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R33 Gtst Cutting Out At 4000rpm

tomgtr

By tomgtr,
in Engines & Forced Induction

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**RB2530** Proficient

**RB2530**

Posted
Posted
hi all, new to the forum just bought an r33 last week. It has a problem where it doesnt want to run over 4000rpm. As soon as it hits it the car stutters and jumps around with the revs bouncing and just wont rev any more. Any ideas?

cheers

Tom

Do a search for 'air flow cut'....

Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted

If it's a stock ECU, sounds like it's on LIMP mode, this occurs when the AFM is faulty or disconnected.

Disconnected cooler piping will result in a fked up idle, leaking cooler piping usually doesn't cut out at 4000rpm, car just runs like a POS

bubba Grand Master

bubba

Posted
Posted

He didn't say it cuts out, he said it coughs and splutters and I HAVE had that happen from a leaking cooler pipe, it was basically a clamp not tightened up, it would be fine until it built enough boost to pop open the leak and then died in the ass (hence asking about it belching heaps of black smoke).

And doesn't limp mode limit to about 2000rpm? 4-5000rpm is usually spark breaking down.. particularly with the coughing and spluttering.

AFM over voltage cut is a harsh CUT similar to the overspeed cut, not coughing and spluttering.

**RB2530** Proficient

**RB2530**

Posted
Posted
If it's a stock ECU, sounds like it's on LIMP mode, this occurs when the AFM is faulty or disconnected.

Disconnected cooler piping will result in a fked up idle, leaking cooler piping usually doesn't cut out at 4000rpm, car just runs like a POS

If it is badly leaking (disconnected) intake pipework I doubt very much you could get the engine to rev to 4000rpm.

If it is a moderate leak (split hose connector hose etc) TC will spool more as it is not loaded as much by the back pressure of the intake. This will still cause excessive air flow through AFM and trigger airflow cut.

**RB2530** Proficient

**RB2530**

Posted
Posted
He didn't say it cuts out, he said it coughs and splutters and I HAVE had that happen from a leaking cooler pipe, it was basically a clamp not tightened up, it would be fine until it built enough boost to pop open the leak and then died in the ass (hence asking about it belching heaps of black smoke).

And doesn't limp mode limit to about 2000rpm? 4-5000rpm is usually spark breaking down.. particularly with the coughing and spluttering.

AFM over voltage cut is a harsh CUT similar to the overspeed cut, not coughing and spluttering.

AFM over voltage is a harsh cut but the reaction time for it to occur and for it to reset is very quick. From what I have seen Nissan don't have any damping or delay on its reistatement of spark / fuel.

In cases where airflow hits the cut threshold very hard (rising rate of air flow is high) , it really jolts the car around. Where if the airflow is close to reaching its peak anyway and is just on the threshold of cutting(threshold rises with rpm) you can get a coughing and spluttering.

The reason there is a difference is that the time taken for airflow to drop below the threshold cut level for both scenarios will be different due to airflow overshoot effects.. ie the higher the rising rate of airflow, the longer it will take for airflow to drop below threshold.

tomgtr Apprentice

tomgtr

Posted
  • Author
Posted (edited)

Yeah the car really jolts around its quite harsh, I have had it rev to over 6000 rpm a few times in one drive where it ran fine.

The car doesnt blow much smoke at all, and a few people have told me it could be a faulty pipe or something,

Thanks for the feedback it is very helpful

Edited by tomgtr
Sean W Experienced

Sean W

Posted
Posted

if you have any friends that own r33s (or you could ask around for kind members on here in the want to borrow section) you could switch their air flow meter for yours and their coilpacks for yours. if either solves your problem you know what to replace.

smokem31 Contributor

smokem31

Posted
Posted

not trying to hijack..... but have a similar problem....

if you put your boost lower, does it still do it?

cos mine is not as bad when running lower boost.... if i run 15psi, as soon as it spools up to 15, car jerks around and cant even drive it, just cuts in and out of power quite harshly.... but on low boost, 9psi, car just flat spots but still revs. see if that happens to you, cos i think its coils packs for me.... i changed plugs and regapped to .8 but still no good.....

dont think its injectors cos AF gauge reads rich while its coughing, jerking and spluttering....

hope it helps, and you can help me!

tomgtr Apprentice

tomgtr

Posted
  • Author
Posted

mines completely stock at the moment, but it runs perfect until it hit 4000rpm. Ill try the coil packs tommorow and check em out. Can anybody show me what the air flow meter is? I have no idea, this is my first import and only just learning.

thanks

tridentt150v Grand Master

tridentt150v

Posted
Posted
who ever is running 15psi needs shooting .

and do a search FFS

its f**ked coils

a f**ked afm will make the car not run over 2500 and sound like a rotor

Hahaha your so touchy feely lachlan, stop messing about and say it like it is................ :P

R33 Eddy Proficient

R33 Eddy

Posted
Posted
mines completely stock at the moment, but it runs perfect until it hit 4000rpm. Ill try the coil packs tommorow and check em out. Can anybody show me what the air flow meter is? I have no idea, this is my first import and only just learning.

thanks

make sure its not over boosting as it could be hitting the AFM threshold with stock ECU.. i used to run about 10psi and on really cold nights it would happen...

if that's all sweet then its your coils, check for cracks and tape them up if that fixes it then buy new coils :P

smokem31 Contributor

smokem31

Posted
Posted
who ever is running 15psi needs shooting .

and do a search FFS

its f**ked coils

a f**ked afm will make the car not run over 2500 and sound like a rotor

mind telling me why I should be shot for running 15psi, when you have no knowledge about my engine?

Trozzle Grand Master

Trozzle

Posted
Posted

Mind telling us why you shouldn't be shot, when you gave us no knowledge about your engine?

It's like asking why your turbo exploded at 30psi, without telling it it's a T51....you let us assume it's stock, so we're also going to assume you're an idiot.

smokem31 Contributor

smokem31

Posted
Posted

i gave no knowledge about my engine because it is somewhat irrelevant to the question at hand.

if someone was asking why their turbo exploded at 30psi you would obviously need to know what turbo they have.

my question was simple, is it worse with more boost?

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