Resolved 1G ECU problem?

[linksys42]

It is a bone stock 91 talon tsi AWD that is missing and having trouble keeping a idle and running pig rich (just runs terrible). What leads me to think that the ecu is the problem is because when I try to log it, all of the data values for most if not all the sensors jump all over the place at idle and while driving and even with the ignition in the on position and not running. Values for TPS, Coolant, battery, BARO, AIRT are all over the place and I cant even log injector duty cycle? It won't allow me to select it? I am using MMCD V1.5d. I verified that the voltage at the battery and alternator is at 12.5 with car off and 14.2 and steady with it running. The logger is just all over the place. I plan to swap out the ecu when I can get a hold of one but what else should I check as a process of elimination while I am at it? Any certain grounds that I should check or other ideas? Really appreciate the help.

Thanks

 

[big_d]

Rule out the ECU first. Pop off the cover and have a look inside.

 

[linksys42]

Pull ECU tonight caps were leaking. Swapped out ecu for one I just picked up. Now I am able to log data all readings are as they should be. Did find out the O2 sensor is dead just reads a steady .02. Also one of the coils in the ISC motor is bad. Does that damage in the pic look repairable?

Thanks

 

[stars]

Pull ECU tonight caps were leaking. Swapped out ecu for one I just picked up. Now I am able to log data all readings are as they should be. Did find out the O2 sensor is dead just reads a steady .02. Also one of the coils in the ISC motor is bad. Does that damage in the pic look repairable?

Thanks

Yes, just get some new Caps. then it is good as new!

 

[linksys42]

Yes, just get some new Caps. then it is good as new!

I was talking about the board, the acid has ate/burnt through surrounding devices and solder. I'm not worried about the caps. Just would like to know if it is worth trying to save?

Thanks

 

[big_d]

Yes, just get some new Caps. then it is good as new!

I hope this was a joke. IC101 is where the A/D conversion takes place for sensor inputs. Give that IC a good look over (underneath the board too), and its leading traces. From the picture you've posted, there's definitely evidence of acid damage. If the 47uF cap closer to the green transistor has begun leaking, the acid could have made its way under the main heat sink and into the cap arrays...

 

[linksys42]

I hope this was a joke. IC101 is where the A/D conversion takes place for sensor inputs. Give that IC a good look over (underneath the board too), and its leading traces. From the picture you've posted, there's definitely evidence of acid damage. If the 47uF cap closer to the green transistor has begun leaking, the acid could have made its way under the main heat sink and into the cap arrays...

What is a/d stand for? the damage is confined to the spot that i outlined in the below pic. There isn't any under the board or heat sink. so do you think its worth trying to fix? On a side note i swapped out O2 sensors and the ISC motor tonight but still cant get a reading from the O2 sensor it still reads .02-.03 and the newer ISC with all good coils changed the RPM up to 1500 and drops to 1000 then back and forth? The old one with bad coils did the same thing but from 1000 to 500 RPM's. I just pick this car up and I'm trying to work the kinks out of it. Any help would be greatly appreciated.


Thanks

Forgot to add boost leak test has been done. Found a couple and fixed them. except the throttle body shaft seals (but they are minor).

 

[rts91tsi]

A/D is an abbreviation for analog to digital. I think what big_d was hinting at is that the ground trace to IC101 may be questionable. You can check it by checking for continuity on IC101's pin 13, and all of the ground pins on the ECU.

I would check the resistance of the ISC coils, and its wiring, as well as confirming that the o2 sensor, and its wiring are indeed good to rule that out as the possible problem.

The ECU in the picture could probably be repaired, and if you have the skills necessary to fix it than I would say it's worth fixing. If not send it off to someone skilled in repair that has the test equipment to confirm that the repairs have been done correctly, IE ECMTuning.

 

[big_d]

 

[stars]

I hope this was a joke.

No it wasn't; repaired more that was worse than his picture looked, I should have said, get some alcohol clean off the board, replace the Caps then re-test it. I figured he already had some knowledge of what to do since this subject has had many V.F.A.Q's and the O.P. has read thru them all...or has he not?

Nice pics b.t.w they were very helpful.

 

[linksys42]

Thanks for the help and info; I will check the ground trace. What is the best way to test the circuit for the O2 sensor? Should I just do a continuity test on the signal circuit from the corresponding pin on the connector at the ECU to the connector at the sensor? Or is there an easier way? Also I pulled the ISC that I replaced that had all good coils in it. and the below picture is what I found when I opened it up. So I pulled the coils out of the corroded one, cleaned them and swapped out the coils into my other bad ISC and just hooked it back up to the connector to visually test it by turning the ignition on and it powered up. Last pick is after swapping coils.

 

[stars]

After seeing that picture you posted I know now why the I.S.C will Ohms correctly and will not work. Brilliant detective work on troubleshooting this problem; one would have to see this post to believe.

You can check the Oxygen Sensor reading with your MMCD now, that the values should will read correctly on the display. I had the same problem you did when I first hooked my DRB2 into my 92, the values were all over the charts and barely visible, data was all distorted.

 

[linksys42]

You can check the Oxygen Sensor reading with your MMCD now, that the values should will read correctly on the display. I had the same problem you did when I first hooked my DRB2 into my 92, the values were all over the charts and barely visible, data was all distorted.

Thanks, I was wanting to test the O2 circuit from the connector side of the ECU. I have already determined that I could log the o2 on mmcd after installing the new ECU. I was just wanting to check for shorts from the ECU connector to the o2 connector. I have already replaced the original o2 sensor last weekend with a old sensor I had from a previous 1g that wasn't bad when I pulled it a long time ago. But it also turns out it is bad. I had another 2g o2 sensor from another dsm I had so I rewired and soldered the 1g connector to the 2g o2 sensor. And wallah! Its good to go. I like to trouble shoot thoroughly before I spend the cash on new parts. Thanks again for everyone's help and information.