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BoomGoesTheDynaMitt
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7,180 Posts
Discussion Starter · #1 · (Edited)
Yesterday I started my car using a nonprogrammed key. The car started and immediately shutdown as it should have. I started it 3 or 4 times before realizing I was using the wrong key. I went and got the programmed key and fired the car up with no probs. During my drive to work the SES came on and the car seemed to loose a little power during lower RPMs.

Codes listed:
P1610 (Immobilizer code)
*makes sense due to usng the wrong key
P0300 Random/Multiple Cylinder Misfire Detected
*this explains the loss in power

I cleared those codes. Then yesterday on my way back to work (after lunch) I got 2 codes:
P0300 Random/Multiple Cylinder Misfire Detected
P0139 O2 Sensor Circuit Slow Response (Bank 1 Sensor 2)

Any idea what I should check for with the P0300? The distributor/rotor, plugs, and wires were all replaced within the last 10K miles. All I can think to do is to check/replace the spark plugs again.... Has anyone ever gotten a P0139?? I searched and the only thread showing that code was the "OBD-II codes list". I'm not sure what could cause an oxygen sensor to have a "slow response" and the wiring still be good/intact. Maybe just the sensor on its last legs??

I am really wondering if the P0139 could have caused the P0300. Seems unlikely as that relates to a rear O2 but figured it was worth asking. If you have any tips or suggestions please advise!

BTW, we have gotten a lot of rain latey but I have NOT driven though any puddles. I'd be amazed if this was related to a wet sensor. Oh, and after installing a CF hood I unplugged the hoses from my sprayer nozzles. I have NOT plugged them with anything or disabled the sprayer motor yet. Could that have caused a vacuum leak and thus caused an SES code? :scratch:
 

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(b)org banugee
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4,549 Posts
The downstream sensors have nothing to do with your fuel trims. It's annoying, but harmless. It's probably was close to going and got a bath in fuel either from the immobilizer cutting in or from the multiple misfires.
 

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BoomGoesTheDynaMitt
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7,180 Posts
Discussion Starter · #3 ·
The downstream sensors have nothing to do with your fuel trims. It's annoying, but harmless. It's probably was close to going and got a bath in fuel either from the immobilizer cutting in or from the multiple misfires.
Do you think this may clear itself up on its own or that I should replace the sensor? My drive to work this AM was fine, no bogging or SES codes. I imagine if they are going to come back then they will on my drive home this evening.
 

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(b)org banugee
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4,549 Posts
The downstream sensor is just there to nag you about your pre-cat if it isn't working or is removed. The only way to eliminate the code is to replace the sensor, but it is not the source of the other issues you are having.
 

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4,097 Posts
i have the po139 sensor issue, and my fuel mileage sucks! i had it replaced last month, and about a week ago the check engine light came on. same code...
 

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BoomGoesTheDynaMitt
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7,180 Posts
Discussion Starter · #6 ·
Thanks for the posts guys. I drove home for lunch and immediately got the following:
P0139
P0300
P0455

I had had the P0455 for awhile but its been cleared for atleast 2+ weeks until today. I clicked the gas cap few times but I don't think its related to that as I make sure to tighten the cap ery well after each fill up :dunno: I had replaced the EVAP solenoid (near the manifold) a few months ago too (with a used one).

I guess I will check the spark plugs tonight to see if any oil has collected in the tubes. Seems weird that would have happened bacause I replaced the oil/tube seals a few months ago.

In case this helps here is some more info. The car starts fine. It seems to idle fine. When I 1st got to drive off it will "skip" (misfire I assume) a little have it has decreased power. I can floor it and it still doesn't have much power. Once I get to about 3.5K-4K RPMs the power comes back and the car takes off like a bat out of hell. This continues for about 5 minutes. By the time I get close to my destination the power has come bak and no misfires are obvious. The P0300 still stays though.

