I have a 2000 Mazda Protege. It stalls when it's hot. The temperature gauge reads normal. If it's hot out and I stop at a light, the RPM's drop down to 500 and then it stalls.The RPM's run low anyhow.Then it takes about 5 minutes to cool and then it will start back up. I've changed the spark plugs, wires, coils, and alternator.....no luck! We hooked it up to the computer, it occured, NO CODES! I'm lost. Any advise?

 

Have you triedchecking base idle speed by grounding the diagnostic connector TEN pin. This connector box is locatedby your wiper motor and brake master cylinder.If that does not work then try unplugging the Idle Air Control valve at idle. RPM should drop considerably when this is done. If it does not then would think you might have a faulty or sticking IAC valve.

[IMG]local://upfiles/1377/529330E9576848F7B22EF40484B5E283.gif[/IMG]

 

babyhuey,
It sounds very logical. I've read about possibly cleaning the valve with carb cleaner. Where is is the ICV located? Is it easy to remove and replace?Also it says to change the gasket. I priced them and they are pricey. Also, someone metioned the MAF sensor? Thanks for your help.

 

You could certainly try cleaning the IAC valve. The valve is located on the throttle body. The 1.6 engine has it located on the underside and 2.0 is on top side. Not sure which engine you have??
What gasket is very pricey?
The MAF sensor has been a horrible problem on the 1.6 engine. Mazda even extended the warranty replacement to 7 years or 70,000 miles. Usually a faulty MAF is going to give you a bunch of different driveability problem such as lack of power, surging, etc and not just a low idle with stall. Have had some very good luck cleaning as well. Only two phillips screws to remove from air cleaner housing. When you have it out and in your hand, you will see a long,black plastic protrusion and an odd looking pregnant wire looking thing at first glance. The wire thingy on the side in the Intake Air Temperature Sensor portion of the sensor. If you get a flashlight and look down inside the black plastic hollow part you will see two, short wires with bulges in the middle. This is the Mass Air Flow portion. If they are not shiny silver but are instead dark gray, black. or even fuzzy looking then a good they are contaminated. To clean both the MAF and IAT portions use a non-clorinated brake cleaner that has a straw to direct a good stream onto the dirty parts. DO NOT try to touch with a cotton swab or something as they will break. Very, very fragile. Allow to dry, reinstall and see what happens. Am still betting on the IAC.

[IMG]local://upfiles/1377/5A8DC98B8C92420D903E703FCDA1D5AA.gif[/IMG]IAC on 1.6L engine

[IMG]local://upfiles/1377/05500E4BE77449BE9163192E1A1D6D4B.gif[/IMG] IAC on 2.0L engine.

 

If it's the IAC valve, would that cause the car to also sputter before stalling?

 

If it is sputtering when you still have foot on the throttle would not think it to be a IAC as it really only makes any difference at idle and closed throttle. Also what you say about having to wait for 5 minutes for it to restart would steer me away from an IAC fault. Even if the IAC were stuck full closed, the engine should be able to be restarted just fine. It would just then immediatly stall unless throttle was feathered.

 

What mods have you made to the engine? Or, what are you running for spark plugs?

What I'm getting at is one of two things - both related. If you have made numerous or a single major change to your engine, but have not changed the heat range of your plugs, it could be your issue. I had an '87 Mustang with the 2.3L OHC motor. I replaced exhaust with a very free flowing system, took off a VERY restrictive factory air filter assembly, and bumped the timing a bit. My car did EXACTLY what you are describing. Luckily the parts store I went to was more than a 22 year old who had just left McDonald's. The owner looked-up my factory plugs, gave me a set 1 range colder and *poof* problem solved. Your car being a mass-air system as opposed to a MAP-system shouldn't be as sensitive, but it may still be.....

The other thing is this - are you trying to run some of the high dollar plugs like iridium or ?? Depending on the type of plug, your timing, fuel quality, etc., you may be experiencing a problem related to the plug. I installed Bosch Platinum in my '92 Integra and the hot idle went to crap. Same thing happened 15 years ago in two different GM Quad4 engines I installed them in.

One last thing - do you have an automatic? If so, check the functionality of your EGR valve. They vary by manufacturer, so hopefully someone here can tell you the test(s) for your Protege.

Keep something in mind - the computer cannot montitor a secondary system such as your cap & rotor, spark plugs, fuel filter, etc. If something like the mass air meter was out of its normal operating range, the computer should be returning a code. Pull your plugs - make sure they look good. Check your cap & rotor and make sure you don't have a lot of corrosion built at the towers. And last but not least - your car is 7 years old - have you ever changed the plug wires? The ones on my Integra were in bad enough shap that when I replaced them after 6 years, it made a very noticable difference in the idle.

Good luck
Karl

 

I pulled the IAC valve and the RPM's went up to about 2500. Now what?

 

Thr RPM's went up and after idling for a few minutes, they dropped. The car is an automatic. Just changed the plugs, wires and coils. I pulled the EGR valve, no difference. I pulled the MAF sensorand that caused the car to stall. All of these valves look pretty new. Changed the PVC valve. The auto parts noticed a possible vacuum leak where the air filter goes. The clamp was broken off, so we weren't getting a tight seal. We clamped it down with a bungee cord.By the way, I just aquired the car 2 months ago, so don't know the history. I did buy the more expensive plugs at Autozone ($2.00) Where is the cap and rotor located on the car. Haven't changed that yet. I used to have an 89 Accord that would have trouble starting sometimes. It was the rotor. The cap had a crack in it. Replaced it and it was fine. Don't know what else to do. I'm about to get rid of the car!!!!

 

Did not mean to remove the IAC but only to disconnect the electrical connector. Am sure the rpm went up quite a ways if you had valve off and engine running. You mentioned in your other thread about the CEL being on a storing a code. Do you remember exactly what code was stored or if it is still on what codes do you have now.
What engine size do you have also? 1.6 or 2.0
When it has stalled and not restarting, have you tried to remove the fuel line to see if you are getting enough fuel pressure. Could have a pump failing on you.
You do not have a distributor cap or rotor. Spark is delivered to the plugs directly by the coils