Jump to content

Photo

Idle Problem


  • Please log in to reply
24 replies to this topic

#1
severvip

severvip

    Newbie

  • Members
  • Pip
  • 13 posts
  • Car: 1998, Mazda 626 LX, 2.0L Auto
I have a 4cl 98 626, and I've had an idle problem for the last 6 months or so, I've tried and tried but I can't pin point the source of the problem. The problem is whenever at idle speed, the idle speed fluctuates. Usually going up and down between 500 and 750, causing the car to shake violently. The fluctuations get worse the longer the car sits at idle speed, and eventually causes the car to die. If pulling up to a stop light that lasts for more than 30 seconds the car will die. I've received one code the first month the car started doing this, stating Fuel to Lean. That code disappeared eventually and I haven't received any codes since.

Now like I said, I can't pin point the issue, but I've tried quite a bit in my quest to fix this car.

I've looked at and inspected all the vacuum hoses numerous times and I can't find any holes or cracks in any of the vacuum hoses. I replaced the timing belt because I heard from somebody it could be a timing issue. While working inside the engine I put new seals on all the valves and re-shimmed the lifters. I replaced the valve cover gasket when I did all that just incase it was leaking. None of that fixed my problem.

I've replaced the 02 sensors and Fuel Filter. I've cleaned the MAF, IAC, and injectors. But still no luck.

I replaced the spark plugs with the proper NGK spark plugs. No luck. I've changed the gap setting from .29 to .32 to .44 and everywhere in between, but it still has the idle problem. Speaking of which, what is the proper gap setting??? Oreilly Auto Parts told me .29 Autozone told me .44 Mazda dealership told me .32 Chiltons books say .44 so which is it???

So any ideas on what could be causing my idle problem. A friend suggested it could be a piston problem? Is that it, or have I overlooked something else. Please any ideas?

#2
severvip

severvip

    Newbie

  • Members
  • Pip
  • 13 posts
  • Car: 1998, Mazda 626 LX, 2.0L Auto
If somebody on here can tell me what the problem is and how to fix it. I will pay that person $30.00. I'm dead serious, I'm that sick of this problem.

#3
Raziel

Raziel

    Advanced Member

  • Members
  • PipPipPipPip
  • 789 posts
  • Car: 1997, 626 LX, 2.0L, Auto
Have you tested the IAC? Or just cleaned it? Test the thing & see if it's reading to specs.

Check your fuel pressure too, might not be right.
Spray carb cleaner around the intake manifold gasket & throttle body gasket while the vehicle is running. If it starts to rev, replace the gasket.
Also spray it on all vacuum lines to see if that will cause the engine to rev, if it does, replace the lines.

Do you have anything on when this is happening? Like the radio, a/c, lights, etc? Or does it happen weather or not anything else is on?

If it only happens when you have something else on, then you have a load issue. Something is drawing to much or the battery/alternator is unable to handle/provide enough for it.

Check & clean all you grounds. You can add extra grounds to help.

I know you said you cleaned the injectors, but did you test them to make sure they are not leaking & are they spraying properly?

Maybe you need new plug wires &/or coil pack.

Sorry got to go now, got some work to do to finish, but I'll be back, mwhahahaha.... Good Luck

#4
toddyvol

toddyvol

    Newbie

  • Members
  • Pip
  • 8 posts
  • Car: 1998 626 2.0 auto
Have you adjusted the throttle cable?

#5
severvip

severvip

    Newbie

  • Members
  • Pip
  • 13 posts
  • Car: 1998, Mazda 626 LX, 2.0L Auto
When I tested and cleaned the Injectors I had it done at a shop around here, they said they were fine. Yeah I did test the IAC also, and just to make sure the IAC worked I purchased one over at Autozone, cost 400. Put it on and the car still had the idle problem so I returned it and got my money back. As for what I have turned on when it does this, I've tried turning everything off and it still has the problem, it doesn't seem to matter what I have turned on or off. Oh and yes I did clean all the grounds but still no such luck, I haven't added any extra grounds, so I might try that.

