Engine Spark problems. wiseman needed.

[Streetracer0442]

okay so heres the deal i posted this topic a few months ago, and got some suggestions tried them did some testing and now i need some more suggestions. okay here is the problem I have a 95 mitsu Gs 2.0 nt, been down for over 5months now. took it to a mechanic awhile back, been there for about 4mo, we have been working on it off and on. car died at a stop sign one day and refused to start back up, just cranked wouldn't fire. so I researched on here found some possiblites, heres what i did, checked for fuel got that, it's alittle weak but i am getting fuel. checked the crank and cam sensors, they were both good, timming is on, even took it all apart nothin was broken inside motor or in the timing area. so i figured maybe my ecu was dead an being that theres not many eclipse's in my area had to get a remanufactured one from advanced auto parts. got that all hooked up pretty simple. so know the car is only getting spark to 2 cyliders, so we thought maybe the coil pack was bad got a brand new one put that on, same deal. so we tested some more came up with the ecu grounding the spark to the other 2 cylinders. so my mechanic said maybe i got another bad ecu, how i dont know. so my questions are, whats the chances of the ecu goin bad right after i got it or could it of been bad from the dealer? secondly what could be causing my ecu to ground the spark to 2 of my cylinders, i should metion it's ground the 2 cylinders on the right side of the coil i think. any info is appreciated, just wanna get this car back up and running again. my mods are only an exaust system and cold-air intake so i dont think those are hurting anything. thanks guys if ya need more info just let me know what ya need. kinda still a newb when it comes to the elec gremlins of a dsm. oh and i also changed the plugs put the recommended ones in it, they are gapped right, replaced the plug wires too, in the correct order triple checked on that one

 

[4UH8ERS]

okay so heres the deal i posted this topic a few months ago, and got some suggestions tried them did some testing and now i need some more suggestions. okay here is the problem I have a 95 mitsu Gs 2.0 nt, been down for over 5months now. took it to a mechanic awhile back, been there for about 4mo, we have been working on it off and on. car died at a stop sign one day and refused to start back up, just cranked wouldn't fire. so I researched on here found some possiblites, heres what i did, checked for fuel got that, it's alittle weak but i am getting fuel. checked the crank and cam sensors, they were both good, timming is on, even took it all apart nothin was broken inside motor or in the timing area. so i figured maybe my ecu was dead an being that theres not many eclipse's in my area had to get a remanufactured one from advanced auto parts. got that all hooked up pretty simple. so know the car is only getting spark to 2 cyliders, so we thought maybe the coil pack was bad got a brand new one put that on, same deal. so we tested some more came up with the ecu grounding the spark to the other 2 cylinders. so my mechanic said maybe i got another bad ecu, how i dont know. so my questions are, whats the chances of the ecu goin bad right after i got it or could it of been bad from the dealer? secondly what could be causing my ecu to ground the spark to 2 of my cylinders, i should metion it's ground the 2 cylinders on the right side of the coil i think. any info is appreciated, just wanna get this car back up and running again. my mods are only an exaust system and cold-air intake so i dont think those are hurting anything. thanks guys if ya need more info just let me know what ya need. kinda still a newb when it comes to the elec gremlins of a dsm. oh and i also changed the plugs put the recommended ones in it, they are gapped right, replaced the plug wires too, in the correct order triple checked on that one

How exactly did you check the cam and crank sensors again? because it requires a special tool to determine whether they are working properly, just knowing that they get power is not good enough. They are both hall effect sensors and require the snap on vantage or equivelant graphing meter to test. If you timing is good then you got a Bad crank sensor sorry thats just too common on the 95's. Thats why they the dealer no longer sells the 95-96 crank sensor you have to upgrade to the 97-99 sensor and splice it into your harness.
A bad crank sensor will cause no spark in cylinders 1 & 4.

 

[Streetracer0442]

well I'm assuming that the mechanic has the right tools to check the sensors, but the cam and crank sensor conversion kit thing does seem to be cheaper than buying a new Ecu. Problems is I dont wanna keep throwing random parts on the car hoping it fixes the problem. I will run it by my mechanic and see what he thinks. any other suggestions or knowledge? thank you for ## contribution 4u8ers, i'll look into that stuff

 

[fast92gsx]

You may want to check to be sure you have the proper ECU for your year. I picked up a used one for my 98, installed it, and I only had spark on one side of my coil pack. I swapped in a new coil pack ... same thing still, so I did some checking and it ended up being the wrong ecu. I went to a local used parts dealer, traded for a 98 model. (the one I had was from a 96) Installed it and ran like a champ.


just to clear this up .. I did this on my 98 RS non turbo and both ecus were non turbo models under the hood

 

[DSMcrazy3]

You may want to check to be sure you have the proper ECU for your year. I picked up a used one for my 98, installed it, and I only had spark on one side of my coil pack. I swapped in a new coil pack ... same thing still, so I did some checking and it ended up being the wrong ecu. I went to a local used parts dealer, traded for a 98 model. (the one I had was from a 96) Installed it and ran like a champ.

2gnt's differ from the turbo models. 95-some96 have one plug ECU harness'. other96-99 have 2 plug harness'. So that's a no go.

To the original poster, it is possible there was a flaw in the remanufacturing of the ECU, the 95's are so notorious for going out it wouldn't surprise me. You're in luck though, I've got an ECU out of a Neon you can use. All I ask is you send me money for shipping both ways in return for my generocity. I keep it for situations like these, you won't want to continue using it however because the A/C will not work using this ECU, I did run it on my car for a couple of months but I will send it to you to help narrow down the problem, but I'll make it clear I want it back. PM me for more info.

 

[Locke]

You say fuel was a little weak, what was the pressure, and was there a drop when cranking?

