Ecu swapping. Looked all over and still dont know

[ReckReason86]

Ok so i have looked all over and haven't found an answer to my problem. I have a 96 gs, and i am having problems with a back fire and bucking. I have already swapped out all the sensors and wires and plugs multiple times. The other day i got a hint that it could be my ecu. Now before i go and drop $100+ on a new one i wanna try it out with another. My question is can i use the EDZ ecu from the chrysler 2.4na in my 420na? i can just swap it out but fear hurting something serious. Thanks for your guy's help

 

[islandertalon]

EDZ ecu (if it will even connect) won't work with out rewiring at the very least. It it timed off of a different cylinder, hence the reasoning for switching coil, injector wires, and turning the cam sensor magnet 90 degrees when swapping in the 2.4 bottom end and using the stock (2.0l) computer.

Get the correct computer.

If you haven't already check:
- the wires that are near the egr tubes (by the intake) for melting/frayed wires
- timing

If the head or block have been resurfaced and enough material removed it can cause a random miss fire.

Have you changed the coil?
Does it happen at idle, cruise, or both?
Does it matter if the engine is hot or cold?
Check Engine light on?

 

[ReckReason86]

Ok that makes sense. Yes, i have changed the coil, plugs, wires, all multiple times, also the crankshaft sensor(other problem). I did notice that when i did all those things the problem would either get better or go away temporarily. The reason i think ECU, was because over a weekend i left my battery unplugged, and when i started her back up and drove her, there was no buck or anything, and it went the longest time without showing problems, about three weeks. then sure enough it acted up again slowly. It bucks at cruising not at idle, usually a drop in the rpm's of about 2-300 hundred. No CEL, or anything else other than a rough idle at times when warmed up, but i think thats a vacuum leak i havent found yet.

 

[GSX77901]

Try your o2 sensor.

 

[ReckReason86]

Yeah gonna pick one up this weekend

 

[KewlWinter]

Here is a list of things that can cause bucking and misfiring.

1. Faulty crank sensor. Could be cracked, or connector is crudded, or someone has replaced the connector and just twisted the wires together or used butt connectors instead of soldering.
2. Faulty cam sensor. Same as crank sensor for problems.
3. Valve cover leaking oil into the spark plug wells causing intermittent grounding.
4. Vacuum leak due to hose popped off/broken/missing, throttle body leak at shafts, intake manifold gasket.
5. Injector plugs crudded, seals failing, injector failing.
6. Bad plug or wire.
7. Crack in coil housing.

Some factors that can make it get better/worse:
1. Is it raining, high humidity, roads are wet? Cracks or defects in sensors, plug insulators, wires, or coil can allow moisture either from the air or due to splashing to adversely affect the component or connnector in question.
2. Has it been sitting for a while? In some cases after sitting, a leak will miraculously seal, usually due to sludge hardening in the gap, and once you start driving again, it will eventually clear and leak again.

 

[miloolim]

You could double check your plug wires are the wright firing order at your coil pack.

 

[ReckReason86]

@Kewl No the car doesnt sit, its my daily driver. when i replaced the crank sensor, i crimped because i dont have a soldering iron. I havent checked my cam sensor yet, thats next along with the 02, When i first got the car, plugs 3 and 4 were drowned in oil but now i check them often and there is only signs of oil residue, not enough to cause alarm. There is something weird that i believe is because of a vacuum leak, my idle often drops to about 7-8hundred and bounces making the car sound as if it were cammed, and also when im coming to a stop i take the car out of gear and the rpms stay at about 2k and come down to normal idle when the car completely stops. I have not checked injectors yet. Plugs and wires and coilpack have all been changed. It bucks regardless of weather, although sometimes i do feel it triggers more often when i go over a big bump or crack or pothole, but im not sure if thats just me being paranoid. It does do it more consistently at lower rpms, somewhere above the 2k range. any more suggestions would be great. Thanks

 

[ReckReason86]

Ok so the backfire has gotten worse. it is getting harder to drive the car, and true i shouldnt be driving it like this, but its my only car. The car now dies occasionally, not too often, but i believe its because the idle drops and a it backfires slightly causing it to die. Other than that, when i get moving at green light, the car bucks and pops ridiculously loud. i can smell the fuel the unburnt fuel now. any suggestions or ideas? any help is appreciated

 

[420a dsm kid]

is your car leaking oil in to the spark plugs? If it is change your valve cover gasket. or try loking into your map sensor or tps ( throttle position sensor) a faulty sensor could cause your car to backfire and die.

 

[bullettdsm]

I'm disappointed that there are no cel's .

I know you don't have a turbo, but you should first try a boost leak test (you can look it up on here) Basically, you will be testing for vac leaks.

As far as the ECU situation that you spoke of, let's address that. Your ECU takes in info from your sensors and adjusts accordingly to try to maintain target numbers that are built into your ECU. SO when you disconnnect your battery for more than 10 minutes, that input information is lost and the ECU goes back to a "base" situation (where it has settings built into it for running your car when all is well).

