Ignition or fuel?

[jetspin_vn]

Anyone else had a problem with a chronic miss when the engine is hot, under acceleration that all but goes away above about 2400rpm?

It's like I have lose heaps of bottom end power, you can hear a cylinder missing. When it gets above 2400rpm or so, it comes right. Its a pain the the arse because I do shitloads of driving every day, and having to keep the rev's high is hurting the fuel bill a tad. I don't have anywhere near the time I used to so diagnosing these things always becomes a weekend job.

I doubt its ignition, unless its the CAS. It and the condensor are the only bits I have not replaced. Everything else from the coil right through to the plugs are less than 20,000km old. It's always had a tiny miss on takeoff, but never this bad. I have a sneaking suspicion it could be an injector, but of course I have no way yet to prove it without either changing all 6 of them, or somehow isolating the bad cylinder and replacing the single offending injector.

I'll get to the bottom of it, of this I have no doubt. But if anyone else has had anything similar happen let me know what the cause was, any time/money that can be saved will be wisley invested in drinking

Mike


EDIT: I should add, the ECU is not giving a fault code. Just system pass - this is the cause of my injector theory.

 

[Bax]

Well the air flow meter accounts for everything below 2000rpm.. You may want to swap it with somebodies for a while.

Apart from that my CAS was on its way to the pearly gates and was showing huge misses and copious amounts of spluttering, usually went away when given a stab but sometimes would come back on twice as hard. CAS didn't show up on the faults because it was still 'there' it just wasn't working the way it was meant to.

I say afm. But as for the fuel or ignition, rip off a lead, hold it there with a stick or something near a bolt, or just rest it if you can.. Start it up, see if its a consistent spark at idle.. Timing light would do that for you if you've got one handy, clip it over the plug and watch the strobe to see how consistent the pulse is compared to each cylinder.

Best of luck

 

[jetspin_vn]

Way ahead of you bex.

Forgot to mention it, but I stuck my timing light on each lead, all appeared well in that department. The AFM is less that a year old, so if thats it I will be mighty pissed.

I had a bit of a chat to Jake last night, and we determined the best course of action between us. I am gonna throw a new CAS at it ASAP (prob next week) to see if that helps. Otherwise, its going to be a weekend of tough diagnosis!!

Mike.

 

[Bax]

Fair enough, just doesn't sound like CAS, especially with the spark still seeming the same.

Maybe its a weak spark though? or faulty fuel regulator? I'm outta idea's

 

[jetspin_vn]

Fuel reg was another suggestion, but then im pretty sure it would happen all the time.