Author Topic: RX7 FD3s plug-in build and install  (Read 28087 times)

Offline rob@vems.co.uk

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Re: RX7 FD3s plug-in build and install
« Reply #15 on: November 20, 2011, 11:45:48 am »
233 is not unexpected, its when you get into the 250's you start to wonder...
1.29 is so lean as to cause misfires...
0.7 is so rich as to cause misfires...

I have, in the past, put the sensor tip in a butane flame, holding it out above the flame shows a lean mix - theres more air than fuel.
Getting it in the rich blue part of the flame gives a rich mixture reading, as theres lots of unburnt butane at that part of the flame.
Its not really calibration but shows something about combustion.

Get your ignition spot on before you worry about fuel - if some of the combustion is occuring in the ports then you're not going to get a proper reading.

Offline DButters

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Re: RX7 FD3s plug-in build and install
« Reply #16 on: November 21, 2011, 07:07:15 pm »
OK so I checked the timing and it is 5 degrees off, not as bad as I suspected. I will change the TDC delay to 65 degrees to fix this (I wonder who verified the defaults in Vemstune for 2-rotor and what version 2-rotor they did it on???)
So my timing is not too bad, but my lambda is still toast - I either get full rich or full lean on the gauge. I free air calibrated while still in the exhaust pipe and it was showing ~20.4.
I will try the breathing on it trick (forgot about that, much safer than a blowtorch) and see if I get expected readings. Once I get the lambda working I can start tuning!

Offline rob@vems.co.uk

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Re: RX7 FD3s plug-in build and install
« Reply #17 on: November 22, 2011, 08:37:10 pm »
I used a butane lighter ;)

Offline DButters

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Re: RX7 FD3s plug-in build and install
« Reply #18 on: November 24, 2011, 09:02:49 pm »
Given the amount of fuel I have around at the moment I would be hesitant to even use a lighter :)

I am still not convinced on the timing though - initially I only checked one rotor. Now it appears the primary coil may have blown during cranking, looks like it got left on somehow. Even going back to the factory ECU I cant get it started. Going to check spark on each plug tonight and diagnose to see if I now need some more coils!

Offline DButters

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Re: RX7 FD3s plug-in build and install
« Reply #19 on: November 27, 2011, 06:13:15 pm »
So I was correct to not believe my initial timing setup. I was out by over 50 degrees! Now I am really unsure what type of rotary the defaults in VEMS were made for - definitely not FD.
Once I had that corrected the engine tone sounds a lot better, and I can get it to drive! The lambda readings also start showing relatively sane values while driving, though light throttle still jumps quickly into super lean regardless of VE settings.
I guess now it is time to tune and see what happens :)

Oh and I got a little external update too:



Offline DevInAz

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Re: RX7 FD3s plug-in build and install
« Reply #20 on: November 29, 2011, 02:15:05 am »
Wow that car looks great! can you post one of your idling logs? I'd like to take to peek.

Offline DButters

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Re: RX7 FD3s plug-in build and install
« Reply #21 on: January 04, 2012, 07:42:46 am »
Had a track day today - sadly before I could get it on the dyno, but still good fun!

Here is the last log of the day, and the config:

http://www.mediafire.com/?o3qud3cq3gx6zeo

http://www.mediafire.com/?3wa86hg11vat7we

If anyone cares to suggest some improvements I am all ears! I was very paranoid about detonation, and had convinced myself I could hear it, so turned the timing down a long way from other peoples configs I have seen. I really would like Knock back in the firmware, so I can confirm this.

One problem I can see is at the staged injector transition point - it suddenly gets a lot richer from then on, does anyone know how to fix this????

Offline jrussell

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Re: RX7 FD3s plug-in build and install
« Reply #22 on: January 05, 2012, 06:22:49 am »
On a Rotary, the only use of a knock sensor is to tell you that you just blew the engine. Sadly. It wasn't knock you heard unless you have no compression now, which is unlikely. Those engines simply don't tolerate knock. Octane is a good friend.

I haven't gotten the staged injection tuned well yet, but as soon as my exhaust gets completed, I'll put it on my dyno and give it some much needed love.
VEMS USA - Located in beautiful Burlington, Vermont
1988 RX7 Turbo

Offline DButters

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Re: RX7 FD3s plug-in build and install
« Reply #23 on: January 05, 2012, 08:18:45 am »
On a Rotary, the only use of a knock sensor is to tell you that you just blew the engine. Sadly. It wasn't knock you heard unless you have no compression now, which is unlikely. Those engines simply don't tolerate knock. Octane is a good friend.

I haven't gotten the staged injection tuned well yet, but as soon as my exhaust gets completed, I'll put it on my dyno and give it some much needed love.
I agree that knock sensors are mostly the ambulance at the bottom of the hill for apex seals, but at low boost and mid-low rpm it would still be nice to know if there was anything, particularly given the severe lack of rotary base timing maps for VEMS :)
Although I did start with over 2 times the fuel in than what I ended up with in that log, and as you can see it is still running well rich! I was also running race gas as I am paranoid about the premix diluting the effectiveness of the fuel, but we also get 98 octane pump gas here.

With regards to the staged injectors,  I am running 2 x 850 primary and 2 x850  secondary so the ratio is set at 100%. I guess I could lower the ratio to help even them out, but after looking at what other ECU's do i think the 80% throttle setting I took from your or the other rotary setup on the wiki is not matched with the actual opening of the secondary throttles, so I am going to test lowering this to match a more factory setting and see how that goes.

I also still have the issue with idle lambda values, they immediately   run the gauge past full rich. The idle is however very stable, and if I drop the VE any lower it immediately starts to misfire.