Hi All,

 

A bit like SRAEs problem I think...

 

I've noticed for some time that my power seems to go a bit flat when I floor it - my head goes back as the turbos kick in but power levels off when I give it some throttle.

 

After a 500 mile journey - trundling along at 70-80mph, I floored it a couple of times when almost home, nice as the turbos kicked in then massive drop in power - really noticeable - even the other half commented. Feathering the throttle allows much better acceleration than flooring it.

 

Apart from that I'm still getting some detonation with moderate acceleration in the higher gears - sounds like air flow sensor or fuel pressure to me - anyone any other thoughts?

 

Any one got a known good MAS I could borrow to test please?? Pretty please???

 

Thanks in advance

 

RobH

http://www.z32.org/html/maintenance.shtml

 

At the bottom of the page there is 'sensor diagnostics'. Checking through those should help.

Maybe when you floored it the knock sensor detected the detting and put you on safety boost. That would mean you would stay on it till you turned off the ignition and started it up again. Would explain big power loss.

 

Did you notice the cut in max boost on the guage?

 

Try Optimax or checking your ignition timing.

 

Sorry if this was already ruled out as too obvious

Not at all, all suggestions appreciated.

 

Been out in it this afternoon and it feels a lot better although still lacking any punch above 5000 rpm.

 

I've recently bypassed the det sensor as it tested bad. Also, using AVC-R which I can adjust to compensate for any boost leaks etc - boosted up to .81 bar yesterday but presume it was the engine holding back that prevented more.

 

Done some checks this afternoon. The air flow sensor was reading 1.2V approx while running but only 0.5V (which then drops by 0.01V per second approx) when warm and ignition off - anyone done this test and have any figures for a known good one?? From what I've read, 0.8V is normal for warm and not running (?)

 

Tried to examine the fuel pump/flow regulator etc but had difficulty locating it - are UK/Jap and US models very different? I'm pretty sure I found my pump under the hump in the boot behind the Drivers side speaker and the regulator next to the rear passenger side seat...didn't do any testing on either as I wasn't sure..

 

Any advice appreciated!

 

RobH

Some info here may help :- http://www.300zx.org.uk/techtom.htm

Rob,

Have you just changed your spark plugs by any chance? It sounds similar to a problem I had when I fitted UK spec plugs into my import. Subsequently there was a theory that it may have been the gap and the boost pressure was blowing the spark out under high acceleration.

....Geoff

Hey Rob!

 

I know of a certain car that's going no where at the mo, and you can borrow some bits to sort your woes out if you need to.

 

Ben.

Just had a thought on this - maybe the EGR valve is buggered? This would cause a boost leak and possibly quite bad running problems. There are 2 ways these can fail:

 

1) The vacuum diaphragm splits/cracks and allows a small(ish) vac/boost leak.

2) The valve jams open and allows boost to be bled off into the exhaust - under boost conditions the valve should be hard closed.

 

HTH

 

CheerZ,

 

Andy

Ben - nice one mate!! Could definately do with some temp replacements just to rule a few things out - especially the MAS as a quick and easy 'rule it out'.

 

Mr Duff - you could have a good point there, it does sound like my turbos are being 'bled off' into the exhaust - a bit of a whistle when I go on boost and a 'gush' when chnaging gear on boost. Problem is how do I remove the EGR - I understand it's a b*gger of a job.

 

I'm highly suspicious of the fuel pump pressure control unit - Mr Duff mentioned this in response to an earlier post. I get a tapping noise from it - not quite the 'buzz' that signifies a knackered unit but very supicious all the same - it also coincides with some light detonation when under moderate load....

 

Any advice/help gratefully received.

 

RobH

Erm, EGR removal is almost impossible in-car - at the very minimum its gearbox off - even then you may really struggle getting it out. Only a last resort really.

 

Fuel pump controller sounds like a good bet first - I replied to your other post as to where it is located ;)

 

CheerZ,

 

Andy