Try disconnecting your battery again for at least 10 minutes. See if it "fixes itself" for any length of time. If it does, then you are probably looking at a sensor/input problem (which would be great because that would narrow it down). If it comes back relatively quickly, then you are on a different search (like bad gas, arc'ing somewhere, a bad wire or even a bad ECU - though I find that unlikely).

It sounds like this is a progressive situation. The ECU is getting bad input (or a vac leak problem) and it continually adjusts to try to get to the target numbers in the ECU (which makes the front o2 a possible suspect - just wish there was a cel).

Start with those two tests.

MB

 

[ReckReason86]

Ok i left the battery unplugged overnight and same thing. Then the car died approaching a stop sign then did not want to start. i let it sit for like 30 seconds then fired up like nothing was wrong. Also while looking for leaks i found that some of the vacuum ports have plugs on them instead of hoses. when i remove them the idle stabilizes at about 1k. also it seems like i have a leak at the headers there is black soot on the block. Im going to get a haynes and a scanner this weekend, on the off chance my cel light is burnt out. going back to the sebring. i know it has some similar parts to my 420, anyone know if the sensors and valves like iac and 02, are interchangeable? not as a permanent solution but kind of to use as a trouble shooter to hint at which one of mine could be messed up. i dont want to run out and buy every new sensor (not that i could ), only the one i need. Thanks for all the help

 

[bullettdsm]

Ok i left the battery unplugged overnight and same thing.

Bah

Also while looking for leaks i found that some of the vacuum ports have plugs on them instead of hoses. when i remove them the idle stabilizes at about 1k.

Normal. You have introduced a vac leak by removing the caps.

anyone know if the sensors and valves like iac and 02, are interchangeable?

I hate to give you asumptive answers without being positive, but if you have the 420a style engine in there, then the sensors are probably the same.

Oh yeah, the higher idle while you coast down is normal. Though at 2 grand that's just a little high.

Ok, so random shut off's and misfires. Yuck.

Let's go to another known problem; the wires by the egr tube (I am inclined to think that this is electronic. Just because of the misfires and the shutting down and not easily restarting. It is obviously past the "battery" part of the electrical system because you are able to work accessories etc. and turn the engine over. So you are into the ignition part of the electrics - just narrowing stuff down ).The wires that run by the egr tube are known to have problems with getting too hot and become fragile, or even burning through. There are wires in there that help the crank sensor communicate with the cam sensor (needed for car to run). If these wires have a problem they can do so randomly and without a cel. These wires are oftentimes jiggled around and not put back in their appropriate wire management. They then get too close to that hot egr tube and it melts or heats them up so they crack.

You can search on here and 2gnt to get some back-up info on that harness.

MB

 

[ReckReason86]

Ok thanks. And yeah so i am on the hunt for any and all loose wires or problems. Just because of work and school dont have that much time during the week.

I did come across 2 things that are kind of alarming. Near the thermostat and cap, there is a wire harness, it runs too the 02 and 2 others that plug into where the coolant hose is and an extra connector. I assume the coolant temp sensor and i dont know what the second is.

The wire wrap has been chewed up and broken some wires seem scratched but not cut although One of the wires has been completely peeled and is exposed. it looks really brittle, but not broken. The other issue is there is a connector that is just dangling there. i cant find anywhere that looks like where it should go plugged in. it looks like its been unplugged for a while. It has a triangular shape just dont know where it goes.

could any of these sensors be a cause for the backfire? And also thank you Bullet, your posts on here and some of your right ups on 2gnt have really saved me. I may not know you but i certainly owe you

 

[bullettdsm]

I did come across 2 things that are kind of alarming. Near the thermostat and cap, there is a wire harness, it runs too the 02 and 2 others that plug into where the coolant hose is and an extra connector. I assume the coolant temp sensor and i dont know what the second is.

This sounds like the power steering switch connector. Really need a pic to be sure. Is it a round hole style connector? (hmm, that's interesting in that....well before we go down that road, let's identify it)

The wire wrap has been chewed up and broken some wires seem scratched but not cut although One of the wires has been completely peeled and is exposed. it looks really brittle, but not broken.

I'd love if you are talking about the harness by the EGR tube here, .

Obviously any broken/exposed wires should be fixed.

The other issue is there is a connector that is just dangling there. i cant find anywhere that looks like where it should go plugged in. it looks like its been unplugged for a while. It has a triangular shape just dont know where it goes.

Sounds like the connector for the AC. Again a pic tells a thousand words. What color is the plug inside?

MB

 

[ReckReason86]

ok the car has no ac because it is the base model. Today when i go home from work i will make a photobucket account to post some pictures. Im going to replace that portion of wire for now. Any other things you might want to see? iim going to pull the plugs out and maybe replace if theyre bad, but i replaced plugs and wires no more than 2 months ago.

