Hey, my car is not running above 4k rpm. the best way to describe is sputtering. It only happens with the petal to the metal and in gear. It comepletely stalls the car. The car has an S14 SR20, with a Walboro fuel pump and a new 300ZX fuel filter. HELP

 

are you sure it only happens when it's in gear and not in neutral as well?

 

Ya, it only happens whens its in gear. Every gear above 4k rpm. I checked the spark plugs today and they are good. The apexi safc says there is no spikes in the a/f ratio. I am stumped..

 

i'm gonna go with faulty fuel pressure regulator.

 

Has it always done it after the install or has it just started doing it out of the blue? Is the engine/ECU all stock? If ti is modified what is done to it?

You say the best way to describe it is sputtering. But then you say it completely stalls the car...which is it?
Also what is "above" 4000RPM? Is it like 4200..or 6000?

I am sure it. But i'll ask anyway.... is it a turbo engine?

 

what safc gives a/f readings? i stand by my fpr guess.

 

I hope you are not just guessing.
The FPR is a BIG possibility. But we need to know what MAF he is using. If it was his stock MAF(from teh KA) that is a problem, he will have the problems he describes. He can use a SOHC MAF to fix said problem(or ofcourse the proper MAF for his engine). Also he needs to check his spark gap & plug wires.
He may have what is commenly known(atleast where I come from & experienced myself) Blowout. Where the spark gets blown out because of a weak coil(s), TIMING, wires or plugs(ANYTHING on the ignition side can cause this) improper fuel pressure(like a bad FPR) can also cause it..but that is uncommon. VERY VERY common on boosted engine..especially SR's. remember, check all connections, wires for cracks, ECU for any codes, umm hell just pretty much go over everything. It could be something as simple as a loose ground( I have had that happen also)

ALSO, when it does stall IMMEDIATELY pull over & check the plugs. Are they sooty or covered in fuel, are they all consistent with one another? If not make note of which ones are not burning proper & check the injector, wires & cap for damage

Just trying to cover as many bases as I can. I'm tired & pulling what I remember out of the top of my head.
I will reserve judgement on my diagnosis until I find out more about the car. An SR that stalls "above" 4000 RPM is VERY common & it could be numerous problems..especially in a swapped car.

 

it's not really a guess, it more or less the best answer i can give with the current information. as you've mentioned there is a number of possibilities but i've ruled the rest out. the biggest problem it that is it s swapped engine and we don't know exactly what parts were substituted in the swap.

 

It just started happening out of the blue. Now the car sputters (not really stall) all the time, from startup. I have a Z32 MAF, Stock ECU, the Apexi SAFC has been installed since the SR20 swap about four months ago. I think it might be the plugs or timing. Thanks for the input. I will try the spark plugs.

 

I'm with Ramos. SAFCs dont give AFR readings.

Run the codes dude.

 

I put new plugs in and it runs great. Two of the plugs were burnt out. I really didnt think that was my problem, but it was. Thanks everyone for your help

 

What did you gap the new plugs to? Was there a difference in gap between the bad plugs & good plugs? Have you checked the resistance in the plug wires of the bad plugs(also check for cracks in teh insulation & make sure they are not touching & arching), also take off the cap & check the posts for burning. Check your timing.
Two plugs should not go bad just like that. Something made them go bad, you need to find out what it was.

 

haha gapping plugs.... who buys plugs that can be gapped anymore?

 

I hope to god you are joking.
Almost ALL plugs are gapable. Most say not to because of the risk of the tip breaking, BUT they are still gapable. You still need to check the gap when buying them. They are all not perfect. Tell the parts guy to bring out the box & find ones with proper gap.
Gapping sparkplugs is one of the easiest & most benifical things one can do to a have a properly running engine. Not all engine perform the same, especially boosted engines. They can have the same exact mods with same exact fuel & air & the spark gap necessary could vary .0250 if not more.