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420A 2gNT 1999 Mitsubishi Eclipse Misfiring

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TheRock0720

10+ Year Contributor
246
0
Jan 5, 2011
Southern, New_Hampshire
Well I started my car and it took a second to start (longer than usual) (and its about 19 degrees ouside, its winter). I let it warm up to running temperature and I drove down the road until I got till the end of my road and aproached the street, I stopped and as I pulled out my cars RPMs dropped and it ran like crap. Its the samething that happened before and we thought it was the Cat (which we just replaced the day before). But before the cars RPMs would only drop when we put it in gear (Drive), but reverse would be okay. Now, its running rough and what not in any gear (Park, Neutral, Drive, Second, First).

The car has no power what so ever, it can't handle any kind of load.

I had to get it back home, so I let it sit for a little so the car could cool (which I did before and that worked), but not this time. The car was smoking and smelt so bad (kind of like oil burning). I started it and it was running at 100 RPMs, and I would give it gas (almost all the way to the floor) and the car would only move like 2 inches. Also, when the car is running the Check Engine Light flashes (when the car is running like it was).

I noticed that it seems to misfiring very bad, the check engine light flashes when the car is running some of the time. Also, the tailpipe smells of strong gasoline.

I checked the plugs and wires and they are in perfect condition, but the plugs smell like strong Gasoline.

Here is a video that I recorded so you could get a taste of what its like.

1999 Mitsubishi Eclipse Misfiring

Things replaced:
Spark Plugs and Wires
Cat Converter (replaced with Walker Brand Direct Fit)
Air Filter
Oil (Mobil 1 Synthetic 5W20)
Lucas Fuel Injector Treatment (into gas tank)
Serpentine Belt
 
is it just me or do you guys also here a knock? Best/easiest thing to do is get you CEL checked, find out if you are really misfirng or have a worse problem. If it is a misfire find out if its multiple misfires, or certain cylinders. If its certain cylinders, try moving things around (plugs/wires, fuel injectors etc) to see if the problem follows it.

Also just for the hell of it, check your compression and oil (to see if its a milky color) then report back here after all that and we will see what we can do for you
 
Yup^^

You got at least one cylinder not firing, but you gotta find out why. Use what fotown said to narrow it down.

The knock noise could be a lot of things, not the least of which is that a cylinder (or two) is not firing. But don't freak out yet. It could easily be something simple and from what you describe, it sounds like something electrical. Doing the comp check just helps us to rule out stuff.

MB
 
compression check would also check head gasket. do that first
then when the car is running like that take out and plug back in each spark plug wire. if the car runs worse than that cylinder is working, if you take out a spark plug wire and there is no change that means that cylinder has a problem, from there check spark/fuel (you already checked compression).

check spark by taking the spark plug out and holding the wire only and have someone crank the engine, you should see spark. if you do then your problem is fuel. if you dont see spark back trace the power, spark plug, spark plug wire, coil, etc

keep us updated
 
Don't think anyone's mentioned it yet but test your coil pack too.

Alright, well I ran the code reader and I got the following 7 codes :/

P0505
P0351
P0300
P0420
P0301 (pd)
P0304 (pd)
P0300 (pd)

---The pd is a symbol I got on my reader next to the code, which I don't know what it meant...

I don't know what these codes mean, so if anyone can help...please
 
There's a thead on here for all the codes. But I will go looking in a minute for them. I know the P0300 is a multiple misfire (which is obvious your misfiring).

301 and 304 mean that cyl 1& 4 are misfiring.

351 is has to do with coil #1 being faulty, 505 has to do with the IAC (could be bad ecu or bad IAC), 420 is for the o2 sensor- when you replaced the cat did you actually put a new cat in or a test pipe?
 
1 and 4 are misfiring.

Crank it up and while its running pull the number 1 wire off the coil pack. hold it close to the electrode on the coil pack and see if you get spark to jump to the wire. Do the same thing to number 4.
 
I don't remember a whole lot from my friends old 420a, but aren't 1/4 on the same coil pack, and 2/3 on the other?
 
Alright thank you!

We actually put in a Walker Direct Fit Cat (cost $$$).

So what would a bad IAC cause symptom wise?

There's a thead on here for all the codes. But I will go looking in a minute for them. I know the P0300 is a multiple misfire (which is obvious your misfiring).

