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Rb30Det Refusing To Run Smoothly!

Nostalgic R31
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Nostalgic R31 Rookie

Nostalgic R31

Posted
Posted

Hey guys

I've finally dropped my rb30det into my r31.

Engine is a bog stock rb30 bottom end with a recon rb25 head with vct welded up.

Engine was dropped into the car with a to4z, 1600cc injectors, Freddy plenum and Nistjne running E85.

Now the car starts and runs. Started almost straight away when I fired it up and idled there.

It idles very lumpy and rough. I put this down to the old tune on the nistune

I have since taken the car to the tuner, who put a base tune on it but couldn't go any further because it revs very rough. Like a constant misfire.

So. I've changed the throttle body, replaced injectors, changed from stock coils to ls2 coils, changed afm (z32 to r35) made a new coil pack harness and made a new injector harness to try and fix the issue but no luck.

Now I'm here left scratching my head wondering why this thing just doesn't want to run properly?

It has fuel on all 6, and it also has spark.

Makes no sense as to why it's misfiring?

The engine wants to run, but just seems like one cylinder doesn't want to play. It starts with a little help of the accelerator, then idles away very rough, then if you rev it it'll roughly rev up. But it doesn't hesitate or cough or splutter. Just very rough.

I'm hoping someone out there with more knowledge then my would be able to help me with this very frustrating issue

Cheers guys

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https://www.sau.com.au/forums/topic/445232-rb30det-refusing-to-run-smoothly/
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Ben C34 Grand Master

Ben C34

Posted
Posted

Have you narrowed it to a cylinder by unplugging injectors or looking at spark plugs?

If it's a random occurrence I would be checking cam timing.

You will have to adjust the dwell to get the most out of those coils. On stock dwell mine missed over approx 14psi with ls coils. Won't cause amiss otherwise though.

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

Key to solving problems is to change one thing at a time. Is the ECU set up right for the new injectors, coils? Should have kept the VCT. Have you done a compression test and/or leakdown test? Have you tried disconnecting one cylinder at a time to see if you can isolate the problem to one cylinder? Double checked the valve timing?

Nostalgic R31 Rookie

Nostalgic R31

Posted
  • Author
Posted

I have unplugged the coils and injectors while the car is running. Cylinder one make no difference when unplugged, but all the rest do.

Took out the coil and injector from cylinder one and swapped them to cylinder 2. Still missing cylinder one.

Now here's where it gets weird.

Take injector out of rail and then manually turn cas by hand, and she fires. Take out coil and spin cas, it also fires.

Test all plugs with multimeter and it has all the right values.

So, why no cylinder one?

Compression test is super low. 100psi exact on all 6

Nostalgic R31 Rookie

Nostalgic R31

Posted
  • Author
Posted

I have swapped over to another set if injectors, so I hope I'm not that unlucky of having 2 bad injectors haha

It is running insanely rich.

You can see fuel spitting out the exhaust.

No, I don't have access to a leak down tester.

Cheers Ben, I'll double check the timing and make sure it's all good

r33_racer Grand Master

r33_racer

Posted
Posted

Its possible you have a dud plug. Have you tried just swapping a plug to another cylinder or putting a new plug in number 1?

I have seen plugs spark when tested outside engine but don't fire properly when installed. Considering a plug is worth about 4-5 bucks its an easy and cheap test.

Nostalgic R31 Rookie

Nostalgic R31

Posted
  • Author
Posted

I'm in perth. The only place I have called who said they will touch it is PZP in Wangara.

Every other place pretty much said "Z32 ecu on a RB30 with E85? Come back with a Power FC"

I have gone through 3 sets of plugs hoping that was the issue. But made no difference. I've also gapped the plugs at different levels to see if that helped.

I tried a noid light and spark tester to see if the coil and injector were firing together. Now I can obviously only test one cylinder at a time but it looked like the injector and coil are firing when they should.

Double checked mechanical timing. It's spot on.

Tried adjusting the cas to see if ignition timing was off, and it made no difference.

I performed countless compression tests, while the readings are low, they are all within 5 psi of each other.

The injectors are 1600cc top feeds.

And I haven't tried new clips, but the noid light shows it working, and also if I put a spare injector on the clip I can feel it clicking in my hand when it should be firing.

I have narrowed it down to cylinder 1 and 6 that are not working. I can take the plugs off both this injecotors while running and it makes no difference.

This really has me confused

Cheers guys for the help so far though!

Nostalgic R31 Rookie

Nostalgic R31

Posted
  • Author
Posted

I'm in perth. The only place I have called who said they will touch it is PZP in Wangara.

Every other place pretty much said "Z32 ecu on a RB30 with E85? Come back with a Power FC"

I have gone through 3 sets of plugs hoping that was the issue. But made no difference. I've also gapped the plugs at different levels to see if that helped.

I tried a noid light and spark tester to see if the coil and injector were firing together. Now I can obviously only test one cylinder at a time but it looked like the injector and coil are firing when they should.

Double checked mechanical timing. It's spot on.

Tried adjusting the cas to see if ignition timing was off, and it made no difference.

I performed countless compression tests, while the readings are low, they are all within 5 psi of each other.

The injectors are 1600cc top feeds.

And I haven't tried new clips, but the noid light shows it working, and also if I put a spare injector on the clip I can feel it clicking in my hand when it should be firing.

I have narrowed it down to cylinder 1 and 6 that are not working. I can take the plugs off both this injecotors while running and it makes no difference.

This really has me confused

Cheers guys for the help so far though!

Nostalgic R31 Rookie

Nostalgic R31

Posted
  • Author
Posted

It has been tuned for the injectors, but I did the coil conversion afterwards, as I thought the old coils might of been the issue.

I ran it today on a stock ecu to see what would happen and it ran exactly the same too

Might re do the wiring for the 3rd time and see if that helps

Badgaz Experienced

Badgaz

Posted
Posted (edited)

just a thought...but have you check your tps is showing between 0.4 and 0.5 volts when throttle is closed i.e at idle? what idle air control are you running on it? factory AAC? was the nistune actually setup for the injectors? - edit realized this has already been asked by kiwirs4t

Edited by Badgaz

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