Rb25det neo breaking up in boost when warm

[zirbmail]

I have ordered new o2 sensor and coolant sensor, I get terrine fuel economy and a miss I'm idle so it's on its way out, and have ordered coolant temp sensor. I don't know for sure it's but the car never gets to operating temp on the dash dial. It sits a 8 o'clock sorta angle. What I read was that the coolant temp sensor can cause the huge regarding of the vct and running rich because it thinks the engine may be over hearing as sorta protective mode. I had intermittent check engine light when engine would ping hasn't pinged since new coil packs however. So from what I hear it is pre ignition will update once I install the new sensors holding for the best

[Ben C34]

Yeah ok. 

Let us know how you go

[Ryno34]

Hey, sorry to bump an old topic but I didn't want to create a new one as this is very similar to the issue i'm having.

Curious if your repairs sorted out your issue? I've replaced coils, plugs, soldered the MAF and fixed a vacuum leak but my car still doesnt like revving past 5k once its hot. Doesnt matter what gear, can even be neutral. Just breaks up like crazy

[wildeagle44]

Check for boost leaks, test your coolant sensor, what fuel pump do you have?

[Ryno34]

It reaches full boost well below 4k(got the restrictor bypassed) and holds fine until 5k. It also does it even if i just use partial throttle, so I dont think fuel or boost leak is the issue. Its running the stock original fuel pump but I can smell lots of fuel when It does it in neutral.

 

i'm wondering if my MAF just isnt any good. Or for some reason its not getting sufficient spark. I'll have to re-check my plugs and maybe swap a known good MAF. It just started all of a sudden. It ran mint up until a few weeks ago.

 

Edit: i'll check out the ECT sensor. My gauge reads fine and dandy as always but ya never know!

Edited August 24, 2018 by Ryno34

[zirbmail]

Coilpacks man... trust

[Ryno34]

I know that was my first thought too thats why the first thing I did was buy some yellowjacket coils and an OEM harness(had them on my R32 and they worked great). But it didnt make a difference

[Leroy Peterson]

Theres a reason why everyone recommends splitfires, yellowjackets do die.

[TaylorS]

@zirbmail hey mate sorry to bring back this old thread but did you end up fixing the issue? If so what ended up fixing it?

Thank you

[Ryno34]

Hey man, nope still doing it lol

 

coils, plugs, maf all good. Gonna go towards crank sensor and timing next

[TaylorS]

10 minutes ago, Ryno34 said:

Hey man, nope still doing it lol

 

coils, plugs, maf all good. Gonna go towards crank sensor and timing next

Thanks mate. Im having a weird issue too. Does your car run perfect when it is cold?

[Ryno34]

It seems fine in all weather until it gets to operating temp. Even once warm it still idles and drives fine. It’s just when I try to put any power down above 4k rpm it sputters and pops like crazy. It’s frustrating not being able to use the fun half of the rev range haha

 

Edit: It also does it if I bring the revs up slowly, and does it in neutral. Boost is good until 4k. Then it obviously starts dropping as the engine starts to misfire.

I tried pushing to redline the one time and it just wouldnt make it past 5500. The cloud of smoke behind the car was rediculous haha so its getting fuel. It holds max boost until it starts to misfire so I can only assume its not a boost issue(maybe i’m wrong?).

 

i dunno. Cars....

Edited October 31, 2018 by Ryno34

[TaylorS]

21 minutes ago, Ryno34 said:

It seems fine in all weather until it gets to operating temp. Even once warm it still idles and drives fine. It’s just when I try to put any power down above 4k rpm it sputters and pops like crazy. It’s frustrating not being able to use the fun half of the rev range haha

That sounds just like the problem i am javing mate.  Mine runs prefect when cold and as soon as it gets to op temp the boost wont kick in till about 3k rpm and then after 4k rpm it pops and cuts in and out. 

I have tried new spitfire coils and plugs gapped to 0.8mm, manual boost controller and redoing vac lines and its still doing it

[GTSBoy]

No-one ever thinks of the fuel pressure.

[Ryno34]

Could be fuel related. But it seems odd that it would be fine (did a 7krpm pull) without issue when it was just below its normal operating temp on the gauge(I know, I know, just wanted to test).

 

i also find if I sit in traffic for a while on a hot day, the rpm at which it starts acting up drops significantly. Like the one day I was in stop and go and it was doing it at around 3000rpm.  Almost like something is getting heaksoaked. It feels like weak soark/coils but i’ve tried two sets of coils and plugs lol

[Ryno34]

So small update on mine. Yesterday it started misfiring while idling. I narrowed it to cyl. 5. Swapped coils and it stayed missing on cyl. 5. The plot thickens!

[niZmO_Man]

LS1 time

[Ryno34]

Hey just updating for anyone that might have the same issue. Mine ended up being the CAS. It eventually got bad enough the car wouldnt even run so I substituted a friends CAS and it runs perfectly