I have a 97 Protege 1.8l, std, 277k kms.

For the past year, the vehicle would intermittently stall at intersections, so I replaced the EGR valve. After about 4 months the stalling would return, so I cleaned the EGR and it would be good for another 4 months.

In August, got the cat removed because it was clogged and replaced the resonator because it had holes. Was told this may help eliminate some back pressure and help with the EGR problem and also not use as much oil.

Shortly thereafter the CEL came on but the car still ran fine. Replaced Air Intake Tube, Air Filter, and cleaned MAF sensor with CRC cleaner.

Then the stalling started again, so I cleaned the EGR valve, which didn't help this time. I replaced the PCV valve, checked for vacuum leaks, tested the TPS and IAC. Not sure about the IAC, as the voltmeter test was good, but there is no change in the idle when I disconnect it??

Bought a simple code reader and I have been getting P0170 codes throughout, with only one P0505 (IAC).

Then I took the Throttle Body off, cleaned it with Sea Foam, replaced the fuel filter (devil of a place for a fuel filter!). I did not touch the stop screw or adjust any other screw, but now the idle starts high ~1200 for a few seconds, then drops to 1000, for a second then to about 850 (used to be around 750).

Took the TB off again and replaced the IAC with a cleaner used one from ebay, and no change. Cleaned MAF and EGR again.

Grasping at straws I did half a bottle of Sea Foam in the Intake, and a new rotor and distributor cap. Plugs were replaced not too long ago and they are not wet and sooty, but look pretty good.

Sprayed carb cleaner all around the intake manifold, injectors, TB, to see if idle would change, but nothing.

Then I noticed a small leak in the fuel rail, aha, but hard to find a used fuel rail and got one from the dealer. Checked the injectors with the voltmeter and they were all good, so installed them and the fuel pressure regulator with new o-rings. Cleaned the TB again. Didn't help the idle at all.

Now the idle is really hunting and the needle bounces on the tach from 1000 to 1500 or so for a few seconds before it settles down to around 850.

The concern is that this behaviour leads to stalling and not being able to keep the car running at intersections, i.e. safety issue.

Any ideas? Thanks!

 

Was allowed to speak with a Tech at the dealership and he couldn't help much, except say that some of the later Protege's had trouble with their EGRs and had to get them retrofitted.

Should also mention that I installed a new O2 sensor a few years ago, and got a new timing belt when the water pump was installed.

 

Found this on a 2005 post from babyhuey:

"If it is a manual trans then also look at the clutch switch signal for the PCM. Faulty switch can cause the intermittent stall or low idle condition when coming to a stop..."

 

k there is a hose that goes from the top of your motor to the intake i know there has been alot of issues with this hose i would check there first cause honestly to me this sounds like a vaccum hose problem cause it might not be a crack in the hose but any hose with an indent when it has pressure running through it, the hose with clamp shut causing your rpm's to flucuate so i would even check the pvc hose not the valve the hose itself that runs to the back of your motor, are you running an after-market intake? and have you had your battery unpluged for longer than 20 min recently?

 

Thanks darkstar, I have tried to check all the hoses because I know vacuum leaks are hard to find.

I found out today that in order for the P0505 (IAC valve) code to appear, you have to at least 2 times have your wheels straight and your foot on the brake for at least 14" while the car is idling.

I did this and the light came on almost immediately, so I read the code and I got a P0170 and a P0505. I am going to bite the bullet and get a new IAC from RockAuto.com (the only place I could find one online, and about half the dealer price here!).

Car is stock and yes battery has been unplugged many times for a lot longer than 20' :-(

 

i have a 1997 mazda protege thats been running rough... the rpms would start reving and then it woul stall when i put it in drive. then it even statred stalling in park i had 4 codes come up0 p0140,p0170,p0455,p0300... i changed my intake hose yesterday and cleaned out the part it was connected to with carberator cleaner and it was still running rough.. but it didnt stall in park and the rpms didnt rev... this morning i went out to start it up and it wont even star the engine turns over but it wont start. im thinking i might need to change my fuel filter but i dont think that would cause the car to not start... im also 5,00 over do for an oil change idk if that matters any advice???

 

meggers:
I think you need to check for the typical vacuum leaks first.
Intake hose, the rippled section. this hose develops cracks. Bend and pull it so you can see the cracks. When the engine shakes the cracks open and let extra air in.
The vacuum hose from the back of the intake plenum to the EGR boost sensor (should be called MAP sensor for manifold absolute pressure) should be pulled off and then you can use a strong wire to push into the nipple. The nipple cakes up with deposits.
Check PCV system.
Clean MAF sensor.
Clean the throttle body again and make sure the EGR ports are open.
Check the ignition system. If in doubt replace plugs, wires, Distributor cap and rotor.
Check fuel system. Fuel pump and fuel pressure regulator. Unless you put crap into your tank the filter should be o.k.

 

I have a 1997 protege too with the 1.8l I have the same problem I have cleaned the throttle body, IAC valve and the EGR valve. It also had the P0505 code I'm stuck on this too

 

Willie: I don't have specific experience with the P0505 code. I suggest you google for the code and don't limit your research to your specific model. I would be looking at all Mazda related posts because they are very similar in design.