Cannot Rev Past 5k rpm

[mxrawr]

a few months back my SR MAF blew. which then messed up my S-AFC2. i removed my S-AFC2 and harness and replaced the MAF with a used but working SR MAF. car drove/idled/boosted like it use to but im not able to rev pass 5k rpm. when i hit 5k rpm, it just bogs there and a big black puff comes out of my exhaust.

what can be the problem?

[noeleven]

Does anyone know the solution for this problem?

[g6civcx]

Check the neutral sensor in the gearbox.

[240srhatch]

It sounds like you are maxing out your maf. Try another maf because I think the one you are using could be shorting out at 5k rpm.

[helikz]

I remember something about a gear(?) sensor for this as well. Unless you have the rev limiter removed by a standalone/romtune you are limited to 5k in 5th gear as a passive speed limiter.

only reason I mention it is the precise 5k mark.

[g6civcx]

I remember something about a gear(?) sensor for this as well. Unless you have the rev limiter removed by a standalone/romtune you are limited to 5k in 5th gear as a passive speed limiter.

only reason I mention it is the precise 5k mark.

Check the neutral sensor, and possibly the 4th and 5th gear sensor as well.

[noeleven]

Thx for replies! :)
but even when he drives his car, RPM does not passes 5k in any gear..
not just in neutral...
im not sure if it's exactly at 5k..
does this make any different to your replies?

[blackcoupe]

id check the maf again. just to be sure.

[gunluvS14]

I'm suspecting faulty 4th and 5th gear position sensor.
which cut into the "speed limiter" and prevent you go pass 5k rpm

[veeates36]

i recently had the same problem after having my clutch changed out and it was a total nightmare since it was happening on the track but then i started playing with some of the sensors on the tranny and "wah-lah"..lol problem solved.. BUT since it sounds like you never touched you're tranny i'd go with the MAF as your culprit..Good Luck

[noeleven]

Actually, this is the problem he had previous to this problem
http://www.zilvia.net/f/showthread.php?t=162642
This is not my car but It might going be so..
He told me I just have to get another working S-AFC and tune it to fix the problem..
but I just wanna hear some feedbacks from other people too
Any other opinions?
thx!

[g6civcx]

Thx for replies! :)
but even when he drives his car, RPM does not passes 5k in any gear..
not just in neutral...
im not sure if it's exactly at 5k..
does this make any different to your replies?

No. A faulty sensor will make the car think it's always in neutral, 4th, or 5th.

[805-240]

That happen to me and it turned out that my cold pipe wasn't on right I get to around 5 rpm and the cold pipe came off which made the bogging so check the hoses make sure everything is tight

[Erjay1]

No. A faulty sensor will make the car think it's always in neutral, 4th, or 5th.

So this faulty sensor will make it so that the car wont rev past 5k rpm in any gear?? Even 1st, 2nd and 3rd? Because the car doesnt go past 5k rpm in any gear.

[g6civcx]

Like I said, when a switch is broken, the ECU thinks the transmission is stuck in a particular gear no matter what gear it's in. Think about it.

[Erjay1]

Where can I find these sensors?

[veeates36]

underneath the car on the right side of the tranny... they look like bunch of different plugs. Good Luck

[John_R]

I have a 92 Coupe with a KA24DE in it. I have this exact same problem whenever it rains. What I found was the 5th gear connector was getting water in it, and "connecting" it. Which told the ECU that I was in 5th gear the whole time. Which won't let you exceed 5000rpm or so. Cleaned it up, sealed it, now I don't have that problem. I guess you could also remove the wiring and connector altogether, but I didn't mind it being there.

[Erjay1]

So I havent checked the gear connector but I did rev the car slowly while in 3rd gear, it went all the way up near 6k rpm. Now, if I just step on the gas it will get to 4.5 o 5k rpm and just start to cutout and buckle. Throws out a ton of black smoke. I also left it in neutral and rev'd it to arounf 6.5k and all this black smoke came out. Any ideas?

[Sileighty_85]

Man ive been saying this alot lately...
Did you check your ECU for codes?

[Erjay1]

nope, but I will tomorrow. Another thing I forgot to mention. My mechanic said the car came with larger injectors, possibly Nismo 550 or 740's.This is on an s14 t28. Could it be that the car is running too rich? Would too much fuel cause the car to bog at around 5k rpm?

