1G 1G Bad ECU?

[1sick91tsi]

i have a 1991 eagle talon tsi awd. ok my car was running fine and just started sputtering and ran like crap wont rev, check engine came on.

next day i took the ecu out took it to a electrical shop had the caps replaced they said it had alot of corrision on it. put it in didnt work still ran crappy still check eninge light. but today it stared up and ran fine no check enine light them about one min later bam back to crappy and check engine light and the check engine light is only on when the car starts up, not when i just turn the key on, all the other lights come on except the check engine light.

also 1 and 4 spark plugs get all fouled out when this happens. what do u guys think? also the ecu has been apart before it has some electrical shops sticker on it and "core" written real big on the back, could it be my ecu, what do you guys think. as of right now its not running right like i said. thanks guys. karl

 

[CurtTSI]

The ECU could be bad. However, I would first check for stored codes and see what is causing the check engine light to come on.

 

[918273645]

The ECU could be bad. However, I would first check for stored codes and see what is causing the check engine light to come on.

if the ecu is bad the stored codes could just be random

 

[bmxrider154]

stop everything and take a very close look at the ecu again. Get a flashlight and look underneath the metal bracket on top of the board. you will see little orange capacitors there. look closely and see if there is any leaking or burning around or on those. Definitely check that out first., my car did the same exact thing. good luck

 

[steve]

I took the ecu out took it to a electrical shop had the caps replaced they said it had alot of corrision on it.

If they didn't fix all the corrosion damage caused by the leaking capacitors then just changing them doesn't help much. There are a bunch of critical circuits that run through the same area of the circuit board as where the capacitors are, like the ones for the ISC.

Sounds like it's time to get the ECU repaired by someone who understands how they work or get a replacement.

Steve

 

[1sick91tsi]

to start out i just finished my rebuild. ok so my car will start and run great one second, the next it just wont start. it will start just fine several times in a row the next it just wont start, it cranks over but doesn't start.

when it doesn't start the plugs are all bone dry, also the fuel pump never turns off when it wont start. like usually it will turn on the shut off after a few seconds but it just stays running. when the car starts the thing runs great no problems, idles great revs up great no problems.

also the car was sitting for about say 8 months with a quarter tank of gas so i put about 7 gallons of 116 in it. also when it wont start for me if i put some starting fluid in it it starts right up and runs great.

if you need more info let me know here are my mods, 20g turbo, 2g throttle body elbow,full 3' magnaflow exhaust, test pipe, dejontool intake pipe, magnecor plug wires, k&n air filter, 2g maf, 550cc injectors, tmo stage 2 chip compenate for 550s, turbonetics external gate, 2g ports ex.manifold, halman boost controler, fluidyne rad, slim line fan, slow boy front mount with short route piping, crushed 1g bov, 2g o2 housing, s-afc, data logger, autometer egt gauge and boost gauge, 6-bolt, 2g pistons .20 over, clevitte bearings, arp rod and main and head bolts, no balance shafts, mitsu 4 piece head gasket.

thanks for all the help guys!!!!!

 

[Old Mitsu Tech]

Well, you just told us it's fuel related. Good. When it won't start, see if you have fuel pressure. It's a pain in the ass to do this, as you need the tool to put inline. Field test by loosening the filter upper nut to see if fuel sprays out.

If it sprays out, check the injector harness to see if it has 12 volts on it key on engine off. KOEO. If it does, put your test light on the positive post and crank the engine while probing the negative terminal of your injector harness. Winking light is good. Steady on or off means injector drive circuit is bad. Just find out if it's pressure related. Pump, or distribution related. Injectors or pcm.

Let us know.
Good Luck

 

[1sick91tsi]

ok, well it has fuel pressure, i took the return line off of the regulator and it sprayed out when i cranked the engine. now as far as checking the injectors, the one side is lit when i turn the key on, now are you saying when i crank it the other side should flicker? thanks so much for the help. oh also now, number 2 and 4 plugs are getting wet from cranking it and they all still have spark.

 

[GVR4592]

Check the caps in your ecu, I bet they leaked.

 

[Old Mitsu Tech]

I agree with the cap thing. Hook your test light to the POSITIVE post of your battery. Probe the wire that does NOT have 12 volts to it. Have someone crank your engine to see if it flickers. No flicker or steady ON or OFF light will mean injector drive circuit which comes back to the PCM.

Just checking.

