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BHM - Owner
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537 Posts
Discussion Starter · #1 · (Edited)
This has been an on going issue for me for the past 3 months with my 99 Galant. I haven't had too much time to deal with it recently due to heavy schedule with work. Now that things are slowing down at the shop for us with SEMA this next week I would like to spend more time figuring out what the issue is.

I have checked all of the following items per the FSM troubleshooting information and I am still back to the MFI circuit for probable cause.

Compression is good in all 6 cylinders (average is 95)
Timing dead on (TDC checked with wooden dowel and bore scope, markings all lined up)
Spark to all 6 cylinders (New distributor, plugs, and wires have been tried)
Fuel Pump is working properly (has also been replaced to be sure)
Battery Voltage is steady at 12.43v
MFI Relay - Terminals 3/4 is 12.43v, continuity between terminals 2 and 4 is 71.4 Ohms, continuity between Terminals 1 and 3 with battery negative connected is 1.0 Ohm, open loop with the negative disconnected.
Replaced ECU (was pulled from a running vehicle)


Now here is where I get dragged back to the MFI system. When I am checking the injector connection terminals one has the supplied battery voltage from the MFI Relay (12.4v), and the other terminal is apprently suposed to have a flucutating signal (0-12v) from what I have been told. Checking this terminal however I am only seeing a 0.01-.02 voltage on all injectors while cranking. Reading the FSM MFI circuit diagrams I see the terminal with the fluctuating voltage is an "input" to the ECU. This leads me to think that the ECU does not distribute the voltage signal to the injector terminal, but the steady power voltage is supposed to "pulse" through the injector and in turn sending that voltage signal to the ECU.


I apologize for the "book" here, but I am seriously sitting at a dead end with the car currently. I have tried searching the FSM for weeks now trying to find information on the fluctuating injector signal voltage but have found nothing.


** Additional Note- The car was running for a good 20-30minutes at idle, rev/decel engine fine. It began to stumble on idle and killed out a couple times. It would start back up, however it was hard starting. As it sits currently the engine will crank over and there is noticeable signs of stumble starting but it will not completely fire up
 

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Moderator
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injectors work like this...

its a solenoid which gets constant power (B+ from a fused circuit) and the ECM switches the ground off and on too fire the injectors.

I hope this helps you.
 

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makin territories
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1,205 Posts
bitter, remember though, thats a saturated injector operation. then you have obviously the opposite of that for the other type of injector.

spd_frk, it definately sounds like either a fuel supply issue, fuel pressure, or something as simple as short term fuel trims. are you ble to datalog or monitor the engine/ecu functions? maybe that would help.
 

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bitter, remember though, thats a saturated injector operation. then you have obviously the opposite of that for the other type of injector.

spd_frk, it definately sounds like either a fuel supply issue, fuel pressure, or something as simple as short term fuel trims. are you ble to datalog or monitor the engine/ecu functions? maybe that would help.
i've yet to come across a car that uses pulsed power for the injectors and i've worked on some strange cars.
 

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BHM - Owner
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537 Posts
Discussion Starter · #5 ·
bitter, remember though, thats a saturated injector operation. then you have obviously the opposite of that for the other type of injector.

spd_frk, it definately sounds like either a fuel supply issue, fuel pressure, or something as simple as short term fuel trims. are you ble to datalog or monitor the engine/ecu functions? maybe that would help.
I hooked up a scan tool to the vehicle but there are no codes set, nor any pending which puzzled me more. I have flushed out the old fuel and even poured in about 10gal of fresh fuel and still no change. Even with a new fuel pump put in I have seen no change. You can smell gas while its cranking (atleast Marc was able to verify that onesince I cant smell lol).
 

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hOpe THIs HElp My FRiEnD..the CRanK sEnsoR IS NOt woRkINg aLRiGhT..yOU sHOuLD CHeck ThaT SenSOr with a MEchaNIc if YoU dont KnOW How to USe a voltiMETEr..ThaT SenSor iN THE voLTimeTEr SHoULD REad 00000000000000000000000000 iNfinItY....BeCaUse THE CRaNk SEnsor WorkS LiKE a PReignitioN MAy BE THats Why DOnt STaRt...aND if it s the problem watch out after you fix it taht sensor with the timing belt.....:wavey:
 

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That was what my boss suggested to try out so we did, but it still wouldn't fire up
do you have spark?


hOpe THIs HElp My FRiEnD..the CRanK sEnsoR IS NOt woRkINg aLRiGhT..yOU sHOuLD CHeck ThaT SenSOr with a MEchaNIc if YoU dont KnOW How to USe a voltiMETEr..ThaT SenSor iN THE voLTimeTEr SHoULD REad 00000000000000000000000000 iNfinItY....BeCaUse THE CRaNk SEnsor WorkS LiKE a PReignitioN MAy BE THats Why DOnt STaRt...aND if it s the problem watch out after you fix it taht sensor with the timing belt.....:wavey:
holy fucking shit kid, get the fuck out of here if you're going to type like that.
 

