Please help diagnose codes... 2001 LX 2.0

Jasonhouse

Member
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01 Protege LS 2.0 Auto with a/c
Hi, have an '01 Protege LX 2.0 with a bit over 150k miles on it. Put maybe 2-3k miles a year on it for the past couple of years while trying to heal from a serious spinal injury. Just now getting well enough that I'm trying out a PT job, so naturally this when the car needs a repair.

It has had a CEL for several thousand miles for one of the O2 sensors. Since this affects mileage and I barely drive (and am super low budget for now), I didn't really care.

However, a few months ago, the car took on a new behavior, the famous rat-a-tat rattle noise on startup, which also comes with partial throttle at any speed above say 40mph. This included the typical intermittent chugging/sputtering/weakness, at idle and until the car throttles up to say 2000rpms or more, and then sort of 'kicks' in to having what feels more like normal power... Again, I read about how this is usually from the VICS or the combustion optimization feature (I forget the acronym for it) having issues, and isn't good for the car in the long run, but isn't like a dire issue. Since I'm disabled and not working, I couldn't fix it, so I just cut my driving back to necessary trips for like groceries or the doctor...


So then the other day I drove it a mile to the grocery store, and it threw new codes that made the CEL flash, and now the weakness at idle/low rpm is constant, and doesn't go away at higher RPMs. I know a flashing CEL is potentially bad news, so I gently drove the car home on side streets and parked it.


Had a buddy pull the codes, this is what I've got.

P0140 - Oxygen sensor circuit. no activity detected. Bank 1 sensor 2
P0031 - Heated oxygen sensor heater control circuit low. Bank 1 sensor 1
P0037 - Heated oxygen sensor heater control low. Bank 1 sensor 2
P0301 - Cylinder 1 misfire detected.
P0303 - Cylinder 3 misfire detected.
P1569 - Intake manifold runner control circuit low
P0660 - Intake manifold tuning valve control circuit open. Bank 1


All I have done so far is pulled and replaced the plugs, which appeared to have normal wear, and no difference in wear between the 4 cylinders.

I haven't tested any of the ignition wiring yet, but the coils didn't smell burnt out, and a visual check the various wires showed no obvious issues. Coils, wires and plugs were last changed about 40k miles ago. (I have a multimeter)



Any insight from past experience on what it could be? Please help!
 

agr99

Member
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1999 mazda protege
Dang..lots of codes. If plugs are gaped properly, and plug wires are on tight to plugs and coils(sometimes they don't go on all the way with autozone plugs), I believe cylinder 1-3 share the same coil, so try switching the coils around and see if you get misfire 2-4, if it happens replace that coil. Than maybe do a pressure test?

Sent from my 0PM92 using Tapatalk
 

Jasonhouse

Member
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01 Protege LS 2.0 Auto with a/c
All I've done to it was changed the plugs, because I already had them.

Not easy for me, as I mentioned I'm recovering from a serious spinal injury (more like learning how to deal with nerve damage in my writing arm that won't ever go away). I was basically wiped out the past couple of days because I overdid it with yard work.

I would just pay a shop $50 to tell me what's wrong with it. but I'm super low budget. Don't want to waste $50 if I don't have to. Same with the O 2 sensor, I would drop the $60 to get it, but will it actually make the car stop misfiring?

I'm concerned that this is being caused by an issue with the injectors. There was work on them like 60k miles ago, but I don't remember if they were replaced or cleaned or what. Or maybe something with the cat being fouled, since I neglected the O 2 sensor issue for a length of time. But IDK how that affects just two cylinders.

I also read where cylinders 1 and 3 receive the negative charge from the coils directly mounted on cylinders 2 and 4, but didn't understand how that may indicate another issue, perhaps with the car's computer.
 

Jasonhouse

Member
:
01 Protege LS 2.0 Auto with a/c
So I had some time to mess with this car a little... Plug wires had looked fine, but I tested them and they had very high resistance and on closer inspection had charring deep in the sockets for the plugs. I removed coils to bench test them, but my multimeter's prongs are too short to reach where needed to test the windings. Gah.

I went and bought new wires... Installed the wires, fired up the car and it feels like it has no more misfiring. However, clearing codes by pulling negative cable did not make flashing CEL go away, so I'm gonna bust out the spark tester, now that I have a car that at least feels like it's running on 4 cylinders, not just 2. Car of course still has the racket that comes with VICS not working right and so on... I'm going to have codes pulled again, see if they've changed (should be no more misfire codes hopefully).

Now that I've read a bit more and feel like I won't destroy anything, I'm going to pull and test the fuel injectors (with new o-rings on hand). Get a better set of wires/prongs for my multimeter and test the coils, replace them if they're out of range. PCV felt functional, but had a fair bit of oil, so that's an easy $4 fix.

Hopefully it's not the cat, because IDK if I can get the access I need with what I've got.
 
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