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Rb25Det Running Badly All Of A Sudden - Cas?

ccpl

By ccpl,
in Engines & Forced Induction

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ccpl Apprentice

ccpl

Posted
Posted

Hi All,

I've had some recent issues with my series 1 R33 that has me thinking that the CAS is dying and needs to be replaced, however I'm looking for a second opinion before I go out and source a replacement.

It started running rough the other night on the highway randomly after driving for around 20 minutes. It was running low on fuel at the time, so as it runs on E85 I assumed it was possibly picking up some water/crud from the tank and limped it over to a mates house quickly. After filling it up with a jerry can of E85 about 30 minutes later, I started it up and gave it a rev and all was fine once again. I ended up driving it back home about 5 hours later and it didn't have any problems for the remainder of the drive (about 30 minutes).

Fast forward to yesterday and my old man takes it for a drive after its sat for a day or two and once again it runs fine for about 15 minutes then starts running really rough. I looked over it yesterday after its been sitting for about an hour and it's still running rough this time. I end up replacing the fuel filter just in case its clogged up and there is no change - fuel pressure at the rail is around 44psi which is spot on apparently and I cannot see any problems with the fuel system (has an E85 460lph Walbro installed). I move onto the spark plugs which appear to be fine and then check and replace the coil packs with known good spares to check that a coil hasn't died and it makes no difference (currently has ~2 month old yellow jackets). I then attempted to disconnect a plug for each cylinder to determine if there was a particular cylinder dropping but it doesn't seem to be any particular one. I also checked the ECU (Link G4+ plugin) which doesn't register any relevant error codes.

After another hour or so of checking lines, wiring, etc I start it back up and its now running worse than ever - barely idling and struggles to rev at all (feels like all the timing has been pulled).

Based on the above I assume its the CAS that's dying, however would love a second opinion/sanity check of the above!

TL;DR;

RB25DET running badly

Initially only happening after 10-15 mins of driving, now all the time

Have checked ECU, plugs, coil packs, fuel filter, fuel pressure

Assume CAS is dying and want a second opinion

Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted

Log your voltage with your ECU, see if the voltage drops as you drive in the higher rpm area.

I had a similar issue where my car would splutter and shit whenever it was warm.

Turned out my alterntor was cactus and voltage dropped to 12.2 volts after 4000rpm or so

89CAL Grand Master

89CAL

Posted
Posted

So you have the software for the link on a laptop? I would start by looking at everything you can on the link software wbile while its having the problem. In one of the top drop down menus there is 'view parameters' or something along those lines which has a heap of tabs with all the stats of the car. Start with that

Have you done simple things like pulling individual coilpack plugs out while running to see if one doesnt change the engine note.

You can idividually check injectors in the link software. I think in aux outputs - fuel there is an injector test option

The link software is great for testing outputs. Can check whats working (options for test pwm or test that just turns it on)

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

Depends...I replaced a CAS on an RB25DET which was running rough. When we got the CAS off it felt like a stuffed wheel bearing - turned roughly and sometimes caught almost solid.

  • 4 weeks later...
ccpl Apprentice

ccpl

Posted
  • Author
Posted

For anyone that cares it turned out to be the ignitor.

I bought a replacement ignitor from a parts shop that was supposed to be "tested in working condition", but it seems it was just as broken as the one I had on. Workshop put a brand new one on and it runs perfectly now.

  • Like 2
jay-rod Proficient

jay-rod

Posted
Posted

Also FYI

I had the exact same issues on my 34.

34s ingiter is built into the coilpacks.

My issue was related to my injectors being blocked from E85 when i change my engine with a different fuel tank, same symptons as you.

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