N/A RB30 Miss/cough/flatspot off idle

[shaunington]

G'day fellas, as a few of you know I've got a VL in QLD that im bringing back to VIC, and ive just flown up to do some more work on it before it comes down to vic for roadworthy etc etc.

Fixed up a few niggling issues, but one that I haven't been able to fix since day 1 has me a bit stumped, I'm not huge with RB30 knowledge, so if any of you experienced lot can weigh in with some opinions that'd be great.

On to the problem!

So, the car starts up fine, has a bit of a lumpy/rough sounding idle (has a cam) and that's all well and good, but as soon as you go to feed on some throttle (either just revving or driving) from a standstill, at about 1000-1300RPM there is a real hesitation, and a splutter/cough, before it picks up and revs happily throughout the range.

I've changed distributor, leads, plugs, fuel filter (was grotty as), new hi-flow air filter, AFM, tried to adjust the AFM (but didn't notice any difference) all from good known-working spares, but the flat spot is definetly still there. If I feather the throttle and nanna it through that part of the range and then hammer it(straight to the floor), it's great, but any more than say 30% or so throttle off a standstill and it hesitates and splutters for a moment and then is alright.

Another thing to note is, The ECU has a chip (of some sort) It's got a 'Chip-Torque' sticker on it, and the original chip or memcal is in the glovebox, but that's all I know about that mod from the previous owner.

Hopefully I'm making sense, any other tips or places to look/things to change would be great

Cheers

[grazm]

If this happens when the vehicle is cold, then I would say that the Air Flow Meter is knackered. Mine is the same first thing until it warms up, then its OK.

[gonnaenodathat]

coil pack issue ? cracks or degradation inside ? (going by my rb25 skylines) they can crack and short on the block or when knackered they can miss ! i replaced mine with splitfire coil packs, not cheap but noticeable differance... but as i said, not familiar with the rb30 !