420A Losing Power, Sputtering, P0300, P0301, P0304 CELs Need Help!

[Abob]

I've done some searching on here to try and find out what is going on with my car but I just can't seem to find anything similar.
My car is running like crap cruising down the road. It starts fine but when I start going it goes to crap. I pulled a few codes, p0300, p0301, p0304, and a couple evap ones. One was no flow and the other was small leak.

Anyway, it doesn't do it all the time. It will be fine for a few days or more, then go crappy for awhile. Back and forth like that. Sometimes it will do it when I start out, like the start of 2nd gear, then go away. Sometimes it won't go away for awhile. Other times it will do that when I'm cruising in 5th gear on the highway or no matter what gear or speed. It seems to loose power, and just run on 2 cylinders. Sputtering, spitting as well as the check engine light flashing at me.

I have changed plugs, wires, coil pack, and check the fuel filter ( its clean). I've been told of a few things have beendone to the car such as exhaust, header, cams.

 

[Abob]

I might have to hit up the junkyard this weekend and go crazy with some parts Lol.

If I were to replace the PCM, is there anything I should look for specifically

 

[We're on Boost]

I believe code 17 is from my thermostat. The PO put a fail safe thermostat in the car, so if the car gets to hot it sticks open. I didn't realize they made such thing. Lol. I reset it and have since ran at normal temp. Although that stupid thermostat doesn't take much to stick back open.

I'm going to start tracing the wires for the coil pack, as well as the injectors. To see if I over looked a bare or broken wire. I am also going to try and get my hands on another coil pack, just to double check it.

I will be ordering my o2 sensor tonight, so I can get it straightened out. I did notice that the plug for the o2 sensor is in the car. Where would in be inside the cab?

Sounds like a good plan here.
That thermostat though, it should never "stick open" for any reason, unless it fails, then it should be replaced.

Here's what I have gathered about thermostats over the years. I classify them in 2 groups. German, and everybody else. In this case, the Germans have it wrong.
In a BMW or a Mercedes, if the thermostat fails, it usually fails closed - it will not open. This of course overheats the engine and all hell ensues, if you don't quit driving the car before it gets too hot. This was bad enough in the old days when the blocks were iron. Now with aluminum blocks it is downright perverse, because in addition to head damage, it can pull the female head bolt threads right out of the block. Ding dong.

With Japanese and most other cars as far as I know, when the thermostat fails, it fails open, so that your car probably won't overheat, but it probably won't get up to normal temperature either. So you still need to replace it of course, but at least you can drive home first, or even drive it for a few days if you need to.

I would get a new thermostat, not from a junk yard, but you don't need to buy it from a dealer either. Something from a local parts house should be OK. I think.

Something we need to check into which I haven't done yet, some cars have 2 coolant temperature senders. One sends to the gauge on the dash, the other sends to the ecu. I don't know yet if your car is this way.
What can happen is this - Let's say the thermostat is good and the sender that sends to the gauge is good and the gauge is good. The engine will get up to normal temp and the gauge shows normal temp and everything should be ok, right? Well if the sender that sends to the PCM is bad, your PCM will get bogus input about the temperature, and then it does wrong stuff that could make your engine run bad.

 

[Abob]

I have noticed that if I mess with the CTS wires my gauge in the car goes to zero. If I mess with again it comes back. I will always buy new thermostats

On another note. It got up to 50 some degrees out today compared to the average 30 something. My car ran like it never had anything wrong with it. Full rpm range, no sputtering, no nothing. Ran just as smooth as could be.

 

[We're on Boost]

I have noticed that if I mess with the CTS wires my gauge in the car goes to zero. If I mess with again it comes back. I will always buy new thermostats

On another note. It got up to 50 some degrees out today compared to the average 30 something. My car ran like it never had anything wrong with it. Full rpm range, no sputtering, no nothing. Ran just as smooth as could be.

Aha! Both observations meaningful!

