2G Lets play a game "name that trouble code"

[Blinkyblinx9]

My 95 has had issues for some time now and I'm sick of seeing the CEL. I know what the code is and have known for years now what caused it. Can you tell what the code is just by looking at the issue?

What I actually need is component specs. The SMDs in the effected area need to be replaced but some of them can not be identified due to corrosion. Does anyone here know what they are? Is R107 even occupied from the factory (EDIT R107 is in fact not used because after cleaning I realized the pads are too smooth to have had a component in that spot), I would assume it is but you never know unless your an expert in this sort of thing.

Also before anyone says anything yes, I know that my socket job is horrible. I made sure it was functional before I put it into service but that it is dirty. I plan on going back in and cleaning that up during this process now that I know better.

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[steve]

What I actually need is component specs. The SMDs in the effected area need to be replaced but some of them can not be identified due to corrosion. Does anyone here know what they are?

Is R107 even occupied from the factory (EDIT R107 is in fact not used because after cleaning I realized the pads are too smooth to have had a component in that spot), I would assume it is but you never know unless your an expert in this sort of thing.

R107 isn't used on that version of the ECU MD309947E.
If you list which parts your curious about I can check.

 

[Blinkyblinx9]

Sorry it has taken so long to get back to you. This kind of work makes for a long long day when it's not what you normally do. My biggest concern was R4 ,R5 R77, R99, Q11, Q10, and C53 as they were all directly in the path of the capacitor goo. Replacements for the 4 caps are already in the mail.

After one at a time removing each piece and cleaning under and around everything I have concluded that they all appear to be fine at least visually. The pads were all in great shape and each component had no obvious visual signs corrosion. I unfortunately didn't know the resistor values and have no way of testing the capacitor and transistors. The trace under R107 also needed patching but all looks good now.

Yeah, if you know those values in case it doesn't work that would be great.

 

[steve]

My biggest concern was R4, R5, R77, R99, Q11, Q10, and C53 as they were all directly in the path of the capacitor goo.

R4 = 333 = 33k
R5 = 123 = 12k
R77 = 683 = 68k
R99 = 473 = 47k

Identifying SMD transistors is a challenge, I usually I'm lazy and replace bad ones from scrap ECUs by matching the markings. I don't have a spare scrap 2G ECU right now so I can't test and measure the Q10 and Q11 transistors or the C53 capacitor.

 

[Blinkyblinx9]

Damn, if anything the rest "should" be okay as they were the farthest from where it seemed to be flowing. The bulk of the damage seemed to be to just that one trace. Say, if I just remove that leaking cap would it be fine for a few drives to work? Idk how how well it's doing it's job as a capacitor and I'm afraid of it shorting as it is now and causing even more problems before the new caps arrive. I have no idea what that cap even does but it's rating says 100uf 16v.

 

[steve]

I have no idea what that cap even does but it's rating says 100uf 16v.

C202 (47uF 50v) up by the edge connector filters the incoming battery voltage.
C203 (100uF 16v) in the middle filters the +5 volts from the voltage regulator to the rest of the ECU.
I forget what C201 (22uF 50v) is used for.
C208 (47uF 50V) by the edge is a local filter for the injector drivers.

 

[Blinkyblinx9]

That's actually really good info. So yeah, probably just leave it be until the new caps come in. Is there a problem with using a higher voltage cap in place of those?

 

[steve]

Is there a problem with using a higher voltage cap in place of those?

Within reason, no problem. As long as the capacitance is the same the you could use a higher voltage capacitor that fits the lead spacing. You can also use capacitors with higher temp ratings. For example a 125C instead of the 105C caps that are in the ECU now. Using an 85C standard cap will shorten it's lifespan.

 

[Blinkyblinx9]

That what I assumed. I guess I was questioning it because I have read that the charge/discharge characteristics of a cap can change with its construction as it changes with voltage rating but I guess it's not in any meaningful way.

I wasn't able to find anything with a higher temperature rating at the required specs on either Mouser or Digikey so I just opted with a slightly higher voltage rating. Please correct me if I'm wrong but doesnt operating a component below it's voltage rating potentially extend its life as well?

 

[Blinkyblinx9]

Update, I sealed up my work with some thinned out silicone and threw it all back together. It chooches with no CEL. The code was P0202 btw but the car ran fine for years.

 

[Blinkyblinx9]

YAY another update!!!
Running it fixed up with that bad cap was not the right idea. It literally ran until the night that I was going to replace the cap. More electrolyte leaked and shorted the legs of the cap which apparently took out q101 and fried the ecmlink chip. This all happened last night on my drive home from work after 5 days, a few hundred miles, and over 10 hours of run time.

So now I'm left with a decision. Another 25-30 year old DSM ECU with link or a new universal linkecu and desoldering my existing board connector to make an adapter board with the included link harness (because an evo8 linkecu costs 2k)? They will cost about the same if ECMlink has any available. If not linkecu would be 400ish cheaper. What's your take?