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Help! 2500 Rpm Bucking, Hunting And Stalling- Help!

GTST520

By GTST520,
in Engines & Forced Induction

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GTST520 Enthusiast

GTST520

Posted
Posted

Hi All,

I hope someone can help- Here's the deal.

FIRST JAP CAR EVER... so please understand, not a mechanically minded girl- (unlike my auto elec.) and I know nothing about this beauty except it used to drive good but now it's broken-ish.

Recently bought a 1991 R32 GTSt which was privately imported- not by me. To transfer into my name it needed to be seen by an import mechanic for RWC.

Since they have had it, they have done an arm full of things to it blah blah blah and all I know is it plays up regularly with us but has never done it with the Auto elec there.

We give her the symptoms and she has the car for a day or 2, charges us a couple hundred bucks for replacing this or that and within the next 24hrs the car starts doing the exact same thing.

Symptoms include:

  • First the car starts to cough whilst driving- just a little miss in the acceleration (feels like an air pocket)
  • Next there is a drop in power and revs so you have to gear down.
  • When you resume acceleration and it hits 2500 rpm the car starts bucking- all gears do this until you have to stop the car or stay below 2500 rpm.
  • Then whilst you're idling the engine is hunting through the 2000-3000 rpm range and then stalls.

What we know:

  • Car was running perfectly before current mechanic fiddled with it to make it 'roadworthy'.
  • Replaced old ECU because they didn't have the cord to connect up with their system.
  • Re- routed intercooler hoses to be 'stock' as old set up was running up and over the wrong way.
  • car has a tempremental immobiliser that sometimes activates whilst driving.
  • No error codes come up on ECU when we return it to the mechanic.

Sometimes turning the car off and waiting 5 mins, resolves the issues and she drives perfectly without missing a beat. This problem is regular but intermittant if that makes sense?

It can be driving fine then happen or it can happen and then drive fine.

I have read some stuff about this type of thing having to do with the MAFS? or a leak in the intercooler or possibly something else.

PLEASE HELP!

I just want to be able to drive her. :P

Trozzle Grand Master

Trozzle

Posted
Posted

Also could possibly be tired coilpacks....

Could be anything really though...AFM, coilpacks (playing up when warm), ECU, CAS etc etc. Unfortunately you'll need to locate someone with these kinds of parts to swap around for troubleshooting

paulr33 Grand Master

paulr33

Posted
Posted

the standard ECU has an RPM cut at 2500rpm if the AFM signal is not working

given your issues all revolve around 2500rpm i would say your AFM is damaged, the wiring is mangled or something is shorted out

Muff Rising Star

Muff

Posted
Posted

unplug afm.

if problem still there replace it.

either ur ecu isnt reading afm correctly (old version ecu or newer)

or ur afm is stuffed.

look at wiring going to computer loom could have a wire pulled out.

gl

Rolls Grand Master

Rolls

Posted
Posted (edited)

sounds like air flow meter, possibly dodgy connection, the fact you get no error codes is weird though, however I had a dead O2 sensor, read 0v all the time but it didn't ever show the error code in consult.

Edited by Rolls
crack Mentor

crack

Posted
Posted

bad afm. i had a f**ked one causing the exact same things. didn't get any error codes either. plenty to be had on ebay. $50.00 should be heaps. make sure it has a green sticker. can be also from a series 1 r33 gts-t. same as r32.

ebay.

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