AFR going lean above 6800rpm on TII

yiug412 · June 29, 2011, 12:26:14 AM

Hi

Just installed my Re-amemiya redom ECU tuned with similar set up with my FC, aftermarket exhaust, more boost, aftermarket IC.

My set up relating to fuelling and boosting:
880cc secondary, 550cc Primary, SAFC, slightly larger turbo. FMIC.

Boosting from 2nd from 3000rpm, 0% setup on SAFC.
Nice 12.5 till 3800rpm then goes rich to 11\'s when the secondary jumps in. MAIN PROBLEM: it start leaning out to 13-14 AFR after 6800rpm. would this be my fuel pump maxing out in high rpm? or the air flow meter giving out false reading? at 7000rpm the air flow rate is approx 87%. would be great if someone has installed SAFC can give me some data to compare

Cheers

Louis

Brett · June 29, 2011, 05:51:06 AM

I would say fuel pump. Also, unless you have a hybrid or aftermarket turbo, the stock one will begin to tail off around 6800rpm IIRC.

TiddlesRX7 · June 29, 2011, 08:17:55 AM

I\'d say fuel pump also.

Have you got a link to the secondery injectors your running? Im thinking of going for 880cc ones now after I had my car mapped.

Prof · June 29, 2011, 08:57:57 AM

+3 on fuel pump - it\'s the most likely cause.

Any emissions stuff would not be working at those rpm\'s - so you can\'t blame that for altering the figures if you still had it attached.

What boost are you seeing - the stock MAP sensor tops out arond 13-14 psi (0.9 BAR) and won\'t alter fuelling after that, but to be honest I would not rely on it after 12 psi.

Also, if you\'ve gone with a larger turbo and still have the AFM in the intake, it\'s output will drop to 0 around 12 psi, leaving the ECU to work off fixed maps using the MAP sensor - if you have any headroom left on the injectors - I would up the duty on primary/secondary pairs if you can - and richen up the top end.

Depending on your power curve, you should be past the peak torque point up there, so the afr can be a little bit leaner - but 12+ is probably unwise..

bnaellis · June 29, 2011, 09:26:57 AM

wiring to the fuel pump tends to lose a few volts also. You could try rewiring bypassing the ignition switch you might find this will help also.

rgds
Brian

Prof · June 29, 2011, 10:39:42 AM

Quote from: bnaellis;772508wiring to the fuel pump tends to lose a few volts also. You could try rewiring bypassing the ignition switch you might find this will help also.

rgds
Brian

Brian\'s not joking about a couple of volts either - I did the rewire on mine, and with the stock pump the voltage went from 10.5 to 13.2 volts !

You need to measure the voltage with the pump on full - by wiring the yellow jumper in the car near the drivers shock tower, this makes the ECU switch out the fuel pump resistor and simulates full load condition running the pump at battery voltage

There\'s a good write up on the 1300cc.com site :

http://1300cc.com/howto/how2/rewire.htm

I used his method which keeps the existing fuel pump resistor in the circuit so it behaves as stock. If you put a walbro pump in, you will see higher voltages as well, as it uses less current for the same fuel flow.

yiug412 · June 29, 2011, 12:35:14 PM

Thanks for the advice guys

My fuel pump receiving 13.3V at idle so it had been rewired. I tuned up the SAFC to 25% now it drops a bit to high 13s. Which fuel pump would you recommend? And where in Uk would be best place to get them?

grinder · June 29, 2011, 01:15:22 PM

out of interest - how are you finding the safc , i have one in the garage and always wondered what it would be like to fit it

does it give you any nice information that the stock gauges doesnt ?

Prof · June 29, 2011, 01:22:54 PM

Quote from: yiug412;772544Thanks for the advice guys
My fuel pump receiving 13.3V at idle so it had been rewired. I tuned up the SAFC to 25% now it drops a bit to high 13s. Which fuel pump would you recommend? And where in Uk would be best place to get them?

I\'ve never had any problem with the walbro pump - but if you do get one - make sure it\'s got the mounting kit for series 5 not the series 4 pump layout (that one comes with a bit of hose and 2 clamps).

If you\'re confident with a soldering iron it\'s an easy fix, but I needed to run an extra ground wire to get the fuel gauging working.

Not sure who you\'d go to for one.

TiddlesRX7 · June 29, 2011, 03:22:07 PM

I\'ve just been quoted Â£72 delivered for a Walbro off a trusted Ebay shop (roadrallyrace I think they are called). I\'ll double check when I get home, Ebay is blocked at work.

TiddlesRX7 · June 29, 2011, 05:13:39 PM

http://myworld.ebay.co.uk/roadracerally?ssPageName=ADME:X:eRTM:GB:1181

These guys are the ones that were recommended to me by the guy who mapped my car.

B.Martin · June 30, 2011, 08:10:32 AM

Quote from: yiug412;772485Hi

Just installed my Re-amemiya redom ECU tuned with similar set up with my FC, aftermarket exhaust, more boost, aftermarket IC.

Off subject slightly - Did you get that Redom ecu that was on eBay? I was watching it but thought better off it as i don\'t even have the car yet :Giggle

Hope you get it all sorted anyway

yiug412 · June 30, 2011, 01:38:13 PM

Th SAFC allows me to fine tune my AFR with my redom ecu as mine is rich with 880 secondary. And i like the peak hold function which sometimes is pretty useful. Also it gets signal from knock sensor so u will always be on the check for knocking (altho it reads 0% even at 8000 rpm on mine but the sensor does give out reading to tapping with hammer)
Yes I got it off eBay

Thanks for the link