97 Mazda 626
4 cyl. 1.8 engine
Manual drive
The engine vibrate at Idle, Idling speed is about 650-700 rpm.
The issue started when I reconnect my thermo switch connection, before now the idle speed was at 1250 rpm.
The car fuel economy is far better than before, but the vibration is not making me feel comfortable with the car while am in traffic.
Please advice and educate me.

Take several pics inside the engine and post, also a pic of gages while engine is running and warm

amosfunmi: 97 Mazda 626
4 cyl. 1.8 engine
Manual drive
The engine vibrate at Idle, Idling speed is about 650-700 rpm.
The issue started when I reconnect my thermo switch connection, before now the idle speed was at 1250 rpm.
The car fuel economy is far better than before, but the vibration is not making me feel comfortable with the car while am in traffic.
Please advice and educate me.

Your thermo switch is linked to your automatic choke which in turn controls your engine idle speed (especially when engine is cold and operating in closed loop). Check to see if auto choke is functioning properly and if not, change it immediately.

sultaan: Take several pics inside the engine and post, also a pic of gages while engine is running and warm

I am just coming from work now, will do that tomorrow morning.

car-doctor:


Your thermo switch is linked to your automatic choke which in turn controls your engine idle speed (especially when engine is cold and operating in closed loop). Check to see if auto choke is functioning properly and if not, change it immediately.

Thank you car Doctor, when engine is cold the idle speed is little higher but when warmed that when the vibration happens.
please,how do I identify the Auto choke and where is it located?

Also do a visual check of your engine mounting, if possible.

The slow running of the car is to much. Adjust it. it happened to my car and i has stopped.

layday2005: The slow running of the car is to much. Adjust it. it happened to my car and i has stopped.

Thanks for the reply, can I do it myself or take it to mechanic?

Do not adjust the slow, have them clean the throttle body, but post the pics first

sultaan: Do not adjust the slow, have them clean the throttle body, but post the pics first

Thank you sultan, here are the pics

Sultan, Ikenna, sienna gurus here, please help me out.

Still waiting for your advice.

I have looked at your pics, everything seems ok, its all connected and temp is good, I just need you to confirm one information I can't read the label on the spark plug wires proper, can you please check if they wrote mazda on the wire and the year/number written after the mazda (just want to know if its factory)

After you post what is written on it you may just have to check on all the black hoses that goes from the air intake(air filter/duct) to engine and have mechanic clean the throttle body(the part with a butterfly valve they call "nozzle")

A scan will also confirm what I suspect, basically you may be running on 3 cylinders

sultaan: I have looked at your pics, everything seems ok, its all connected and temp is good, I just need you to confirm one information I can't read the label on the spark plug wires proper, can you please check if they wrote mazda on the wire and the year/number written after the mazda (just want to know if its factory)

After you post what is written on it you may just have to check on all the black hoses that goes from the air intake(air filter/duct) to engine and have mechanic clean the throttle body(the part with a butterfly valve they call "nozzle"

A scan will also confirm what I suspect, basically you may be running on 3 cylinders

Thank you sultan, would do that tomorrow morning, however< I wish to let you know that the problem started when I reconnect the therrmo switch.

Everything that should be connected should stay connected, disconnecting it covers up your problem, reconnecting will let engine run normal so you'll see if you have issues with the car(your high idle was covering the misfire)

But you should have a check engine light on if its a misfire which is why I said you should check vacuum for leaks first the clean throttle body.

Thank you Sultan, I appreciate your efforts and concern.
The plug wire I don't think its factory fitted, they are black in colour and the Inscription on it is [b]R-16-AIPS [/b]and the numbering from ignition cover.
I attempt to adjust from the idle adjustment screw and having listen very well its as if there is a air leak some where as I tend to increase the idle and the rev is not increasing.
I also got to know that, that was not the right way of doing it, that the best way is to jump STI(TEN) and GND on the diagnosis port before the adjustment can be effected, How true is that?
Do you stay in Lagos, can you refer me to a mechanic or where I can have the scan done.

@ Sultan waiting to read from you. Gurus here please help me out.

layday2005: The slow running of the car is to much. Adjust it. it happened to my car and i has stopped.

he

This may be true except the auto gurus have a different opinion, thats why we are still waiting for more contributions from our respected gurus.
Based on the advise i got here, recently changed bak to the thermostat option (rewired my fan to only start working wen the engine temp is almost at halfway or when the A/C is on) and i noticed a slight vibration that wasnt their before. On motion, i noticed that the car is no longer picking as b4 (requires me to step more on the gas b4 it gains the normal speed).

I am considering goin to my mech this weekend to increase my gas (acceleration) power, please let me know if i should go ahead.

Seems likely you are running on three cylinders instead of four. Check ur plugs, coils and plug wires. Check ur fuel lines too (fuel filter) and clean out your air filter.

The easiest way will be to scan first and make sure you don't have a misfire.
Imagine if you are suppose to have 4 beats but you have 3 beats at a high frequency, you might not realize you are missing a beat until you slow things down; which you did.

You can change the spark plugs and wire as part of your regular maintenance, just make sure you use the right type not just what your mechanic tells you but you do the research.

Thanks all, I have change the plug and fuel filter, yet no difference.
I took it to a mechanic he could not help, he has to disconnect the auto choke connection
to get it stabilized but while I was driving home with AC on the engine almost stall in trafic.
when I got home, I did a check and observe he has disconnect the auto choke and I have to plug it back.

I have no idea what auto choke is but when you change plugs check/change wires too. Look online for throttle body cleaning and idle air controller.These things get dirty and its part of maintenance to clean them.I'm recommending maintenance items.The problem you have now is usually caused by misfire, vacuum leak and bad/dirty/disconnected sensors.You have to look at how dirty the IAC/MAF.

I'm not in Nigeria so I can't recommend any mech.As far as I know you can be better than you mech if you take time to understand how it works

thank you sultan, appreciate you

I had this issue, My car had exactly the same issue use to vibrate so much and would take ages to accelerate. Took it to my mechanic and he said it was a coil issue, he had it taped as a temporary measure but advised me to change the coil, which I did last weekend.

No longer have the issue, the vibration has stopped and the car accelerates well now.

Just change your engine seating bushings