GustavOllufsen

I went non-sequential and now if i go over 8 psi it starts to feel like the ecu's 12psi fuel cut. there is a hissing comeing from somewhere by the UIM hinting to a small boost leak but i can't imagine that making the car hesitate like it is doing. even at 8 psi it hesitates at around 2500 rpm then becomes normal at 3000 and goes fine till redline. I replaced sparks plugs and wires. My luck it's a bad ground for that part...but the fact that it won't let me drive normally over 8 psi has got me stumped

GustavOllufsen

nothin?

GustavOllufsen

GustavOllufsen

well **** i'l just find andl fix that vacuum leak and take off my intake piping and couplers and see if it persists

GustavOllufsen

stupid sig

dgeesaman

iTrader: (7)

If that leak affects the double throttle soleniod, that might explain it.

Dave

GustavOllufsen

the solenoid is gone.

dgeesaman

iTrader: (7)

IIRC you're not running the stock computer, and I don't think the PFC cares whether the solenoid or an equivalent resistor is there or not.

I don't have any great ideas other than the usual suspects: fuel, TPS, computer(?), etc.

Dave

GustavOllufsen

I wish i was running a pfc or something I'm still stuck on the stock ecu

well **** it was retarted just a boost leak from the AWS solenoid block off plate gasket. Running a healthy 11psi


Second part...3k hesitation:

I think I've been in denial about the 3k Hesitation, but I think I'm ready to admit that I have been bitch slapped by it. It's so strange though. I'd really like to know WHY 3k ? I mean it gets to 3 k...pauses for a second...then keeps going like normal

I was thinking maybe it's just a coincidence that this just happens to occur at a time where 3k rpm begins to draw a substatially larger current or something that a bad ground may hinder. but the fact that after the pause at 3k it goes as normal indicates that the system performs fine after 3k so in my mind it seems like somethign must be happening at 3k rpm. something must be switchign voer or a major change in ignition timing or some sort of alteration in the electrical system must be occuring when the computer sees 3k RPM. but WHAT!!!!

I did plugs and wires. stock setup of 11's and 9's and NGK Wires. I thought at first it may be wastegate related but that would affect boost. the boost seems to stay the same, just the RPM pauses for a bit then keeps going. in EVERY gear it's 3k. it almost makes it feel sequential lol. cause it starts to spool up, then pauses at 3k, then swifty gets to 11psi and pulls to redline lol.

7racer

you shouldn't be getting a 3k hesitation in non-sequential mode

GustavOllufsen

I though the 3k hesitation was due to bad grounding and therefor faulty ignition

lilgt6

It's my understanding that it has nothing to do with sequential/non-sequential and it is in fact electrical. A bad ground is a likely cause. Do you have it only when the car is cold, or is it all of the time? On my old car with the stock ecu it only seemed to happen when the car was cold and only at light throttle. I installed the PFC and with no other changes the problem was all but gone. Still there, but only if you were really looking for it was it noticable.

Was this problem there before all your recent work? I know you had the exhaust off, there are ground straps there. Did you re-connect these?

Dennis

GustavOllufsen

actually the only part of the exhaust that i removed was the downpipe, but i did realize afterwards that the cat to catback gasket was blown for like no reason. maybe the flange surfaces got moved around during all the work and perhaps the ground strap back there came loose i forgot about that.

can onyone explain to me exactly where all the grounds are??? i keep seeing people refer to one that's "by the oil filter" but even when i took everything around there off i did not see a ground

dgeesaman

iTrader: (7)

I've never heard or seen a reason to believe it's related to the boost system. So non-sequential and sequential cars will have it just the same.

dgeesaman

iTrader: (7)

People have theorized that it relates to the fuel pump, which switches from 12v to 24v at 3k or something like that. But IMO that theory is as easy to rule out as installing a fuel pressure gauge and watching if it changes at 3k.

Another theory is that the primary injectors are working alone at that rpm, but air can be coming in from both primary and secondary ports. But that doesn't explain why all stock cars don't have the problem, or why it doesn't happen when the car is brand new.

Another theory is the O2 sensor isn't getting fully heated even though the ECU is reading from it. But that doesn't explain how cars with the stock downpipe have the problem, or why it doesn't happen when the car is new.

One thing everyone agrees on is that a PFC will always solve the problem, regardless of the maps it's programmed with. Apexi has not and probably will not disclose the difference, assuming they even know what the difference is.

I've wanted to do a real investigation of it by doing a little DAQ setup and monitoring the inputs/outputs at the ECU. I believe it's due to tired connections or components in the ECU itself. Logically, if fuel pressure stays the same during a 3k hesitation, then the issue must be the injector cycles, ignition settings, or an airflow change controlled by the ecu. I suspect that something like a capacitor on the stock ECU goes bad slowly, resulting in a bad ECU output, or an undervoltaged signal because the ECU the most power at 3k. That would sort of explain why some people have seen improvements by upgrading the grounds, and why it appears slowly after the miles accumulate. To really prove that it's internal to the ECU, a brand new/unused ECU should in theory solve the problem.

Of course, this whole investigation isn't worth more than the cost of a PFC, which explains why the problem hasn't been fully uncovered. I figure a clever DAQ system would run a few hundred bucks - which would be a very interesting tool, but I don't have hundreds laying around just for curiousity's sake. And I'm a mechanical engineer, so my circuit-building experiment would take a lot longer than it would for someone with an electrical background.

Dave

lilgt6

For comparison's sake I "think" I still have a stock ECU in my garage. If you would like to swap it out with yours and see if the problem worsens or gets better you are more than welcome to do so. Give me a call or an e-mail if you want to try this.

As I said above, the other car (from which this ECU came) only had the problem at light throttle and only until it warmed up. I don't know how bad yours is, but if there is a marked change in your car with a different ECU, then that points to ECU or connections at or near the ECU.

dgeesaman

iTrader: (7)

Yeah, the classic 3k hesitation is only at light throttle, almost exactly at 3k, and only happens when the car isn't fully warmed up. Any other hesitation IMO should be troubleshooted until it's solved.

Dave

GustavOllufsen

yea my 3k hesitation is also at WOT and happens if warmed up or not warmed up

lilgt6

That's not the typical 3k hesitation as was already pointed out. The Typical 3k hesitation was more like a hiccup then a pause. Just a very short stutter if I remember correctly.

GustavOllufsen

well it's a really mellow hiccup ;-)

7racer

Dave,

you are right as always, I was thinking about the 3k "hesitation" as the transition between the primary and secondary turbo...that is the dip from 10-8-10. Therefore in non-sequential...this shouldn't be present.

This is actually kinda funny, because since my rebuild, I haven't had it and totally forgot what it felt like! sorry for the confusion

maybe all my new grounding really did something good!!