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Rb25 Neo Refuses To Start - Full List Of Everything Tried/tested - Halp

Plainy

By Plainy,
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Plainy Apprentice

Plainy

Posted
Posted

Hi all, I'm a long time lurker, very rare poster...

So I have an RB25 Neo from an R34 that has been recently shoved into my GQ Patrol.

Now three weeks ago I hooked up the ECU (factory) for the first time, turned the key, and fired it up straight away. Idle was perfect, pressures and temperatures were A-OK (read from a full suite of gauges) and everything seemed dandy. I didn't have any brakes as I reversed the lines on my vacuum tank, but I sorted that out and everything was great.

I don't touch the car for 6 days after this, and six days later, the engine refuses to start. It will sit there and turn the starter over to it's heart's content, but the motor will not kick over. I need to stress that I DID NOT TOUCH THE CAR AT ALL as people straight away asked what I changed, and I tell them I literally did not even open a door on the car, let alone fiddle with anything.

So essentially, the car was running fine one week, and not running the next, without any screw ups from myself.

So here is a list of things I have tried and tested, and parts used/replaced:

Timing/Compression:

  • Timing belt was changed and timing was checked and double checked to conform to factory timing, as per replacement procedure.
  • The fact that the car purred like a kitten one week, and then refused to start the next, puts timing out of the equation for mind. If the timing was out enough to prevent the car from starting, it wouldn't have run the week before.
  • While compression hasn't been tested, it is obvious compression is there. You can't just drop compression in one week, can you? When the car was running, it idled beautifully.

Fuel:

  • Obviously checked fuel pressure between the return end of the rail and the regulator. 3 bar A-OK.
  • Removed the return line, and checked for fuel flow, of which was there was plenty.
  • The fuel itself was not stale as it would be pretty noticeable if it was.
  • Checked for injector pulse using an injector light, and each injector is doing its job.
  • Injectors are factory top feeds, and all 6 were cleaned and flow tested before use
  • Regulator is brand new 3 BAR Bosch regulator.

Spark:

  • Despite having spark the previous week, checked spark by pulling the coil packs, placing spark plugs back in, grounding them, and then turning the CAS by hand with IGN on. Each spark plug was sparking as per.
  • To be sure, replaced spark plugs. All tested and working fine.
  • Coil packs are brand new Yellow Jackets. Can't imagine why they would be malfunctioning, but I haven't replaced them with stock ones yet to troubleshoot.
  • CAS is used, one of the sensors I haven't replaced yet...

Air:

  • Pulled the MAF sensor, to see if it would start in limp mode, to no avail. MAF sensor is brand new OEM
  • Air is coming through 4" snorkel into custom airbox with LS1 panel filter
  • Running standard turbo - with 3" intercooler piping going through tube and fin front mount
  • Using Plazmamann intake with matching throttle body and brand new OEM TPS

Power/wiring:

  • Battery is brand new Full river 600CCA battery - voltage is 12.5V with IGN on
  • Wiring loom is brand new from Wiring Specialties in the US. Every factory sensor is plugged in with new connectors and all

Now here is the weird thing, if I pump the throttle a bit, I can actually get the car to start. But it is lumpy as hell, and I can only maintain it if I bounce the throttle. A whole bunch of smoke pours out the back reeking of fuel. Soon as i get off the throttle, it dies. How did this happen in a week without touching the car? What is going on here?

So short of replacing CAS and ECU, I'm just about out of options and ideas. I don't understand how a car can go from running perfect one week, to not running the next, without touching it at all....

If anyone could help me, you would make my life. I've dropped a tonne of cash into this beast and I'm itching to get it back onto the tracks. But for some reason it's just not playing the game.

Thanks in advance,

Plainy

Ben C34 Grand Master

Ben C34

Posted
Posted (edited)

Could be leaky injector has flooded the engine.

Seeing as you can get it to start I'd give it some decent revs and see if it clears up, otherwise I would be either cleaning or replacing the injectors. Running mega rich fouls plugs quickly , so that could also be playing a part.

Edited by Ben C34
zoomzoom Mentor

zoomzoom

Posted
Posted

When you say you read a suite of gauges, do you mean aftermarket ones you've installed?

If so, then you need to check the ECU's sensor values via a consult cable. Eg, if the coolant temp was reading something anomalous like -15 degrees, it would run a very rich cranking and post start enrichment. It would be very hard to start and it would blow lots of soot. Purely a guess though...that's why you need to see what values the ECU is reading.

Plainy Apprentice

Plainy

Posted
  • Author
Posted (edited)

@Ben - I'll pull the rail and see if that might be the case...

@John - Aftermarkets gauges. Boost, EGT, water temp, oil temp, oil pressure etc. I did check the factory ECU values with a consultBT and water temp was reading 24 degrees, MAF voltages was put 0.3V.... I'll have another look at the values though.

Edited by Plainy

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