301 and 304 mean that cyl 1& 4 are misfiring.

351 is has to do with coil #1 being faulty, 505 has to do with the IAC (could be bad ecu or bad IAC), 420 is for the o2 sensor- when you replaced the cat did you actually put a new cat in or a test pipe?
 
Bad IAC will cause a "scavanging idle." Basically your car won't stay at a certain RPM while idling.
 
I am a little Leary of this misfiring issue... I had a 1998 Chevy Lumina once and it had a misfire issue. I replaced the Injector, Spark plugs and wires, Coil Packs, etc and it didn't solve the issue. I know this isn't a Chevy, but I don't know. I know the Lumina had a Head gasket issue (thats why I junked it). I know these 420a motors have Head Gasket Issues too...so hmm
 
Also, last Friday I stopped at a stop sign that was on an incline, I went to give it gas and the car would not go, it felt like it was blocked by a wave of air. It had a very rough and low RPM idle (at around 200 RPM in Drive). I pulled off to the side and put it in park, it ran a little better but still iffy. I shut it off and waited a few. I started it again a few minutes later and put it in Drive and it was still rough and wouldn't go. I let the car cool off for about 30 mins and I started it and it was fine. I made it home safely. We thought it was the Cat, so we replaced that. Issue is still present (as seen in video).

Why would it one day act the way it did and then you would be able to sit and let the engine cool and then try driving again and it would be fine and now its being like this all the time?

Just boggles my mind a bit.
 
I have a similar issue but I get the codes random misfires and ignition coil b primary/secondary.. but it only misfires when its cold when it warms up it runs perfectly fine.. I have changed plug wires, coil, and crank sensor (spark plugs ordered will show up shortly) and it all started around the same time my clutch started to go bad. I haven't figured out much myself I will keep your symptoms in mind when I research
 
Also, last Friday I stopped at a stop sign that was on an incline, I went to give it gas and the car would not go, it felt like it was blocked by a wave of air. It had a very rough and low RPM idle (at around 200 RPM in Drive). I pulled off to the side and put it in park, it ran a little better but still iffy. I shut it off and waited a few. I started it again a few minutes later and put it in Drive and it was still rough and wouldn't go. I let the car cool off for about 30 mins and I started it and it was fine. I made it home safely. We thought it was the Cat, so we replaced that. Issue is still present (as seen in video).

Why would it one day act the way it did and then you would be able to sit and let the engine cool and then try driving again and it would be fine and now its being like this all the time?

Just boggles my mind a bit.

Your coil pack is overheating and dropping cylinder 1 and 4. It cools off and it's fine, then overheats when the engine gets warm.
 
Ok, once you find symptoms of one thing wrong, fix that thing before you move on. You have symptoms of a bad coil. Fix that first.

Just for clarification (though some have already pointed it out, others seem to have a bit more confusion on this); our coils are a "twin" set-up, within one of our coils are two seperate coils. One coil fires the number 1 and 4 cylinders and one coil fires the number 2 and 3 cylinders. By all appearances, you have a problem with the coil that fires the 1 and 4 cylinders (easy check to this was already pointed out. Simply pull the number 1 cylinder plug wire and see if it affects the problem, then do that with 4).

Now that doesn't guarantee that its your coil. It could also be somewhere in the wiring to your coil. But 99% of the time, its your coil (yeah I made up that percentage, LOL. But most of the time....). Common for our cars because of the location of the coil (above the head in a location to accept a lot of heat - like some alternators are prone to go when they are located above a high heat source).

Best/easiest check for this, is to simply install a "known good" coil and see if it fixes the problem. There are procedures to test the coil, those normally require a bit of knowledge (electrical understanding) and the proper tools (multi-tester) and even then the coil could test out OK and still be bad.

Let's see you are located in New Hampshire? You are certainly welcome to come down to Ct and use one of my "known good" coils, LOL. If you were a little closer, I'd shoot up there.

MB
 
Last edited by a moderator:
Thank you! I replaced the coil pack today and the car, she runs great!

Your were right on the money with this one!

Your coil pack is overheating and dropping cylinder 1 and 4. It cools off and it's fine, then overheats when the engine gets warm.
 
I just have to worry about my oil leak thats increased... reminds me of the exxon valdez :ohdamn:
 
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