicative of running lean. I didn't see a fuel pump in your upgrade list. If you're running the stock fuel pump and you have your boost set at 10lbs, and your plugs are white...then there's a 99% chance you're leaning out. Turn that boost down and just don't use the AFC until you upgrade your pump.

[mayorquimby]

i already have a walbro 255lph

[SHIFT_*grind*]

It does sound like you're leaning out, what are your fuel settings at? I don't know much about AFCs, but you honestly shouldn't even need it on a stock motor at 10psi.

[Sr20det>Ka24de]

white plugs are always a sign of lean misfire, try running with just your ecu with no fuel control, at 10 psi it shouldn't misfire, I am assuming you have a stock sr mafs. Try cleaning the mafs and make sure the connector is seated and tight, doesn't sound like a boost leak and if you are still hitting 10psi up until it sputters I would not worry bout a boost leak. Check your plug gaps next time you have em out and what are your plugs part #? ignition timing ever set?

[mayorquimby]

yeah, i just put my straight pipe back on and removed my cat. converter. Man, my car runs a lot better. Still some break up!! I thought I was running rich about a month ago, so I put on the SAFC. But the guys at JE import performance dyno'd it and said it was running a good mixture. I'll get back to you with the part number and air/fuel ratio.

[fliprayzin240sx]

You double checked your timing yet? I'd start with that...dont sound like a vacuum leak. Something is causing your shit to run lean as fuck.

[iwishiwas-all*]

mine is like this too, I vacuum fine at idle, and when im not in boost its pretty civilized, but man under boost, its shitty, and my plugs are white and i have a walbro with similar mods but at stock boost.
fucking sr20's