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sirchadd
05-27-2007, 09:41 AM
I recently purchased an ITS car from an intern of Speed Source, the car is great, but I am trying to find more info on the air fuel mixture setup. Car appears to have 89 MAF, we are installing FP regulator today. We were going to have the car dyno tested but what is the best way to adjust AF. Should I hook a three wire O2 sensor up, I already have a gauge laying around, I ordered an EGT 2000 degree as someone told me that was the best approach. We just got the car and I ran the Daytona school for SCCA and reccieved signoff to run due to AMA road racing experience. We are prepping the car for Sebring June 2.

I am new to SCCA Club Racing and the RX-7 seemed the way to go, I have learned so much reading your post and if anyone has any information it would be greatly appreciated.

Thanks, Chadd


PS, my bad. Anyone now the procedure for TPS adjustment, told if it isn't right than car can go into limp mode. Really not happy that Mazda dealer has not recieve Factory Manual I ordered. Okay, back into the garage to turn the wrench.

Thanks again.

Chadd

NCRX7RACER
05-27-2007, 12:44 PM
What year fuel injection/ tps set-up do you have? 86-88 fuel injection has one tps. It works only in the lower ~20% of the throttle position. Past that throttle position it sends the same signal all the way to wot. The 89+ fuel injection has 2 tps sensors, a low throttle range and a high throttle range. You can adjust them using an ohm meter to check resistance values or the low tech 2 light bulb method usually on 86-88 cars (2 bulbs, hook the negative sides together, leave the pos. seperate. 2 bulbs light up or no bulbs light up indicate out of range. Set it so only one bulb lights. You use the 3 prong green connector to hook up the bulbs.

sirchadd
05-27-2007, 01:52 PM
Awsome, yes it appears the TPS is 86-88 model. Soldering light bulbs as we speak as we have just finished the Fuel Press. Regulator install.

Much appreciated NCRX7RACER!

We will get this car ready for Sebring, its all or nothing but its hard being driver and tech sometimes.

Thanks Again.

NCRX7RACER
05-27-2007, 02:20 PM
The green connector has 3 prongs, 2 parallel 1 perpendicular. To hook up the bulbs, connect the 2 wires hooked together into the perpendicular prong, the 2 separate wires into the 2 parallel prongs. After adjustment pull the throttle open several times and check again to make sure it is correct. Engine should be warmed up to operating temp for final adjustments. Check the sensor with the ohm meter to make sure its in range if you have problems. 1k at idle pos, 5k at wot. Connect to perpendicular prong and prong on right (holding plug with perpendicular prong at top.

sirchadd
05-29-2007, 11:51 PM
TPS Setup Check Satisfactory, Fuel Pressure regualtor Installed, EGT Gauge sent was 1500 degree, new gauge comes in tomorrow should have been 2000 degrees and HPF usually makes no mistakes.

Appreciate the TPS adjustment, now I jusst got to get the A/F setup after gauge installed.

C. Ludwig
05-30-2007, 03:46 PM
If you are using a 3-wire O2 sensor with one of the led gauges don't even bother. The single, three, and four wire O2 sensors are all narrow band sensors and are useless for tuning. Their non linear output will essentially only tell you when you are above or below stoichiometric and not by how much. You need to know exactly what the a/f ratio is. For this you'll need a wideband a/f meter. There are many types on the market. At this point they are all basically the same and shopping by price is not a bad idea. Innovate and PLX both make good products and sell a display that fits in an ordinary 2 1/8" gauge pod.

Autometer has a pretty good write up...

http://www.autometer.com/tech_faq_answer.aspx?sid=1&qid=48

sirchadd
05-30-2007, 04:21 PM
Thanks Ludwig so much. I thought about that but didn't want to shell out the big dollars yet. We hooked an EGT setup from Autometer in the car today and are going to tapped the pipe. I will check out the wide bands but I think it won't be an option till after Sebring.