7-sins

Ok...... I just did the non-sequential mod (like it by the way) now when I take my car up to 6k+ it sorta stumbles. Not strong jerks back and forth, it just stops pulling but feels like it’s trying to. Also during this the car pops a lot. I am pretty sure it isn't because of the non-sequential mod; I had no boost above 4 so I didn't feel it before. Ideas that come to my head are Fuel Filter, Spark Plugs, or Air/Fuel Ratio (Don't have the gauge yet).

Next.... Ever since I installed the PFC I have had a weird idle. Searching on the forum helped somewhat because I have it lower now and not so jumpy. The idle varies a good amount, usually around 1000-1400. From time to time it will drop down to 800/below. When this happens it might die, or when I start off mixing the gas + clutch it bogs down and dies unless I start off with a good amount of throttle. This didn't occur before installing the PFC and my driving habits have not changed.

Observations:
When coasting at low rpms it pops a lot.
I have seen my peek injector duty as high as 94%.

Mods are listed below...

Thanks in advance,
Chris

Pressurized

Well, I think you're thinking in the right direction. It's most probably either fuel or ignition related, at least, that's where I'd start.

It could be fuel cut coming on since it happens at high RPM, which isn't a good thing, most likely you're running too lean or your fuel filter needs replaced.

But if it were me, I'd start at plugs and/or wires. I had a similar problem, I'm still sequential though. My car arund maybe 3000rpm when I let of the gas at cruise would backfire pretty bad and pop all the time, I also would get that jerky feeling and loss of power above 6000rpm. So I just recently changed the plugs, wires and o2 sensor(I was using leaded race gas and I think that's what did mine in) and so far it's smooth, all the way to 8000rpm.

You didn't state how many miles are on the car or when the last time you've done a tune-up, but a fuel filter, plugs and wires couldn't hurt. It's a good place to start and plus it will keep the car healthy.

7-sins

I got the car with 60k and a brand new rebuild, now the car has 66k. The engine rebuild wasn't done perfectly, a few things were half assed. I was really thinking the plugs but the fuel filter is starting to stand out.

FD Racer

It might be that your running too rich, especially if you say its popping allot. As far as the missing, it might be classic high-end miss. The stock ignition system has a hard time igniting all that fuel. This is why people get ignition upgrades, like the HKS Twin Power for example.

Also, what is your boost set at on the pfc? Make sure your not hitting your boost cut.

7-sins

I am running .90 kg/cm2 on the PFC. My boost gauge only goes up to 10 PSI but the PFC reads up to 1.10 (15.6 PSI). I think my PFC is off because I remember it hit 11 PSI on the gauge before I installed the PFC. I dont think it is fuel cut but I can play around with it.

One of my friends said it was blowing out black smoke when the power loss happens.

50tooslow

I am having a similar problem with the high rpm stumble. my problem is sensitive to the fuel level in the gas tank. When it first started any time I had less than a 1\4 tank of fuel and ran the rpms up aroun 6000- 6500 it just falls flat on its face, shift it will pull strong back to that range and fall flat again. I changed the fuel filter, plugs, wires, and some vaccume lines and did not help. It is now alittle worse, it does it around 1\2 tank now. I took the little screen off the fuel pump and it feels better but still does it. I have a new pump on the way so hopefully that fixes it. The wierd thing is that it runs perfect with a full tank of fuel. Oh, well I just thought I might be able to get some help too and maby we can get both our cars back on track.

7-sins

bump

pjw72

I have the same problem (popping) and found that taking away some of the fuel from the idle setting (using Peter's paddle to adjust his settings-on his web site for ~$200). PF sets his idle fuel to -10% of stock (on all settings from him). I backed it down to -16% and just about elimnated the popping. I did have to increase my fuel on the part load settings (LL, ML, and HL) for the 2200 and 4000 rpm set points, but that was from a driveablity issue - new engine that was ported and was not running well on stock factory settings - lean stumble.
However, my car is also dieing at idle and I have not figured this one out yet. It also likes to idle between 1100-1400, but when it idles down it just keeps on loosing rpm until it dies (seems to stop around 500 rpm but cant sustain itself). I have tried adjusting the air bleed screw and even messed with the idle fuel settings - no avail.
I will have another post for this issue, but if you have any suggestions please help.
thanks

7-sins

Thanks for the reply, I'm not talking about the PFS computer though, It is the Apexi Power FC or PFC for short. My idle problem sounds a lot like yours... I am planning on relocating & replacing the fuel filter if this doesnt help then maybe changing the spark plugs. Unless anyone else has some help to add?