The right sides of the coilpack send spark to cylinders 3 and 4. The only way to get spark on the left and not the right would be for the right side towers to be damaged or shorting to ground inside the coils. Therefore, (if it is actually the right towers not sending spark) your coilpack is bad.

I would ask for more elaborate test result be posted, such as your resistance measurements of the coilpack, o-scope logs for the cam and crank sensors, fuel pressure, and whatever means was used to determine the ECU was not sending a trigger signal.

Most average mechanics don't have the equipment to diagnose signal problems. (oscilloscope or special tools) If basic troubleshooting and parts swapping doesn't pan out, you may want to take the vehicle to an actual diagnostic shop.

 

[VelocitàPaola]

Actually, one coil controls cylinders 1 and 4, while the other controls cylinders 2 and 3.

 

[4UH8ERS]

The right sides of the coilpack send spark to cylinders 3 and 4. The only way to get spark on the left and not the right would be for the right side towers to be damaged or shorting to ground inside the coils. Therefore, (if it is actually the right towers not sending spark) your coilpack is bad.

BTW: When refering to right and left sides of the vehicle, and parts in the vehicle, give us an idea of which right and left your talking about. When you order parts from the factory they are listed as your right and left when sitting in the vehicle, some people tend to stand in front of an engine or in front of a car and pick the side from there.

 

[4UH8ERS]

Thats stuff I already personally knew, but that diagram would be sweet for explaining something to someone. Nice find paul.

 

[Streetracer0442]

wow lots of info, okay i will try to get some numbers for you guys, not sure what tools he used to check stuff. i know there were wires goin every were when i looked at it. a for the left and right. i do it from the front of car, thats were i am at when i'm lookin as for the weak fuel, i'll get some numbers for that on monday when the shop is open.

 

[Locke]

Actually, one coil controls cylinders 1 and 4, while the other controls cylinders 2 and 3.

Thats what I was getting at, Paul. Since the right (looking from the front of vehicle) sides of the coilpack are two different coils, and the computer is firing one coil at a time, you cannot get spark at 1 without 4, or 2 without 3, unless your coilpack is bad.

I hope I was not being too vague.

Regardless, Streetracer0442, the more information you provide to us, the better the diagnosis we can give. Test results are always preferred. It keeps the guess work to a minimum.

Hope you get it going again soon.

 

[dr1665]

Have we verfied the ASD relay is still good? I've heard of intermittend no-start conditions when the ASD shits the bed. I guess, if you're getting some spark, you could say it is, but I don't know if that relay delivers power to a single lead or through two, so it's just a thought at this point. Electrical gremlins suck.

Also, you don't really have to have a O-scope or Snap-On scanner for the CAS and CMP. You can backprobe the sensors and crank it over to watch for your alternating 5VDC.

Try ohming out the connections between the coil and the ECU to first be sure you don't have some kind of short. Then ohm out both the CAS and CMP between sensor and ECU. If you do this, you can pretty much rule out a short in the harness and it's totally free. Then backprobe the sensors and verify the alternating 5VDC while cranking. CMP will be easier to see, since the cams turn at 1/2 crank speed.

Good luck to you.

 

[Locke]

Have we verfied the ASD relay is still good? I've heard of intermittend no-start conditions when the ASD shits the bed. I guess, if you're getting some spark, you could say it is, but I don't know if that relay delivers power to a single lead or through two, so it's just a thought at this point.

The coil triggers come straight from the ECU, and it's hot comes from the ASD, so if the ASD was bad, you would get no spark at all.. Unless it was gunked up or something, in which case it could be intermittent.

Streetracer0442: Check for a +12V source at the ASD, then close the relay, listen for a solid click sound and check for 0 ohms across the switched side, and infinite ohms when open.

Electrical gremlins suck.

No doubt.

Also, you don't really have to have a O-scope or Snap-On scanner for the CAS and CMP. You can backprobe the sensors and crank it over to watch for your alternating 5VDC.

I suppose you could do that, never really thought of it. As least this way you can see if it is doing something. A Fluke logger would be beneficial here.

 

[TheCykotik1]

so it just happens i work at advance auto parts where you say you got the computer. i love my job and the company, but from experience i have seen MANY computers come back. if i were you i would take that computer back and tell them you want another one. just go in say it worked fine and went out again. it has a warranty and advance auto cannot refuse you the warranty, they have no way to check your computer for faults. they will go with what you say. definately tell them it worked at first though or else they will just make you keep it and say thats not your problem. and if the second one does not work just take it back and tell them you want your money back because you got one that worked somewhere else. unless of course you already turned in your old computer for the core charge.

 

[Streetracer0442]

The ASD relay is the little black boxes on the firewall on the drivers side right? if so i changed all 3 of mine in the start of this problem, they make a constant clicking sound from some were over in that area, but my battery was crap so i think thats what was causing that. The advanced auto parts here kinda have stupid return/exchange policy. The will not refund or exchange any electrical parts after you buy them.(relay, fuses, sensors, etc.) and the only warrantied computers threw them are like $500 and i would have to wait a mo. or so cause there on back order, so i ordered the cheap one cause i got it in 2 days that way.(i know i'll pay for that eventually if i aint now.)still working on those numbers for ya the mechanic workin on my car has been out of the shop due to family issues. hopefully he will be back in this week. I did do the back probe trick for the sensors, and so did the mechanic, when i did it it check out alright and he said the same. I also forgot to mention that the computer i have in there now will let me key cycle the check engine light code were as the original one would not, the engine light wouldn't even come on. the codes i would get were for dead batter/unhooked in last whatever cycles, and the no more codes one.

 

[TheCykotik1]

they gave you a bunch of bs. that computer has a warranty. they just didnt want to return it because it would hurt the stores sales. PM me the number to your local advance auto parts, and the name of the guy who told you that. i will definately set him straight.