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Suddenly dies

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Hakmak

15+ Year Contributor
173
5
Aug 28, 2007
Brooklyn, New_York
I think I may have a bad ecu but I'm not sure, let me explain. driving one night my car suddenly dies on me. When I finally got it home, first thing I did was check for spark so I pulled number 4 wire out from head then put a long bolt in there to make contact with the lead (to basically extent the lead out from the rubber housing) then held the bolt about half an inch away from a ground point. Cranked her (have automatic start so I was able to do it outside while outside the car) and guess what she started right up (weird). I thought it might have been my spark plugs or wires so I changed the plugs but the next day she died again. So I proceeded to check for spark using the same method but nothing happened then check for fuel nothing there either. I checked the resistance of my MFI relays and they seem to be good. I read about the Crank Angle sensor but I know this wasn't the issue because I recently replaced it due to the balance shaft (which is also eliminated) knocking it out and I'm not getting fuel so I know thats not my problem. Same thing goes for the Cam position sensor. I looked at my ecu at the back look like it had some kind of copper looking residue on it but I read that is normal so I dont know where else to look. So before I by another one from ebay for $200, I'd like to know what you guys think. Oh I also check the DTC and boy oh boy I got like 5 codes see attached.
 

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I know you said it couldn't be the Cam Position sensor, but when my DSM's have broken down it is ALWAYS that POS. I carry an extra one now in my glovebox, ready to go! :)
 
I hope it works for you. I'm just taking a slightly educated guess at it honestly, which probably isn't the help you need. I'm thinking if the ECU gets nothing from the Cam sensor it doesn't send fuel or spark. Need an expert to confirm that hunch though...
 
From my own personal experience that I have had with my DSM's, it's always a good idea to check for a vacuum leak and the Throttle Positioning Sensor (TPS). I had to change the tps on my 95 talon tsi to get it to start and on my current 97 gst I have to rerun some vacuum lines due to the previous owner being dumb. If that doesn't work let me know and I can find out for you. Between myself and a DSMer that I have we can pretty much tell you from experience of what it might be LOL.

Also you could check your Idle Air Control (IAC)
 
Funny that you mention TPS because ever since I redid my head and throttle body, I have been having trouble with that damn tps...I can never get it to read the correct reading of .63v, always right below or above. But now I'm reading some other post saying something about SAS (not sure what that is yet) have to be right. I'll do some more research and see what I can find.
 
If you're not getting fuel, I wouldnt initially suspect the cas, It could be the intermittent no spark condition. but as for the fuel and spark together not working. ecu is probable. when your car is "dead" check to see if your "check engine" light is on. if it is not on then your ecu is not responding. I've had this happen to me once before on my 1g with an ecmlink ecm.
also those codes seem to be for obd1 car and are multiple different system malfunctions. youre avatar says you have a 98 which is obd2?
 
How is oil pressure? Some ECUs will kill the engine if it sees that oil pressure is below a certain number. This happened on my 3000GT, something to check.
 
If you're not getting fuel, I wouldnt initially suspect the cas, It could be the intermittent no spark condition. but as for the fuel and spark together not working. ecu is probable. when your car is "dead" check to see if your "check engine" light is on. if it is not on then your ecu is not responding. I've had this happen to me once before on my 1g with an ecmlink ecm.
also those codes seem to be for obd1 car and are multiple different system malfunctions. youre avatar says you have a 98 which is obd2?

Its a flashable 98 ECU with Ceddy Mods. That setting in evoscan is the only one that would read the DTC codes any other setting I'll just get that J2534 java error. Yea the check engine light does come on.

How is oil pressure? Some ECUs will kill the engine if it sees that oil pressure is below a certain number. This happened on my 3000GT, something to check.

Oil pressure is fine, getting plenty.

From my own personal experience that I have had with my DSM's, it's always a good idea to check for a vacuum leak and the Throttle Positioning Sensor (TPS). I had to change the tps on my 95 talon tsi to get it to start and on my current 97 gst I have to rerun some vacuum lines due to the previous owner being dumb. If that doesn't work let me know and I can find out for you. Between myself and a DSMer that I have we can pretty much tell you from experience of what it might be LOL.

Also you could check your Idle Air Control (IAC)

were you experiencing no start due to no spark and no fuel as well?
 
MPI/MFI relay.
Engine Fuse.
Crank and cam sensor.
Might as well pull the ECU out, inspect/smell the caps, make sure connections are tight and good, while also inspecting the wires.
 
MPI/MFI relay.
Engine Fuse.
Crank and cam sensor.
Might as well pull the ECU out, inspect/smell the caps, make sure connections are tight and good, while also inspecting the wires.

From doing my research and having the crank sensor going out on my once before, I still got fuel so I don't believe that nor the cam is my problem. I have a 98/99 ECU so it only have one cap which is in good condition (I also red that the cap issues were on the 1G ecu's) I did see some copper looking residue on the back of the ecu but I also read that was normal as well) connection and wires seem intact. The engine Fuse did blow on me but that happen the last time I removed the ecu I have brand new one in there and its intact. I checked the resistance of the MPI/MFI relay and it checks out, I just need to put some power to it now and check the voltage. If that relay checks out then I'm going to bite the bullet and order an ecu from ebay and hope for the best. I wish there was another gs-t I could test my ecu on in my area.

have you resolved this?? I have a somewhat similar problem..

