Help Identify My Misfire Problem

[lwboosted]

my car is a r32 gtst type m 1992.

things i have done to fix the problem...

- clean AFM

- change fuel filter

- change O2 senser

- changed and re gapped plugs to 0.7

- cheacked coil packs.. no cracks but siliconed them up anyway...

this misfire is not the usual cough or flutter when you hit boost, this misfire happens when i am cruising at low revs, it is very random. and the whole car basically turns off for 1-4 seconds then runs again... sort of like the car stalls then role starts itself and runs again.. but smothly..??? i hope this is making sense...

could it be the ignitor box? because this controles all the coil packs? or a loose wire? i have no idea any help would be good..

thanks leigh

[juls33]

you could check

1. air flow meter on the way out

2. check the wiring to the o2 sensor isnt damaged

[lwboosted]

yeah i know the o2 sensor is fine.. what is the best way to find out if the afm is gone??

the car idols fine without a hint of a miss.. as i said it is very random when it happens, like it will happen 4-5 times in a row then be fine for another 15-20 mins of driving...

[juls33]

it only happens at a certain speed at low load , like carpark etc

?

[lwboosted]

nah all speeds, all gears but yeah under low load... it even happens under no load.. like coasting down gears..

[skylinegtts]

fuel pump?

[mattymagoo22]

with your engine idling give the wiring around the engine bay( injectors, igniter, etc etc) a good pull/wiggle and see if it plays up as it may have a bad connection somewhere and its playing up under the torque loading of the engine under acceleration

just a thought.

[lwboosted]

yeah thats a good idea.. i doubt its the fuel pump i have a bosch 040

[O.I.C Napster]

yeah thats a good idea.. i doubt its the fuel pump i have a bosch 040

Is there enough voltage to the pump???

[lwboosted]

i just hooked up the standard wires to it... but t has been like that for about a year.. wha should i do? run a relay?

[govich]

Try a different (known working) AFM. I've had a similar problem.

[R31Nismoid]

i just hooked up the standard wires to it... but t has been like that for about a year.. wha should i do? run a relay?

There is a link in FI Guide (sticky thread) about correctly wiring the pump

The stock loom generally is not upto the task.

So begin there.

After that, you need to mix-n-match. Swap stuff off cars you know are working and try it.

[juls33]

mine did exactly the same

just changed air flow meter

good as gold

[lwboosted]

ok guys thanks for all the help i will get onto those things and if the problem persists i will post again.. it doesnt bother me to much as i am puting a rb25 with r31Nismoids old gt30 in, in the next couple of months.

thanks leigh.

[R31Nismoid]

lol so many people have old gear of my now

[Birth]

Is there a way to test the AFM with-out swapping it out? Can it be done by an auto electrician?

[BHDave]

I had a similar problem 2 years ago, completely random miss but mine would happen at cruise, on boost, on idle whenever it felt like it really. It would happen maybe once every 5 minutes at worst, sometimes it wouldn't happen at all.

In the end i solved it in the same way you are planning to

But i tried (not in order);

afm swap

cas swap

ignitor swap

coil swap

ignition rewire

removal of emanage

plug swap

injector clean

injector swap

ecu swap

checked tps (probably should have swapped it)

rb25 engine loom and ecu swap (problem solved)

[limpus]

Sounds like a problem i had with my old silvia. The problem in my case was that there were 3 damaged wires going into my ecu which was shorting against one another. Maybe just have a look at the wires in that area. Its unlikely but worth a shot.