Unknown "Limiter" HELP!!

[SonySlave]

Ok guys, take a look at this dyno sheet (sorry it's bad)... I just got this thing dyno'd today and these are the results I got... very unusual I'd say... My profile is updated so those are my mods...

My problem is... when I did my dyno and when I go to the track, hell even normal driving, I can rev my car all the way to 7000rpms in 1st gear ONLY! I have tried and tried and tried to rev my car to 7000 in 2nd, 3rd, and 4th, but my car just will not let me... It starts bogging down EXTREMELY bad right at about 6000rpms according to my tach and just sits there at 6000rpms and barely moves... It feels like a limiter... And as you can see on the graph, the powerband drops right after 6000rpms and I don't even make it to 7000! And I've never redlined 5th, but I assume it does the same thing... What could possibly be wrong!?! Is there a limiter in the ECU for all gears past 1st gear? I've been with BigRand all day long at the dyno trying to figure this out and no luck! He, of course, has his '99 GS w/ turbo and even when he was N/A he never had this problem... Help me please!

 

[DSMcrazy3]

That is really weird, what were your A/F's like when the drop-off occurs?

 

[SonySlave]

That is really weird, what were your A/F's like when the drop-off occurs?

Well the problem is that since I haven't turbo'd yet I don't have a wideband or aftermarket A/F Ratio gauge, but my buddy at the dyno had the "wideband-on-a-stick" sitting inside the end of my exhaust, so it's better than nothing, but I don't have that sheet... I may be able to get it tomorrow.... Any ideas without it? BigRand will probably be on later and he might add more to what I've said if I've missed something since he was there...

 

[DSMcrazy3]

My only ideas would be Exhaust leak, or Vacuum leak. I'm leaning more towards exhaust leak, and the o2 gets a false reading causing it to make the car run rich, which will kill power. I don't know why something that drastic would happen though.

I dyno'd on a dyno dynamics, and my printout had the A/F going across the bottom. Try to get that sheet.

 

[SonySlave]

The only problem I see with it being a "run richer"/"run leaner" problem due to a false o2 is that we ran the car on the dyno at least 10 times and the problem would occur at the EXACT same point (6000 or so) everytime, as if there was a limiter built in... And I'll see what I can do about getting that other sheet... But if anyone has any other suggestions while I try to get that, let me know! Thanks in advance!

 

[DSMcrazy3]

Well right now I can pretty much guarentee there is no limiter installed in your car at 6,000 RPM in gears 2-5.

 

[XMasta19]

yeah man, definitely something wrong...there is no magical hidden limiter at 6k

 

[SonySlave]

Yeah, and I knew that, and that's why it confused me so much... But I'll try to get that other sheet with the A/F ratios ASAP... But keep any ideas coming!

 

[BigRand]

Hey I'm gonna go and try and pick up the dyno sheet for sony slave today, if our dyno guy is back in town. (cinco de mayo last night ya know)

Anyways we took out his bosh platinum 4's that were in the car, and put in some good old NGK standard plugs just incase it was a timing issues. well no such luck, but the car did pull up to 6k better.

I'm leaning towards it being an exhaust problem too. He just installed my old 2.5" catback and maybe while we were doing that something happend to that rear o2 sensor. Or there might be a problem between the headers and the cat that is restricting power.

Should have the air fuels if not this weekend then by monday.

 

[XMasta19]

word...DO IT

 

[SonySlave]

Well here is the best I've got... I re-did the dyno page and added the A/F Ratio sheets... The point where the A/Fs go from 11.6 to 13.9 is when the car starts acting up... Right at 6k... Notice I hit 6400rpms but I had to really keep on it to get it past 6k and it was slow as hell getting there... I think I could hit 7k eventually if I kept on it, but it shouldn't hold me at 6k like that... And again, the "wideband-on-a-stick" was sitting inside the tailpipe, so I hope these A/Fs accurate enough! Hell I even threw my best timeslip out there just for good measure... Let me know what you guys think! Thanks!

