Went to dyno, but didn't go well...Hopefully FET coil packs will solve the prob.

[JDMSIL80]

So I finally went to dyno yesterday, hopefully to lay down some nice numbers.

We started with low boost around 8psi, and worked our way gradually.

As we increased the boost to 14psi, but the car cut out early 5800. It was a clean ignition cut and the car would not rev higher to make power.

Then we tried 15psi, and the cut off came even sooner at 4800.

Basically, the higher boost we go, the lower the cut off becomes. When you're driving it feels like hitting a brick wall where both fuel & boost totally cuts out. Only at or below 12psi the car revs normal and would not cut-out early.

I have had this problem before, gapping down the plugs to 0.028" have solved the problem.

Knowing the plug gaps played a role in this scenario, we tried gapping down the plugs further to 0.023" and did another run. This time, I was able to rev up to 6600 at 14psi (vs 5800 previously), slightly higher than before but still not perfect.

My final run at 17psi and the cut out was at 4800.

No tuning was done because of the cut-out problem, my A/F ratio is around 10 in all boost range so I'm running rich and safe.

We have checked and confirmed that there is absolutely no boost leak in my setup. It seems like my ignition is not strong enough to produce the spark needed in high boost/load. So my next step is ignition upgrade, this is what I found and bought from ebay:



Hopefully this coil pack is stronger than oem and solve the cut-out problem.

here's my mod list & dynos:

Power FC + CommanderZ32 MAF444cc injectorsGT28RCopper plugsWalboro 255Blitz ID-color boost controllerBlitz gauges (pres, EGT, boost)FMICXS manifold3" turbo backHKS filter

13.5psi cut out at 6600:

16.8psi cut out at 4800:

[c-rad]

This sounds like a MAF overrun issue and not spark related at all. Particularly because the increased airflow is causing the cutout sooner. I definitely wouldn't suspect the coils of being the problem since they can handle a lot more than 15psi... Did you go to a colder range of plugs or are you still using the 6's?

[AmoebAssassin]

I agree...ignition blowout almost always looks like an erratic or peaked and valleyed HP/TQ curve, and never a clean drop.

[nismoplsr]

You should not be having a problem with the plugs. .0028 is the gap i am running without any breakups. Just to be sure make sure your gettting good ground on the coil stick and engine ground. But like everyone else is saying sounds more like are outflowing the maf which should be happening at those power levels.

Also lean out your mixture some any ignition system is going to have trouble igniting liquid fuel. Also most widebands dont read anything lower than 10 so if it flatlines at 10 you are most likely running even richer. This will foul your plugs pretty quick and also wash your cylinders.

[top_secret]

I don't think a Z32 mafs should max out that early...

[c-rad]

I don't think a Z32 mafs should max out that early...

No, but a big enough boost leak will outflow anything. If it feels like you are hitting a brick wall, that is fuel cut. Like the other guy said, ignition cutout would look more like \/\/\/\/\/\/\ on the graph. It wouldn't kill the ignition altogether.

[JDMSIL80]

I am already running BCPR7ES plugs. Changing the gap smaller did make a difference in the cut-off, I think my coil packs are too old and weak so they are starting to take a crap. My motor has already got 170K on there and so as the coil packs.

This sounds like a MAF overrun issue and not spark related at all. Particularly because the increased airflow is causing the cutout sooner. I definitely wouldn't suspect the coils of being the problem since they can handle a lot more than 15psi... Did you go to a colder range of plugs or are you still using the 6's?

[JDMSIL80]

I think my spark is too weak, so in high boost/load it gets blown out and thus there's no spark to continue making power.

I have already ordered the FET coil packs, see if that would help the problem.

I agree...ignition blowout almost always looks like an erratic or peaked and valleyed HP/TQ curve, and never a clean drop.

[JDMSIL80]

With boost leak, the graph would also show spikes which didn't happen in my case. Im running Power FC standalone, there shouldn't be any fuel cut like in stock ecu.

No, but a big enough boost leak will outflow anything. If it feels like you are hitting a brick wall, that is fuel cut. Like the other guy said, ignition cutout would look more like \/\/\/\/\/\/\ on the graph. It wouldn't kill the ignition altogether.

[originalsin]

do you have an fpr?

[JDMSIL80]

No, but do I really need one even running a standalone?

do you have an fpr?

Modified by JDMSIL80 at 8:53 PM 3/5/2006

[originalsin]

yea i would think so, i mean a stand alone isent controling your fuel pressure
Modified by originalsin at 4:47 AM 3/6/2006

[c-rad]

yea i would think so, i mean a stand alone isent controling your ful pressure

LOL.

If you are running a Walbro 255 "high pressure", than the stock FPR is probably choking off flow pretty bad and raising the fuel pressure.

On that note, I dont know why everyone gets the "high pressure" version. It forces you to buy an adjustable FPR whereas the standard pressure one you don't need to.

[originalsin]

On that note, I dont know why everyone gets the "high pressure" version. It forces you to buy an adjustable FPR whereas the standard pressure one you don't need to.

the high pressure is +27.568 hp .... lol

[JDMSIL80]

In other words, is FPR the missing link in my setup? To you it sounds like the stock FPR is choking so Im not getting the fuel in high boost?

However, my A/F is still running rich so I thought my fuel delivery is more than enough.

If you are running a Walbro 255 "high pressure", than the stock FPR is probably choking off flow pretty bad and raising the fuel pressure.

On that note, I dont know why everyone gets the "high pressure" version. It forces you to buy an adjustable FPR whereas the standard pressure one you don't need to.