Wiggling the wires making the gauge go to 0 - That sounds exactly like the experience I described with a connector that was making marginal contact (up in post #6). The marginal contact is likely due to the female part of the connector relaxing with age and not gripping like it should. But it could also be due to light surface corrosion on the metal contacts in the connector. Or possibly a broken wire. There is supposedly (sometimes) a way to take those connectors apart without destroying them, but I've never tried it. It is described in the factory shop manual. I could post those diagrams if you want to try it. When we had the problem on our car, we went in there with a tiny screw driver and bent the female part a little bit to make it closer together. Before that we put a tiny piece of aluminum foil in there to kind of shim it, just to verify that was the problem. That worked, but only for 2 or 3 days, then the foil burnt through or something.

Anyway, your car does have separate ECT senders for the PCM and the temp gauge. In fact if your car has A/C you might have 3 ECT senders!
So the wire wiggling thing, if that is only on the one for the gauge, that is not the signal going to your PCM.

But your ECT sender that goes to the PCM could have that problem too, or it could be just bad, worn out. That, I think is suggested by the improved warmer running in warmer weather! Or, wait a minute, that could suggest the problem is thermostat sticking open, or it could suggest the AIT (air intake temperature sensor) is bad.

Well, I'm going to post these words before they get blown away by some solar mass ejection or something, then I will add pictures of what the manuals say about the ECT senders.

First, some stuff about the ECT sender for the gauge. The diagram is very poor but it's all I could find for this sender:

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Now the good stuff - ECT sender for the PCM. Notice the part about how when this sensor is bad, the PCM defaults to 176 deg F, which is not so far off when the engine is warm but is way off when the engine is cold!

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Below, a few pics of the sender that goes to the PCM:

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Unplugged:

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Removing with deep socket:

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They do also give tests you can do on the senders using an ohm meter. I can post those if you want. Most of these pics are from the Chilton manual # 50400. A few are from the official shop manuals, but my copy of the shop manuals is sometimes pretty poor.

 

[Abob]

OK so I've played with the wires to the coolant sensors and found that the one to my gauge has a loose wire. The other to the pcm seemed to have a loose connecting. I'm hoping this and the o2 fixes the problem.

Now all I have to do is wait for it to gets cold again. Its suppose to be 60s over the weekend. Lol

 

[We're on Boost]

Sounds good. Hopefully if it doesn't, it will be something that we've covered.

One thing that could fool ya if you are still running the old thermostat. If that thermostat has been goofy for as long as you've owned the car, you might not really know where "normal" is on the gauge.
It looks to me like the coolant cap is pretty much at the high-point of the cooling system, so you could take it off without loosing coolant. You could take the cap off while the engine is running at idle just after a cold start, so there is no pressure in the system. Stick some kind of cooking thermometer in there (an accurate one). Watch the water in there so you can see when it starts to flow. That is when the thermostat is starting to open. Check the thermometer and look at your gauge. The thermostat should start to open around 190 deg F, I think, although I couldn't find any number for that. I don't think you'll lose much if any coolant doing this. Normal operating temp is probably about 204 deg F. You might be able to let it get that hot without boiling or burping out of the opening. Having the normal 50/50 mix of water and antifreeze helps, because it raises the boiling point. I would put the cap back on while it is still hot so the system can pull coolant out of the overflow bottle as it cools down.

When I did this test on my 1g, it was to check not only a new thermostat, but also to see if my logger (ecu+) would show temperatures really close to what the thermometer showed. It did, within only 3 or 4 degrees, as I remember. So those senders can be really accurate.

 

[Abob]

So it got cold here again. It seems to run good at idle and drive normal. Now it spits and sputters around 4000-4500 RPMs. As well as looses power, like it hits a wall and stops pulling. Almost like I'm at the rev limiter

 

[We're on Boost]

When it hits the wall, does it recover and pull normally the rest of the way up through the revs if you keep your foot in it, or does it just keep running bad?
Does it do this only before the engine is fully warmed up, or only after the engine is fully warmed up, or both?

BTW, Merry Seasonings!

The section about the Intake Air Temp sensor in the Chilton manual sounds very promising. Note where it says "The driveability of the vehicle may become poor during cold temperature operation. The trouble may not be noticeable when the ambient temperature is around 77 deg F."

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Gotta post the next page too, for 2L non-turbo testing:

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[Abob]

It seems to stay the same or get worse when I keep into it or give it gas. The temp of the motor does seem to matter. It does it either way.

