1. Join the Community!

    DSMtuners is a massive archive of DSM information - but more importantly, it's a COMMUNITY! Join in and participate with other DSMers, and invite all of your DSM friends to make this place their home. Chat with others, create a build thread, post questions and answers. Get involved! Logging in will also remove many of the advertisements, along with this notice. ;)

Possible ECU problems 1g Eclipse GS

Posted by Cherry, Jun 16, 2019

Please Support JNZ Tuning
Please Support VR-Speed Factory
  1. Cherry

    Cherry Proven Member

    120
    16
    Joined Jun 16, 2019
    Hull, Georgia
    So I have been trying to do some research on this issue. I recently did a rebuild of my engine and it started fired up but had a miss in it for some reason which seemed to fix itself the next day and I broke the cams in while I could. The day after that it was a no start. It would turn over, no fuel pump kicking on so I pulled the fuel pump and checked it and it works fine. The next thing I checked was if I had spark which was also a no go. I did rewire the fuel pump to a toggle switch just to make sure I was getting fuel to the engine to test to see if the injectors would puff, and thats a no go. At that point I checked the cam angle sensor voltages and a big fat nothing.

    I then pulled the ECU checked pin 103 and no contant power though the #19 Room Fuse is good, as is the MPI fuse and the Ignition fuse. I also checked pin 10 on the MPI relay and there is power at that but not to pin 103 to the ECU.

    I also opened up the ECU since I read that the compositors leak and damage other things on the board itself. And it looks like there is corrosion as well as some things. It is a refurbished ECU from back in 2011


    20190616_123115.jpg

    20190616_123133.jpg

    Any input is greatly appreciated and hopefully I have given enough information to proceed.
     

    Street Build 186  3

    1991 Mitsubishi Eclipse N/T
    fwd · manual · 1G DSM
    Loading...
  2. motomattx

    motomattx Proven Member

    1,636
    454
    Joined Dec 9, 2010
    wampum, Pennsylvania
    The ecu turns on the mpi relay and thats why you have no fuel pump, that ecu looks trashed enough to cause no mpi relay function, its got problems in all the right places for that symptom, someone did try to repair it at some point.
     

    Drag Race Build 2K  16

    1995 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
    Loading...
    ThunderChild likes this.
  3. Cherry

    Cherry Proven Member

    120
    16
    Joined Jun 16, 2019
    Hull, Georgia
    Yes it is a refurb ECU from back in 2011. Any ideas or solutions on why there would be no power to pin 103 to the ECU with power to the fuses as well as no blown fuses?
     

    Street Build 186  3

    1991 Mitsubishi Eclipse N/T
    fwd · manual · 1G DSM
    Loading...
  4. ThunderChild

    ThunderChild Supporting VIP

    2,428
    639
    Joined Jan 5, 2012
    Rathdrum, Idaho
    That ECU is toast, needs a full rebuild, I'd get ahold of ecmlink or source another known good unit to inspect/install.

    As to why, something in the circuit is flawed and either shorting the voltage or just flat out not letting it get to it's destination.
     

    Street Build 106  3

    1990 Plymouth Laser N/T
    fwd · manual · 1G DSM

    229  8

    1987 Toyota Pickup/Hilux
    awd · manual · Misc Vehicles

    Street Build 743  7

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM

    Street Build 942  1

    1992 Eagle Talon TSi AWD
    manual · 1G DSM

    Street Build 2K  10

    1992 Eagle Talon TSi AWD
    awd · manual · 1G DSM
    Loading...
  5. Cherry

    Cherry Proven Member

    120
    16
    Joined Jun 16, 2019
    Hull, Georgia
    Alright, will I'll just run a new wire to pin 103 from after the room fuse and get a new ECU and then go from there. Thanks for the input.
     
    Last edited: Jun 17, 2019

    Street Build 186  3

    1991 Mitsubishi Eclipse N/T
    fwd · manual · 1G DSM
    Loading...
  6. o0GuitarKid0o

    o0GuitarKid0o Proven Member

    750
    105
    Joined Dec 12, 2013
    Winnipeg ,MB, MB, Canada
    20190618_072648.jpg The mpi circuit runs directly under the orange 8 pin EMI network capacitor/ resistor.

