bad ECU? [resolved]

[crimsondragon]

So I bought a 95 GSX EPROM on ebay. I installed it just now after trying for the past 5 hours to get my fuel filter off. The car would not start. In fact after like a few cranks, it would make a clunk noise and the oil pressure light would come on. I do not know if this is important but I did not put the ECU into the bracket since my current one is still on it so whatever ground it may use through the casing, it has none. As soon as I plugged everything back into the old ECU, she started up though a bit rough, probably from the excess fuel dumped into the chamber. So what are my options at this point? Is the ECU repairable? Or should I just be pissed at myself for buying off ebay on an auction that said "as is?"

 

[pj91gsx]

can you hear the fuel pump runing? Not cranking doesnt necessarily mean the ecu is bad. You may have a gas leak. A small gas leak can cause not cranking.

 

[kwbunn]

You can't install a 95/96 ECU in a 97-on car without doing two things:

1. Inverting the CAS signal (some say it's not a big deal, some do).

Here's a link:

http://www.dsmtuners.com/forums/tuning-engine-management/178907-dsmlink-cas-inversion.html

However, unless you have DSMLink (which does the CAS inversion as an option), you have to hack the ECU pinouts to do CAS inversion:

RRE Instructions

Scroll down to the part on the page where it says "CAS Inversion".

2. The other thing you need to do is make sure the spark plug wires are connected correctly for the 95 style ECU's, which is detailed in that link, as well. That's the more important part. Here is the link to the DSMLink Wiki:

swapplugwires [ECMTuning - wiki]

Notice, that even with CAS inversion, you have to swap the plug wires.

This begs to ask the question: Why not wait for the DSMLink to be installed in your ECU before putting it in your car? The other ECU works fine, correct?

 

[crimsondragon]

You can't install a 95/96 ECU in a 97-on car without doing two things:

1. Inverting the CAS signal (some say it's not a big deal, some do).

Here's a link:

http://www.dsmtuners.com/forums/tuning-engine-management/178907-dsmlink-cas-inversion.html

However, unless you have DSMLink (which does the CAS inversion as an option), you have to hack the ECU pinouts to do CAS inversion:

RRE Instructions

Scroll down to the part on the page where it says "CAS Inversion".

2. The other thing you need to do is make sure the spark plug wires are connected correctly for the 95 style ECU's, which is detailed in that link, as well. That's the more important part. Here is the link to the DSMLink Wiki:

swapplugwires [ECMTuning - wiki]

Notice, that even with CAS inversion, you have to swap the plug wires.

This begs to ask the question: Why not wait for the DSMLink to be installed in your ECU before putting it in your car? The other ECU works fine, correct?

Ah ok, now it makes sense. Theoretically if I did invert the CAS, and swapped the plug wires, it should start? I wanted to test the ECU first to make sure it was working before I shipped it out to have it chipped with DSMLink but the whole 95/96 thing slipped my mind. Is there any other way to test it to make sure it works correctly without having to put it in a 95/96?

 

[gheintz81]

he said the car started up when he hooked up the orig ECU. try opening up the ecu and checking for maybe leaking caps? not sure if 2g's have those same probs as 1gs..

 

[kwbunn]

From RRE's page on CAS inversion RRE Instructions they say, and I quote:

"The difference is subtle, but the motor will start easier, provide smoother idle, and have less hesitations during mild acceleration."

They don't say "CAUTION! YOUR MOTOR WILL BLOW UP!" so I just say install the ECU, swap the plug wires, and see if it works. That should be good enough for at least a smoke check.

Don't hack the ECU for the CAS inversion. DSMLink will do that for you- that's why you've gotten this ECU, correct?

 

[crimsondragon]

When I first got it, I did open it up to check for anything fried or leaking and it was clean from what I could see. No smell either. I think kwbunn got itwith the CAS and plug wires.

 

[kwbunn]

Hey, if you swap those plug wires and it works out for you, post a response to the thread and let me know - mine's coming in the mail ASAP. I didn't even think about putting it in the car to test it before I shipped it off to ECMTuning- that's a darn good idea. So, I'd like to see what your results are. Or, if you want to wait, I'll do it and you can see my results. As I said before your last response, I don't think the CAS inversion will matter much for a simple smoke check.

 

[crimsondragon]

Kwbunn you hit it square on the nail man. I swapped the wires and she started right up. The ECU is good. Thanks man.

 

[kwbunn]

No problem! Glad to help. I can't wait till mine gets here now. Don't forget, when you order your DSMLink, to click the "CAS Inversion" check box on the order page.

 

[crimsondragon]

I have mine and it was one of the things I made sure to do before clicking "place order." Thanks for the heads up