WAYNE88N/A said this:
"On to the controversial "boost sensor grounding". As I've stated in several posts before, grounding this sensor's alleged "ground" wire is WRONG. The boost sensor does not have a ground wire that actually bonds to the chassis- the wire in question leads to the ECU, who decides when to ground the sensor. Several other sensors also are wired like this, and the injectors are also "grounded" through the ECU. You wouldn't ground your injectors' wiring, would you? Of course not, then they would be open and flowing 100% of the time, with absolutely no ECU control over them. Same scenario with the sensors, guys, don't take away ECU control from them, it'll just lead to problems..."

 

I'm not entirely sure I believe that... Too many sources state otherwise.

 

I guess I could try it out, probably no harm in that.

 

w00t got my SAFC 2 today, I might have time to install it tonight. Initially I think I might be able to use it to monitor sensors and injectors, maybe giving more insight to this problem.

 

safc is a must at minimum when you change injectors, every car is different, therefore not pre programed chip is sufficient.

start at stock timeing, and throw lots of fuel to it, lean out and advance as you see fit..

if its a tuneing problem this should be fixed quick.

are you gonna tune of EGT or wideband?

 

From what I know now, using a wideband would be easier for me, but I don't know the pros/cons between the two. Cost is a factor, but if one is more accurate or more effective I may go for that regardless of cost.

 

I know that several have already stated this but when I had this problem it was my fuel pump. I would hit a brick wall at 6500 under load but in neutral it would go to the redline. My voltage was well under 12v and once I had the mew pump installed the 6500 wall was lifted. Check the your entire fuel system.

 

trying a new fuel pump would not be a bad idea, in fact i would do this if i was in your situation.

if you are new to tuning i would get a wide band, and from the boost you are running it would be a safe bet to ditch the AFM altogether, and go with either a gm 3 bar or a LQ4 MAF sensor.

maybe its just me but a sensor like the LQ4 has no chance of being outflowed, there for fuel cut will never be a problem, and its smaller than the s5 AFM and cleaner looking.

 

How could I be outflowing the AFM? Haven't people made 350hp+ with the stock AFM? I'm hitting the wall at very light acceleration, as in minimum airflow for that RPM, yet if I'm WOT and boosting past 5psi I still hit the wall at exactly the same spot... I don't see how it could be an 'outflowing the AFM' issue.

 

i just threw it out there, i run stand-alone, so the first thing i ditched was the AFM for the LQ4, every car ive modded ive ran a LQ4. so i guess its just a habit.

i feel the impede flow alot less and they get better readings because the mesh screen distributes the air equally as it passes the sensor.

i would no know if you are outflowing the AFM unless i had a spread sheet to get numbers of off.

i dont even know the capacity the stock AFM can handle, but if if it is out flowed it leans out hard core

 

I'm sure they can, certainly flowing better and possibly reading more accurately, but this is the simplest option for the moment. I've basically made it my goal to fix this 6500 RPM wall before doing my swap because it could cause horrible problems.

I have some more information to add if I haven't added this already. Sometimes when the motor will be warmed up I can't rev under load very easily past 5.5-6k RPM, and similarly I sometimes can't free rev past 5.5-7k RPM. However when these occur the A/F gauge reads rich instead of full lean like the wall causes and it isn't a wall, it's just very rough and I can often push higher, but it's like the motor doesn't want to do it. I haven't had time to discover a strong pattern to this yet, but it might be warmer ambient air temperatures that cause it.

 

sounds like the AFM is telling the injectors to throw more fuel when it dose not want to...... Rtek fuel cut defender hard at work there

 

What about a faulty knock sensor??? I was just reading about how to adjust the knock correction for my fuel controller (which I installed last night/this morning) and realized that maybe my knock sensor is picking up vibrations too so easily for some reason at that RPM.

I will also add a fuel pump resistor relay to my WTB thread in case that is my problem.

 

Ran some tests using the SAFC 2 tonight.
-Doesn't look like the knock sensor is seeing anything crazy.
-Doesn't look like the AFM is throwing a high or wrong reading at 6500RPM.
-My tach is almost dead on, within 100RPM at about 6000RPM.
-Tried maxing fuel delivery at 7000RPM for both low and high throttle to see if the ECU was running lean on purpose or something. No dice, same result, so I set it back to zero correction.

I will do what I can asap with the injector wiring...

 

Hm... could I not be sparking at 6500RPM? Although it would have to be at least the leading coil not firing, right? I will test the igniters soon, though I'm not sure if that would tell me if they're failing only at a certain RPM...

 

I did a once over on the last 4 pages... could just be something as simple as a clogged cat if its only doing it under load..... Don't yell at me if this has been covered.. I skimmed it. hehe.

 

No cats. See sig. Maybe 'straight exhaust' isn't quite specific enough, if not, I'll change it.

 

Sorry, read the first post and saw "COMPLETELY stock" and figured it was.... uhmm... COMPLETELY stock. The first post also didn't have your sig..

MY BAD! Good luck!

 

fuel pressure.......................................... ..........
.................................................. ............................
.................................................. ...................
.................................................. ..........................
.................................................. ...........regulator

 

cant read sorry

 

Tps

 

I have done the LED test with the TPS and it is fine by that method. I haven't checked for dead spots via sweep check, but it's maxed out before you even open the secondary throttle plates much if at all and it operates fine at its peak voltage. Which I should find out though... Back to the FSM once again.

edit: I checked it's resistance a while ago (and it was fine), which is the most the FSM specifies. It does not address voltage while the car is running.

 

Tested the freakin' FPR tonight.

MAP ~ -14mmHg = 30-32psi fp
MAP ~ 0psi = 35psi fp
MAP ~ 5psi = 45psi fp

Doesn't look low to me. Also doesn't look crazy high. Also remember that this issue was around before I ever changed secondary injectors or the fuel pump, and that it occurs regardless of MAP being positive or negative...

I think I asked once, but I'll ask anyway:
Could this be due to a mechanical problem with my TB?

 

it's floating the valves, hehe. couldn't resist sorry.

To be honest it sounds like the spark is breaking up but with dual plugs/coils I find it unlikely.

Checked fuel pressure under load yet? a dirty filter or crimped fuel line can do this.

also if you can run a jumper wire from the ground side of the injectors to a nitrous button and back to chassis ground you can hit it at the "wall" and MAKE the injectors go static to see if they/ECU is shutting down.

 

Yes, I did. That's how I got the results for MAP at 0 and 5psi.

lol, wouldn't I be likely to fry them if I did so?