    Since the ecu sits up and down when the old capacitors leak it makes its way down into those 2 EMI filters and if I'm not mistaken CM105 is your mpi circuit and "pin 4 on cm105 should have a connection on the mpi pin on the ecu harness/ecu connector pins"

    I can gaurntee they never removed the heat sink And cleaned up the electrolyte that went on the 2 orange EMI filters . Heres a picture with the heat sink removed.

    I did clean up abit under the heatsink before I took this picture 20190611_082458.jpg
     
    Last edited: Jun 18, 2019

    Street Build 553  7

    1991 Plymouth Laser RS Turbo
    fwd · automatic · 1G DSM
    Loading...
  7. ThunderChild

    ThunderChild Supporting VIP

    2,428
    639
    Joined Jan 5, 2012
    Rathdrum, Idaho
    No pic?
     

    Street Build 106  3

    1990 Plymouth Laser N/T
    fwd · manual · 1G DSM

    229  8

    1987 Toyota Pickup/Hilux
    awd · manual · Misc Vehicles

    Street Build 743  7

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM

    Street Build 942  1

    1992 Eagle Talon TSi AWD
    manual · 1G DSM

    Street Build 2K  10

    1992 Eagle Talon TSi AWD
    awd · manual · 1G DSM
    Loading...
  8. o0GuitarKid0o

    o0GuitarKid0o Proven Member

    750
    105
    Joined Dec 12, 2013
    Winnipeg ,MB, MB, Canada
    Im out of town for work LOL trying to upload it it, reception is kinda bad out here
     

    Street Build 553  7

    1991 Plymouth Laser RS Turbo
    fwd · automatic · 1G DSM
    Loading...
    ThunderChild likes this.
  9. o0GuitarKid0o

    o0GuitarKid0o Proven Member

    750
    105
    Joined Dec 12, 2013
    Winnipeg ,MB, MB, Canada
    Just a heads up I'm actually slowly putting together a ECU repair tech article

    Im hoping to be able to help alot of people who have some electrical background or complete noobs who are willing to learn .

    Seems like no ones is willing to show how to rework these ecus other than a few members like Steve , its not hard just super involved & time consuming .

    My 500$ fluke meter broke itself a few weeks ago so it has slowed me down . Cant trust my crappy auto parts store meter when testing anything . You dont know what you got until it's gone LOL
    Let's hope I get a few days of work to get this finished.
    My tech article will be always available for new/more information .
    I litterally have about 6 1g ECUs that I've repaired. 3 1g TCUS (one unrepairble eprom tcu ) and 4 ecus on the bench from local people looking to get there ecus fixed.
    One 2g ecu that I've already replaced the caps on .
    Hoping to find some time to make a basic schematic of 1g ecus in the problem areas with some stuff to look for .

    On a side note all the ecus I've ran in my car have been repaired by me with a few little hiccups that I've learned from.
     

    Street Build 553  7

    1991 Plymouth Laser RS Turbo
    fwd · automatic · 1G DSM
    Loading...
  10. Cherry

    Cherry Proven Member

    120
    16
    Joined Jun 16, 2019
    Hull, Georgia
    One thing I have learned from watching Louis Rossman is to look for corrosion. You can usually spot the problem that way. What that circuit might be though is a whole other story. 3 bolts, 4-8 screws depending on if you take the board completely out of the case is worth it to look inside of it yourself just to try to notice anything that is obvious.

    I am going to talk to ECMlink soon though. Thinking back I should of just kept my 1.8L but everyone likes to make their car better and better if possible.
     

    Street Build 186  3

    1991 Mitsubishi Eclipse N/T
    fwd · manual · 1G DSM
    Loading...
  11. Cherry

    Cherry Proven Member

    120
    16
    Joined Jun 16, 2019
    Hull, Georgia
    A little update, I have power on pin 103 now, and I also checked that it was flowing into the computer by checking the voltage on the inside of the connector that then goes to the board. I then tried to crank it with the fuel pump running and nothing. I did it because my dad wanted to test it. I am going to test the MPI relay and if it checks out then I will just have to either wait for a reply from ECMtuning or source another ECU which I can get from Autozone for around 270 bucks.