FD Racer

When was the last time, if ever, you sent your injectors out for cleaning and recalibration? Also, are you still running the stock intake and stock intercooler? If so, you really should'nt run much more than 10psi boost. What pfc maps are you running? Have you given any thought about an ignition upgrade and fuel pump upgrade? You definitely have a problem if the PFC reads 1.10 boost and your gauge reads ~10psi. If the pfc thinks your running that much boost no wonder your seeing 94% duty cycle. Also you probably hitting the fuel cut if the pfc reads 1.10 boost, didnt you say that you set the boost at .90? Fuel cut kicks in at .25 after your boost setting. Other than that, it still sounds like your running too rich.

7-sins

I got the car with 60k and a brand new rebuild, now the car has 66k. The engine rebuild wasn't done perfectly, a few things were half assed. I want to get 1300cc injectors but I just added PFC, MP, DP, new Pulsation Dampener, and silicone hoses. After all that I am kinda tapped out as far as money. Not to mention I am in between jobs. I am running the stock IC, when I get more cash I am going to buy some K&N cone filters (For now I have the K&N drop in). I am running base maps on the PFC. After looking over all the records he gave me I don't see anything about the injectors.

Thanks again,
Chris

Edit: My PFC is reading the absolute manifold pressure. After seeing the post in the PFC forum about it, it makes complete sense. Because of the altitude my PFC is +.26kg/cm2 higher (3.6psi) I checked this by turning the key to only the on position and looked at the readout. It doesnt really feel like fuel cut, I have felt that and its a really harsh jerk. This feels like the power cuts out and it trys to pull a little.

FD Racer

3.6 psi is way too much to be off. You might have a problem with your map sensor, I dont think its the altitude. You and I live basically at the same altitude, but my pfc is only off by ~1psi.

7-sins

What would be the best way to go about that, buy a new sensor? It makes sense because the PFC's actions would be off.

FD Racer

start by checking the map sensor by measuring the voltage it gives when you apply pressure to it, then compare the voltage to what the manual says is within specs. You can also check the pfc under etc/sensor check and look at the voltage there.

wptrx7

when you say map sensor do you mean for the injectors? cause i'm having similar problems with a surge at 3000 rpm when i start to spool up. i have similar mods as 7sins , right now i have to result in putting the factory ecu in , but now i am seeing 15lbs of boost. i plan on sending the pfc to xs to look at and to make sure my maps are correct and at the sam time i plan on upgrading the secondaries as well (and hopefully a fmic).

my mods are:
hks dp, pettit resonated mp, apex gt spec cb, act ss, ast replaceemnt, and pfc (taken off because became to much of a headache so far).

luigi

7-sins

I used to get a small surge at 3000 or so with my stock ECU. With the PFC I haven't noticed it. The map sensor is up on the driver side of the firewall (the little black box).

FD Racer

The map sensor is the little black box that says "Sensor - Boost" on it and has a vacuum line going to it. Its mounted on the backwall of the engine compartment. If I were you I wouldnt run 15psi on the stock ecu.

liamn56

Check your fuel pressure, fuel pump, fuel filter,etc. Plugged catalytic converter, main, pre-cat. Melfunctioning double throttle.

EugeneChoe

yo 7- sins is see youve got a ton done since i saw your car last. mines the same because im debateing on a bunch of stuff like what to do about the whole car itself thining of trading. still have the same boost problem and i cant figure it out. sometimes i see 5-5-5 and some 8-6-6. starting to get to me. did going non sequential help the boost prob. maybe we can meet up cuz i need mad friggin help yo maybe even try to do something about my car. oh yeah i saw ernies car run at mir and its hella fast with the single and he didnt even have the boost up. anyways peace out

eugene

wptrx7

i have to run the stock ecu because the pfc keeps freezing up (surging when i hit boost at 3000rpm), i feel like i'm putting myself in danger. what if i am an intersection and i need to get out of it, i don't want to be stuck. i try not to go over 10lbs i was using the pfc as my boost controller. i'm going to look around to have someone check the pfc for me.

luigi
liamn i don't have any cats (if you were refering to me)

maxpesce

If it's puffing black smoke when your loosing power you have too much fuel and/or an ignition problem - check plugs, wires, coils and ignitors then check you fuel maps for excess fuel.

also the Sock ECU will fuel cut at about 12.5psi making it impossible to run more than that on the stock ecu alone - discounting spikes shorter than .5 sec or so

7-sins

Thanks for the response. Thats what I was thinking; my map sensor is reading a little high that could come into play. When I get some more cash I will pull out the plugs and replace them, maybe get some new wires too.

liamn56

Previous post refers to one having a problem with "loss of power at high RPM's". Things to ckeck to find a solution.

7-sins

*Update*

Checked the map sensor.... It is reading within listed voltages. I guess time to get some cash for plugs, ect. I still dont know why PFC reading is off though.

FD Racer

hmmm thats weird, did you check both the actual voltages on the sensor with a multimeter and on the commander screen to make sure they match? If your commander is reading positive pressure (>3psi) with the engine off you still have a problem there.