As for adjusting the throttle cable, I did that and it raises the idle a bit, instead of shaking violently between 500 and 750, it shakes violently between 750 and 1000. It doesn't die at every stoplight now, but the idle problem is still there.

Oh again, what is the proper gap setting for the spark plugs, or does nobody know???

#6
97Mazda

97Mazda

    Senior Member

  • Members
  • PipPipPipPipPip
  • 2,118 posts
  • Car: 1997 626ES 2.5L V6 ATX
Spark Plug Gap = .044"

I'd be doing a compression test!

#7
toddyvol

toddyvol

    Newbie

  • Members
  • Pip
  • 8 posts
  • Car: 1998 626 2.0 auto
Almost sounds like a bad motor mount.

#8
severvip

severvip

    Newbie

  • Members
  • Pip
  • 13 posts
  • Car: 1998, Mazda 626 LX, 2.0L Auto

Almost sounds like a bad motor mount.


Motor Mount how would that cause an idle problem?

#9
toddyvol

toddyvol

    Newbie

  • Members
  • Pip
  • 8 posts
  • Car: 1998 626 2.0 auto


Almost sounds like a bad motor mount.


Motor Mount how would that cause an idle problem?


You said "it shakes violently" at different rpms. I would imagine that if a motor mount was bad, the engine would shake violently just as you mentioned.

I could be way off but I have seen other vehicles exhibit the same or like symptoms from a broken motor mount.

#10
Raziel

Raziel

    Advanced Member

  • Members
  • PipPipPipPip
  • 789 posts
  • Car: 1997, 626 LX, 2.0L, Auto
If you have a shaking/vibration problem, mounts would do that. But you also said your idle was going back & forth between 500-750 rpms & it has died. Unless you had the a/c on when that was happening, idle will drop when the compressor comes on for a second. That is normal. But it shouldn't cause it to die.

So I would rule mounts out due to what you have said. But it still doesn't hurt to check your mount to see if they are split. Which I would say yes if the previous owner didn't take care of that.

So the shop told you the injectors are good, did they check fuel pressure?

Did you adjust the throttle plate sitting position? That would cause it to behave erratic. That adjusting screw should never be touched, unless you know what you are doing.

For some weird ass reason, pretty much all aftermarket replacing parts for these cars seem not to work right. I have no idea why, except for they can't build products with good quality like in the good old days. But, whatever. You do get lucky once and awhile and do get a working aftermarket part.

You can try to get an IAC from the dealer & see if that will work. And I know how dealers are on SOP, you can't return them or if you can there is like a "15% restocking fee." Which is bull.

Did you test the MAF. And like 97Mazda said, do a compression/leak down test. Have you try spraying carb cleaner on the gaskets/hoses like I mention before yet?

#11
severvip

severvip

    Newbie

  • Members
  • Pip
  • 13 posts
  • Car: 1998, Mazda 626 LX, 2.0L Auto
Raziel

I did do a compression leak down test once, it wasn't loosing compression in any of the cylinders. It would build up and stay up, but cylinder 3 didn't build up as high as the others. It was like 10 pounds lower than all the others. I asked somebody about that before, they said that was normal for cylinder 3, or it was still within normal parameters or something.

I have sprayed carb cleaner directly into the Intact Manifold, and I've sprayed it directly into some hoses, but that's never done anything. I'll try again, see if it causes any reactions or something. I've checked the MAF, I didn't go buy one and see if replacing it fixes it like I did with the IAC, but I did check it. The Ohms were within the normal operating parameters. I may buy one tomorrow and see if I get any different results, but I can't imagine I would.

I'm taking my car to Mazda on Friday, have them run an complete engine diagnostic. If I can't fix it by then. Right now it doesn't look like anybodies getting the 30 dollars. If I spend 80 for an engine diag, yall can forget it.

