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Rb25det Intermittent Power Loss

BlackLine33

By BlackLine33,
in Engines & Forced Induction

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BlackLine33 Contributor

BlackLine33

Posted
Posted

Hi guys,

Have done some research on SAU and online but haven't come up with a definitive answer yet.

Car details: bog stock except turbo back exhaust, aftermarket bov, turbosmart boost tee @ 8 psi, brand new yellow jackets,

Milliseconds after hitting boost it feels like I've hit a brick wall (like foot is off the accelerator when it physically isn't). I'll try to accelerate again but instead it's an intermittent violent herky jerky motion as if I'm repeatedly on and off the accelerator. If I attempt to smoothly apply throttle without boost it may pick up again. Sometimes I will come to a stop and car will stall. While car is decelerating I can see the boost guage fluctuate according to the pressure I'm applying to the accelerator. Though not as pronounced, the engine sometimes will also cut out intermittently after a warm start on idle and stall...doesn't happen on a cold start. The other night also had trouble starting the engine from warm. It would crank fine but would only fire for a second then stall. Tried starting repeatedly and got it to idle fine after about half an hour of attempting.

Thought it could've been coilpacks so I got brand new ones along with plugs and dropped them in but same issue.

I've recently cleaned the AAC valve and AFM in the past month.

I've read that it could be the cam/crank angle sensor? Possible timing issue - RnR? Fuel cutting?

Any advice appreciated. Thanks.

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https://www.sau.com.au/forums/topic/464480-rb25det-intermittent-power-loss/
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GTSBoy Grand Master

GTSBoy

Posted
Posted

Coils were the obvious choice. Next most obvious is a dodgy solder point on the AFM. You might be able to fix that yourself. Have a search for howtos.

Faling CAS is possible, but doesn't often give the symptoms you report. Failing fuel pump could.

It is not R&R unless someone has advanced your CAS all the way.

BlackLine33 Contributor

BlackLine33

Posted
  • Author
Posted

Thanks for the responses. Last time I cleaned the AFM I had a look at the soldering on the joints and it seemed fine. Maybe the actual measuring element is playing up.

Will be trying another AFM. Is the R34 AFM interchangable with the S2 ECR33? The part number for the S2 ECR33 AFM is 22680-31U05 and the website says it is compatible with R34 as well (http://www.rhdjapan.com/nissan-oem-maf-mass-air-flow.html). However I'm looking to buy an AFM with the part number 22680-31U00 since it is cheaper..I'm thinking this is the R34 GTT one. Can anyone confirm before I hit the buy button?

Sklyn Grand Master

Sklyn

Posted
Posted

just to be sure, when you say 8psi, that is on an aftermarket boost gauge right? and not the stock gauge. Stock one is not psi.

If you cant boost properly how do you know its set at 8?

Was it all working fine then suddenly one day this started? or Did it gradually get worse over time?

what was the last thing you did before this happened?

  • Like 1
BlackLine33 Contributor

BlackLine33

Posted
  • Author
Posted

Yep 8psi as seen on an aftermarket boost gauge. I've since had to remove it due to it being a defect but when I had it on it did read 8 at WOT.

Prior to the issue the car was running fine and it read 8 psi.

Just happened suddenly. I remember first time I experienced it.. I was at a red light and gave it a decent launch and the car got all herky jerky on me. Didn't know what it was but I cleaned the afm with CRC but didn't resolve the issue. It has since gotten worse over time. I don't remember doing anything major prior to the start of the problem.

BlackLine33 Contributor

BlackLine33

Posted
  • Author
Posted

Also, just as a precaution I checked the coil packs and plugs. I found one of the coil packs didn't have a spring in it as seen through the hole which sits on the plug. I thought this was the problem. Spark plugs didn't look to have any abnormal wear. So I bought brand new YJs but issue still persists.

Sklyn Grand Master

Sklyn

Posted
Posted

The reason I went with YJs is for the post sale support.

I have only ever heard bad things about their post sale support, but if thats what you want.... Would be nice if you can report back with positive feedback on the YJ's eventually though.

try replacing the afm ( borrow before buy :) ), double check all piping and connections, remove boost T and just run wastgeate actuator pressure.

Just starting with the basics and cheap options. hope you find the problem soon.

BlackLine33 Contributor

BlackLine33

Posted
  • Author
Posted

Not too sure how this turned into a flaming thread.. Didn't ask for anyone's opinion on the coil packs I bought.

Anyway I got a working afm and it has seemed to fix the problem. Thanks to the guys who provided feedback about my problem.

  • Like 1
Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted

Hopefully when your coil packs die they're still in the warranty period so you get a brand new set (brand name clearly not mentioned, so vendors don't has a sads).

I had two coils die out of warranty, bought two new ones. Kept missing firing gave up, bought Splitfire coil packs and they're still running like a cut snake till this day, even with added dwell because I live life on the edge.

#keepdosing

  • Like 2
admS15 Grand Master

admS15

Posted
Posted

Hopefully when your coil packs die they're still in the warranty period so you get a brand new set (brand name clearly not mentioned, so vendors don't has a sads).

I had two coils die out of warranty, bought two new ones. Kept missing firing gave up, bought Splitfire coil packs and they're still running like a cut snake till this day, even with added dwell because I live life on the edge.

#keepdosing

Ffs u blokes r all missing the point here. Who gives a shit what brand coils he bought. A dose pipe will cure all misfire issues. That is my new recommendation for these type of threads. Should of bought a dose pipe.That is all.
Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted

Ffs u blokes r all missing the point here. Who gives a shit what brand coils he bought. A dose pipe will cure all misfire issues. That is my new recommendation for these type of threads. Should of bought a dose pipe.That is all.

Ahh very true, excuse my ignorance and lack of knowledge.

Yes a dose pipe will fix the issue and introduce good backfires on deceleration like a bawse!

Suuuuuutututu pop flame brap lol

  • Like 1

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