Looks like my actual numbers came out: 103.6whp/5350RPMs and 114ft-lb/3100RPMs

 

[BigRand]

So we took his whip to my friend who works at Mitsubishi, and after talking to him it sounds like we need to test the fuel pressure, at that high rpm.

Just out of curiosity, how often are we supposed to change our stock fuel filters?

 

[XMasta19]

...every 10-15k last time I checked

 

[Focker420]

might be totally off.But my pretty much stock 420a motor when i bought it had only cold air and i could still pull it to 7200 and after i got new cams that range was increased even more but the whps gain is lost for me at 7000 rpm anyway so is a good shift point to me. now i had i problem were my car would lose power and buck / missfire at high rpm it turned out to be my cam position sensor so u can check the cps and crank position sensor very easly. Do u have any engine codes to go off of ?.

 

[dr1665]

my pretty much stock 420a motor when i bought it had only cold air and i could still pull it to 7200 and after i got new cams that range was increased even more

I'd like to know more about how installing camshafts increased your rev limiter.

 

[4UH8ERS]

I'd like to know more about how installing camshafts increased your rev limiter.

Yes! me too WTF

 

[rs_smoked_you]

i think he ment it will rec to 7000 easyer or something??

 

[BigRand]

Anyways to get back on topic

We took Sony Slave's car to another shop and they hooked up a fuel pressure gauge to his test port, and took it for a test drive. Turns out he's running only 30psi of fuel pressure. I believe stock is supposed to be 43psi.

We unplugged his FPR to check for that, and tried to spike the fuel pump, but it would only get up to 32psi.

I'm thinking the problem maybe his fuel pump, hopefull a new one will make everything better. Do you guys think running a walbro 190 on a basically stock motor is a bad idea? I didn't think it would be, plus I have an extra one from my star kit I was going to pass on to him.

The only other thing I can think of, is maybe he has a bad injector when its flowing at high rpms. I guess we'll just have to wait. Any other thoughts?

 

[rs_smoked_you]

no a 190 lph will be fine on a stock motor, ive been running my 255lph for couple months now cause im gettin ready to turbo and its been fine! not even that loud either!

 

[SonySlave]

Ok guys... I recently changed out the fuel pump, fuel filter, spark plugs, coil-pack, and plug wires and nothing has worked. Now, I have no idea what was done to my car by the previous owners, besides that they put in leather seats and put an aftermarket moon/sunroof into a 98 RS. Now, I'm really desperate here because I'm losing all of my power... What's left that I could possibly try?

The only thing I can think of is the ECU... Now this is where it gets interesting... My tranny has always looked much cleaner and newer looking inside the engine bay, which leads me to believe that maybe an A/T to M/T swap was completed... I also think this because the A/T 420A's have the 8k tach, and they have a redline at 6.5k or so, and that redline matches up very very closely to the M/Ts 7k redline... My car has a set of aftermarket white gauge faces that were on the car when I bought it. So if the person who possibly did a swap didn't change the ecu, and I have a 9k tach, the ecu wouldn't know the difference in the gauges from the 8k or 9k versions and what they say is the redline, it would just move the needle as always and if the gauges were wrong, could I possibly be redlining the A/T 6.5k redline with a manual tranny? I hope that makes sense...

Any other suggestions would be greatly appreciated!!!

 

[Talon ESI-T]

I am leaning towards the fuel map issue. If it was a weak pump or clogged injector the AFR would slowly go lean as you raised into the upper RPM range. Yours is all of a sudden its 13.X AFR. Something is telling the ECU to lean out. You need to datalog.

Here is what you want to know:
While on the Dyno at high RPMS you want to watch the throttle % the ECU sees. If the TPS is faulty and the ECU thinks you are not at WOT then the ECU goes into closed loop operation and will lean out.

You also want to make sure the ECU is still in open loop at that RPM with the pedal all the way down. I have troubleshot many TPS sensors that were failing causing drivability issues and were not throwing codes. An automotive Scanner like the MT 2500 is easier to monitor but i am sure you can use a datalogger.

Terry