So what should I check to diagnose the P0300? All I can think of is:
-oil in spark plug tubes
-spark plug wires not seated properly
-damaged/worn/dirty spark plugs

Anything else? I guess if none of those is the culprit then I should check the internals of the distributor?

This really pisses me off because I haven't done any work on the car lately other than installing a new hood.
 

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(b)org banugee
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4,549 Posts
i have the po139 sensor issue, and my fuel mileage sucks! i had it replaced last month, and about a week ago the check engine light came on. same code...
Your fuel economy is unaffected by the P0139 code.
 

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95 Posts
I'm not sure how relevant this is, but I've recently been attempting to swap my fed spec ECU to a flashable one. During nicer weather the car ran great and code free with the new ECU, but a couple of days ago I was driving during a nice hard rain and got the same symptoms as you. The same exact codes (as well as another or two regarding no response from the o2 sensor) and a car that bogged and ran so poorly that I ended up stopping and reswapping my ECUs (with the original ECU the car ran great and code free). I'm not sure exactly what caused this, but it seemed directly related to the rain in my case.
 

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BoomGoesTheDynaMitt
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7,180 Posts
Discussion Starter · #9 ·
So I am in need of some more guidance.... I am still getting 3 codes and can't seem to pinpoint the problems.
P0139 Bank1 Sensor 2 O2 sensor slow to respond.
P0300 Random Misfires
P0455 Gross vac leak in evap/fuel system. (I think).

P0139:
I have ohmed out the O2 sensor. No shorts. Resistance measured at 3.96. Very close to spec which is 4-6ohm. I guess I still need to replac it with a new one :( :dunno:

P0300:
I have replaced leaking spark plug tube seals. I checked all the spark plugs and they seemed ok (not corroded, no gapping as they are platinum). They have fewer than 5K miles on them. They are NGKs. I have reseated all 6 Magnecore spark plug wires. They seemed fine and have less than 3K miles on them. My rotor and cap were replaced within the past 15K miles (probably much less than that). I have heard the crankshaft position sensor can cause a P0300... any truth to that? Any thoughts on other parts to test or try replacing? I'm about to make a car parts order so if there is anything else I should try I would love to hear it.

P0455:
I can only assume this is from a faulty Evap purge solenoid or a bad vapor canister. I guess I will try rplacing both. The FSM also states a bad EGR could cause this so I plan to test and possible replace mine.

Anything else I should look at? I've had these codes for awhile and am getting to the point where I am ready to start throwing money at the problem :twitch:
 

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Relapsed.
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P0300 was my crankshaft position sensor, thing is my 3g still throws the code but starts up and drives fine.
 

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BoomGoesTheDynaMitt
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7,180 Posts
Discussion Starter · #11 ·
PROBLEMS SOLVED
So I wanted to let everyone know what had caused my issues and how I fixed them, just in case someone else searches for these codes in the future...

For my P0300 - I replaced my spark plugs and my plug wires. The code came back on occasion so I reseated the wires onto the distibutor. Problem solved.

For my P0139 - Holy fucking hell... this was a doozy:devil:!!! I replaced the B1S2 sensor. Code came back. I then dropped my Y-pipe to discover a piss poor welding job had left some pinhole air leaks right next to an O2 bung. I had the bung relaced and the pinholes sealed up. I then replaced my rear O2 mechanical sims and ensured that they were snug against the header piping using crush washers. previously I used 2 nonfoulers stacked on top of each other which pulled the sensors WAY outof the exhaust stream. This time I only used one nonfoulerper sensor. I also replaced some old looking exhaust gaskets (collector and catback gaskets). Codes are now gone! God it feels good....
:wackit:

I believe the P0139 was mainly related to an exhaust leak close to that sensor (whether it was from a bad gasket or poor welding I'm not sure but I tend to think it was from the welding).

Many many thanks for everyone's help. Without your suggestions I probably would have ended up lighting this car on fire!
 
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