Help with CEL

[2GturboTALON]

Ok so the other day i wanted to see if my car hada an eprom ecu so i pulled it out check the numbers and then proceded to check the inside. I slightly scratched a lead going from the eprom but it wasnt bad at all. SO i reinstall my ecu and start it up. It idles very lumpy so i let it sit. Turn it off after a lil while. Next day start it up idle still lumpy. I go to drive it and it is barely goin and sputtering. I get a CEL so i check it and it is:

P0202:Injector circuit malfunction
in cylinder 2

Before i ever took the ecu out i had a cel about fuel trim malfunction in bank 1.


Anyone have any ideas? Bad injector?

 

[olmytsi]

The way you describe it, it has to be the 'scratch' or perhaps a wire on the harness that you accidentally screwed up. Only one way to check, either try another ecu, or test the ecu.

 

[ReebisTSI]

even tho it is just a "scratch", those traces are very small and thin and will not let the reguired voltage thru. They are made a certain size in order to maintain a certain level of flow thru them and even the tiniest of scratches will mess them up. My friend scratched a trace on his motherboard on his brand new computer intalling a new power supply and ended up parting the whole thing out becuase it was junk after that.

 

[zippyshoe]

One simple item to check is to make sure all the connectors to the ECU are fully seated. If that does not fix the problem, you may want to pull the ECU and examine the scratched trace more closely. Follow the path of the trace to see what component pins on the board are connected by this trace if you can. Connect a multimeter set to measure resistance between these two component pins and check for continuity (close to 0 ohms) between these two points. If you do not see continuity between these points, then the trace has been completely broken and the circuit board will either have to be repaired or replaced. If you are handy with a soldering iron, you could try repairing the board yourself by soldering a wire between these two points to restore continuity. However, don't attempt this unless you feel comfortable with a soldering iron - you don't want to inflict more damage to your ECU.

 

[ReebisTSI]

One simple item to check is to make sure all the connectors to the ECU are fully seated. If that does not fix the problem, you may want to pull the ECU and examine the scratched trace more closely. Follow the path of the trace to see what component pins on the board are connected by this trace if you can. Connect a multimeter set to measure resistance between these two component pins and check for continuity (close to 0 ohms) between these two points. If you do not see continuity between these points, then the trace has been completely broken and the circuit board will either have to be repaired or replaced. If you are handy with a soldering iron, you could try repairing the board yourself by soldering a wire between these two points to restore continuity. However, don't attempt this unless you feel comfortable with a soldering iron - you don't want to inflict more damage to your ECU.

I would reccommend not trying to repair the trace yourself. The trace is a specific size and shape to allow the correct voltage thru. By adding solder to it, your changing its resistance and changing the amount of voltage being allowed thru, possibly causing more problems. just my .02

 

[2GturboTALON]

Thanks guys ill try to get back to you aorund my Lunch time a report what i found.

 

[2GturboTALON]

should i be checking the resistance with the ecu pluggged in. I have a mulitmeter im using but i cant get any readings with the ecu out of the car on any traces.

 

[2GturboTALON]

IT read 11.53 at 20k on the multimeter. and all the otther leads looked good. I got a new eprom for 188.83 anyway so ill send this one out to get repaired and sell it.

 

[steve]

The trace is a specific size and shape to allow the correct voltage thru. By adding solder to it, your changing its resistance and changing the amount of voltage being allowed thru, possibly causing more problems.

Please don't repeat this anymore.

While it's true than in high performance computers there are various circuit traces that are optimized for resistance, capacitance, inductance, and length, there isn't anything really special with the circuit traces on a 1G or 2G ECU. Yes, 2G traces are fine line and easy to damage but they're not a bunch of highly optimized transmission lines.

Steve

 

[zippyshoe]

IT read 11.53 at 20k on the multimeter. and all the otther leads looked good. I got a new eprom for 188.83 anyway so ill send this one out to get repaired and sell it.

When you measure the trace resistance, you will want to set your meter on the lowest resistance range (200 ohms on many meters). Also, be sure to place the meter leads at soldered locations such as component pins. Many circuit boards have soldermask that covers the surface of the circuit board except for soldered locations - I'm not sure if this is the case for the ECU's circuit board. Soldermask is an insulating material that will prevent you from getting a good measurement if you place either meter lead on a soldermask-covered location. You should measure very close to 0 ohms across a good trace.

 

[steve]

I'm not sure if this is the case for the ECU's circuit board.

It is. That's what is making the circuit board look green. We also have a waxy conformal coating that insulates and protects the board from mositure. That covers everything and you need to probe through it to get a measurement.

Steve

 

[zippyshoe]

It is. That's what is making the circuit board look green. We also have a waxy conformal coating that insulates and protects the board from mositure. That covers everything and you need to probe through it to get a measurement.

Steve

Thanks for the info Steve. Yeah, that conformal coating can be a bit of a pain when you are troubleshooting a circuit board.