Okay, I am really getting sick of this. Give it your best shot if you have any ideas.
And firstly, yes, I have read basically every thread regarding the poor design of the Protege5 EGR and plug/coilpack setup.
About two years ago, I had a problem with stuttering on my 02' Protege5. I changed the coil packs and wires and cleaned the EGR. Problem solved, though I can't remember which of the two fixed the problem.
Then the stuttering came back, particularly when I was coming to a stop. My car was throwing P0300 and P0421. I waited until the problem got really bad. I drove around with the problem for a good six months, maybe more. As in, stuttering so bad it started stalling out and I had to keep my foot on the gas at stop lights to keep it from dying. I eventually took it to a decent mechanic and we basically just ran the car at idle in the garage and waited for it to happen. The mechanic, not being a Mazda specific guy, didn't see how it could be an EGR, but I told him that the EGRs on our cars were notoriously bad. He went ahead and checked the voltage on the front and rear 02 sensor and they appeared to be functioning properly. He wasn't sure what was going on and I needed the car, so I didn't leave it with him.
I ended up ordering the Canadian recall EGR (with the coolant lines) as well as a cheap eBay cat that I planned to put on so I could pass emissions which were coming up. I installed the new EGR, reset the codes, and noticed no problems for a few weeks. I went and did my state emissions test and looked at the results and I passed with ease. To me, this said that my catalytic converters were still quite good, despite driving around with a potentially faulty EGR for a really long time, which people on the forums said we shouldn't do. This doesn't appear to have fouled up the cats from an emissions perspectiv and if the cats aren't clogged to hell, then the stuttering problem is likely something else otherwise I never would have passed.
Anyway, about a few weeks later, the codes came back, but with an additional one, P0660 regarding VICS. Car still runs fine 99.99% of the time (I'll get to the .01% further down). I checked the connectors that I would have undone to install the new EGR and they all appeared to be connected properly, and I know that a lot of people get this code, particularly on Mazdas, but with even greater frequency on Protege5s than other cars. I looked back at the wires/coils.
I checked the resistance of the two plug wires and compared them to a set of fresh factory plug wires that I had bought for comparison reasons and they were reading exactly the same. Did this with the two coil packs as well, however, because of the nature of our cars, I cannot do a visual inspection for arcing because of how the plug boot sits inside the engine for two of the cylinders. I also didn't have a reliable way to test the resistance of the plugs under actual load and cannot think of a way to do so on this particular car. At this point, the plugs are a few years old and I cannot remember if replacing them the last time fixed the problem or if it was the cleaning of the original EGR that fixed it.
I reset the codes for "fun" and they came back. My car started the running rough once at high altitude (11,000 feet or so on a descent) and the check engine light began blinking, but this stopped after a few minutes and power resumed back to normal, but the three codes remained.
I ask this. What is with our cars? Why do so many of us get the P0300/P0421/P0660? It seems that we suffer from this problem with a much greater frequency than other manufacturers. Has anyone formulated any ideas about what might be causing this? I am leaning toward "maybe" plug wires/coils again and I guess possibly the pre cat, but that is a $700+ part even through mazdaonlineparts and I need to be sure before dropping that kind of wad, plus passing the emissions test so easily makes me think it isn't that.
This is frustrating. Should I take it to a dealership and hock up the $100 for a potentially worthless diagnostic?
And firstly, yes, I have read basically every thread regarding the poor design of the Protege5 EGR and plug/coilpack setup.
About two years ago, I had a problem with stuttering on my 02' Protege5. I changed the coil packs and wires and cleaned the EGR. Problem solved, though I can't remember which of the two fixed the problem.
Then the stuttering came back, particularly when I was coming to a stop. My car was throwing P0300 and P0421. I waited until the problem got really bad. I drove around with the problem for a good six months, maybe more. As in, stuttering so bad it started stalling out and I had to keep my foot on the gas at stop lights to keep it from dying. I eventually took it to a decent mechanic and we basically just ran the car at idle in the garage and waited for it to happen. The mechanic, not being a Mazda specific guy, didn't see how it could be an EGR, but I told him that the EGRs on our cars were notoriously bad. He went ahead and checked the voltage on the front and rear 02 sensor and they appeared to be functioning properly. He wasn't sure what was going on and I needed the car, so I didn't leave it with him.
I ended up ordering the Canadian recall EGR (with the coolant lines) as well as a cheap eBay cat that I planned to put on so I could pass emissions which were coming up. I installed the new EGR, reset the codes, and noticed no problems for a few weeks. I went and did my state emissions test and looked at the results and I passed with ease. To me, this said that my catalytic converters were still quite good, despite driving around with a potentially faulty EGR for a really long time, which people on the forums said we shouldn't do. This doesn't appear to have fouled up the cats from an emissions perspectiv and if the cats aren't clogged to hell, then the stuttering problem is likely something else otherwise I never would have passed.
Anyway, about a few weeks later, the codes came back, but with an additional one, P0660 regarding VICS. Car still runs fine 99.99% of the time (I'll get to the .01% further down). I checked the connectors that I would have undone to install the new EGR and they all appeared to be connected properly, and I know that a lot of people get this code, particularly on Mazdas, but with even greater frequency on Protege5s than other cars. I looked back at the wires/coils.
I checked the resistance of the two plug wires and compared them to a set of fresh factory plug wires that I had bought for comparison reasons and they were reading exactly the same. Did this with the two coil packs as well, however, because of the nature of our cars, I cannot do a visual inspection for arcing because of how the plug boot sits inside the engine for two of the cylinders. I also didn't have a reliable way to test the resistance of the plugs under actual load and cannot think of a way to do so on this particular car. At this point, the plugs are a few years old and I cannot remember if replacing them the last time fixed the problem or if it was the cleaning of the original EGR that fixed it.
I reset the codes for "fun" and they came back. My car started the running rough once at high altitude (11,000 feet or so on a descent) and the check engine light began blinking, but this stopped after a few minutes and power resumed back to normal, but the three codes remained.
I ask this. What is with our cars? Why do so many of us get the P0300/P0421/P0660? It seems that we suffer from this problem with a much greater frequency than other manufacturers. Has anyone formulated any ideas about what might be causing this? I am leaning toward "maybe" plug wires/coils again and I guess possibly the pre cat, but that is a $700+ part even through mazdaonlineparts and I need to be sure before dropping that kind of wad, plus passing the emissions test so easily makes me think it isn't that.
This is frustrating. Should I take it to a dealership and hock up the $100 for a potentially worthless diagnostic?
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