    I have a day off today so I might as well get as much done as I can. I will probably reconnect the fuel bump back to the original harness at this point. Just put a new waterproof connector on it that I used when I rewired my headlights because for some reason those went out as well so I just made an independent wiring harness for it with some toggle switches. It would be nice to hook that up to the switch on the column though which I might do in the future but that is a lower priority than getting it running again.
     

    Street Build 186  3

    1991 Mitsubishi Eclipse N/T
    fwd · manual · 1G DSM
    Loading...
  12. o0GuitarKid0o

    o0GuitarKid0o Proven Member

    750
    105
    Joined Dec 12, 2013
    Winnipeg ,MB, MB, Canada
    If you want I can show you a quick way to test for a few trouble traces that will cause the ECU to not power up.
    I've rarely heard of the mpi relay breaking tbh but you never know .
    I'd open it up and look at the contacts inside the relay .
    If I'm not mistaken the ecu sends a signal to the mpi relay which in turn will trigger the ecu to power up. I've made a 1g ecu come alive with a jumper (for testing purposes ) and she gave me 3 hz on the logger LOL didnt try n run it tho . I'm just at work but should be home in about 5 hours
     

    Street Build 553  7

    1991 Plymouth Laser RS Turbo
    fwd · automatic · 1G DSM
    Loading...
  13. Cherry

    Cherry Proven Member

    120
    16
    Joined Jun 16, 2019
    Hull, Georgia
    Well I did test the MPI relay and it is clicking and im getting 12v on pins 4&5 on one side which I think is the engine side of things and then 12v on pin 2 which is the fuel pump side. All this is pretty much just because my dad wants to test everything even though the computer has the tell tale signs of corrosion and burned parts. It would seem like the capacitors leaked, the fluid touched a component and just burned it up. I dont know if there could be a fusible link between the room fuse and pin 103, but it would seem that wire is dead somewhere which I would assume I would have to take the dash apart and find it so I just jumped the radio constant 12v memory that also works off of the room fuse.

    I dont know if that circuit burning up could of blown a fusible link saving the room fuse and everything else that fuse powers. I even checked all of the red wires at the fuse box that looks like the pin 103 wire and they all have power to them.

    The only thing that I know of at this point is to try another computer since the inside of the computer just looks horrid and even the back side of the board on where the capacitor closest to what I guess is the heat sink, of if you look at the second picture the capacitor under where it is marked C106 and D109 had some slight corrosion around where it is soldered to the bored.

    But what I understand is that the ECU grounds out pin 8 on the MPI and I think pin 10 has constant 12v. I think pin 110 on the ECU is the ignition switch power, and when pin 8 is grounded that sends power to the CAS and a bunch of other things probably including the ECU again to be able to start the engine. Later when it gets a little cooler outside Ill put a new connector on my fuel pump, soldered connections and heat shrink since its out in the elements, and then see if that gets power to it since I know the MPI relay is good. If it doesnt then I would say that the ECU is bad and just have to wait for ECMtuning to email me back. If they dont soon then ill just get the Autozone one and then go from there.

    I got to the point of setting my TPS since I did get a 2g TPS for the S90 throttle body from STM and well I dont like it at all LOL. You barely touch the throttle and it whistles like crazy and I have heard that the throttle cable side of those throttle bodies dont have a seal so I swapped over the new FIAV housing to my n/a throttle body and just have to set the TPS on it. Went out there to do that and low and behold this problem came up.

    I will probably make another thread on turboing this thing since I did swap out the na pistons for the turbo pistons and got some BC street cams from STM since I planned on doing a turbo set up. Ill go through all that on my build thread or something to explain why and what I did to the engine itself and maybe ask some questions there as well. But first is getting this thing running so I can drive it again.
     

