Mitsubishi: 90 Eclipse GSR4 repaired ECU diagnosis

"Bornish" <com> schrieb im Newsbeitrag
news:talkaboutautos.com... 
located, many cars are coming from Japan) 
and the ECU burned while driving, luckily in second gear at ~30 km/h. 
the PCB and repair the hole in the PCB since I could not find a
second-hand replacement anywhere.

Hard to say , if there haven't been other components as well which may be
blown as a cause or a result of the burning.

 
considering the price I paid for the entire car, is out of the question. 
I can hear & feel a repeately short combustion as long as I keep trying to
crank it. 
(I'm a software developer, so I believe them) 
and conectivity. 
ON, and a variating 10-12 V while cranking.

As I understand this are open circuit measurements. It may well be, that
the driving circuit can not pump the necessary current, if it sees the low
impedance of the injector coils. An overheated power stage may have been the
primary cause for the ECU to get in fire.
 
testing values to make on the board, I cannot be sure if something else got
damaged.

The best way to get more informations would be to connect a scope in
parallel to the injectors, to see the impulse shape and duration at the
coils. You further should check the fuel pressure, which should be about
1,8 - 2 bar with the throttle in starting position ( almost closed). Remove
the plugs after you have cranked the engine for a reasonable time. They
should be wet after all. If not the injectors haven't properly opened.
 
and that's a good reason for me not spending money on another ECU, until I'm
sure mine is not functioning correctly. 
diagnosis.

If the above mentioned tests seem to deliver appropriate results, it still
may be that the injector pulses are out of phase with the ignition sparks.
This can be due to a problem with the crank- or camshaft sensor or the
corresponding circuit on your PCB.


Marcel Baum

Hi,
What is trouble code? Can't you pull the code?
Tony

Bornish wrote:
 

Hi Tony!
I've just found the manual of my car on www.alldatadiy.com and bought it.
Since not all DSMs are having the same trouble codes and same configuration of the diagnosis port, and because my car doesn't start makes it complicated to get it to a garage which has a proper scan tool, I don't have yet an error code.
Moreover, since the ECM (ECU) was damaged, I would not trust too much a trouble code of a possible faulty board.
I am still planning to connect a multi-use tester to the diagnosis port, now that I have the correct way of doing it.
As I read in the manual, there are lots of condition to be met previously the code extraction, in order for it to be correct.
The wiring seems very complicated and must be checked before installing a new unit, to ensure that will not get damaged.
Thanks for posting, and if you have some experience with code interpretation, please share it, because I'm sure I will get stuck again after reading one from a repaired unit.
Please remember that I'm not even an electrician and I didn't have a scheme when trying to repair the damage.
What I can tell you is that I found a site where the repair routine was nicely described & luckily the pictures were of the same circuit board.
So, at least I know that what I did was not wrong, but not necessarily sufficient.
I promise to post again as soon as I will have more details.

Marcel, please excuse my rush when I've posted.
I'm so happy to find ppl trying to help me.
I'll tell you the whole story as much as I know it.
I don't have the technical history of the car, so many infos may not be actual facts but observations of an unexperienced driver (me).
All seems to be original on the car (no modifications), which was maintained quite good by the previous owner.
Since I bought the car (8 months back) I've changed the front axel boots, the oil in the gear boxes, topped the coolant, changed the oil every 3000 km, filled with gas and washed it
I was very happy driver, but I was wrong.
Ever since I bought it, the car randomly and rarely failed to start from the first try, when the humidity was very high or the car stayed for a couple of days in the parking.
I thought was normal for an old car, or at least ok.
Wrong! Moreover, I've ignored other symptoms like engine stalling after it started, and once, even after about 1 min. after I've started driving.
That was the time to take out the ECU and check the electrolytic capacitors for leaks, and replace them after cleaning the board.
But I didn't, misinterpreting the symptoms as many others, as I read later on the internet.
One day it happened: the leaks made enough corrosion on the circuit board creating the short that "killed" my car, as I described in my first post.
Was no use to check the fuses or try starting the engine.
I've even seen a small thread of white smoke coming from the dash-board.
From the sound and the smell, I knew that was an electrical short.
The car was craned to my friend's garage, and the ECU was removed and opened.
I've started looking for a replacement and at the same time research on internet for possible causes, etc.
I was also afraid to try a new one which could've been damaged if the cause was not "inside that box"
But, as much as I've tried, I couldn't get one that at least matches the number of pins, not saying about the product code.
Next try was to order a used one on the net, but all answers were "Sorry, we don't have it in stock".
Only Foreign Auto from Tampa replied possitive on rebuilding mine but when I put some delivery & warranty questions they replied too briefly: "CALL ...", so I lost my trust.
In the meantime, I've decided to try myself rebuilding it.
My appologies for making you read so much, but I'm almost done now
Went to the garage and test it:
- spark is coming on all 4 plugs (don't know if timing is correct, yet)
- fuel comes on the pipe when cranking, so I assume the fuel pump works (also got repeatedly combustion for a fraction of a second)
- didn't measured the fuel pressure with a gauge as supposed to, but the mechanics said "looks ok"
- suplying the engine with fuel directly, the engine runs (with incorrect combustion, of course); we did a short test only
- suplying the injectors with fuel from a can, engine doesn't start; our guess will be all injectors are staying closed
- plugs were removed, cleaned, but no sign of being wet, so again we guess no fuel cames from any injector.
- checked the wiring for connectivity, resistance & supplied voltage, but I had no data to compare with (only today I found some in the manual I bought from www.alldatadiy.com)
- a couple of relays I found were checked and passed, but I'll post again after checking all mentioned on the electrical diagram (I would bet on the noise filter)
I am really appreciating your help and patience.
I hope is all more clear now and is making sense.
Many thanks,
Bogdan

