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yeah mate, lean idle issue - RB25DET

hardsteppa
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hardsteppa Grand Master

hardsteppa

Posted
Posted

so, car is a 1996 s2 R33, RB25DET engine, running a PFC and aftermarket fuel rail. The unused centre cap of the rail had a fine leak spraying fuel out so pulled it out and put a new cap/seal on, and black Toyota FIPG on the threads cos it's a bitch to pull out and i don't want it to leak ever again. Rail/injectors are just on 6 months old (1/2 length Bosch ev14 960cc injectors). Had a real problem finding o-rings in stock though so only found new o-rings for the top (fuel) end of the injectors, and re-used lower manifold-end o-rings, which were still flexible/compliant. Starting it up this morning after finishing the job last night -  no leak from the fitting, but now idling 18:1 + afr. Afr's go back to normal 14.7:1 range as soon as driving and up in the rpm range, it's just at idle, and is lumpy as a rotary too. I am thinking slight air leak through manifold-end o-rings on one or more injectors, enough to make it run lean, but any further thoughts or feedback would be appreciated.

Further info

- when coilpack connections are pulled off one at a time it becomes a definite misfire, so all cylinders are still firing, just not fully/normally.

- fuel pressure is still fine, 2.5bar at idle, changes under load/vac.

- ign timing is still fine and 15 deg (Had tuned up idle and timing just before i did this job, was idling bang on 800-830rpm where i want it, and 15 deg timing). 

- new throttle body gasket was fitted too. 

- Only issue before doing this was the slight fuel spray/leak, the car itself was running freakin fantastic, and pulling out/refitting the injectors and rail was all that was done - apart from removing/refit all the other shizz you need to, to get to the fuel system.

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https://www.sau.com.au/forums/topic/477888-yeah-mate-lean-idle-issue-rb25det/
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GTSBoy Grand Master

GTSBoy

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Posted (edited)
  On 23/07/2019 at 3:02 AM, hardsteppa said:

apart from removing/refit all the other shizz you need to, to get to the fuel system.

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Made a leak somewhere else? Could try the spray and pray with some carby cleaner. See if you can affect the idle.

Edited by GTSBoy
  • 2 years later...
Pattey21 Proficient

Pattey21

Posted
Posted
  On 23/07/2019 at 9:26 AM, hardsteppa said:

Yep disregard...man i am a 'tard sometimes, probably should have waited till i got home and had a proper look before posting. All sorted; gtsboy on the money again lol.

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I'm actually in the same boat right now. What did you find as the leak?

Pattey21 Proficient

Pattey21

Posted
Posted

Good memory. Im playing with mine as it's leak past the injector collars (Taarks top mount kit) on 5/6 but seemed to seal under fuel pressure pushing injectors down.

I pulled the rail out a bit to re-lube the o-rings bit I think the process made it worse and I'll need to replace the o-rings regardless.

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