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#14224 - 02/04/05 09:46 AM help me understand mopar ecu's
Anonymous
Unregistered


hello all,
i need help understanding the difference between the stock ecu and the orange box and the chrome box. each one is supposed to give you more spark power at a higher rpm right??? how do they accomplish this?? is it because each one has a longer dwell time and more voltage to the coil or both? over the last 8 months i have ran all 3 and haven't noticed much if any difference except that with the chrome one my idle is smoother. please explain these to me. also please answere this question: when i do a compression test on my cylinders i just unplug the connector on the ecu to disable the ignition system. run the test on each cylinder and plug her back in and go. does unplugging it hurt anything??? it's easyier than pulling the coil wire and grounding it. i just don't want any surprises. thanks for your help and knoledge. dynamododge:

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#14225 - 02/04/05 10:54 AM Re: help me understand mopar ecu's
Anonymous
Unregistered


I could write a book on this one.....

I'll try and keep it simple
Each box has a dwell to recharge the coil
The windings or resistance of the coil will determine how fast it can recover and how much voltage it'll shoot at the plug

The stock box and coil are what we call a Low Band ignition system, designed to run from crank to about 45-4800 RPM after that they will drop off and the output to the plug will fall to below 16KV which is what we consider failure. As it starts to approach it's max operating speed it will also start dropping some cylinders and retarding the timing.

The Orange box is notorious for retarding the timing, from about 5200-5800 it's going to pull out probably 8* of timing, we just throw that stuff away.

Standard Motor Products used to make the best General Purpose ECU their LX101 and it would work with about any coil to the max of the coils ability anyhow up to about 5800. Unfortunatly they bought Echlin last year and discontinued the SMP LX101 and opted to make only one ECU and because the Echlin unit was so much ccheaper to build they went that route instead of maintaining the quality that SMP has been known for for 100 years.

The Chome box is faily decent when teamed up with the correct coil like our FBO Dual Pattern Coil

Here's some test results that we conducted, the rpm is where the system either started dropping cylinders, KV dropped to below 16 or the timing fell back over 2*:

FBO Box #A688...FBO Coil #G642...8800 RPM
Chrome Mopar...FBO Coil #G642...8800
FBO Box #A688...MSD Blaster 2....5300
Chrome Mopar...MSD Blaster 2....5300
FBO Box #A688...Mallory 29216...4500
Chrome Mopar...Mallory 29216....4500
FBO Box #A688...Crane 730-0020...3800
Chrome Mopar...Crane 730-0020...3800
FBO Box #A688...OEM Coil.......4500
FBO Box #A688...Accell 8140....5500
FBO Box #A688...Accell 140001...5500
Mancini Brand...Accell 140001...3500
Orange Box....Accell 140001....4200
Orange Box....MSD Blaster 2....4400
Orange Box....Mallory 29216....3800
Orange Box....FBO Coil #G642...5400

You can see here that the coil is critical to the overall performance and when the correct coil and ECU are matched up the result is a perfect system.

We worked for 2 1/2 years on our box and coil combination to make it work right, since Standard dumped the LX101 the demand for our ECU's has been brisk to say the least.

Go to our tech section and read the articles on ignition and tuning, I'll think you'll find all you questions answered there:

http://www.4secondsflat.com/Technical_Information_for_Ignition_and_Carburetion.html


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#14226 - 02/04/05 11:32 AM Re: help me understand mopar ecu's
Anonymous
Unregistered


Quote:

Orange Box....MSD Blaster 2....4400




What exactly to you mean by dropping cylinders?

This is the combo I was planning to run on my wagon.

I have a stock coil and Orange box on there now and it will spin to 6200 without a hiccup.

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#14227 - 02/04/05 11:58 AM Re: help me understand mopar ecu's
Anonymous
Unregistered


thanks for the info that's great. my current set up as of yesterday was orange box and blaster 2 coil today i put the chrome box on with my blaster 2 coil. like i said my idle seemed smoother. it pulls hard clear to 6,000. under load in 3rd gear it seemed to fall off around 5,000 rpm with the orange box it does not do it with the chrome one. i am also gonna check out fbo for his box and coil or kit. thanks very much. o yeah!! does it hurt to unplug the ecu so you can crank your engine over to do test stuff? then plug it back in to go?

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#14228 - 02/04/05 12:40 PM Re: help me understand mopar ecu's
dave571 Offline
master

Registered: 12/02/03
Posts: 5314
Loc: Carstairs, Alberta, Canada
Quote:

does it hurt to unplug the ecu so you can crank your engine over to do test stuff? then plug it back in to go?




Better to pull the bith leads off of the coil primary when doing what you are suggesting.
_________________________
www.davesmopar.com 11.85 @ 114,3890 pnds, all iron, hyd cam, 750 carb, 440, 3.73 gear Im a musician too www.davesmopar.com/davesmusic.htm

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#14229 - 02/04/05 01:29 PM Re: help me understand mopar ecu's [Re: dave571]
Clair Offline
Pot Stirrer #4

Registered: 01/20/03
Posts: 8215
Loc: Cornfield. IN
Why do you say that ????
I donít see any problem unplugging the ecu to get a no spark situation.

Whatin the ignition system will get damaged buy just unplugging the ecu ????
And donít say the ecu

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#14230 - 02/04/05 03:42 PM Re: help me understand mopar ecu's [Re: Clair]
Anonymous
Unregistered


What about the mp brown ecu? Any tests? And why are they race only? The msd coil should be better, why does it drop off so fast? I replaced my stock coil with msd and it was worse. Sorry to jump into somebodys post but you guys are great at answering q's.

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#14231 - 02/04/05 03:59 PM Re: help me understand mopar ecu's [Re: Clair]
dave571 Offline
master

Registered: 12/02/03
Posts: 5314
Loc: Carstairs, Alberta, Canada
Quote:

Why do you say that ????
I dont see any problem unplugging the ecu to get a no spark situation.

What in the ignition system will get damaged buy just unplugging the ecu ????
And don't say the ecu





I say that, because it is specified in most service manuals that the ignition primary circuit be disconected when doing things like a compression test, etc. Pulling the plug on ECU is not disconnecting power from the primary circuit(coil low side)

Ecu plugged in or not, the coil pos lead is live, the coil saturated, when the key is on.

Will it do any damage to do it with just the ecu unplugged? Probably not. Crappy way to find out when it won't start at a show or the track.

_________________________
www.davesmopar.com 11.85 @ 114,3890 pnds, all iron, hyd cam, 750 carb, 440, 3.73 gear Im a musician too www.davesmopar.com/davesmusic.htm

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#14232 - 02/04/05 05:03 PM Re: help me understand mopar ecu's
Anonymous
Unregistered


(318 fish) what balist resistor were you using with the chrome box/blaster2 test?

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