What are your symptoms? Is something going on with yours that I haven't listed? Have you done any troubleshooting? Maybe we can bring our findings to the table and knock this out.

update: MFI/fuel pump relay checks out ok, I'm getting 6.7ohms at injector resistor instead of 5.5-6.5 ohms as the fsm calls but its 49 degrees outside not 68 degrees indicated by the fsm so i think its safe to say, I'm good there as well. Against all my beliefs I'm going to autozone to pick up a Cam Position sensor just so I can truly rule it out.

Update: Changed the Cam position sensor and still nothing. I think its time to try out a different ECU
 
Sorry the Cam Sensor didn't work. I'd still keep that extra one in the glove compartment if I were you though ;)

Any updates? Just curious as to what the issue ends up being. Good luck!
 
Sorry the Cam Sensor didn't work. I'd still keep that extra one in the glove compartment if I were you though ;)

Any updates? Just curious as to what the issue ends up being. Good luck!

Thanks for checking back with me. So I bought a ecu from the junk yard and still having the same issue. I'm absolutely stumped now. I did notice that neither my viper system nor the stock security system is working. I can't get them to arm or disarm. I think that might have something to do with it but don't know where to start. I checked all the fuses, none are tripped. I unplugged the two harness from the viper 5901 to see if that would help but all that did was prevent the car from cranking at all. I once suspected the TPS sensor but then I remembered that I was able to start this engine with just the wire harness connected and the intake mani alone (no TB or mas) few years ago when I first dropped it in so I don't think a TPS sensor would cause this.
 
So now I'm getting spark at all cylinders but still no fuel. I don't know what changed. I think my fuel pump maybe the culprit. I recently did a rewire. So I thought it may be the relay. So I tested the relay for resistance (88 ohms) and voltage. Getting a reading at pin 87 on the relay with but nothing at pin 30 with the key in the on position. I thought that might be my issue but the new relay I bought was doing the exact same thing. So from taking an educated guess I'll say there is no power flowing thru the relay but its funny that the brand new relay would be broken too. If I'm getting power to the pump then I would say that its no good and time for a change.
 
So I fed 12v straight to the pump and it didn't come on at all. Like I mentioned before, I rewired the pump so I'm able to check the connections from the pump while the engine is cranking via the 40amp relay. So here's what I did, I disconnected the pump connector then tested the ECU signal wire (harness side) then the wire on the connector side, both are getting signal from the ECU but once I plug the connector in I no longer get signal from the ecu on the connector side just the harness end (coming directly from the ECU). If my pump was bad, wouldn't I still get signal from the ECU on the connector side once its plugged in? I'll appreciate any help on this. I was reading something about a pump test connector, if that was busted would it cause my pump to malfunction? I doubt it but I'm just throwing it out there.
 
I figured it out. It was the 30A fuse holder in the 12v line routed from the battery to the relay from the pump re-wire. The contacts were loose, so I squeezed them with a pair of pliers. She fired right up! only thing is that my engine fuse blew after it idled for about 15 minutes. No sure what that's all about though. It didn't blow anytime after that though. I'm wondering if the Fuse is no good even if its not blown....haven't heard of that before though.
 
I figured it out. It was the 30A fuse holder in the 12v line routed from the battery to the relay from the pump re-wire. The contacts were loose, so I squeezed them with a pair of pliers. She fired right up! only thing is that my engine fuse blew after it idled for about 15 minutes. No sure what that's all about though. It didn't blow anytime after that though. I'm wondering if the Fuse is no good even if its not blown....haven't heard of that before though.
Sounds like your grounding out somewhere which is why the fuse blows. The ground is more than likely contacting middle somewhere be sure to check it
 
there should be a relay along with that re-wire.. the exact same thing happened to me. it was the first start after some 10 years parked. however mine started right up the first time. about 5 minutes of monitoring it started to sputter and saw smoke coming from the relay. when I reached for it, it stalled. followed it back to the re-wire (im the 2nd owner) and found the relay to ground. hope this helps
 
Only and true way to test a fuse is with a ohm meter just to be sure. Sometimes (more than you would think) the fuse LOOKS good but upon testing, it has blown but in an area you cant see. Just throwing it in the mix.
 
there should be a relay along with that re-wire.. the exact same thing happened to me. it was the first start after some 10 years parked. however mine started right up the first time. about 5 minutes of monitoring it started to sputter and saw smoke coming from the relay. when I reached for it, it stalled. followed it back to the re-wire (im the 2nd owner) and found the relay to ground. hope this helps[/QUOTE

There is definitely a relay along the rewire. Thinking it was the relay at first I bought another..I got one from radio shack and the other from autozone. I'm not sure how to test them though. I was searching but couldn't find a solid answer, does anyone know how much resistance suppose to be in the coil of the relay or it wouldn't matter? One of them didn't even state it on the package.

Only and true way to test a fuse is with a ohm meter just to be sure. Sometimes (more than you would think) the fuse LOOKS good but upon testing, it has blown but in an area you cant see. Just throwing it in the mix.

Oh yea duh...LOL. I hate over thinking things.
 
check the ground at the Sending unit... also using continutity on a multimeter would help you check for any grounded circuits . you're definitely grounding somewhere...
 
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