    Street Build 186  3

    1991 Mitsubishi Eclipse N/T
    fwd · manual · 1G DSM
    Loading...
  14. sacrileger

    sacrileger Proven Member

    225
    15
    Joined Jun 26, 2016
    Orillia, ON, Canada
    if it's of any help, and unless you've already explored them, here are links you might use for further testing:
    No power to ECU

    I am currently dealing with a similar problem you are here:
    no spark, no CEL

    Can you do me a favor and check what voltage you get on fuse #18 and #12 with ignition key in position ON?
     
  15. Cherry

    Cherry Proven Member

    120
    16
    Joined Jun 16, 2019
    Hull, Georgia
    I see that you said that you only had 1v on #18 and 9v on #12. I do remember checking pin 110 on the ECU with the ignition to the on position and I had power going to it but I will check the voltages on those tomorrow.

    It would also look like the information on this site doesnt add up looking at the junction block for the interior fuse box, and the fuse box diagram. From what I am looking at #12 on the junction block is #5 on the fuse diagram which is for the turn signals. Doing the same thing for #18 its #12 on the fuse diagram is backup lights.

    junction_block_1g.JPG evaphose007.jpg

    Pin 110 from https://www.dsmtuners.com/threads/1g-basic-ecu-mpi-circuit-function.435961/ says that it comes from the ignition switch.

    I dont know why its so hard to find information on 1g's but it gets to be a pain to find stuff sometimes. 2g stuff is all over the place though.

    I will still check those tomorrow morning though if you want.
     

    Street Build 186  3

    1991 Mitsubishi Eclipse N/T
    fwd · manual · 1G DSM
    Loading...
  16. sacrileger

    sacrileger Proven Member

    225
    15
    Joined Jun 26, 2016
    Orillia, ON, Canada
    you're right about the inconsistency b/w the diagram layout, the numbering on the cover, junction box etc. i already addressed this with @steve a few days ago as i ran into a similar inconsistency when i was not sure what fuses he referred to... but one has to rotate one or the other by 90degrees for them to line up but they do in fact line up if rotated so the four-in-row on the cover and the junction box match up. Here's to supplement what circuit each fuse protects:
    fusebox-diagram.jpg

    yeah, if you could check the voltage on those four fuses for comparison ... that would be great as i am not sure if that's by design or if i have some type leak/draw/short along the way...
     
  17. Cherry

    Cherry Proven Member

    120
    16
    Joined Jun 16, 2019
    Hull, Georgia
    It looks like the page with 1g and 2g fuse box post is what's messed up. Instead of going left to right it goes from right to left on 2 lines and the last line is correct. The junction box also labels all fuse slots with a number while the 1g and 2g fuse box post skips over unused slots. One goes to 19 while the other goes to 11 or12 I think.

    And the 4 fuses would be 11, 12, 18 and 19?

    I know 19 goes to pin 103 on the ECU and pin 10 on the MPI relay which should both be 12v. It's the same as the 12v constant for the radio which in my car all of it was a red wire with black stripe. I tested it by measuring power, then pulling the fuse and checking again. I think you said in the other posts that fuse 18 had 9v with the key on and so did pin 110 on the ECU. I would see if pulling that fuse cuts power to pin 110. I think that is what you were getting at from another post about your issue since you measured 9v at those 2 locations. One was backup lights though and the other turn signals which is what is throwing me off.

    One thing I hate is trying to find and solve are electrical gremlins.
     

    Street Build 186  3

    1991 Mitsubishi Eclipse N/T
    fwd · manual · 1G DSM
    Loading...
  18. Cherry

    Cherry Proven Member

    120
    16
    Joined Jun 16, 2019
    Hull, Georgia
    Alright, so I just checked the fuses for you and #19 read 12v, and 11,12 and 18 read ~11.5v. Pin 110 also read 11.5v.

    Im guessing that they read around .5v lower is because they dont come directly from the batter like #19 does and must go through something else to draw the power down slightly. I would guess its possible for the ignition switch to only allow 11.5v or it pulls .5 volts and is just the nature of it. Its so close to 12v though that I dont have any issues there.

    You could possibly have some bad grounds. Bad grounds could drop the voltage down because there isnt a good enough connection due to corrosion or rust to allow the full voltage to flow even if you have 12v at the battery. That has happened to me before and you just have to remove the blockage.

