flyrotary@lancaironline.net Mailing List Archive

Hi David,

Rail pressure could not be too high or richening the mix would make it worse. 99 PSI at the injectors and the engine would stop running so I think that yoiu are correct about the sender, on the other hand something must have caused the sensor to fail like that - it is out of calibration not an open ciruit so it is more likely that it saw more fule pressure then it could handle and the housing bowed or something like that.

I think that your logic is pretty sound, I would rule out the same things that you have.

Turning to full rich increases the RPM slightly but does not make it normal.

This could mean that it is too lean, could also mean that you have a plug failing, a denser fuel air mix is easier to ignite. However you covered that below. Probably too lean. Fuel pressure makes a big difference to injector quantity. I'll put my money on your fuel pressure regulator and let it ride :-)

Occurs on controller A or B.

So it is probably not the map sensor

No change with disabling leading or trailing plugs.

I guess it is not a plug

BTW, the new turbo sounds awesome! :-) with that nice whurr that I never heard with the stock turbo.

Know what you mean I have a tube header and a 96/60 T04 in my 90 Coupe Quattro :-)))

My current thoughts about cause are:

1) Timing: I advanced the timing a while back when I went N.A. and I seem to recall I set the timing retard to occur around 30". But a little bit of timing retard shouldn't hurt that much. Maybe the advance I gave it was too much and I am detonating?

Not at 35"

2) The Evans coolant really cant keep the metal surfaces cool because it doesn't vaporize and I am getting pre-ignition. Unlikely because the race car guys don't report the problem and they are putting out much more h.p.

I doubt it

3) Fuel - something... maybe a sticking injector. Is it harder for the injector to open when the fuel pressure is higher?

Injector should be seeing the same relative pressure.

4) SAG - but that is a lot more than typical SAG and the plugs are only 20 hrs old.

Hmm, SAG is a unknow for me...

5) ??? The answer probably lies in that list, but it all seems so unlikely...

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On Behalf Of David Leonard
Sent: Thursday, June 09, 2005 12:52 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Very strange problem after installing new turbo

On 6/8/05, Ian Dewhirst <ianddsl@magma.ca> wrote:

Hi David,

Are you using a fuel pressure regulator that regulates fuel pressure relative to manifold pressure? Tou would have a hose from the FPR to the manifold. Your fuel pressure indicated should rise at the same rate that boost pressure rises. If your normal fuel pressure is 40 psi it should be 50 psi at 10 psi boost. You probably know this already, just trying to help.

-- Ian

Ian, yes I have a manifold referenced fuel pressure regulator.

But I like the way you think. :-)

Actually that is something else that has been acting funny, and may be related. My fuel pressure is going up much faster than it should. Idle is 32 PSI, but by about 30" it is showing 99 PSI (max for instrument). I spent several days on that one, and eventually figured out that the sensor is not right - fuel flow (which is dependant on pressure) does not change, and if the pressure really ever reaches 60psi the engine will not run well. Waiting on a new sensor.

--
Dave Leonard
Turbo Rotary RV-6 N4VY
http://members.aol.com/_ht_a/rotaryroster/index.html
http://members.aol.com/vp4skydoc/index.html