[originalsin]

not this is prolly the reason y your running tooo rich, its ok down low cuz your injectors arent firing as much and your motor can run off it, but once you got wot, and the revs/air flow climbs its opening the injectors faster and faster, and prolly dumping in fuel in liquid form, bogging the engine down, get a nismo fpr for an rb

[CA19DET]

yup sounds like FP issues, coilpacks would be goot till about 300hp and 20psi.. those are a nice upgrade anyway. the Z32 afm is good for 500hp

[JDMSIL80]

Not that I'm trying to cheap out in buying the FPR, but wouldn't tunning (leanning out) the fuel map of the Power FC can compensate the high fuel pressure problem of running too rich?? My A/F ratio at WOT is in the 10s, so I still have a lot of room for tunning. I just don't want to spend money on extra parts which are not needed.

Secondly, what is the ideal fuel pressure on the CA?

not this is prolly the reason y your running tooo rich, its ok down low cuz your injectors arent firing as much and your motor can run off it, but once you got wot, and the revs/air flow climbs its opening the injectors faster and faster, and prolly dumping in fuel in liquid form, bogging the engine down, get a nismo fpr for an rb

Modified by JDMSIL80 at 7:49 AM 3/6/2006

[c-rad]

Not that I'm trying to cheap out in buying the FPR, but wouldn't tunning (leanning out) the fuel map of the Power FC can compensate the high fuel pressure problem of running too rich?? My A/F ratio at WOT is in the 10s, so I still have a lot of room for tunning. I just don't want to spend money on extra parts which are not needed.

Secondly, what is the ideal fuel pressure on the CA?

Modified by JDMSIL80 at 7:49 AM 3/6/2006

No, because an overrun FPR will not give you linear flow. It would be damn near impossible to try compensating for that. Not to mention, it may not be the same flow everytime you are at a certain pressure. Just drop the $90-100 on an adjustable (+ $15 for a gauge) and be done with it.

[Kouks]

Cant go wrong with that I agree with c Rad.

[nismoplsr]

This problem has been pretty much solved. I just want to make sure people get the fact that "The richer the better" is not a true statement when it comes to tuning.

[JDMSIL80]

Thanks for the help guys! I will get the FPR and see what happens.

[float_6969]

Sorry to come in on this late, but I was running the stock FPR with the high pressure walbro and was definatly overruning it. My problem wasn't cutting out at high boost, but erratic AFR's. I'd make a run, compensate my low/high AFR's, and then the next run would be totally different. I got the NISMO FPR, and the erratic AFR's were solved.

In reference to your problem, I am going to have to agree with you that this may be a spark issue. The reason being, that although weak spark can show up as a rough curve, if they used smoothing on the dyno, you wouldn't see it. You've already got the coilpacks, try them first. If that doesn't solve the problem, get the FPR.

Also, unless you're exceeding 500hp, you're not overrruning the MAFS.

[JDMSIL80]

Thanks for chiming in!

On the dyno, my A/F was pretty consistent after each run, didn't seem to have any erratic AFR's like you did. What type of ECU are you running? I wonder if running standalone would make a difference.

I'm gonna try out the FET coil packs first and go from there.

Sorry to come in on this late, but I was running the stock FPR with the high pressure walbro and was definatly overruning it. My problem wasn't cutting out at high boost, but erratic AFR's. I'd make a run, compensate my low/high AFR's, and then the next run would be totally different. I got the NISMO FPR, and the erratic AFR's were solved.

In reference to your problem, I am going to have to agree with you that this may be a spark issue. The reason being, that although weak spark can show up as a rough curve, if they used smoothing on the dyno, you wouldn't see it. You've already got the coilpacks, try them first. If that doesn't solve the problem, get the FPR.

Also, unless you're exceeding 500hp, you're not overrruning the MAFS.

[JDMSIL80]

I installed the FET coil pack tonight and took the car out, the cut-out issue still exists in high boost/load just like before.

Last option to solving the problem comes down to FPR as you guys have suggested. I'd most likely go with the SARD version that comes with the pressure gauge. Hopefully FPR is the missing link in my setup...

My question is what is the ideal fuel pressure on the CA?

[biosehnsucht]

The ideal pressure is only the correct pressure.

You don't get adjustables to increase it, unless you plan to remap the entire fuel mapping and base injection pulse width etc to accommodate it.

Set it to 36.3 psi relative to intake pressure IIRC. If you want to round off (and how are you going to be so exact with a gauge anyways) go for 37.

[c-rad]

Also, keep in mind that you want to set it with the vacuum line disconnected from the fpr. Just put your finger over the vacuum hose. It should be 43psi at a 0 boost 0 vac condition. Under vac and at idle it should settle to around 36-37 psi.

[JDMSIL80]

Great info guys!

I'll probably settle for the SARD/Nismo FPR, B&M FP gauge & AEM wideband gauge.

Hopefully with the tunning it would solve the problem and see the power I should be making.

[float_6969]

I'm still not convinced. If your AFR's were stable, I don't think the FPR is going to fix the problem.

Also, BIO has the pressure correct, c-rad, I love you man, but you're retarded. It's 36.7psi RELATIVE to intake pressure. At idle (vac) it will be LESS than 36.7 psi. The way I set mine was to dissconnect the vac line for the FPR. Bypass the fuel pump relay so that it ran constantly, and than adjusted it until my gauge read about 37psi.

I would look at ALL of the settings in the PFC CLOSELY. I REALLY think you've got a cut or a part of the map not programmed in that you're missing.

You might have someone else familiar with tuning take a look at it. Sometimes a second set of eyes will catch something you didn't.

[biosehnsucht]

ditto ! 43 is for KAs foolio! :P

36.3 is what we want RELATIVE!

and yeah i set mine the same way as float.