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yeah mate, lean idle issue - RB25DET

hardsteppa
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hardsteppa Grand Master

hardsteppa

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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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GTSBoy Grand Master

GTSBoy

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Posted (edited)
33 minutes ago, hardsteppa said:

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

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
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  • 2 years later...
Pattey21 Proficient

Pattey21

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On 23/07/2019 at 7:26 PM, 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.

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

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Pattey21 Proficient

Pattey21

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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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