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Rb25 Neo Misfire Low Compression All 6?

Cyifly

By Cyifly,
in Engines & Forced Induction

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Cyifly Community Regular

Cyifly

Posted
Posted

Hey guys have an rb25 neo.

The problem is it won't idle, feels like its lost all power.

Misfiring like no tomorrow from word go.

It's a fully built motor adjustable cam gears VCT etc.

So far..

I've changed plugs changed coil packs.

Checked harness injectors etc still no luck.

Readings from compression test:

1 50

2 51

3 50

4 50

5 49

6 53

Could the timing have jumped out and cause such low compression ?

It's also running a 2 mil steel head gasket.

Simon-S14 Grand Master

Simon-S14

Posted
Posted

thats way too low.. does it go up when you do a warm test? i spose its hard to tell if it doesnt even run.

has it been like this since it was built? have the correct pistons etc been used to work out the CR?


Do a leak down test also

Cyifly Community Regular

Cyifly

Posted
  • Author
Posted

Literally got it off the dyno a week and a half ago didn't miss a bear then threw an intercooler pipe off the cold side of turbo then ever since then all over the place misfiring.

Never missed a beat previously.

Motor since build has only done 20,000 tops. Doesn't get molestered either always roll on power.

Cyifly Community Regular

Cyifly

Posted
  • Author
Posted

When car warms up it manages to hold idle.

Still missing and gutless as all hell when accelerating but can idle.

Tried posting photos of cam gears and alignment but won't allow me to through app ...

tranman Enthusiast

tranman

Posted
Posted

I second that a Leak Down test would be in order.

Low compression highlights a possible leak, whether it be the valves, pistons or headgasket etc.

I put my second hand engine through a leak down test at the workshop for assurance before purchasing. It's a quick affair, and relatively cheap.

Cyifly Community Regular

Cyifly

Posted
  • Author
Posted

Sorry guys been hectic at work will be doing it all on Saturday correct timing first tdc compression test theneak down and hope like hell compression returns..

Definitely will post results

  • 2 weeks later...
Cyifly Community Regular

Cyifly

Posted
  • Author
Posted

Yea it was freshly dyno'd as I had to fix turbo gasket. Just downloaded software for vipec and hooked in.

The tuned advanced way to far. About 6 degrees advanced basically the whole way very odd

  • 3 weeks later...
Cyifly Community Regular

Cyifly

Posted
  • Author
Posted

Sorry bout the late update so timing and everything's was fine.

So did a hit more hunting could not hear the click of the vct module. Found it had blown.

Replaced it and wow she's alive..

Positive things found out from jhh engineering and a few other people responsible for building this my compression is 110 which returned.

Put it back on the Dyno with a bit more boost and at 18 pound it made 518whp.

So now changing it to e85 and upgrading the supporting fuel mods.

Should be interesting.

Thank you so much to everyone's comments and suggestions.

Hopefully can create a log of my journey from unleaded to e85 (flex fuel)

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