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Rb25 Miss Fire Saga

Lacey

By Lacey,
in Engines & Forced Induction

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Lacey Rookie

Lacey

Posted
Posted

Okay so here goes, started my car one morning and it ran fine warming up but as soon as i took off the car started miss firing and running like sh*t. Thinking my plugs had finally given up i replaced them with bpr7es (they were NGK iridium ones gapped to 1.1) the new ones still miss fired. I've also replaced all my coil packs with ones that are known to work. Also cleaned the AAC valve and replaced the fuel filter thinking it was fuel related. The car still miss fires and i am out of ideas on what to test or look for next. Also reset the ecu and no change.

Car has full 3' exhaust, FMIC, Electronic boost controller set to 10 psi, Apexi pod filter.

Any ideas on what to check or look at next are much appreciated!

Daniel

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The Dan Grand Master

The Dan

Posted
Posted

Plug gaps should be 0.7-0.8mm. Iridiums are crap plugs too. Coppers are fine.

Gap the plugs down and I can almost guarantee the miss fire will go away.

If not, it's time for a set of split fires.

Not exactly true. Nissan never had a problem with them. Iridiums may be the cause of problems for a lot of people with modified skylines but that doesn't make them a crap plug.

Also to the OP: They should be BCPR6ES unless you are making over about 400-450hp at the wheels

The Mafia Grand Master

The Mafia

Posted
Posted

Not exactly true. Nissan never had a problem with them. Iridiums may be the cause of problems for a lot of people with modified skylines but that doesn't make them a crap plug.

Also to the OP: They should be BCPR6ES unless you are making over about 400-450hp at the wheels

You are right, but the reason I think they are a crap plug is because they are expensive and give no more value than copper plugs.

Lacey Rookie

Lacey

Posted
  • Author
Posted

I put a set of brand new set of BCPR6ES in this morning and still miss firing, the plugs i put in previously were gapped at 0.8mm

Anyone think dry solder joints in the air flow meter might cause this?

And it miss fires constantly, under acceleration and at idle.

Got the multimeter out for a couple hours this afternoon and couldn't find anything out of the ordinary.. Think it's almost time to send it to the Auto Lecky.

GTSBoy Grand Master

GTSBoy

Posted
Posted (edited)

Nah. If it is missing all the time it will be ignition or injector. You will need to go through and diagnose the lot. Start by pulling coil loom plugs to see if you can isolate which one is not going. Then try to work out if it is sparks or fuel. Remember, looms, connectors and pins all fail as well as the devices at the ends thereof.

Edited by GTSBoy
GTSBoy Grand Master

GTSBoy

Posted
Posted

That is why i put a whole set of coils in that are known to work and it's still missing, might pull my injectors out and flow them tomorrow at work if i get a chance.. Other than injectors though, there's not much else it can be.. right?

Hmmm. Perhaps read what I wrote about the loom and connectors etc again. It's not just devices that fail.

DC_GTST Experienced

DC_GTST

Posted
Posted

Had exact same issue, got car back late last night. Was the ignition module. Have splitfires and they were fine, block is only producing 2/3rd of rated power (built for) - compression all good. Checked vacuum hoses etc, cables etc. Thought it may have been the 040, but it primed for the 3-5 seconds once ignition on.

So would say check AFM, if not AFM get ignition module checked pending the plugs have been changed/gapped etc.

Lacey Rookie

Lacey

Posted
  • Author
Posted

I had the injectors flowed at my work this morning and one of them flowed almost nothing, the others were all below what they should have been as well.Changing the baskets and sonic bathing them monday, really hoping this is what was causing it!

Thanks for all the advice guys!

Daniel.

FordyR31 Mentor

FordyR31

Posted
Posted (edited)

Had exact same issue, got car back late last night. Was the ignition module. Have splitfires and they were fine, block is only producing 2/3rd of rated power (built for) - compression all good. Checked vacuum hoses etc, cables etc. Thought it may have been the 040, but it primed for the 3-5 seconds once ignition on.

So would say check AFM, if not AFM get ignition module checked pending the plugs have been changed/gapped etc.

Just to add. my 040 primed ok, car idled ok and would rev ok under no load but as soon as it was in gear and under the load is when it wasn't holding any presure so although you have found an issue with your injectors, if it doesn't fix it don't rule out the pump or pressure reg until u have had it all tested.

Edited by FordyR31
Lacey Rookie

Lacey

Posted
  • Author
Posted

Just to add. my 040 primed ok, car idled ok and would rev ok under no load but as soon as it was in gear and under the load is when it wasn't holding any presure so although you have found an issue with your injectors, if it doesn't fix it don't rule out the pump or pressure reg until u have had it all tested.

As soon as it's all back together i'll get the fuel pressure gauge on it and check pressure at idle and under load just to make sure. I'm just curious, How long did you have your 040 before it gave up like that? I'm thinking about upgrading to one eventually and just wondering about reliability?

Thanks again! Daniel.

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