Spark blowout below 4k

[articzap]

I'm getting spark blowout below 4k well in boost, ~3 psi roughly or more. I had my plugs gapped at 1.1 mm and have since changed them .8 mm. It still does not help any. My butterflies are hooked up and working properly. Above 4k, the car pulls like a raped date with no issues at all. I'm confused as to what it might be. I think theres a possibility it could be the igniter. Is there any way to test to see if thats my weak link? Any one else have any other ideas?

NGK coppers with 7 heat range.
Modified by articzap at 4:17 PM 7/21/2008

[meminto]

You can check the contiunuity between pins on the ignitor, the fsm has the process in the ef & ec pages.

Is it definatley spark blowing out?

[articzap]

It feels exactly like spark blow out, but I can't be sure. I doubt it fuel cut since I can drive it fine above 4k. I'm at a loss for words right now. I just want to get this issue fixed so I can crank the boost some.

[slo]

Maybe be a maf issue? Which maf are you using?

[articzap]

SOHC KA MAF right now but I also have a MAF from a B13 Sentra SR20DE.

Even so it was fuel cutting it'd continue to do it above 4k. Thats the weird part. Its only down low.

[meminto]

It seems strange that spark is blowing out in the lower rev range.. I will have a think about it..

[articzap]

Its so damn strange that its only down low. It makes no sense to me. I have no idea how to diagnose it either.

A/F looks fine too.

[float_6969]

If it was spark blowout and you were getting failed combustion, your AFR's wouldn't be OK. Something else it going on. Try unplugging the mafs and driving the car around.

[Buddyworm]

I have a similar issue with my car. It's only around 3000 to just under 4000rpm and it's the worst when I'm getting on the throttle when the revs are around that range. Within that range I sometimes get a misfire or two, but just like you, once I'm above 4G's the engine goes like mad. My plugs are gapped to 1.1mm as well and my butterflies are also hooked up properly.

I'm pretty sure I know the cause; I noticed it the other day when I was tuning with a wideband. The "why", however, is still a mystery. Anyway, at that particular rpm range and that particular load, the engine runs pig rich, like 9:1 AFR. For some reason, the target pullswidths Nissan put in that particular section of the fuel map are huge, and the throttle tip-in enrichment as you get on the gas certainly wouldn't help things.

You wouldn't happen to have aftermarket cams would you? My theory is that because of the differences in the cams yadda, yadda [insert a bunch of cam design jargon here], perhaps the secondary butterflies are openning at the wrong time to suit the cams. And maybe need to open sooner because they're restricting the higher flow capabilities of the cams.

Of course, that theory goes out the window if you've got stock bumpsticks and I'm probably wrong anyway.

[Buddyworm]

Another thought I just had: O2 sensor. I know mine is buggered because in Nistune it reads 0.3v. Constantly. Irregardless of anything. So the ECU thinks there's a lean condition and adds more fuel. It seems to me the ECU would still operate in closed loop at this point as well and leaves it once we hit the magic 4000rpm threshold.

This seems most likely than my previous theory, now that I think about it.Thoughts?
Modified by Buddyworm at 9:46 PM 7/13/2008

[articzap]

I'm running 10* timing as per Jap FSM and have stock cams along with a stock turbo.

[RS12Turbo]

Hmmm, thats weird.....the fsm I have, that I downloaded from here (I think) says 15 degrees + or - 2 degrees

[meminto]

That is because it is for the euro version, the base timing is correct for jdm motors 10 +- 2

Have you checked the fault codes articzap?

Definatley check the continuity of the ignitor....

[articzap]

The FSM that you can get through links on this site seems to be for a CA18DE only.

I searched through the FSM and couldn't find the test. Does anyone happen to know the page its on? I wonder if I'm having a similiar problem. My narrow band O2 sensor is reading 14.2-14.6. I'm starting to think its running a lot richer then that. I wish I had a way to test it though. I'll pull fault codes in a few minutes.

[articzap]

Went outside and pulled the codes. I got 55 which should mean no problems at all.

I'm just more and more confused with everything I check being in perfect condition. How do you set the TPS in case that could bumped during install? I don't know if that would cause this issue or not.

[kapower06]

I would suggest a correct ca18det mafs.

The SOHC ka is not the same.

[articzap]

Yeah I know I should be running one of those but it wouldn't effect me where I am having problems....It would effect me up top.

