Author Topic: No CEL when key is turned, wait 5 minutes, hear clicking noise, then fires  (Read 2681 times)

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calvinh

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Here's the problem... When my jeep (92 YJ 2.5) has been sitting out overnight on cold days, when I get in and turn the key, there is no CEL on and it will just crank forever. However, if you wait 5 minutes or so, or warm up the ECU with a hairdryer, it makes a clicking noise and then starts up.

Does this sound like bad capacitors in the ECU? or could it be my fuel pump? the fuel pump relay is what makes the clicking noise.

Also, sort of off topic, but would an exhaust leak hurt performance? I've got a pretty bad exhaust leak, but I'm wondering if it is really worth fixing it right away or just waiting until next summer... thoughts?

Thanks!

Nicks92jeeper

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I had a pretty bad exhaust leak in my car and I noticed that once I fixed it I got a bit better performance. Depending on how bad it is depends on the back pressure and back pressure is needed. In my car though the setup is headers and catless. Runs much better without the cat. I also do not have smog checks!!!

Offline Jeffy

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Can you hear the fuel pump prime when you turn the ignition to ON?
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Offline grumpygy

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The exhaust leak I had was really hurting my performance.  But it was right at the head too.
94 YJ, Cool Air intake, 19lb Inj, 4.0 Throttlebody with spacer,  31/10.50/15's

Offline neale_rs

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Unless the bulb is burnt out, no cel when the key is turned to run pretty much means the ECU has a problem.  It is supposed to turn on as a bulb check, it doesn't depend on anything besides the ECU itself. I went through this a few years ago.  You might want to check the power and ground to the ECU, but it will most likely be a waste of time.
'95 YJ, 33 x 12.5 mud tires, RE 4.5 ED lift, Atlas 4 speed, rear D44, ARBs front and rear, 4.56 gears, 8000# winch

Offline Jeffy

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Unless the bulb is burnt out, no cel when the key is turned to run pretty much means the ECU has a problem.  It is supposed to turn on as a bulb check, it doesn't depend on anything besides the ECU itself. I went through this a few years ago.  You might want to check the power and ground to the ECU, but it will most likely be a waste of time.
Yeah, the CEL light should come on for a few seconds then turn off when you turn the key to ON.  It's not only a bulbcheck but a sign that the ECM is doing a quick diagnostic check.
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"If the motor car were invented today, there is absolutely no way that any government in the world would let normal members of the public drive one."

Offline sharpxmen

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with this hairdryer heating up thing: could also be a connection issue at the PCM connector, if that's not it then it's the PCM/ECU most likely.
'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
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Offline Jeffy

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Strange that it's starting up at all though.
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"If the motor car were invented today, there is absolutely no way that any government in the world would let normal members of the public drive one."

Offline sharpxmen

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Strange that it's starting up at all though.

just as a test i would try moving the connector a bit instead of the hair dry thingy and see if if it works, if it does could be a bad pin
'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
Latest: Corbeau BajaRS heated seats :dance: keeping warm the rear end

Offline neale_rs

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Mine acted the same way, working better in warm weather than in cold and then slowly getting worse until it would no longer start at all.
'95 YJ, 33 x 12.5 mud tires, RE 4.5 ED lift, Atlas 4 speed, rear D44, ARBs front and rear, 4.56 gears, 8000# winch

Offline rcrovo1

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Re: No CEL when key is turned, wait 5 minutes, hear clicking noise, then fires
« Reply #10 on: October 17, 2011, 05:19:38 PM »
sounds like capacitors going bad just as you described to me. i had the same issue...no cel and would crank forever, wait a few minutes, and it would start right up. there is write up floating around somewhere (i think it is on ju) about how you can dissect your ecu and replace the capacitors for about $5 in parts at radioshack but i was a little leary and elected to buy a remanufactured one on ebay that came with lifetime replacement. as soon as i swapped the ecu out ...problem solved.
1995 YJ 2.5L, 4in RE susp., 33x12.50 mtr, 4.0L TB, TB spacer, 4.88 gears, borla header, magnaflow catback, highflow intake, warn 9000#, lock-right up front

Offline rcrovo1

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1995 YJ 2.5L, 4in RE susp., 33x12.50 mtr, 4.0L TB, TB spacer, 4.88 gears, borla header, magnaflow catback, highflow intake, warn 9000#, lock-right up front

calvinh

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Re: No CEL when key is turned, wait 5 minutes, hear clicking noise, then fires
« Reply #12 on: October 17, 2011, 11:41:46 PM »
Well, I got around to taking apart the ECU today and taking a look at it, and just by looking at it it was obvious that one of the caps was bad (bulged head on it) I didn't even have to put any new solder on the board, just warmed up the stuff that was on there, slid the old ones out and slid the new ones in. Turned the key to ON and it primed right away. Problem solved! I'd recommend this to anyone with these problems... cost $10 in parts (including a soldering iron) and it was surprisingly easy. The whole process took about a half an hour.


Thanks for the help!

Offline sharpxmen

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Re: No CEL when key is turned, wait 5 minutes, hear clicking noise, then fires
« Reply #13 on: October 17, 2011, 11:49:04 PM »
wow, good job on saving that one

good to know for future, i thought the caps on these would be high grade and not blow up like on the cheap electronics, i guess the dealer price for one of these does not account for the low grade capacitors in them  :yikes:
'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
Latest: Corbeau BajaRS heated seats :dance: keeping warm the rear end

Offline neale_rs

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Re: No CEL when key is turned, wait 5 minutes, hear clicking noise, then fires
« Reply #14 on: October 18, 2011, 08:08:09 AM »
Great job!  I'll have to try this first if I ever have problems with it again.
'95 YJ, 33 x 12.5 mud tires, RE 4.5 ED lift, Atlas 4 speed, rear D44, ARBs front and rear, 4.56 gears, 8000# winch