[Mk2] [Turbo] What AFR does a stock Rev 3 run at (Idle/Cruis/WOT)

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Danbob
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Joined: Mon Nov 14, 2011 8:06 pm
Location: Wellingborough

[Mk2] [Turbo] What AFR does a stock Rev 3 run at (Idle/Cruis/WOT)

Post by Danbob »

Been monitoring my AFR's as engine break in is just about done and boost will be raised shortly.

Seems a little rich, so want to know if anybody has a wideband fitted to a stock Rev 3 to compare.

Car is running stock Rev3 ECU (for break in) currently on 10PSI boost. HKS 264 cams.

Cold Start Idle AFR ~ 10:1
Warm Idle AFR ~ 12.7:1
Cruise/part throttle ~ 14.6:1
WOT High revs 10PSI ~ 12:1 --> ~ 11:1


Idle AFR's seem rich. and it doesn't idle great, it needs more air than usual but I thought that was just due to the cams.

Does anybody have some data for stock Rev 3 Idle AFR?

Thanks
Dan
jon
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Location: Cambridge

Re: [Mk2] [Turbo] What AFR does a stock Rev 3 run at (Idle/Cruis/WOT)

Post by jon »

Warm Idle AFR should on average be 14.7:1, it will oscillate around from 14.3:1 to 15.0:1 due to feedback from O2 sensor.

Cold Start Idle AFR can be anywhere from 10:1 to 14.1 depending on coolant temp.

Cruise/part throttle should be around 14.7:1. Again it will be oscillating due to O2 sensor feedback.
Danbob
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Joined: Mon Nov 14, 2011 8:06 pm
Location: Wellingborough

Re: [Mk2] [Turbo] What AFR does a stock Rev 3 run at (Idle/Cruis/WOT)

Post by Danbob »

Yeah cruise and wot seem about right to me and the car feels right under those conditions aswell, just idle seems too rich and idle is also where the car struggles.

Wonder if it's due to the fuel pump resistor not being used, that would explain it only running rich at idle. Maybe the stock fuel pressure regulator can't handle the full flow from the walbro pump at idle to keep the pressure down...
jon
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Joined: Tue Dec 14, 2004 10:23 am
Location: Cambridge

Re: [Mk2] [Turbo] What AFR does a stock Rev 3 run at (Idle/Cruis/WOT)

Post by jon »

Could be due to the fuel pump resistor not being used, or it could be that the 264 cams are pushing the volumetric efficiency at idle so far out that the ECU can't compensate.

If you raise the idle a bit do the AFRs go to 14.7:1?
jimGTS
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Location: North Kent

Re: [Mk2] [Turbo] What AFR does a stock Rev 3 run at (Idle/Cruis/WOT)

Post by jimGTS »

i dont run a fuel pump relay or resistor.

afrs at warm idle should still be in the 14.3-15.0 range.

and ive ran all manor of fuel pressures, from 33psi to 46psi base pressures.
granted most of that was on the stock pump, but my walbro its still fine.
simpson_eh
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Location: south wales

Re: [Mk2] [Turbo] What AFR does a stock Rev 3 run at (Idle/Cruis/WOT)

Post by simpson_eh »

looking at mine today 2.2 gt3076 264 always in 13 drops to 12 maybe 14 now and again boost drops into 9 time for a remap i think:(




but i have added a frp at 41 psi to set no vacuum and high flow pump swirl pot etc so injectors prob getting a throat full
If you see an MR2 with a raised engine cover, the bottom line is it's probably faster than your car.
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