fuel or spark... i need the pros on this one.

[compactfean]

So I have the s13 sr, tomei cams lifters forged pistons sleeves bla bla bla, 740 inj gt3071r turbo. So what's going on is it pulls like crazy until about 5000 rpm and then cuts out. My motor is tuned for 8500 rpm. My plugs are the bgp7e or what ever gapped at 32 with the splitfire ign. Is that still too big for splitfire? Also I have a walboro 255 with a tomei large diaphragm pressure regulator but use a stock fuel filter and am running 36 fuel pressure with vacuum. Is the stock fuel filter too restricted? I'm running 16 lbs for dd. It also cuts out when I dip down out of my driveway ( weird I know) and it happens everytime! Anyone with confirmed diagnosis's pich in.

[1KleenS13]

Have any o2 numbers when this happens? Could be the spark being blown out ( get rid of the splitfire's) or a short somewhere or both. Is the line in the tank clamped to the sending unit good? Is fuel PSI rising 1:1? What kind of valve springs do you have?

[compactfean]

I have tomei valv e springs. So this is what I've done so far. Checked maf voltage which is perfect 1.10 at idle which for the 300zx specs is good. Power to it is 14.3 volts when running. Replaced fuel filter with 300zx fuel filter (turbo). Re gapped plugs to 28. Fuel pump wiring and lines were just done with walboro pump and tomei fpr and I'm very anal about my wiring. Ill get back t o you tomorrow with a/f numbers when it does this. Do I need to do the fuel relay/ bigger gauge wire upgrade? Kind of an odd one to monitor voltage to the fuel pump while driving. And my regulator is 1:1. Problem still persists. Keep coming with ideas and I will test and respond daily to get this figured out.... thanks guys!

[compactfean]

So today I checked fuel pressure tps voltage and timing. Fuel pressure still solid at 3 bar no vacuum line, tps was at. 38 volts and adjusted to. 45. Checked timing and boom! When I rev it it retards to 0-3 degrees! But would this effect top end? From what I have heard about sr's if it detects knock it doesn't effect top end... either way its not right. So I talked to an eclipse buddy and he said if a knock sensor is over torqued it can detect knock from unwanted areas. The over all question is, is there anything else that retards timing that much besides knock sensors....please help!

[compactfean]

Bump, anyone?

[1KleenS13]

Wish I could tell you more about sr's but i'm not familiar with them. I knock sensor that is too tight will give you problems. If the car is pulling timing down to 3 or 0 thats not good, I had a Grand National with a stupid missing problem and I found a fuse with 30 ohms of resistance, that wouldn't give the ign module 12 volts and screwed up the ESC (spark control). The GN also pulled timing down to 4 degrees when power braking, and ran like chit. I'm not sure about your MAF getting battery voltage, normally they should get a 5 volt ref signal, but I could be wrong.

[compactfean]

thanks 1kleens13! you just reminded me that i have a code 21 that i haven't been able to figure out forever now! (code 21 is ignition signal failure during cranking or starting) my only problem is that ive check the fsm for this diagnostic procedure and dont even know where to start. if anyone has dominated this trouble code please help.

[compactfean]

So I was doing some more research today and found that the main ignition power wire has two different stories. In fr sports wiring how to it shows a bue/ red wire that goes to nothing. And no description of funtion. Others say to wire black/red wire with blue/red wire into one (black/red wire) I can't find what the blue red wire goes to. Anyone know what it runs? Any diagrams? Maybe a solution to the dreaded code 21?

[compactfean]

So update time.so went through the harness, found a loose wire...the power wirr to coil packs. Fixed it and still code 21. Still high rpm misfire. So a new one to add is when boosting as soon as I give it gas afr drops from stouch to 9.2 to 9.8 all the way through.

[1KleenS13]

Is this a Wideband or narrow? I'm going to assume Wide. If your seeing 9.XX you are PIG rich, could be the timing being pulled down, fuel psi to high. Is there a way to determine Actual timing at WOT? What are your plugs looking like, probably black. I would start with a new set of plugs, get NGK's and gap them to .030, the s*** are fouled and are junk to begin with. Next you need to see what controls timing with your SR. A MAF will cause problems under load, I would get a manual and backprobe the MAF wires and make sure they have what they need. Also your code is saying theirs a problem with your ignition signal, could be a bad ground, signal wire, or ign. module (or whatever you kids are calling it nowadays ) Get a wiring diagram and start checking things.

