GnubberLang

When I rev to 7000 in 2nd or 3rd (I guess same with 4th or 5th) I get a little blip of a misfire/cutoff or something almost always right at or after 6500. Only under WOT. I've got an AEM open filter, a RB cat back and a fuel cut defenser, just replaced the fuel filter a few days ago. both cats are in place? I've got a profec A just set up to read boost and it was spitting out 0.5/0.6 bar. Anyone have any ideas?

I first noticed this right after putting the intake on. I assumed it was the boost cutoff because it was happening a lot even not under WOT, just hard accelerating around 5k. I put that FCD on and I had thought it went away.

gildardo

I get a bit of missfire at start up, but it goes away as it warms up.. I think i experienced something similar when i had boght a used Apexi AFC. It would cut off at 5500rpm, i replaced it with a new one and problem fixed. Maybee its your computer, my car ran on one rotor once, all because of the computer, it freaked me out...So, you might want to swap the engine computer.

Gil

eriksseven

iTrader: (6)

I'm actually dealing with a *scary* high-RPM misfire right now, that is also at 5500 RPM's... Does anyone else have more imput on the causes of a high-RPM misfire? I just set my timing, my spark-plugs are tight, I have no vac-leaks etc...

Regardling ECU's, I'm currently running an R-tek 1.7 chipped ECU but I'm seriously considering swapping it out if I can't figure this out.

Also, (gildrado) you mentioned allowing the car to warm-up--well, my T-stat stuck on me a few days ago so I pulled it out until I can replace it (no one has the 180F T-stat that I want). So now, the absolute hottest my car runs is around 150F... Not ever fully warm.

I think what I'm going to do is drive my car gently for 20 minutes just to get the car as warm as possible and see if it still does it. If it does, then I'm going to check the coils and plug-wires and if it still does it I'm going to pull out the R-tek ECU and put in an extra stock one...

eriksseven

iTrader: (6)

BTW, it really does feel like a strange 'fuel-cut'...

RotaryEvolution

iTrader: (30)

it is either a lean/rich condition or an ignition issue, you both had better pray it is ignition if you keep testing to see if it is a lean condition. replace all your plugs if they have more than a few K miles on them, they aren't super expensive and sometimes hard to tell whether they are fouling or not.

be sure your fuel filters are new and i can't stress enough how much a good wideband will help you determine if your car is running safe or not. a way to control fuel is also a must when modifying your cars. get an SAFC, RTEK2.0 or a standalone and make some adjustments with the wideband but the only true way to tune is with a dyno, an experienced tuner can tune on the road by experience but it isn't suggested for the novice tuner.

lastly, make sure all your intake pipe hose clamps are nice and tight, at higher boost levels a loose clamp that may not fully blow the hose off could "burp" causing spikes in power.

eriksseven

iTrader: (6)

Hmm... I'm actually really thinking it's my TPS.

RotaryEvolution

iTrader: (30)

unless your TPS is faulty completely it should have nothing to do with WOT operation, keep in mind the TPS shows full open to the ECU at approximately 30% throttle and is basically just to let the computer know when the car is at rest or under a load. the TPS should sweep fluidly from 1volt up to appox 4.3-4.6volts at 30% throttle

eriksseven

iTrader: (6)

Muhahah... It was my TPS. I got it set correctly to around 1.0ohm's at rest. Although when I did the sweep, at around 4.0ohm it went into "infinity" and by WOT it had gone all the way up to 9ohm's...

Regardless, I reset it and crossed my fingers. I took the car out for a spin, tensely awaiting a misfire in the upper RPM's *shudder*. Well, it didn't misfire and my car is FAST. I went through 2nd and 3rd gear multiple times with the boost creeping to 11psi max. This is really the first time I've been able to really allow my Turbo II to stretch it's legs since doing my recent bout of mods/work. I want to say that it's *almost* as quick as my old Turbo II when I was running my TO4b wheel'd hybrid.

For the first time since owning my Turbo II, the street-port is able to breath! I'm very impressed. The previous owner/builder created a nice port.

One last thing: My "old" turbo is working great after I was forced to swap it back on after my "new" turbo failed... The reason I replaced it was because it was having issues before with the compressor wheel hitting the housing... It's not doing it now and I have a theory as to why. I mentioned in another thread that I created a large vac. leak on accident and didn't realize it, when I removed the TID on my Turbo II for the first time. Well, it created such a large gap for the turbo to suck in extra air, that in the higher RPM's there was so much turbulence created by this leak coming in at an angle and striking the compressor wheel's blades... The turbulence was so powerful in the higher RPM's/high boost that it was causing the wheel to hit the housing... After I fixed the leak though, I was too wary to run high boost--so I kept my EBC OFF and would rarely take the car above 4k RPM's. This theory has been bouncing around in my mind for a couple weeks, so I decided to test it and sure enough--with no vac. leak in front of the turbo, there is no hitting.