revs302

you'll just need to hit it for a second or two so no worry there.

SpeedOfLife

iTrader: (16)

Also, is that intended to allow me to pass 6500RPM then or what?

revs302

well I'm having my own RPM problems, and I'm kinda new to the 7's...but I've been working on race cars for years. It'll let ya know if the injectors aren't getting a long enough pulse from the CPU...it won't show a low fuel pressure problem though but you said that's been covered (at the RPM cut though?).

If the car runs worse you're getting the fuel and you need to look towards the ignition.

lax-rotor

iTrader: (1)

solution: Time for a rebuild and stand alone. Those should fix your problem since everything else checks out okay.

SpeedOfLife

iTrader: (16)

Eventually. The rebuild is en route basically (I have to port, assemble, then install, I have all the parts), but since I won't be able to afford a standalone* (plus it isn't worth it yet for the modest power I'll be making) I need to make this work. Plus I'd never be at rest not knowing what the problem was.


*shouldn't afford. We are have enough debt as it is.

SpeedOfLife

iTrader: (16)

revs302, I think I did forget to mention. I slowly took the car up to 6500RPM and watched the fuel pressure before during and after the cut event and fuel pressure stayed the same. I did that twice just to be sure.

texFCturboII

iTrader: (17)

Agreed, if the fuel pressure stays constant while the injectors cut at 6500, then the computer is telling them to cut. I'd look into that..... but you got Rtek and a S-AFC? Just go Haltech and call it a day lol.

lax-rotor

iTrader: (1)

When this problem came up/when you first noticed it, did it happen all at once or was it gradual?

If it happened all at once I'd wager a guess that your ECU might be on the fritz. Have you checked the points? I think there's a write up somewhere on here...

FC3MAN

are the connectors all green in side on those secondarys?? high resitance tends to cause signal break down not loss, but lower voltage ie not opening fully ect. tends to mimic all simptoms mentioned id take them off clean them and put some dielctric greese in there to just a thought at least the front one is east to get at but check both sounds like corrosin at connector to injector to me

SpeedOfLife

iTrader: (16)

It was there since I bought the car. I never had anything better to compare it with. Again, I've used two different ECU's. I know that wasn't the problem. Wanna know how I know that?

Because I FIXED IT TONIGHT, WOO FRICKIN' HOO!!!!

So I was thinking I'd test the TPS for the second time (I believe it was one of the first things I addressed when I bought the car), and I found ~6.6kOhms. Hrm, not good. I try a sweep test, and somehow that didn't work on it... I tried the same sweep test on my spare I bought a while back (I kept hearing the TPS goes bad frequently, so I picked up a spare) and had the same result, BUT it sported a healthy 5.5kOhms. (d'oh, wait, I see what I did wrong for the sweep test) HM! Very interesting indeed, so I replace it (At much trouble, I might add. My frackin' 1/4" ratchet fell down in that little hole by the battery so I spent a good ten minutes cursing at the car until it spit it out underneath and if you've ever changed an S4 TPS you would benefit from having a shaved 10mm wrench. Like pullin' teeth, I tell you...). I finally get it installed, reassemble, crank it up and set the TPS and idle, then take it out for a cautious drive. Long story only kind of long, I take it up to 6500, she lets me in slowly and once I realize what's happened I just ripped into her. REDLINE at last, SWEET. However, I do have trouble redlining at WOT in first, it struggles a lot with that but pulls hard up there in the other gears.