    That being said I dont really know much about the circuits and my haynes manual that I bought like when I first got the car has basically fallen apart so I cant really look up any wiring schematics on these areas. But a no cost check at least would be to go over all the grounds, even check the negative battery terminal and its ground and the terminal itself and just go ahead and clean the posts and the inside of the connector so you know that you have a good ground there. I think you did say that your car sat throughout the winter so that sitting unless you disconnected the battery could cause corrosion at the battery. If that turns out to be the case then thats good, if not then Im at my limit of knowledge.

    I havent heard back from ECMtuning for a few days now though so Im just going to have to go to a parts store and go that route and put a new connector in for my fuel pump and see what happens.
     

    Street Build 186  3

    1991 Mitsubishi Eclipse N/T
    fwd · manual · 1G DSM
    Loading...
    sacrileger likes this.
  19. sacrileger

    sacrileger Proven Member

    225
    15
    Joined Jun 26, 2016
    Orillia, ON, Canada
    great, thanks for double checking this for me. i need to fix this problem first before i start looking into refurbishing ECU which shows corrosion... just like yours. it's very likely my ECU does not power up due to the low voltage.

    yeah, i am using haynes manual as well; however, there are FSM on line.. here's the list:

    https://www.dsmtuners.com/forum/articles-manuals-documents.262/

    i am using these ones for now...
    1990:
    https://drive.google.com/file/d/1NmdPhGj7sToROhQBQhzogGdsSC8VrFbS/view
    1991
    https://drive.google.com/file/d/16cI4di5vQVT1ze9XhkCGfDowaZCvrya_/view
     
  20. Cherry

    Cherry Proven Member

    120
    16
    Joined Jun 16, 2019
    Hull, Georgia
    To me it sounds like a ground issue that is bringing the voltage down due to the current not flowing well. Also check that the power side of the battery is tight and making a good connection, where the fuse box bolts to the terminal connector. That being loose and dirty could also cause a drop in power.

    Also since what you are looking at is voltage when the ignition is on there could be something wrong with the ignition switch. But to me it sounds like ground or not a good power connection and more power is being pulled to more important things possibly. Just remember that electricity takes the path of least resistance.
     

    Street Build 186  3

    1991 Mitsubishi Eclipse N/T
    fwd · manual · 1G DSM
    Loading...
  21. sacrileger

    sacrileger Proven Member

    225
    15
    Joined Jun 26, 2016
    Orillia, ON, Canada
    so it looks like i am good with getting 12V on all four fuses #11, 12, 18, 19.

    I checked out the electrical online manual to see where all the grounds are, sanded all down, cleaned up the door light switch on the rocker panel which turns on/off the dome light and it came alive. i get 12V (~11.5V) on ECU pin #103 and #110 so i can proceed with the rest of the ECU test. here's the electrical if you need it:
    https://drive.google.com/file/d/1UKettrv_AVM2eg1-lNQdtDt3ojCxIr8k/view

    also, @steve has some ECU's for sale here:
    https://www.dsmtuners.com/threads/1g-2-0l-na-ecu-md166255-100.523588
     
  22. Cherry

    Cherry Proven Member

    120
    16
    Joined Jun 16, 2019
    Hull, Georgia
    Yeah Steve messaged me earlier and I bought one from him.

    And it's crazy what some bad grounds will do or a loose cable. If the current isn't able to flow well it will draw the voltage down or cut it out all together. It's like turning on the sink, if you turn it on the way there is no blockage and you get the full current, but if you just open it slightly it turns into a trickle.

    At least you got that issue resolved.
     

    Street Build 186  3

    1991 Mitsubishi Eclipse N/T
    fwd · manual · 1G DSM
    Loading...

Share This Page

Support Vendors who Support the DSM Community
Archer Fabrication ECM Tuning ExtremePSI Feal Suspension Fuel Injector Clinic Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications OHM Racing RockAuto SouthBay Fuel Injectors STM Tuned VR Speed Factory WheelWell.com White Shed Speed