My Apexi turbo timer is showing around .6-.7 volts during those RPMs.

[meminto]

Thats a good start, it means the ecu is detecting the sensors fine, the downside is that one or more still could be faulty as all the ecu does is check detection of the circuit..

I will find the pages you need for the continuity check and the tps setting tonight and let you know..

Out of curiosity, does it happen more often at WOT or does it have the issue regardless of position?

[articzap]

Seems to be regardless of throttle. Although if your very smooth with it, you can edge out about 5 psi before it starts to blow out. Now if I straight floor it, it blows out almost right away. Right around 1 or 2 psi. This is making the car very awful to drive. You have to drive like an old person to get going. God it sucks so bad.

I just lost to a third gen Camaro because I couldn't accelerate at a light. Had to play to catch up and was pulling on him, it was just to late.

Thank you very much meminto. If theres anything you need, please let me know.

[meminto]

Ok, you need pages :

Power Transistor (ignitor) EF&EC 125

Idle Switch - EF&EC 100

Throttle Position Sensor - EF&EC 98

You don't actually adjust the TPS, you adjust the idle switch...

This is from the euro manual which is the most common one floating around...

[articzap]

I know the TPS doesn't need adjustment, I just don't think its in the factory position.

Now to add to possible light to the problem. After work I'll test the power transitor. But on my way to work today I was getting spark blow out around -8 inHg. Then when I'd let off the gas it would almost die all the way out. I then got it up to 4k and floored it. It had spark blowout for a few seconds then proceeded to pull like normal when in boost above 4k.

I'm starting to think its a going power transitor, which I'll check when I get home or I have and over fueling issue causing the plugs to foul out in the low RPM's and causing the spark blow out because of an over rich condition.

I'm going to assume this condition is caused by the Walbro 255 lph pushing to much volume through the injectors. Does anyone else think I should try pulling some fuel out of the mix with SAFC?

[meminto]

Check your igniotor first, eliminate that possibility...

The fuel pressure is regulated, so the pump couldn't be pushing to much volume as such...

Actually how healthy are your injectors?

[articzap]

Gabby sent me a set because mine were stuck closed. These ones seem to be operating just fine. And an FYI, fuel pressure is regulated, not volume. You could regulate volume with a fitting change within the Synapse FPR, but I have set to stock right now. I may need to change that.

[RS12Turbo]

Does anyone else think I should try pulling some fuel out of the mix with SAFC?

Wouldn't hurt to try. I've got my afc set all in the negative range...like -8 and -9 throughout.....because it was running pig rich. Found this out when I got it dyno tuned a couple of years ago. before the tune it would cut out at wot ONLY in 4th and 5th gear at 4000k-4500k. After the tune the afr's are where they should be, and it hasn't cut out like that again. Still not sure if my stock fpr is to blame because of the walbro 255

[articzap]

RS12Turbo, do you remember your throttle point settings? Was your low and high map the same?

drftsilva, I would like to borrow a wideband for tuning but I need to get a bung weld it in my test pipe then. Stock injectors are 370cc. I doubt fuel was getting pushed past them, I just think to much fuel is being let through when they are open.

[RS12Turbo]

RS12Turbo, do you remember your throttle point settings? Was your low and high map the same?

My lo map is 0

My hi maps are..........

800 rpms: 01600: 02200: 02800: -93400: -93800: -104600: -105200: -95800: -86400: -87000: -107600: -10

[articzap]

So what was your throttle points set at.

[articzap]

I think I figured out my issue. My car is running very rich. I was reading my Synapse manual and it stats that if you run a Walbro 255 lph fuel pump, you need to install a larger bypass fitting so the volume of fuel in the rail isn't greater then stock. I'm pretty sure this will solve all of my issues. I'm going to mess with that Sunday when I have some free time again.

[float_6969]

I assume Synapse is the brand name of your FPR? If so, it's very easy to hook up a fuel pressure gauge and see what the fuel pressures are like.

[articzap]

I have a fuel pressure gauge and its set at 38 psi. I'm not a complete idiot here. Theres a bypass fitting inside the regualtor it self that can be swapped for different sizes depending on fuel volume. I think I have the wrong fitting in there.

I took about 10% out with SAFC and it is indeed running a lot better but I'm still having issues.