Yayers! First problem with RB25- stumped.

3577 Views 13 Replies 9 Participants Last post by RikRong, 2 mo ago

Boardman

Discussion Starter · Mar 1, 2005 (Edited)

Setup: bone stock RB25DET series 1
walbro fuel pump
running beautiful for 7 months.

This alll started 1 minute/half mile after I pinched the vacuum hose leading to the Nismo Adjustable Fuel Pressure Regulator to check pressure- almost wish I never pinched it! It's crazy all this because of that- but can't rule it out.

Problem: Normal everyday driving below 35mph or even when going 15mph- an intermittent (happens once during 15 minute trip then whenever it wants- it's hard to repeat) hesitation and gas pedal goes unresponsive, feels like the fuel pump is cutting out for just a second or the throttle cable doesn't work- but within a second everything will sort itself out by letting off the gas and blipping the throttle.
I'll pull over and the engine runs but once at a complete stop it will suddenly and immediately die.
Other times the car will be idling at a light or in the garage and just cut itself off.

This is not a driveability or boost issue. It cannot be repeated by making turns or accelerating/decelerating. It is quicker than "stalling" because of lack of fuel it's more like the spark plugs stop sparking.
Car will crank up but not catch right away as if fuel still needs to reach the engine. But car always starts back up fine after 2 seconds. Never been stranded.

There are no sounds (interior/exterior) or other warning (voltmeter/vacuum gauges) when the engine decides to shut off.

Replaced fuel pump- no change.
Went back to stock fuel pressure regulator- no change.
Car runs fine and boosts fine otherwise.
No visual wiring problems and I shook the engine harness/ECU area wiring to see if wires are shorting- doesn't seem to be it- all wiring is soldered +taped well. Engine grounds are secure.

I always figure my own problems out but this one has got me stumped.
Brainstorming:
possible issue with mass airflow sensor
issue with ignitor
issue with coilpack grounds loose
variable voltage controlling the fuel pump shorting out

At least this is documented so when I figure it out we'll have it on here for future reference.

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240z4u

· #2 · Mar 1, 2005

Whoa bro youve got me spooked LOL

James, if you want to come out to my house you can try out my rb25 maf. I think i actually have a series one unit.

It may be prudent to tap onto your fuel pump leads and roll around with a multimeter in your car for a bit.

Just curious, you try swapping your ECU's? I know youve got an extra one.

I almost have to think that the hesitation/stalling problem is not related to your pinching the fuel line.

Drop me a PM if you would like my help. It is rare something electrical can elude me for long! I would be happy to try to lend a hand.

Evan

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240z4u

· #3 · Mar 1, 2005

Do you have a fuel pressure gauge? are you seeing a pressure drop at any time during this problem?

Evan

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JonPowell

· #4 · Mar 1, 2005

Did you try teplacing the spark plugs since you think its possible they are the culprit? Get the NGK V-Power copper plugs it will cost you $13 and be a cheap attempt to fix it.

I would check the signal from your TPS...might have vibrated loose...might be going bad? You say blipping the throttle seems to help bring it back to life....

Check the IAC...might be sticking.

Hard wire the fuel pump relay to kick on when you turn the key on...might help with any intermittent wiring problems PLUS be a little safer/slight upgrade to allowing the ECU to drop the voltage going to the pump when idling.

Any codes from the ECU in diagnostics mode?

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Syline

· #5 · Mar 1, 2005

I have heard of some people haveing problems like this due to a bad idle motor. Sometimes the shutter gets stuck up usually do to a build up of carbon, but when enough pressure builds up it gets fored open.

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foCk

· #6 · Mar 2, 2005

i'd replace the spark plugs

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gabedude

· #7 · Mar 4, 2005

I gotta watch this so when you junk your 240 after not figuring it out, I can poke fun. Isn't this like your 12th car old man? O wait your younger than me, I see why you had 12 cars....

lol.

I'd help but this is too much fun...

:thumbsup

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Boardman

Discussion Starter · #8 · Mar 4, 2005 (Edited)

^
awww, someone is still butthurt from getting owned :gaylaugh
you must of enjoyed how it felt

edit: 12 cars? I coulda sworn it was double that :supercool

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gabedude

· #9 · Mar 4, 2005

Now we know why. Someone doesn't know how to use a ratchet...

lol.

Seriously man, it could be alot of things. Better learn how to use a multimeter...

:happyfing

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