#12
MazRedMan

MazRedMan

    Advanced Member

  • Members
  • PipPipPipPip
  • 670 posts
  • Location: Albuquerque,NM
  • Car: 98' 626LX 2.0L (4cyl) ATX 'Lazer Red' color
First, easy test of IAC valve by dis-connecting electrical connection. Your idle should change (go down) if IAC is working.

If your idle still fluctuates, even if connection is un-plugged, then your problem is maybe something else. Note: A dirty or improperly assembled (after cleaning) IAC valve still could be part of the problem.

If you changed the idle (set by manufacturer) then you will need it re-set by qualified people/garage equipment.

Question 1: Was your car running properly before you noticed the problem with idle?
Question 2: Did you have work done to your car that may have started/caused the idle problem?

At proper idle, 700-750 rpms.....no fluctuations (in 'Park', warmed up, no load 'ON').

A dirty EGR valve/system could also cause idle problems....try Seafoam treatment to your car (gas tank and brake booster or PCV vacuum hose).

Add extra ground wires to electrical system.

I use NGK G-Power #7090 BKR5EGP (pre-gapped; platinum) spark plugs and works great for my 98' LX.

And 'yes' broken motors mounts can cause 'shaking' but irradic or fluctuation of idle rpms....maybe....check mounts any ways.

Good luck!!

#13
severvip

severvip

    Newbie

  • Members
  • Pip
  • 13 posts
  • Car: 1998, Mazda 626 LX, 2.0L Auto
MazRedMan If I disconnect the IAC valve the car dies almost instantly.

Now to answer your questions, this problem happened suddenly, it just started idling rough one day.

About a month before that I replaced the Master Cylinder and one brake line, but I can't imagine the Master Cylinder would have caused this, plus that was a month before the problem all of a sudden started.

#14
OzTelstar

OzTelstar

    Newbie

  • Members
  • Pip
  • 9 posts
  • Location: Adelaide, South Australia
  • Car: 1992 Ford Telstar (Mazda 626 I4) - Auto
Hi,

Couple of suggestions

Test the PCV valve for 2 things;

1) That it is pulling a vaccum when disconected from the rocker cover (put your thumb over it)
2) Verify that the one way valve is operating correctly by blowing through the rocker cover connector (should be flow) and then from the other side (should be no flow)

Have a look at the condition of all of your air intake system.
ie, no loose hose clamps, nothings popped of at the bottom or there are no splits in the ducting. Is the air filter clean and is the box clamped down properly

A long shot - but crank angle sensor?

good luck!

#15
Mario

Mario

    Member

  • Members
  • PipPipPip
  • 382 posts
  • Location: Estonia
  • Car: 1999, 626 STW GW, 2.0FS H.P. 16V, manual
And you guys never mentioned one thing - coolant level.. Mazda's idle depends on coolant level.. if it is only a few mm under the Normal, it keeps fluctuating.. So check that.. I had the same thing with my GE, it did the same thing and after i filled it, it stopped.. Also, when you recently replaced the coolant, it might have air bubbles still left in.. but if the radiator's valve is working, it should let the air out by itself, also you would notice high temp. on the dash..

Another possibilities -
*engine mounts - heavy vibration in the chassis, but not the reason for dying..
* if it dies, when you hit the brake pedal, it is the vacuum membrane in the brake distributor.. Or a massive vacuum leak..
*check the spark plugs and replace them if necessary.. factory suggestion is NGK BP6ES (same as V6's) should be a 16 dollar investment..
*spark wires - hardly ever.. only when you have trouble cold-cranking..

my other guess would be fuel filter, AFM.. but i guess you've already cheked those..

This fluctuation also happens, when your temperature sensor is dead - thi causes the ECU to turn on the "Save power" mode and does not work properly..

Someone mentioned a distributor malfunction.. but the I4's distr. doesn't break that easily..

Hope this helped..




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users