AFR & IAT Readings on stock St165 - everything ok?

Talk EMS and Computer related performance

AFR & IAT Readings on stock St165 - everything ok?

Postby Bers » Tue Oct 18, 2011 5:00 am


I'm on my way for my very first attempt at upping the boost on a car.
Before that, I'd like to hear your opinion on these readings, I'd just like to make sure everything is in proper working order before turning up the boost:

(rolling start, lazy shifts barely past 6000 rpm)

AFR: 11.0@4000rpm, down to 10.2@6000rpm, 7.8psi
IAT: 115-120F, outside temp was about 70F. Rises about 1.5-2.0 degrees per second on hard acceleration.

Car is bone stock except for a larger compressor trim and a decatted exhaust. No boost controller or hacks.



More questions :
- "USER1" signal is an analog input that I connected to check the TVSV Actuator signal from the ECU. Why would it stay on 5V then fall to 1.8V on boost? Seems strange, I was expecting more like 0V/5V. Furthermore, isn't this TVSV supposed to limit boost on 1st and 2nd gear?
- Boost used to drop down to 5-6psi@6500 rpm on 1st gear, and to 6.5-7psi@6500 on 2nd before the turbo compressor upgrade. I don't know if that upgrade was of any use, or if my old turbo was just tired. What do you think?
Members don't see the above ad. Register now - it's free!
User avatar
Posts: 4
Joined: Sun May 01, 2011 11:51 pm

Re: AFR & IAT Readings on stock St165 - everything ok?

Postby BNZ » Tue Oct 18, 2011 7:13 am

Really nice graph's ! Good to see a stock W2A IAT's witch are in the "green zone" !
I have changed my W2A to the ST205 one. I will do a log on my Megasquirt and post the temps,just to see the differences on that IC change,although i think it will not be as big of a difference on a single straight line pull. The big difference is made on sustained racing like a special stage or circuit.

As for the TVIS,the system is active (valves closed under vacuum force) for increased torque in low revs and open after a certain rev (i've set mine to 3200rpm) the valves open under spring force (solenoid closes - low V - to bleed air) to increase airflow

L.E. On your graph it seems 4000rpm is the opening limit for TVIS
Street ST185
Rally ST165
HillClimb Renault 5 GTE
User avatar
Club Member
Posts: 321
Images: 31
Joined: Fri Oct 03, 2008 7:22 pm
Location: Timisoara/Romania

Re: AFR & IAT Readings on stock St165 - everything ok?

Postby klue » Tue Oct 18, 2011 2:10 pm

numbers look good, nice and fat
#xiiimotorsports ON instagram
User avatar
GTFour God
Posts: 3893
Joined: Thu Nov 04, 2004 9:47 pm
Location: Greater Toronto Area

Return to EFI Corner

Who is online

Users browsing this forum: No registered users and 1 guest