X16xe fuel cut off?

[st3vo]

Alright, just got opcom working on my laptop, showing no fault codes stored, but on the measuring blocks it shows the fuel cut off inactive/active in relation to the idle going upto 4000rpm then dropping back off to normal, and repeating over and over and over, it shows the cut off inactive as it the revs rise, then active when they start to drop, is this a problem with the fuel cut off? And if it is where abouts is it? I've got a new ICV on there too so i don't think its that thats causing the odd idle speeds, the TPS is showing 0 on what should be idle so thats ok too? Pretty stumped about the fuel cut off though any thoughts or suggestions (or anyone know where it is )

Cheers

St3vo

[GaryVaux]

No, from what im led to believe the fuel cuts when decelerating, so that sounds prefectly normal.

[st3vo]

Oh bumcheeks, so if thats working well, why the hell is the idle hittin 4000rpm then dropping to 850rpm and up and down, its more like a yo yo than a car at the moment!!!! I also noticed that its flipping between lean and rich on the air fuel mix while its doing it too, is that bad? I got the inlet and exhaust slightly skimmed to make sure they were flat before fitting them with all new gaskets and the stethoscope is showing no signs of air leaks anywhere, all vacuum hoses are siliconed round where they enter the rubber bends so i'm quite sure there's no leaks in the system, new clips and rubber hoses onto throttle body tested with soapy water and showing no leaks, new ICV, TPS is good, i've totally run out of ideas now!!!!!

[GaryVaux]

hhmm, i would have said an air leak, but you have ruled them out. Has the timing been upset since it was last running properly? I once had the exhaust cam pulley a tooth out on a c16xe and it gave odd idle and a flat spot.

[st3vo]

I have done a timing kit and water pump on it but they went on exactly the same as what came off, there isn't a flat spot at all, just odd idke, the engine itself pulls clean to 6500 in every gear, and i have just noticed now that if i hit it with a big stick around the throttle body area the idle slows back to almost normal..... lol, could that mean the throttle body is jamming? Strange though as i think that would show on the TPS values wouldn't it?

[GaryVaux]

you would think so, how is the throttle cable routed, may be getting stuck/be too tight. Other than that i would take the tb, icv, and tps off and check all are free/working

[st3vo]

i swapped engines on tuesday/wednesday, and while i had everything off i cleaned the inlet, TB in degreaser and a wire wheel, had it and the exhaust manifold skimmed slightly, then when i got them back cleaned it all again with brake cleaner, and before re installing everything, checked the butterfly in the TB was working well and sealing shut, checked the TPS while it was off that it spun smooth with no grinding or notchyness, it has a new ICV on it, the car is LHD too so the cable is pretty well straight out from the pedal to the throttle, dropped a tiny tiny bit of EP80/90 onto it to further lube the cable inside the outer, pedal movement is spot on, nearly broke me little finger when i let go of the throttle spindle and it closed the butterfly on me (must remember not to do that again..)

its almost like a switch when it does it, like on when it revs upto 4000, then off and it drops right down, really confusing!!!

edit: It did it on the old engine too (thought it might cure with the new ICV) checked all wiring too and all seems well