RB25 heartbreak HELP PLEASE

[EH240SX97']

I have an rb25 in an s13. The motor will NOT rev and build boost past 3 grand. Is there a "safe" mode that the computer runs in. OO and the self diagnostics says 55 all clear.

[IvoryJ30t]

probably have a bad MAF.

[xjon]

Boost leak. Check all your intercooler connections.

The motor will not rev past 3k also? Don't know. How are you checking the RPM? RSM, stock tach with or without adapter?

[EH240SX97']

The maf is ok. Thats what McKinney Motorsports said. And no Boost leaksThats what i thought because the front clip was hit pretty hard so we by passed it. STILL ON LUCK. thanks any more ideas?

[IvoryJ30t]

the maf might be ok, but hows the wiring?

did you check the signal at the maf, or at the ecu?

how is the cas?

[EH240SX97']

Yea Ill check the signal for the cas and maf at the computer do you know what the signal specs should be?Thanks

[gprodigy85]

this is off topic but IvoryJ30t ... aqua teen owns!

[IvoryJ30t]

yes. yes it does. [athf]

back to the maf. you should have a wiring schematic. i cant help you with pin numbers, since i dont have them on hand.

basically, what you need to do is find the signal line comming from the maf, and the pin on the ecu that it goes to.

check the voltage between the maf connector signal and ground, then check the signal at the ecu between the pin and ground.

just make sure the voltage drop is not excessive.

[Joe]

im willing to bet it is a boost leak.

[accel junky]

When I blew hoses off of my Turbo Integra, the motor still revved. So I doubt its a boost leak.

[Yellow4g63]

Integra is a map based system. on a Air meter system the car will sputter and prob won't rev out because there is more unmetered air entering the motor than the computer knows about.

[accel junky]

oh...gotcha. Thanks

[IvoryJ30t]

you should build yourself an intake pressure tester. all parts are available at home depot.

also, check for vacuum leaks, such as a cracked brake booster hose, a cracked pcv hose, disconnected sensors, ect etc.

[Joe]

hell yes. the poor mans boost leak check. i love those

[IvoryJ30t]

hell yeah. a pcv pipe cap, a pressure gauge, a brass T, and a shraeder [sp?] valve.

cant forget the epoxy/silicone

[Joe]

ive seen systems be sealed to 80psi before lol

aint NOTHING leaking out of that.

[EH240SX97']

Ill check the vacuum but it seems to pull fine until 3 grand. i Know that there are NO boost leaks but i dont know about vacuum the car idles fine. This problem is really anyoing. If anyone has the ohm specs for the crank angle senor and maf please let me know

[Real Boring 240]

try lookin around for fuel issues, bad pump?, switched fuel lines at the fuel rail, my sr (when i had it) would do the same thing, rev fine until 3-5 grand then nothing. It was due to fuel restriction caused by an inline pump the previous owner decided to install. Took it out and rev'd fine. so maybe take a closer/2nd look for fuel?

-Rafael

[JonPowell]

Your problem is probably a bad MAF/no signal from the MAF. That is what they do. I was messinga rouind yesterday and forgot to plug it back in and that is EXACTLY what happened. If you blew the hoses apart, then it would not idle/rev at all...boost leak it would sputter and pop like crazy.

[EH240SX97']

Hey Jon this is Brandons 240 i dont think its a bad maf because its new. I appreiciate the help and ill check its not fuel new walbo pump i need to check the signal output of the maf

[Imissmyturbo]

Since he is getting code 55 I don't think his MAF signal is bad. I bet his timing is off. That's what my car didn't when I first got it running. It would free rev up to 5-6K but under any load it wouldn't rev up at all. When I first started my car It wouldn't free rev up at all. I check for codes and got a MAF code. I then checked over the wiring and found that I didn't soilder the wires right when I extened them.

[IvoryJ30t]

its such a pain to diagnose through words.

what i was saying is to check the maf voltage at the maf, then check the voltage that the ecu is seeing at the ecu plug.

were looking for voltage drop here.

if the ecu is getting a signal from the maf, but the signal is way off, the car will run, and not throw a code. the CEL is not the end all of diagnosis.

[EH240SX97']

Figured it out. Its kinda dumb but here goes. We were waiting for an adapter for the filter for the maf. So we used the end of a sock until then. The sock was too restrictive and wouldnt let the car rev. Thanks for everyones help and sorry for the stupid mistake

[JonPowell]

You have GOT to be kidding me...

Telling everyone that you had a sock over the end of the MAF would have helped us diagnose your problem up front....

It's little details like that that make it IMPOSSIBLE for us to acurately figure out your problems.

[93RPS13]

lol

[goofynick6]

BAN!

heh

[accel junky]

omg....

[BoostFab]

that's kinda funny....it's like tightly with both hands sqeezing someone's neck and tell to breath.

[UncleBen]

I appologize for the stupidness of EH240SX97. He is just dumb.

[FAST-DATSUN]

check timing, TPS SETTING, compression, fuel pressure. plug gap. To a cylinder balance test to make sure all cylinder are holding there own..... 55 mean computer see no electrical input problems to the computer....