Another things, it is still having a hard time starting, but now after i crank it i either here an extremely loud backfire, or a loud gasp from the motor. like a cough almost, not sure how to describe it. Im going to look into my injectors.

Question is if i remove them to clean them do i need new seals to put them back? i know its preferable to replace if you can, but is it mandatory? im tight on money for the rest of the year

 

[bullettdsm]

Yeah, probably AC plug (they'll use the same harness regardless). On the other connector, if its a round hole connector look on your power steering pump. You will see a sensor on there (it will look like just a round post). That's where the round hole connector goes.

As for fuel, I gave thought to that. If it was a bad tank of gas, it would be gone by now. This doesn't sound like a clogged filter either (though its always good to have a good filter in there). Could there be an injector problem? Sure but those almost always throw a misfire code and to check those is a bit of labor and then you need to spend some cash to have them checked (as for the seals, generally they can be re-used if you take out the injectors. You just have to check them for "pliability"). So I would shy away from that right now.

I would check the labor stuff first (you know the stuff that doesn't cost you anything ) and the wire harness by the EGR tube is a good place to look.

Just a note here about the process we are following. In order to troubleshoot a problem, you have to follow a process of checking things. Now we are following that process over the period of days because we are talking on a forum. If I had this problem, I would be follow the same process but I would be jumping from one thing to another rather quickly (we're talking in chunks of minutes not days. And random misfires can be tough to diagnose check). What I'm getting at is that I can't just give you all the possibilities at once. And without being there to actually look at it, this process takes time.

Meh, just a heads up to keep you from getting to frustrated

Oh, and if you're popping out the plugs, maybe get a pic of them as well (the electrode end)

MB

 

[ReckReason86]

OK yeah i just wanted to have everything listed as far as what i was doing all at once. the weekends are the only free time i have to work on the car. thanks for your patience. I should have a scanner sunday, to double check.

I fixed the exposed wires, checked the plugs they seemed fine, the egr harness and tube seem intact. everything else checks out. i went ahead and did an oil change because im just about up for 1. looked around at every sensor and plug all seems fine, there are no hoses disconnected or ripped. fixed the leak at the header. also checked all my fuel lines. how could i check my fuel pressure, do i have to install a fpg?


here are some of the pictures
plug1-4

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dangling connector

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exposed wire

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this wire seems to be a ground or connector of some sort but is just hanging there, and im pretty sure it is the end of the exposed wire

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Also is the crank sensor suppose to be making contact with the plate on the crank? i know its a magnet but im not sure of actually suppose to be making contact. it doesnt seem like its shaving anything. didnt find any metal shaving in the pan

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Ok now this brings me to my next lead. The o2 sensor. after finishing all that and not being able to keep going because of the rain, i went to start the car and again crank crank crank and nothing. i kind of expected it but this time it seemed liek it wanted to fire up but was being starved of fuel or air or something. she would start and die instantly. after checking and looking around i decided to unplug the o2. and sure enough fired up on the second crank. after being on for about a couple minutes i plugged the o2 back in and she died. didnt start back up again until i unplugged the o2 again.

Now as i moved to park i stalled, but she started right back up no problem. I then let her sit to see if she would die like she had been doing. Nothing she held a steady idle for about 20 minutes. let her sit for a while came back and started right up on first crank. All this with the o2 unplugged. I smelled the gas, but other than that no issues.

So am i onto something here? what happens if i leave the o2 sensor unplugged until i can get a new one next week? thanks for all the help.

Ok just walked outside early this morning in the cold, and car started up on first try. Has not done that all week regardless of temperature. The o2 sensor is still unplugged

 

[bullettdsm]

Sorry OP, wasn't ignoring you. Just had some work to do due to the Newtown events.

I don't know where you are (with your problem) right now so I'll just say that the green plug is for your AC (which you don't have) and the round hole plug is for your power steering (it goes on the sensor I previously described. Also the crank sensor should not touch, but it should be real close. It picks up the gaps in the crank (via a magnet) to "talk" to the cam sensor.

MB

 

[ReckReason86]

Ok sorry the thread went dead. the bucks and start problems got so bad i had to park it for a while... Actually got it running good and healthy now though. Has been for almost a month no problems so far.

So here is what i did...

Ended up replacing all the gaskets on my intake mani and throttle body, junk yard replaced all my emission and intake sensors, just because. i think that that fixed my rough idle.

replaced my entire harness. when inspecting the pigtails for the crank sensor i noticed chunks of it were very brittle. I also replaced all my grounds, many of them had corroded away.

and lastly i reset my timing. because after i got it running, it bogged bad and figured i might of jumped a tooth. so after getting that right everything went well.

So far everything seems good, idle is good, no bucks, can rev to redline and everything feels great...

Thanks bullett, i really owe you won!!