[Sileighty_85]

nope, but I will tomorrow. Another thing I forgot to mention. My mechanic said the car came with larger injectors, possibly Nismo 550 or 740's.This is on an s14 t28. Could it be that the car is running too rich? Would too much fuel cause the car to bog at around 5k rpm?

Only if the ECU is not tuned for those injectors.

740's on a T-28, thats just overkill
I could imagine 550's

[Erjay1]

As far as I know, the ecu is not tuned at all. The prior owner said the car ran fine when his safc was hooked up. Then when it went out, the car started to run like it does now. Could it be that there is too much fuel and this is causing the car to bog at around 5k rpm? Do these have some sort of fuel cut out?

[Sileighty_85]

its flooding the engine 80% of 550's or whatever is alot more than 80% of the 370's

SAFC is not set up properly

Pull that SAFC crap off put stock injectors back in, or get a real tune to get the most out of your engine

[Erjay1]

No there is no safc. There used to have one and it ran just fine until it went out. Since the safc has been removed, the car has not been able to get past 5k rpm. I'll have to find some stock injectors and try those out. Thanks for the help.

[Sileighty_85]

well thats your problem then , if your running a stock ECU with larger injectors it flooding the engine

[98s14inaz]

well thats your problem then , if your running a stock ECU with larger injectors it flooding the engine

I bet you hit the nail on the head. The whole time I was reading this thread that was what I was thinking.

[Erjay1]

Ok so I think we've narrowed it down here. Ive read so many posts on here where ppl absolutely hate safc's. How else can I tune the car aside from PowerFC amd ROMtune? Or are those the only options? Just seems too expensive to go out and buy smaller injectors and buying an safc is probably out of the question. I dont need to make huge power, just need the car to run w/o bogging all the way through the powerband.

On another note, my mechanic also said that one of te blades on my turbine was messed up some how. Is there a possiblity that this is causing an insufficient amount of air at around 5k rpm which leads to the car running super rich?

[Sileighty_85]

yeah in the end it might be better to get an Enthalpy Tunefor like $500 actually squeeze some more power out of that engine. Nah the blade wouldnt do that, what ever the turbo pulls through the MAF is how much the MAF will read

[98s14inaz]

Ok so I think we've narrowed it down here. Ive read so many posts on here where ppl absolutely hate safc's. How else can I tune the car aside from PowerFC amd ROMtune? Or are those the only options? Just seems too expensive to go out and buy smaller injectors and buying an safc is probably out of the question. I dont need to make huge power, just need the car to run w/o bogging all the way through the powerband.

On another note, my mechanic also said that one of the blades on my turbine was messed up some how. Is there a possiblity that this is causing an insufficient amount of air at around 5k rpm which leads to the car running super rich?

SAFC's suck, lousy excuse for a tuning solution. You have to pay to play, get the rom tune and be done with it. Do a search and you will find what you seek. You could just throw some 370cc injectors in until you can get a tune.

Not related but stop driving the car until you get a different turbo. If the blades are really "damaged" it won't be long before they break apart and grenade your engine.

I would also add checking that your knock sensor is still good. If it goes your car goes into limp mode and pulls timing.

[Erjay1]

Yikes! Cant have those blades break apart. Im gonna have to pull the turbo off and verify that the blades are damaged. If they are, then its time for an upgrade. I just dont want to spend money on a rom tune only to find that it didnt fix my problem. Im stuck here. I guess I'll have to just wait and fork out the cash for a new turbo and rom tune :mad:

[Sileighty_85]

im sure you could find some used 370's for like $100 somewhere

Take a pic of these damaged blades

[Erjay1]

im sure you could find some used 370's for like $100 somewhere

Take a pic of these damaged blades

I'll look around and see what I can find. I put up a wanted ad and had a few pm's. Just need to find the best deal. Other than that, I'll snap a pic of that blade. My mechanic said its just one blade that is bent back a little or rounded?? Not sure.

[Erjay1]

Ok so here is what Ive found. Pulled out one injector and found it was a Denso 550cc. So is this why the car is not reving past 5k rpm?? Stock ecu, no safc, stock maf.

[jaysoi]

i have the same prob car breaks up at full throttle around 3 grand if i just ease it through the rpm it will go all the way through put once you stomp on it it wont rev past 3 breaking up bogging out?? i hear its the maf??but dont know

[Erjay1]

Do you have bigger injectors?? Or stock?? Hmm...I have an extra maf here. Gonna try it out and see what happens. I gave up and ordered a Power FC. Gonna tune it to these bigger injectors.