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Help - No power after 2500 rpm.

Leadfoot

By Leadfoot,
in Engines & Forced Induction

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Leadfoot Enthusiast

Leadfoot

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Was driving home last night and every time after pulling up at lights the car would surge momentarily when accelerating away. Whatever was causing this, it must have got worse because a couple of blocks from home I couldnt get above 2500 rpm. The more I put my foot down, the less power the engine had.

It felt similar to fuel starvation however after popping the bonnet I noticed there was no pressure in the radiator hoses. The overflow tank was mostly full so I had not lost a lot of water. I am going to give it a throrough checkup after work today but could this be a ceased shaft turbo and blown water seals. Stock turbo at 75,000 km. I already have a spare fuel pump ready to go as these are renown for blowing up but I am still confused by the lack of water pressure.

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Race__24 Experienced

Race__24

Posted
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I think the ECU has a limp mode, from what i've heard this stops the engine from reving over 2500, this could possibly be what's happening to you.

As for why it could be in limp mode, i'm not sure what causes it but i would guess overheating would be one main reason, faulty sensors could be another.

Did you notice if your radiator was hot or not? If the radiator doesn't get hot but the engine does you're car could be suffering from a busted water pump.

Could be anything mate, I'm just throwing ideas out there

Leadfoot Enthusiast

Leadfoot

Posted
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Posted

Good point, will check the AFM. Not sure about limp mode as the car has a Power FC which I forgot to mention. IT s not a hard 2500 rpm limit, just feels like fuel starvation at anything above this.

The PFC lets me see all the engine instruments from the display. The water temp was only 95 deg C, and I recall the AFM seemed to be producing a sensible reading when revving up and down.

It doesnt know the A/F ratio which would be handy.

I am going to have a closer look tonight to see if I can hear the turbo spooling and some sort of boost being made and post back tommorrow.

krush Collaborator

krush

Posted
Posted

ive got the intercooler prob also. its got a leak and does what youre saying at around 3000rpm (where it hits about 0.5bar). before it would be at 0.9bar at 3000rpm, but not it gets there and just dies, constant 0.5bar reading, and no power at all. with all the windows open i can hear the leaking of air, and the bov also sounds slightly different in a funny kinda way. but yeh, im got boost leak, which if i were to describe would sound very similar to what you are saying..

something that could help, if i dont have the accelerator down quite as much, it will tend to act 'normal' again, and continue to rev through the range until it is creating too much boost, then i ease of the accel a bit more and it will continue to rev another 500rpm til doing the same thing.

as long as i dont create too much boost (in which case air would be leaking while too much fuel is being put in.. im guessing..) and keep it around 0.3bar by lifting off the accel when it gets too much, it will keep on reving. easy to do between 2000 and 3500rpm, but the higher the rpm's, the easier it is to create boost and more precise i need to be with the accel pedal as to not give it too much exhaust gases to spin the turbo thus create boost.

i hope this dribble helps somehow :D just sharing my expreience..

shaun.

Leadfoot Enthusiast

Leadfoot

Posted
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Okay,

Thanks for all the input so far. I made some more checks last night. Just idling in the gargage I can sometimes get the engine above 2500 rpm by letting it idle for a while but it still seems to be lacking pickup and power at all rpm's. Sometimes it will rev over 2500 rpm and then other times it wont, theres no rhyme or reason. All engine sensors appear to be behaving sensibly according to my power FC hand held. ie Air flow, air/fuel ratio, timing, rpm, water temp, voltage, injector output and boost pressure.

All intercooler pipe connections seem to be sound as far as I can tell and there is no sound of air escaping. Water temp is okay it did not exceed 90 deg C.

Turbo appears to be okay or at least I can hear it spooling and there is no exhaust coming from the radiator cap or water from the exhaust so I think the seals are okay. The problem starts from a cold engine so problem is not engine heat related.

Idle is very smooth but then the missing (or lack of power) at higher revs appears to be all cyclinders at once so this seems to point to either fuel supply or complete ignition breakdown.

The spark plugs are at least 10,000km old so I will change them tonight, not being really sure how long to expect in an RB25. If that doesnt fix it I will change the fuel pump over to the Bosch 044 I have waiting. Failing, that I'm thinking an electrical breakdown to the coils and something for a workshop to sort.

Cheers for all the help.

R32_GTR Newbie

R32_GTR

Posted
Posted

Hey,

Have received my 32 GTR from japan in last fortnight and have this exact problem. Did not seem to have it when i first got it, but has pretty bad now. Seems to be a totally random thing. SOmetimes drives sweet then does it, other times does it as soon as i start the car, comes and goes all the time. I have found that if, when it does it, I get out and jiggle the wires on the top AFM the idle will cahnge and is now sweet again, only to come back again. Have had both airflow meters run througha diagnostic with no evident problems. Will be getting some spares to test with soon. If you have any luck pls post as i would love to fix this also.

The Mafia Grand Master

The Mafia

Posted
Posted

check the airflow meter setting in hte powerfc hand controller.

If you set the setting to something other than what you have, it will cough and splutter when trying to rev after 2500rpm, and stall when the revs come back down. You will also blow alot of black smoke.

I know this because my mate ****ed around with the powerfc setting and chaged the afm type.

Had me stumped until I had a look.

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