Bogdan,

It seems as if the engine was running on the weak side from the very
beginning . You may either find a low fuel pressure (its essential that it
reaches the pressure I have mentioned in my last reply)
or you may have troubles with the starting solenoid valve . I would not rely
in just seeing that fuel is pumped, the fuel pressure regulator may have a
broken membrane and you will still have flow under open conditions but no
sufficient pressure to overcome the injector nozzles.

The following links are dealing with different BOSCH EFI systems , but even
so Mitsu doesn't use Bosch, it seems to be a license production of a
Japanese brand. So you definitely will find similarities between both
systems
http://www.ludd.luth.se/~rotax/motronic/motronic.html
http://www.vectorbd.com/peugeot/bosch.html

In http://users.exis.net/~audserv/bench.html you will find a bench test
setup for the EFI , however I am not sure the pin layout is the same you
have.

As long as you haven't checked whether the power stage of your ECU is really
capable to open the injectors and your fuel pressure is OK its really hard
to come to a better conclusion.






"Bornish" <com> schrieb im Newsbeitrag
news:talkaboutautos.com... 
actual facts but observations of an unexperienced driver (me). 
maintained quite good by the previous owner. 
the oil in the gear boxes, topped the coolant, changed the oil every 3000
km, filled with gas and washed it  
the first try, when the humidity was very high or the car stayed for a
couple of days in the parking. 
started, and once, even after about 1 min. after I've started driving. 
capacitors for leaks, and replace them after cleaning the board. 
on the internet. 
creating the short that "killed" my car, as I described in my first post. 
opened. 
internet for possible causes, etc. 
cause was not "inside that box"  
number of pins, not saying about the product code. 
we don't have it in stock". 
I put some delivery & warranty questions they replied too briefly: "CALL
....", so I lost my trust. 
(also got repeatedly combustion for a fraction of a second) 
mechanics said "looks ok" 
combustion, of course); we did a short test only 
guess will be all injectors are staying closed 
guess no fuel cames from any injector. 
I had no data to compare with (only today I found some in the manual I
bought from www.alldatadiy.com) 
after checking all mentioned on the electrical diagram (I would bet on the
noise filter) 

Hi
I have more news about my car, still not fixed though.
I couldn't pull any diagnostic code... the ECM is still faulty.
I've measured the injectors's resistance and were not damaged (lucky me).
I've read on www.alldatadiy.com how to check the harness wiring to be sure I'll not damage another unit if installed.
Since I could not find another ECU, and in this country nobody wants to be responsable of rebuilding it, I had to try to repair it again.
Each injector is directly connected to ECU through 2 wires.
/-------\
| 1 | 2 |
\-------/
No 1 goes to the same pin, probably being the ground.
Having 5 pins to pulse the injectors, the ECU uses 5 transistors sticked on it's radiator for this purpose.
Took them all out from the board and the one connected to the "ground" stays opened at all times.
Must be destroyed. I hope it's my last problem.
Was located near the capacitor blown-up.
It seems that the short made possible a high intensity current to flow through it's base and damage it.
Unfortunatelly, was not on stock on the shops I've been.
I'm sharing my experience with you because it may help somebody else facing someday the same problems.
Please DO NOT IGNORE any symptoms that your car may show.
I've learned this lesson in the hard way.
If anyone knows a good forum about electronics, please share.
Thanks for reading,
Bogdan

Bornish wrote: 

You better bet the injectors are pulsed by the ECU! (I'm a computer
scientist and a) don't belive my mechanics friends because we're talking
about electronics here, b) wonder what else might pulse the injectors
besides the *engine control* unit and c) know better, check the ECU
pinouts: http://www.vfaq.com/mods/ecu-harness-1G.html vfaq.com has many
more on Mitsubishis...)

Norman

Bornish wrote: 

IMHO this should have fried your catalytic converter, right?

Norman