It has a cold air intake on it with actual pipe. I know it doesn't have an IAT sensor. I wouldn't even know where the plug would be. Lol

Merry Seasons to you as well

 

[We're on Boost]

Ah yes, the old modified by the previous owner problem.
Never fear, I'm pretty sure you have an IAT, and if you don't, that's the problem! And if there's no IAT and there is a cold air intake, that would make the problem even worse than just not having an IAT, because the intake air would be colder, and there'd be no compensation for it.

Look at Fig 68. That shows the IAT on the back side of the intake manifold plenum. That puts it pretty close to the firewall. If you still have a stock intake manifold, that IAT should be there. The cold air intake/air filter stuff is somewhere else entirely and would not remove that IAT.

In Fig 73 you can see a guy's hand unplugging the IAT, looks like his hand is right up against the firewall. Not much room for putting ohm meter probes on it back there, but it looks like once you get the connector off it should be easy to take the sensor off with an open end wrench, like in Fig 74. Then you can check it with an ohm meter like in Fig 72. The other figures are for other engines.

On the next page, which I didn't post, it gives the tightening torque for the IAT sensor. It is only 5 ft-lbs, not very much. It does say to put Loctite 24200 or similar on the threads when you put it back in. I think Loctite 242 and Loctite 24200 are the same thing.

The temp of the motor does seem to matter.

If the temp of the motor does seem to matter, then does it run better after it's been warm for a while, or worse?

 

[Abob]

Definitely the modified by the previous owner is a pain. All I know is what I was told Lol. I'd rather build it myself so that way I know what is in it.

I overlooked your post. Lol. I do have that sensor in the plenum so I am going to have to take a look at it. It also doesn't help I get the pop up ads on the pictures that are posted.

The car doesn't seem to be affected by how warm or cold the motor is. It does it regardless. I did notice once I cleaned the CTS wires and connections that my car revs up higher on a cold start. It use to idle around 1000 but now its closer to 1800 or so until it warms up.

 

[We're on Boost]

Hmm that change in cold start idle speed is interesting, like the cleaning did some good. 1000 rpm is definitely too slow for cold idle speed, and 1800 sounds about right, until it's warmed up.

On the pictures - I don't know why you would get pop-up adds on them, what the heck? The way they are supposed to work is like this: You first left-click the yellow bar that runs across the top of the pic. That opens up the pic in a new window. But since these pics are huge (pixel by pixel count is huge) they are still reduced size. So when you hover over the pic with the mouse you should get a + sign, then you left click again and it will jump the pic up to full size. Then you should see it in its full glory. Some of these are 1640 pixels tall by 1252 pixels wide. They look better on the screen then they do in the darn manual!

Actually though this Chilton manual is pretty good. The Haynes manuals are good too. People like to rag that the official shop manual is better, but actually these aftermarket manuals are a lot easier to use, especially for trouble shooting, and they explain things better. I would get both the Chilton and Haynes manual for this car if you are going to keep it for a while. The Chilton covers 90-98 Eclipse and Talon all USA and Canadian.

are the pop-up adds coming from Image Shack? I don't get pop-ups but I'm a registered Image Shack user. I wonder if that is the diff?

 

[Abob]

So its slowly working out. The idle issue, running rich and stuttering during driving have been fixed. New post o2, another coil pack, and wires seem to have straightened out a lot.

Now I just need to figure out why it stutters and acts up under WOT. the sad part is if I give it 3/4 throttle its nowhere near as bad. I'm thinking I've got a bad fuel filter and possible a fuel pump going out or clogged

 

[We're on Boost]

Hmm, sounds like the traditional DSM fix. Just fix everything in sight.

I suppose that if the problem is worse the closer you get to WOT, if would make sense that it could be a fuel filter or pump.

I remember a while back you asked for tips on buying a used pcm. One thing worth trying is a PM to MY1GDSM who is a member here, and ask him if he has any opinions about how to buy a used pcm. He tunes eprom chip ecus for people. He might also repair used ecus, might even have one on hand, I don't know.

If I had to go with a web search for a used pcm I would probably pick one like this:
http://automodulesourceusa.com/1997-mitsubishi-eclipse.html

 

[Abob]

Cool. Thanks for the info