Potential Fix for SOHC Idle problem

[guyaverage]

No offense to anyone (and I do mean that), but it constantly boggles my mind why people dont START with the IDLE Air Control valve. Thats what it is THERE for. To CONTROL the IDLE.


Sits back and waits for the verbal onslaught....

[hondah8er13]

hahaha, I'm laughing my a$$ off! i had the same thought but never posted because i did not want to take the verbal abuse, thats what was wrong with mine... lol i love your posts by the way

[atlantamx3]

Originally posted by guyaverage:
No offense to anyone (and I do mean that), but it constantly boggles my mind why people dont START with the IDLE Air Control valve. Thats what it is THERE for. To CONTROL the IDLE.


Sits back and waits for the verbal onslaught....

bwahahahaha-- Agreed.

[Darcy]

And we're all here to learn

/me goes off to research Idle Air Control Valve system...

[mxprecidia]

Originally posted by maldo:
Another good idea is to replace and add new grounding wires. I have added several 8 guage ground wires (soon to be 4 guage) that have helped in solving the idle surge. I run wires from the MAF, tranny, head, and intake manifold to the -ve battery post. The car is poorly grounded in stock form. With these upgrades I still get the occassional idle did, mainly when I have the stereo on and my foot on the brake. Ideally, it is best to have approx. 0.30 Ohms or less of resistance at each grounding point. Currently, depending on the grounding point, resistance is between 0.67-1.56 Ohms. Another fix is to run a 30A relay to trigger the head unit directly off the battery using 8 guage wires, upgrade that ground as well as the stereo puts a lot of stress on the electrical system. Since stepping on the brake at idle tends to cause the surge as well, a time consuming fix would be to replace the +ve and -ve wires in that harness with 12 guage wires. Mazda has a tendency to use too small of a size of wire within their harnesses so it can't hurt to upgrade. The stock power wire for the fuel pump is very small. Just as an example, on the 323GT and GTX, Mazda doubled up on the power wires, running 2 instead of 1 like our car.

would making either a bigger power wire or adding another power wire for the fuel pump make a differance?

[mxprecidia]

i have TWO ground contacts and one ten contact? what should i do?

[BuGS]

We (meaning my brother and I) have had our 92 SOHC MX-3 for about 3 years now. We have never had this idle problem. But then again we have always had a good running battery. We have had a Les Schwab Gold start on (or sumtin like that) and now we currentyl are running an Optima Red top. They only cost $100 and keep everything powered up. I am running a 800W amp with 2 10's and A DEH-930 Pioneer Priemer Headunit along with stops and goes. MY brother when he had the car was running same head unit but a 1400 w amp for 2 months then got a capacitor and neither of us had ever noticed an idle problem. So i don't know what kind of Batteries you all have but i would invest in a nice Optima. The deep cycles are the top and at $160 can save money for a lot of things (capacitor $100, problems with power loss). I don't know maybe i am just stupid but when i replaced the battery in my 1st gen eclipse who has a idle problem with an optima they seemed to clear up good. I don't know about anyone else. Maybe i am jsut lucky i don't have the problem.

[maniac]

Hey, just an opdate on mine. I redid all my ground points in the engine bay with 4 gauge wire, along with cleaning the iac valve and that really fixxed mine up good. The grounds were in rough shape and now it can handle a bunch of electrical stuff turned all with my stereo cranked, no drop in idle.

[andr3y]

hmm so i am not the only one. however i think my problem may be a little different. when on idle it whould stall sometimes when going down from high revs or go donw really low like 200 or soo and then go up and be fine. its would stall one in a wile like once in a 3 weeks some times even when just standing on the red light. well any way. i had to do my emission test and it failed coz of HC level on idle was way too high, i went to the garage and all they did is cleaned my injector and VAS (MAS). my emissions went down from 700 to 120 and i my idle RPM are much more stable now, didnt stall so far.

[mxprecidia]

is it bad to have too high of an idle? im thinking it may solve my problems of loosing electrical power when i stop by keeping the engine a little faster...yea or no?

[Bamaspeedy]

Hi,
Great that you have found a "Work Around" for your idle quality problem.
After reading all the responses to your post I decided to post a little information for everyone. I specialize in automotive electrical/electronic systems. So lets get on with it.
1) As several people noted the idle problems usually are caused by IAC valves becoming slow to operate or failing to allow the proper airflow for the given request(its stopped up). The real cure would be to clean/replace iac valve. If there is alot of oil in the inlet pipe you probably have a terminal engine problem(ring blowby)butthe filter and cleaning will alleviate the problem until you can get the BPT swap.
2) Maf Sensors contaminated with chemicals(usely silicon from rubber dressings or other sources)can also cause these problems if you have the heated wire type sensors. Try cleaning with electronics type spray cleaner.Do not use any type cleaner that leaves an oily residue.
3) Going nuts with ground wires is not really all that important. What is important is that the grounds you have work!! The best way to check an engine ground is by checking voltage drop not by checking resistance. If you need help with this let me know. Ill explain in another post or email. I only reccomend adding/ Replacing two grounds. Use one 2/0 wire( same size as battery cable) from battery to trans bellhousing and one 4 guage from battery to body. If you would like you can also add another ground strap from engine to the same body grounding point. It will be alot cleaner engine compartment then having multiple grounds from battery to engine.
4) Improperly adjusted base idle will also cause the computer to act stupid. This usually happens when you monkey with the little screw on the throttle body. If anyone needs the proper procedure id be glad to email it to them.
Well thats my two cents. By the way..My son has a 94 MX-3 with the blowby problem and im planning on doing the bpt swap real soon.

[atlantamx3]

Originally posted by Bamaspeedy:
If there is alot of oil in the inlet pipe you probably have a terminal engine problem(ring blowby)but the filter and cleaning will alleviate the problem until you can get the BPT swap.

Ding ding ding.

That was the MAIN cause of My problem, thats why I got the filter. When I was changing my intake, I noticed A LOT of oil in the pipe and flowing down to the back of the MAF. The crankcase ventilation was really too good (or bad??)and was allowing WAY to much oil to escape thru the valve cover and into the intake which went back down to the MAF.

The breather filter is really just a cheapo mod that temporarily solves this problem unitl you can afford to fix it right/replace the whole damn engine.

Nice post though.

[guyaverage]

If there is alot of oil in the inlet pipe you probably have a terminal engine problem(ring blowby)butthe filter and cleaning will alleviate the problem until you can get the BPT swap.

Is this a terminal engine problem that so many of us have, or just a crappy design? I had a Honda with almost 300k miles that had enough blow-by to choke an elephant, yet the intake was oil free, I would assume because of the multi-chambered baffle in the valve cover under the pvc valve. On the other hand, my Mx3 has had the idle problem since about 3-4 months after I bought it new in 1993. After break-in, I switched to Mobil 1 and have been using it ever since, and my compression is spec across the board (still, even at 142k miles), I cant imagine whatever blowby IS getting past the rings in this engine is enough to justify the amount of oil that gets into the Mx intake tract.

I'm getting ready to sell the Mx, so I'm not going to bother doing it, but if I end up keeping it for whatever reason I'm going to pull the valve cover and built a Honda-ish baffle under the breather to shield the valve from oil spray coming off the cams and I would be willing to bet this problem will go away for good.

[killerkeller]

I have a question would moding a oil catch can help to keep some of this blow by form reaching the intake and fouling the throttle body and sensors

[atlantamx3]

Originally posted by killerkeller:
I have a question would moding a oil catch can help to keep some of this blow by form reaching the intake and fouling the throttle body and sensors

Yes.

And, BTW, Guyaverage-- there is a baffle under there.