Adjust Idle NB

Does anyone know why the ECU still takes over adjusting the idle via the "short term fuel trim" after I have placed jumper on TEN/GND in the Diagnostic Port? I know the the placement of the TEN and GND are different than in the NA. See this. After I have placed the jumper, I notice that there is a slight change in RPM, but ECU will take over within seconds. Also, is it normal for the sort term fuel trim to go back and forth 25% each way to adjust the idle? Any suggestion? I am trying to fix my CEL P1170 problem and I think it may idle related.

What are you using for a jumper? Are you sure you're making good contact on both sides?

Quote:

---

Originally Posted by sammm

What are you using for a jumper? Are you sure you're making good contact on both sides?

---

I fashioned several different jumpers and still no go. When it first made contact, the RPM does change but was never able override the ECU. The OBDII scanner still showed short term fuel trim still at work in managing the RPM!

http://www.saidaonline.com/en/newsgfx/paperclip.jpg

Did you consult the '99 Mazda Service manual??

Yes, it doesn't mention the jumper at all! It is odd that they have a caution statement in the shop manual "not to adjust the TAS (throttle adjusting screw)"! The dam ECU just taking over everything and is not very good in doing that. The RPM going up and down from 1100 all the way down 700! The shop manual says it should be 800+/-50!

This would solve all you problems - http://www.dfwmiata.com/showthread.p...e-black-Dallas ::Banana::


;)

Quote:

---

Originally Posted by POS Racing

This would solve all you problems - http://www.dfwmiata.com/showthread.p...e-black-Dallas ::Banana::


;)

---

The problem is to find another poor soul to take my car off my hands! I talked to Stevan just now. We think it is time to take it to Town North! :-(

Quote:

---

Originally Posted by gabkwong

The problem is to find another poor soul to take my car off my hands! I talked to Stevan just now. We think it is time to take it to Town North! :-(

---

Can you get your hands on the scanner they mention in the service manual??

I have an OBDII scanner from HF. It can read life data, freeze frame data and more. I am sure in the competent hands, the freeze frame data (the data from the car when it throw the CEL) is very useful in diagnosing the problem. For me, I can only tell if the O2 sensors, MAF, temp, and speed sensors are working. I just don't have what it take to see the picture. I can see the trees but not the forest! Do you think the scanner they mentioned in manual is different? or Mazda specific? The CEL code is in the shop manual page 01-01A-82. I have done the stuffs I know how to in the diagnostic procedures. The rest are Greek to me or I don't have the tools. So far I have ruled out MAF (put in one from a running 99), new fuel filter, new plugs, new plug wires, new PCV valve, new oil change, no vacuum leak w the HF stethoscope, new OEM O2 sensors, throttle butterfly cleaned with TB cleaner, upper intake manifold cleaned and sinuses de-clogged, Seafoamed (w traffic ticket to proof :-( ), Techron'ed twice, filled up w Chevron gas x 2 tanks, cleaned the cold air intake foam filter, and screamed profanity many times!

Yep, time to take it in. Maybe they will offer you a good trade for a NC!

Ask for Jim Otterbine at Town North to work on it. Good tech and knowledgeable. We go to him with lots of tough questions.

I don't recall adjusting the idle on the NB being different than an NA. Is it?

Could it be the ISC valve?