4A-GE with 264º HKS Camshafts running very rich

[apardal]

Hi guys!

I've recently installed a AFR meter to try to understand how my 4A-GE is in terms of fuel efficiency.

My setup is the following.

- Stock bottom end
- HKS Camshafts 264º/264º
- Shaved head (0,5 mm)
- TRD head gasket (0,5 mm)
- Port & Polish (with 3 angle valve job)
- Bronze valve guide bosses
- Ignition Timing 10º BTDC
- Both camshafts at 110º BTDC and ATDC
- Stock fuel pressure regulator
- Stock injectors (200 cc's)

The AFR meter gave me the following readings:

1st attempt:

Idle at 1000 rpm - A/F 11,0
Light accel - A/F 12.8
WOT at 3rd and 4th gear 7800 rpm - A/F 11.4

2nd attempt (after correcting the CO to a leaner position while idling):

Idle at 1000 rpm - A/F 14.7
Light accel - A/F 13.5
WOT at 3rd and 4th gear 7800 rpm - A/F 11.5

I've also done a compression test which gave me the following values.

Cylinder / Compression (Kgcm2)

1 / 11.5
2 / 12.2
3 / 12.3
4 / 12.6


I have several options.

1st - try different injectors (maybe 182 cc's dark grey injectors)
2nd - try a fuel pressure regulator, lowering the pressure.
3rd - spend a lot of money in a piggy back system

Say what you think

Thank you

[Rasteirinho]

Hi André,

Can't you adjust the CO to an even leaner position because at idle and with light load you can run with lean mixtures (above 16).

You can also try to adjust the timming in order to achieve a more complete combustion.

If your injection system runs well with OEM camshafts it does't makes much sense that it would run richer with more wild ones.
Normally it's the the inverse that happens.

For example, in my Pug 106 GTi when i fitted wild cams (280º) i had to fit a fuel pressure regulator in order to increase the pressure to avoid melting the pistons due to lean mixtures.
After some time, i fitted an upgraded ECU and so i decreased the fuel pressure again to standard values because the new timming maps and injection pulse were changed to fit the cams.

Timming is very important when new camshafts are fitted.

Cheers,
Pedro

[Knudsen]

I would deffo buy an piggyback. For less than 100 usd, you can get a Apexi S-afc.
I have one installed (the old model) and i can adjust the fuel +/- 50% for every 500rpm.

http://cgi.ebay.com/ebaymotors/APEXi-S-A...6665QQrdZ1

[ZDoman]

I don't really advise the SAFC because as I know it operates only with the sign of the air measuring (AFM or map) and if you lean the mixture the stock ecu will give the ignition later so probably you'll lose power.

If you have the possibity to see the AFR you shuld change the injectors to smaller ones, or reduce the fuel pressure. Or buy a greddy emanage

[Knudsen]

The S-afc operates with map-signal, throttle 0-100% high/low and revs.

ZDoman
Do you know how the ECU could adjust the ignition, when it doesnt have a knock-sensor?

[ZDoman]

Knudsen Wrote:The S-afc operates with map-signal, throttle 0-100% high/low and revs.

ZDoman
Do you know how the ECU could adjust the ignition, when it doesnt have a knock-sensor?

The ECU has an igniton table for different loads and different RPM.

I have read an article what was linked here in the aeu86.org about the working of the 4AG ECU. I advise you to read it!

this is the topic: http://www.aeu86.org/viewtopic.php?t=249...c&start=25

this is the link where you can find the infos:
http://www.jmross.freeserve.co.uk/
you should check the "part....html" ones!

[El_Camino]

ZDoman Wrote:I don't really advise the SAFC because as I know it operates only with the sign of the air measuring (AFM or map) and if you lean the mixture the stock ecu will give the ignition later so probably you'll lose power.

If you have the possibity to see the AFR you shuld change the injectors to smaller ones, or reduce the fuel pressure. Or buy a greddy emanage

I've heard many bad opinions, but never explanation why about the SAFC, so I'm trying to understand your post.
But it is difficult to me to see the connection you are doing between "lean the mixture" and "the stock ecu will give the ignition later".
To have feedback from the mixture, you need to have 02 sensor, which we dont ?

But then you are saying it: "The ECU has an igniton table for different loads and different RPM. ". Which is true.
The maps are RPM/Load based and not connected to the mixture.

[ZDoman]

Quote:But then you are saying it: "The ECU has an igniton table for different loads and different RPM. ". Which is true.
The maps are RPM/Load based and not connected to the mixture.

Here is the answer! The ECU is load and rpm based. With the SAFC you change the load sign (MAP/AFM) it seems like to the ecu you have less load so it will give "less ingition"

[El_Camino]

ZDoman Wrote:

Quote:But then you are saying it: "The ECU has an igniton table for different loads and different RPM. ". Which is true.
The maps are RPM/Load based and not connected to the mixture.

Here is the answer! The ECU is load and rpm based. With the SAFC you change the load sign (MAP/AFM) it seems like to the ecu you have less load so it will give "less ingition"

Ok, I see now! In this case this should happen.
For enrichment should be maybe better.

[Denmark]

Hmmm,

I would think that if that do change the ignition,then i would ofcource be more advance,

If you have seen how a map vs rpm scale work, you would know that if lower load, then more advance!


This is how i would see it,


Regards,
Skassa