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Unread 02-02-2008, 11:53 AM   #1
AhmedTheCamel
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ECU problems AGAIN (crash course in brain surgery)

alright so a little while ago I replaced my capacitors on the ECU and everything has been running smoothly then all of a sudden ive been having to put a blow dryer on the ECU before I will get the check engine light, due to the fact its been about -7 around here, I was wondering the reason I just breifly read abuot the trick to get it started but I never understood what it does.

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Unread 02-02-2008, 12:43 PM   #2
sasquachYJ
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try redoing the capacitors
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Unread 02-02-2008, 06:31 PM   #3
NewdRiver_
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....why are you messing around inside the ECU

Go down to I-55 Auto Salvage and have them get you one.

They ordered a new one from Texas for me for (get ready)......$400

Hey maybe us three could get together sometime to wheel?
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Unread 02-02-2008, 07:57 PM   #4
Berb_15
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Quote:
Originally Posted by NewDriver95
....why are you messing around inside the ECU
because electricity and circuits are awesome

Are they ceramic or electrolytic caps?(ive never pulled my jeep's ecu apart but im assuming electrolytic) did you get the polarities correct?? that can make a big difference in any circuit(with electrolytic anyways...)... and what made you switch them out to begin with?

And I'd price around for an ecu, I got one off of ebay from a salvage yard for 175 when i did my 4.0 swap, if you do have to purchase one...
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Unread 02-02-2008, 10:42 PM   #5
cruz 45
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If your interested in a used ecu I have my used one that I can part with ?
1993 2.5 mpi
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Unread 02-03-2008, 12:31 PM   #6
AhmedTheCamel
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thakns for the response

first off i would love to meet up sometime and go wheelin, but yeah on the rebuild i did check the polarities my step brother helped me do it and he is a computer wiz i actually did a write up on this topic but it has backfired on me, but i cant figure it out i know its the capacitors but like im just not sure whats causing these problems besides the cold
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Unread 02-04-2008, 12:05 PM   #7
HalfShaft
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double check the solder joints on the caps. A bad solder job will possibly cause issues as the ecu, and the case and the board, and the components, and all the other things involved shrink at different rates due to the temp.

Double check for a grey color at the joints they should also be smooth and have flowed onto the board. If they are lumpy and/or shiny redo them they are probabally no good.

Also, check to make sure none of the traces around the caps were damaged during the replacement. A small scratch in a trace may seperate when it gets cold.

As for why anyone would change the caps themself, I fixed my ecu with bad caps for 4 bucks. If anyone would like I will change theirs for 175.00 and even throw in free shipping. I used the 171.00 leftover to buy my wife a present so that I can spend more on the toys.

Its always a good idea not to bite the hand that can make your life miserable.

Hope to help had the same issue now it is fixed.
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Unread 02-04-2008, 01:36 PM   #8
Berb_15
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Quote:
Originally Posted by HalfShaft View Post
Double check for a grey color at the joints they should also be smooth and have flowed onto the board. If they are lumpy and/or shiny redo them they are probabally no good.
Shiny joints are actually what you want, and just to back my statement up look at any circuit board like a computer for example.
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Unread 02-04-2008, 03:37 PM   #9
HalfShaft
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Berb 15 is correct and I am not.

Sorry, my fingers were a typin and my brain was a little behind. Shiny - good, grey - bad

I will now do my pennance, 10 hail marys or is that 10 bloody marys?
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Unread 02-04-2008, 09:24 PM   #10
Berb_15
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for such a big mistake I think it needs to be upped to 15 bloody marys...

To the OP, do have the link for the writeup you did?
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Unread 02-05-2008, 02:30 PM   #11
HalfShaft
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I believe I will drink to that.

Halfshaft
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Unread 02-06-2008, 01:49 PM   #12
papa_panda
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I would check how well they were re-insulated after being soldered on. If moisture managed to get trapped in and short the circuit I could see how you'd have problems.... Hope this helps...
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Unread 07-31-2010, 04:28 PM   #13
jaketolsen
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well i did the same thing replaced the capacitors and it fired right up but its summer time now so hopefully when it gets cold mine dont start having problems i live in northern wisconsin so it gets really cold
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Unread 08-01-2010, 07:52 PM   #14
bob082484
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I had the same problem and thought I messed up my capacitors. Turned out that it was the intake air temp sensor. Hope that helps.
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