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R.I.P. silverside
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hOpe THIs HElp My FRiEnD..the CRanK sEnsoR IS NOt woRkINg aLRiGhT..yOU sHOuLD CHeck ThaT SenSOr with a MEchaNIc if YoU dont KnOW How to USe a voltiMETEr..ThaT SenSor iN THE voLTimeTEr SHoULD REad 00000000000000000000000000 iNfinItY....BeCaUse THE CRaNk SEnsor WorkS LiKE a PReignitioN MAy BE THats Why DOnt STaRt...aND if it s the problem watch out after you fix it taht sensor with the timing belt.....:wavey:
:lmfao: OH SHIT!!!! :lmfao:
 

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4g64-T Powa!!!
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yeah he does have spark
 

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BHM - Owner
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537 Posts
Discussion Starter · #14 ·
Yea I have spark, the crank sensor works just fine...unplugged it and absolutely no spark. I bought a new compression tester gauage this past weekend to re-check compression again. I haven't got the chance to check it after work any night yet, but for the most part I am pretty sure I lost compression somewhere (cracked head, blown gasket, etc..). I read through all my notes and the Galant FSM and everything it goes through has been checked out as "good"...everything but compression.


At this point I decided to just say screw it and stuff the car away for winter, pull the motor and do something else.
 

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makin territories
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1,205 Posts
matt, did you get my IM about all this? if not let me know. i have some things for you to check or at least some things for you to answer so i can get my head around whats going on and give you a synopsis.
 

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BHM - Owner
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537 Posts
Discussion Starter · #16 ·
matt, did you get my IM about all this? if not let me know. i have some things for you to check or at least some things for you to answer so i can get my head around whats going on and give you a synopsis.
Yea I sent one back to you on wednesday night, but my computer restarted in the middle of it I think...

I will hit you up on IM tonight when I get home from work...you will laugh lol
 

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Senior Dangler
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2,093 Posts
he has spark, but is there a carbon trace between the plugs and the wires? we had a car that had spark until you put it under the compression, and then the 15k volts would shoot throug hthe carbon trace. if you change wires the leak on the side of hte plug is still there. if you change plugs it is still inside the wire and re-makes the trace. the way we got it working was wires and plugs at the exact same time. Also, if its bad enough, if he is tracking inside the ignition coil bad enough, just the extra voltage required to jump the gap with compression could be causing the tracking inside the coil.

have you ever run the engine with a sparkplug wire not grounded to something?

you also should use a noid light in the injectors. it is the the same resistance range as an injector, and you just crank the engine with one on and it will light up if the injector has the proper voltage to fire. crank the engine and listen to the injectors with a stethoscope..do they fire?

check fuel pressure, if you have no other way...get a cloth and loosen a fitting. if no fuel shoots out at all, you have a pump or filter problem.

ontop of that make sure there is gas in the tank, not to be smart... alot of no-starts are because the owner doensnt realize there is no gas
 

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Moderator
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54,462 Posts
he has spark, but is there a carbon trace between the plugs and the wires? we had a car that had spark until you put it under the compression, and then the 15k volts would shoot throug hthe carbon trace. if you change wires the leak on the side of hte plug is still there. if you change plugs it is still inside the wire and re-makes the trace. the way we got it working was wires and plugs at the exact same time. Also, if its bad enough, if he is tracking inside the ignition coil bad enough, just the extra voltage required to jump the gap with compression could be causing the tracking inside the coil.

have you ever run the engine with a sparkplug wire not grounded to something?

you also should use a noid light in the injectors. it is the the same resistance range as an injector, and you just crank the engine with one on and it will light up if the injector has the proper voltage to fire. crank the engine and listen to the injectors with a stethoscope..do they fire?

check fuel pressure, if you have no other way...get a cloth and loosen a fitting. if no fuel shoots out at all, you have a pump or filter problem.

ontop of that make sure there is gas in the tank, not to be smart... alot of no-starts are because the owner doensnt realize there is no gas
good trouble shooting advice, especially about the carbon tracking. i've seen it cause some really stubborn problems.
 
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