[compactfean]

Yeah wideband for my gauge and new narrow band for ecu. I don't have splitfire plugs. I have the splitfire Coil setup with ngk bpr7's gapped at .28. Fuel pressure dead on. New ignitor chip, maf voltage is perfect. And actually just did plugs and they look normal. (Only because I try not to boost it, if I'm cruising afr if 14.5 ish) when it idles its rich 11ish and when I first start the car. Since last post fixed ALL my boost leaks (missed a couple). Could an cts.cause.any of these issues? Ill ohm test it tomorrow and try to start tackling this ignition code issue. ( I've.looked in the fsm before its a very lengthy process)

[1KleenS13]

Coolant temp sensor could very well cause a problem if its always reading a high temp. Best thing to do is look that the sensor with the engine cold with a scan tool, it should be within a couple of degrees of the IAT.

[compactfean]

Ok to make a long story short code 21 is a pita to diag. Especially because the s14 fsm gives ecu pin locations not function ( had to have both s13 and s14 pinout and description) pretty much you check all signal wires to ignitor, ecu signal ground continuity, and power. Where I think I found my problem is voltage when cranking. But the fsm only says to check voltage to coils with key on wrong. I checked my ign switch and is coming apart! Got one ordered and we will see if that fixes it. (All other tests were fine) coolant temp sensor was also bad even though I replaced it like two years ago. 1.7 ohms at 68 degrees and when it got warmer outside couldn't get an ohm reading. (Dvom is good...matco) iat? I've never ran one. Can I just wire in a b13 iat? I know they have em.. how much do they help?

[1KleenS13]

Not sure about that. Some MAF's have the IAT sensor built in already, not sure about Nissan's. Sounds like your on a good path, and not throwing money at it. Also try disconnecting your battery and see if the code comes back. Is code 21 for circuit high/low or just a generic code?

[compactfean]

So today I installed the new ign switch and temp sensor. When I had them both out I ohm tested both and the new one was at 2.3 ohms old was at 1.8 ohms. It still runs rich during warm up. Also with a new cts readjusted timing.don't know if I got rid of code 21 yet. The z32 mafs claims to have a temp sensor in it.. ill disconnect batt. And get back to you. But yeah, code 21 is generic. You ever heard of someone running lower than stock fuel pressure for higher elivation? Oh and thanks for sticking wirh me on this one. Seems its out of everyone elses Leauge.

[1KleenS13]

Temp also affect's resistance. If you are running low fuel psi your not going to atomize the fuel that well. I see where you are going in your reasoning to lower the fuel psi, but it might be causing it to puddle. No problem, glad I can help.

[compactfean]

Fixed the high rpm missfire! So I did a billion hours of research and stumbled accross an article about velocity and turbulence. Well turbulence is way bad for mass air meter. The mafs that I got the screen was missing because of the greddy air filter. Put new mafs in and got one pull on the car and the new mafs died! Took the screen off and put it on the old one and bam! No more misfire. Still runs pig rich at low rpms at wot. Do you think a apexi air filter will get rid of the rest of the turbulence in the mafs and give me propper mafs voltage?

[1KleenS13]

Air filters with oil will screw up mafs sometimes, the oil coats the element and throws off the reading. I don't know if the air cleaner will solve your problem, I doubt it but freakier have happened. Is there anyway to pull some fuel out of the ecu at idle? No vac lines leaking?

[compactfean]

The apexi is a dry air filter. I think a screen fixing my misfire I freakesh enough! And. No no vacuum leaks. I used a boost leak detector and fixed every leak big and small. 7 if I remember correctly including pcv valve. I think its worth the gamble to try that air filter to get rid of the turbulence. But I'm pretty happy how it runs now. Yeah I've got an emu but haven't used it yet until I fixed the issues I had first. Plus there isn't to many diy's for the emu.you know anyone with an emu that can help subtract fuel correctly?