Bad ECU?

[Teknix420]

I have a 91 Talon TSI and I have run out of ideas on how to get this thing started. I pulled the ECU and noticed that there are a couple of what appear to be, rust marks on the caps. Anyone have any ideas?

 

[Rsawd95dsm]

Looks more like a burnt spot. Stick your nose in right up to it and smell it. Does it stink like shit?

 

[Teknix420]

Lol no, but I'm guessing it's been like this for a while since the car hasn't been able to start for about a month.

 

[Tsisaman]

Send it off and get the caps replaced or do it yourself then try it again

 

[ChiTownHussla]

FIND SOMEONE WITH A 1G AND SWAP REAL FAST. IF IT WrKS REOLACE WITH Nw

 

[steve]

Somebody changed the capacitors but didn't clean up the leaked electrolyte and the damage it causes.

So when you turn the ignition switch on do you get a CEL light for 5 seconds?
Does the factory boost gauge move to 0 and stay there until you crank the starter?

If these don't happen it's very likely the ECU is bad.

 

[94allwheeldsm]

I would defiantly try swapping in another ECU first. If that doesn't work check your fuel pump make sure it's turning on. Then check to make sure you are you getting fuel, spark. Also, check the timing.

I have had my car run great then park it for an hour or so and come out to leave just to find it wouldn't start. Swap one of the 5 ecu's I have in my trunk and it will fire right up! Then I can take out the ECU that just work and swap in the one that didn't and it will fire. Really really stupid but it happens.

 

[steve]

It's generally a bad idea to put a good ECU into a questionable car since things like shorted ISC or MPI relay coils can blow the drivers in the good ECU. It's usually recommended to validate the bad ECU by putting it in a car known to be in good condition.

The simple diagnostic above usually identifies if the ECU is working. There can be other problems but if the CEL doesn't turn on at power up the car isn't going to do anything interesting.

 

[Teknix420]

Would it be a big problem if the ISC isn't even plugged in? Lol

 

[steve]

Would it be a big problem if the ICS isn't even plugged in? Lol

Think about it.

Is the ISC the only risk?

 

[Teknix420]

Ok so the ISC was plugged in, I thought it wasn't for some reason. When I turn the key to the on position, the check engine light doesn't come on, the boost gauge goes to 0, and I hear a sort of buzzing noise coming from the engine which I am assuming is the ISC initializing or something along those lines.