MA61 5ME not smooth over 4000RPM. sounds like limiter bashing?

[RyleyMA61]

fuel economy seems good by your figures - definately sounds like ignition breaking down though?

[CrUZida]

Side question here, are plastic filters rated for EFI pressure ? (40psi as opposed to 4psi).
I've never had a plastic filter on any of my cars (and I've had lots of 80's EFI cars).

[patrickleslie]

Side question here, are plastic filters rated for EFI pressure ? (40psi as opposed to 4psi).
I've never had a plastic filter on any of my cars (and I've had lots of 80's EFI cars).

http://www.rycofilters.com.au/catalo...ies//part/Z195
That's the listed stock replacement. It's metal...you might be onto something there? I do actually have one lying around somewhere but the hoses are not stock and will not bolt up to it.

EDIT: I'm on the phone to Ryco right now, going to check the flow rates of the metal one and the plastic one.
EDIT2: They don't know and are calling me back once they check with the engineer.

[patrickleslie]

Any and all Ryco plastic filters have a maximum flow rate of 60L/H. I was also told that the two particular filters that were and are on the car are almost definitely less than this maximum value.
The Z195 metal filter has a flow rate of 90L/H 150psi

Cruzida I reckon you might have nailed it!

[crowncustom]

No plastic filter is rated for EFI.Its a wonder it didn't explode.All EFI filters are steel to accommodate the high pressures the system produces.
Cheers Brett.

[patrickleslie]

I've sourced a metal filter with appropriate pressure rating and barbs at each end so it will fit onto the cut hoses. I think it's out of a Commodore?

Anyway, didn't seem to make a difference to the rev limiting problem after a quick drive

[mattysshop]

Z200 i have used on pretty much anything, cheap & available anywhere, just a plain 8mm in and out straight.

not good that it didn't fix anything.. Broken valve spring?

[patrickleslie]

So...
This? http://www.ebay.com.au/itm/FUEL-PUMP...item1e7f3fd70e
Or this? http://www.ebay.com.au/itm/Genuine-W...item27d12b7eec

Would a stupidly uprated pump blow out the FPR?
And are the Walbros actually as loud as i keep reading online?

[CrUZida]

Walbro's are only loud when they get hot and you are low on fuel.
Other than that they are a lot quieter than Bosch 040's.

[allencr]

If you ease your foot down and push gently through the 5000rpm band it doesn't do it as badly, if at all...

So it does rev to redline, just not when you want it to, and it it does it under a load(3rd or 4th)?? If it does, then it isn't a fuel supply problem. If it revs without load, when it needs much less fuel, then it does have a restricted fuel problem.

[patrickleslie]

Cruzida: I've got no idea what a Bosch sounds like lol Assuming the other than that case, how about compared to stock pump? A little louder? Twice as loud? 10 times as loud? Is it 'annoying' when driving?

Allencr: Apart from one single time where I hit 5900rpm in 4th on a VERY long gradual run up I have never knowingly redlined (6000rpm) the car under load because it just won't haha Average limit is around 4500rpm. It will hit the 'limiter' in 1st, 2nd, 3rd and 4th any and all days of the week. I can't say for 5th, that'd be a bit too fast for my liking on public roads. I can't ever recall free-rev redlining the car while stationary. That seems a silly thing to do to a car you're trying to take care of so yeah...I'll have a go and report back tomorrow

[allencr]

Fuel demands under a load in 1st @ 4500 and 3rd @4500 are very different, and to me, that proves there isn't a fuel supply problem.

[patrickleslie]

It could be 3800 in 1st, then 5200 in 2nd, and then 4800 in 3rd. Or 4500 1st, 4000 2nd, 5200 3rd. Or it could be anything else for that matter. It's not a bible truth 4500 limit all the time, every time, for every successive gear change. That's just the average spot where it does happen overall.

If not a fuel supply problem, then what? I've checked all the electrics and that's all okay. Something mechanical maybe?

[patrickleslie]

Just did that little test. Cold start, let the car idle and warm up to normal temp in the drive way, and rev. It was fine. Redline is at 6000rpm. I went to 7000rpm and the engine showed no sign of hesitation or 'limiting', so I stopped there. Did this a couple of times and it was the same, no limiting problem

[patrickleslie]

Thread revival!

High RPM/load breakdown is normally caused by shitty leads/plugs/dizzy cap/rotor, or maybe a blocked fuel filter.
Start there.

Plugs were changed at the initial service it had after i bought the car, wouldn't even be 10,000km old yet...honestly can't see these being the problem but it wouldn't hurt to check i guess!

So the other day spark plugs were on a really sweet special at my local so for the hell of it I looked up the listing on the MA61 Part Number thread as BPR6EY, I also confirmed this in an online TSRM, and then bought a set intending for them to sit in the shed for ages just in case for some horrible reason they stopped making this part spark plug or whatever.

For shits and giggles I decided I would also check these spark plugs again since quite a few people suggested it the last time. By now these ones have done maybe 15,000km at the very most.

Two things I noticed this time.

1) They are so white and crusty on the tips and have decay and uneven gaps, plus the ceramics look ehhh...That's fairly normal right? Right fellas? Yeah? :/

Not sure why they look like this after 15,000km, or even this change since I checked them last in October but they do...overtaxing them because they're the wrong plug? poor mixture? oil leak and burn? idk whatever. I'm not sure this is the cause because the hesitation was happening before and after these plugs went in new the first time.

2) These are BPR6ES plugs, not BPR63Y. I'm not sure what the electrical difference is but there is a definite visual difference in the nodes. If this was the reason then it sucks because at the time of buying them I was fairly new to the car and just bought the ones listed on the catalogue at the shop without a second thought.

So I replaced them again with my new on-sale plugs and it hasn't hesitated since!