3SGTE weird AFR's

**sw20r** · 18-03-2006, 07:25 AM

Hi we finally got the motor running and its being broken in on the dyno.. But!

at low revs below four grand the car runs upto 10.1 afr. on most throttle conditions.

but as you approach four grand rpm. it starts leaning out to 14afr.

we reckon the tvis isnt working. as during the build it only had one wire going to the sensor near the tb.

the other thing i can think of is the ecu is going to limp mode. any ideas?

**spectral** · 18-03-2006, 09:01 AM

If an ECU goes into "safe mode", it would go fully rich, not lean.

TVIS not operating wouldn't make it go lean either as if anything it would restrict air and lower the AFRs.

I'd be looking at fuelling. Blocked/bad injectors, crap fuel filter, or perhaps the fuel pump.

You didn't say what mods you are running on your motor?

**Joshstix** · 18-03-2006, 12:51 PM

If you think it's the computer going into limp mode pull the codes and see what it's doing.

If the TVIS isn't working it will default to open so I don't think that would be too related. I'd be wanting to get fuel pressure and flow checked if I were you.

Things I'd be interested in checking would be O2 sensor and AFM.

**sw20r** · 18-03-2006, 01:42 PM

specs : 9:4:1 static comp, forgies, shot peened rods, balanced crank, shave head/block. ct26b gt4 205turbo stock ecu afm

**TurboRA28** · 18-03-2006, 03:12 PM

No knock sensor being damaged or not connected can cause this problem. On other toyota engines anyhow.. So assuming 3s would be similar.

**c2888** · 18-03-2006, 03:21 PM

fuel pressure - check it out with a guage
vac lines to the pressure reg
pump wiring, sw20s have a 2 stage fuel pump, it slows the pump during low loads to reduce noise and wear. i don't know if this can be hooked up in reverse, but something to look into.

dan

**Joshstix** · 18-03-2006, 06:21 PM

Originally Posted by TurboRA28

No knock sensor being damaged or not connected can cause this problem. On other toyota engines anyhow.. So assuming 3s would be similar.

Good call Joel. This should throw a code 54 when you check the ECU diagnostic codes.

**sw20r** · 18-03-2006, 09:59 PM

All sorted!

The afm was way off so it was opened up and calibrated.

so far shes good!

100rwkw at 3000rpm. 7psi boost. done the 1st hundred now approaching 200kms.