Oh yeah, the reason I did this in the first place was because I searched "6500 hesitation" tonight and found a bunch of threads about various kinds of hesitations around 6500RPM, some of them I read a while ago, but managed to miss this one thing. In one thread I found a statement that wasn't confirmed in any of the threads I read, but I thought I'd try it because it made good sense.
So it just happened to work pretty well except at WOT (which was misleading about the TPS since I'd only heard of a bad TPS causing hesitations somewhere in the middle of the RPM range). I also noticed my SAFC-II showed a max of about 3.8V for my TPS when I installed it last weekend. Didn't think anything of it then because I didn't realize it used a 5V vref. Once I learned about the 5V vref that 3.8V struck me as odd so when I installed the new TPS I saw about 4.7V at 100% throttle. But now even after initializing then reentering the settings into the SAFC-II it won't read 0% throttle... Maybe the SAFC-II has a maximum low throttle voltage of 1V. We'll see what happens with that. I won't be doing any worthwhile tuning until I change the setup to use the boost signal and install a wideband.

Now to figure out why I can't hit even 5psi until 5.5k+. FUN! I know several things to look for though, and I plan on pressure testing the intake tonight or tomorrow.

GAH! Measured my 0-60 on slick roads and without a straight start trajectory. It's slightly faster than before even with the crappy boost, I'm sure redlining helps more in the higher gears since the higher speeds are when the extra power makes more difference; it's much easier for the car to pull at WOT from 2.8k to 3.8k in second than in any higher gear, so I'd guess my 0-100 time is not insignificantly better.

CLIFFNOTES: Despite testing the TPS a while back it was in fact the problem, I installed a spare I bought as a contingency for my TPS ever going bad. I learned a few new things searching the forum today and decided to install the spare TPS, and VOILA we have a happy RX-7 and RX-7 owner.

SpeedOfLife

iTrader: (16)

also, 0-60 is probably a bit faster much because I can actually hit 60 in second gear now...

FC3MAN

if there not all corroded inside check the resitance of the wires back to injector resitor block most harnesses are old and brittle and can corrode inside. due to high eng temps you afc should let you monitor a/f meters capacity ie maxed out, but not at 9lbs boost, high resistance sucks in small old wires with old loose connectors

SpeedOfLife

iTrader: (16)

Now that this is over I have to say I'm kind of disappointed. This really wasn't anything spectacular, exceptional, unique, or terribly complicated. Don't get me wrong, I'm glad I didn't have to buy more injectors or something like that. My spare TPS cost me like $25. Moral of the story? BUY A SPARE TPS, lol, it will save your butt.

FC3MAN

check vacum line to twin scroll valve its green and connection east to pop off with intercooler off

SpeedOfLife

iTrader: (16)

I'm not sure what you're saying here (I know what you're talking about, but I don't understand how the high resistance of old wires directly relates to my afc or AFM).

SpeedOfLife

iTrader: (16)

Oh yeah, I don't want to forget. Thank you, guys, for being patient. Some day we can all look back at this and laugh. At me. For looking like an idiot.

lax-rotor

iTrader: (1)

TPS was my first problem... which led to my fuel filter breaking up, which led to clogged injectors. haha, good thing you found it out! w00t! Go drive it for me (2 weeks without my car... i'm suffering withdrawls, hurry up boroscope!)

SpeedOfLife

iTrader: (16)

Oh don't worry, as soon as I found out I could finally redline I beat the snot out of it for a while. Too bad the roads are kind of slick in town, I'd keep hitting 3500RPM in first then it'd feel like I broke my driveshaft because the tires would break free so fast, haha.

I think I'm going to spend all night pulling vac rack/rat's nest stuff, cold start, fast idle and do the TB mod. Some because of the result of my pressure test (not good, I guess I was leaking big time under the TB somewhere... difficult to track down without smoke or something), I'm hoping to get rid of any vac/boost leaks.

blwn rtr 89'

iTrader: (5)

i was think of why his problem was occurring for quite sometime... it actually started to bother me....

turned out to be human error after all

SpeedOfLife

iTrader: (16)

I'll still never know for sure if I tested it wrong the first time or if I just got misleading results, I do know I did the best I could back then. I read that some people have tested their TPS and it tested fine, but it wouldn't read WOT right and so this happens.

hhn2002

woot! job well done. sorta.

texFCturboII

iTrader: (17)

nice, enjoy redline!