Good Luck

 

[1sick91tsi]

ok well only number 2 and four cylinders are flickering, and it takes a couple cranks to get them to do it and its very faint. so i dropped my ECU off this morning and got it back already with new caps, they looked it over said that there wasn't much corrision a little bit if that. tried it after that and still no better. so what do i need to do, get a new ECU or send it out to be fixed? Or does the injector drive circuit lie somewhere other then the ECU? thanks so much for the help guys

 

[1sick91tsi]

ok, so i think that i have a bad ecu, please help me out here. my car sat all winter while i finished my rebuild. went to start it up and im only getting injector pluse to number 2 and 4 injectors, and i am getting spark to all four plugs. i can hear my mpi relay kick on when i turn the car on and click agian when i shut the car off. also when i turn the car on i get no check engine light, it doesnt come on or blink and my boost gauge doesnt move. i took the ecu out and had the caps. replaced. and still the same problem. one more thing i have a chipped eprom by tmo with a stage 2 chip. any insight or help as to if my ecu is bad or not would be greatly appriated.

 

[Quasimondo]

Have you tried putting that ecu in another vehicle, or had a friend put his ecu in your car?

 

[steve]

Your getting mixed results. The TMO chip will cause differences in how the boost gauge acts but the CEL should still come on is the bulb is good.

The MPI relay can activate and not have the ECU power up but you won't usually get any spark or injector pulses if it didn't power up.

Like suggested you need to try swapping ECUs and see what happens.

Steve

 

[1sick91tsi]

ok well would a bad ecu cause only number 2 and 4 injectors to get a pulse? what causes the injector pulse? thanks for the help guys.

 

[steve]

Injector pulses are caused by the ECU seeing positioning signals (timing) from the CAS. The airflow/rew is used to figure out how much fuel to inject and at the right time the ECU pulls on side of an injector low. The other side of all the injectors are connected to the injector resistors and to the battery. I forget off hand is the battery connection uses the MPI or Ignition fuse but it one of the two. Later the ECU fires the spark plug(s).

There are also test to make sure that a cylinder is working. If it doesn't seem to be it gets turned off.

Steve

 

[1sick91tsi]

ok so i got a l.e.d. to check for c.e.l. codes. and heres the weird thing, once min. it will give me tons of codes, everything from crank position sensor, to speed sensor to o2 sensor and collant temp sensor and barometer sensor, and a few other codes as well. then i turn the car off let the ecu power off and then i will turn it back on, i will get no codes what so ever, from what the book says is normal the never ending quick blinking, and the car will start and run fine. and as long as i dont let the ecu power turn off the car starts back up everytime. but if i let the ecu turn off and i turn it back on agian i will get a million codes agian. turn it off and on a few times and it will go back to normal state of never ending blinking and run great agian. no what the heck is that all about? im definitally leaning towards bad ecu now what do you guys think. thanks a lot.

 

[1sick91tsi]

ok well my car hardly ever starts and when it does it runs great. when it doesnt start i get no injector pulse to number 1 and 4 injectors. also i have no check engine light and the boost gauge wont move when i turn the car on. so i got a l.e.d. to check for c.e.l. codes. and heres the weird thing, once min. it will give me tons of codes, everything from crank position sensor, to speed sensor to o2 sensor and collant temp sensor and barometer sensor, and a few other codes as well. then i turn the car off let the ecu power off and then i will turn it back on, i will get no codes what so ever, from what the book says is normal the never ending quick blinking, and the car will start and run fine. and as long as i dont let the ecu power turn off the car starts back up everytime. but if i let the ecu turn off and i turn it back on agian i will get a million codes agian. turn it off and on a few times and it will go back to normal state of never ending blinking and run great agian. no what the heck is that all about? im definitally leaning towards bad ecu now what do you guys think. thanks a lot.
heres a link to my original post. http://dsmtuners.com/forums/showthread.php?t=217854

 

[19Eclipse90]

Bad ECU. Take it out and have a look, it only takes like 5 minutes anyways. Not very probable for all of those sensors to fail at one time like that and then correct themselves.

 

[steve]

No question that ECU is having problems.
Have you checked it for capacitor leakage?

Steve

 

[1sick91tsi]

i checked it and had them replaced, it didnt look to bad, they said there wasent much damage but the board did look bare underneath the caps, like bare metal and not green anymore. i think im just going to replace the ecu. it so unlikley that all them sensors will go back in one instant and be fine the next. thanks for the help.

 

[steve]

i checked it and had them replaced, it didnt look to bad, they said there wasent much damage but the board did look bare underneath the caps, like bare metal and not green anymore.

There you go, the caps leaked and damaged the ECU. Time to either get this one fixed correctly or get another.

Steve

 

[1sick91tsi]

where would i get it fixed correctly?