Silly question but... change timing after swtiching ECU?

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D_Toro

D_Toro

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I'm still running some tests but apparently I had a bad ECU for a very long time.

Yesterday I replaced it and the car seems to be running fine but was popping a lot in high acceleration.
Is it normal having to check timing after replacing a bad ECU? Don't want to start fiddling with it and mess everything up. :)

Thanks.
 
Not much info....
Check the p/up air gap. Should be 0.006-8". Check shaft for movement, make sure it is not closing this gap.
 
Bewy said:
Not much info....
Check the p/up air gap. Should be 0.006-8". Check shaft for movement, make sure it is not closing this gap.
Click to expand...
Long story short the car was turning on, doesn't matter how long warming up on the drive it would stall after 300 yards to a mile after start driving. Not a chance to make it work again, the only way was to wait about 5 min and it would turn on and work as normal for the rest of the day without any issues.

Replaced the ICU yesterday and it started straight away (ig got to a point where it wouldn't start straight away as well) and loads of smoke from the pipes that wouldn't happen / never happened before, I turn the car on almost everyday. That's was very strange already.
Went for a quick drive and it seems to even have a better response but it's popping a lot.
Didn't touch anything else carburettor wise or anything. Had the voltage regulator replaced as well.
 
What are you working on?
Year
Model
Engine
Modifications
PHOTOS
 
D_Toro said:
I'm still running some tests but apparently I had a bad ECU for a very long time.

Yesterday I replaced it and the car seems to be running fine but was popping a lot in high acceleration.
Is it normal having to check timing after replacing a bad ECU? Don't want to start fiddling with it and mess everything up. :)

Thanks.
Click to expand...
Your "new" Ecu is probably a junk one. many/most new ones are. Contact @halifaxhops for a quality replacement.
The ECU shouldn't change timing unless it's bad. You should go through a timing loop just to make sure. (check base timing and advance to total at around 3000 rpm or so)
 
If you are going from a stock box to a high performance box I have seen timing changes. It is possible that one of my boxes was bad as well but the car ran fine after I changed the timing . Stock black box to orange to chrome....
 
Short answer is yes always check/adjust the timing after changing a spark box. even electronics have different "dwell" rates and this affects timing thru out the rpm range.
 
Dunno why you guys continue to torture yourselves with the outdated, obsolete Chrysler ECU Box and ignition system. Upgrade to MSD. Your performance will go thru the roof.
These postings never stop here and on FaceBook.
They quit making these ECUs for a reason...they suck.

My suggestion in your case is to take it to a good Auto Electric Shop with an MSD AL6 unit, MSD Coil in hand and get them to install it. Moolah well spent.

msd BLACK.jpg
 
MSDs are expensive and many want the stock appearance. Besides there are plenty of posts about MSDs going bad .

I run a Mopar ignition on my Barracuda and it works just fine .
I run a Daytona Sensors CD-1 on the 408 in my 69 Swinger because I like the 3 step rev limiter and programmable advance curves.
 
Sounds ike the ecu was bad. New one suck lots of "not real ones' around. Poping can be a few things, like TMM said check the timing at idle and RPM, could have the MP springs in the distributor and it is advancing to fast,
 
mbaird said:
MSDs are expensive and many want the stock appearance. Besides there are plenty of posts about MSDs going bad .

I run a Mopar ignition on my Barracuda and it works just fine .
I run a Daytona Sensors CD-1 on the 408 in my 69 Swinger because I like the 3 step rev limiter and programmable advance curves.
Click to expand...
Exactly. Everybody at the strip uses MSD and everyone has at least 1 spare in their trailer. They are always announcing if anyone has a spare 6AL*** box over the loudspeaker. There's a much higher failure rate for the MSD boxes than the old ECU's. The problem is the latest ECU's are cheap Chinese copies and nothing like the originals.
 
Google up "rotor phasing." What happens is, that depending on "box" design and or wiring polarity of pickup coil, the trigger point can change. Remember, that with points, unless the dist was worn out or something wrong with advance plate, the points cam "the trigger point" was tied to the rotor. If it was in phase, it could not change

But with electronic trigger, if the wiring of the trigger is reversed, the trigger point moves because the magnetic trigger is a positive going spike and a negative spike. Only one of them fires the box. You reverse the wiring, the spikes reverse relatively, and change in time (rotation)

But the design of the box can ALSO affect this. We have no idea, over the year, who changed what in the box internal circuitry. If the "china" box triggers on positive spike, and the OEM triggers on neg spike, then you have changed timing and rotor phasing
 
D_Toro said:
Replaced the ICU yesterday and it started straight away (ig got to a point where it wouldn't start straight away as well) and loads of smoke from the pipes that wouldn't happen / never happened before
Click to expand...
This is what has me puzzled, if there is smoke (I assume black) it is running WAY too rich, but if the timming was WAY off you might be running in a unhealthy place and lots of unburnt fuel making it out.

D_Toro said:
. That's was very strange already.
Went for a quick drive and it seems to even have a better response but it's popping a lot
Click to expand...

Popping out the exhost or intake?

I say set the timming and report back
 
67Dart273 said:
Google up "rotor phasing." What happens is, that depending on "box" design and or wiring polarity of pickup coil, the trigger point can change. Remember, that with points, unless the dist was worn out or something wrong with advance plate, the points cam "the trigger point" was tied to the rotor. If it was in phase, it could not change

But with electronic trigger, if the wiring of the trigger is reversed, the trigger point moves because the magnetic trigger is a positive going spike and a negative spike. Only one of them fires the box. You reverse the wiring, the spikes reverse relatively, and change in time (rotation)

But the design of the box can ALSO affect this. We have no idea, over the year, who changed what in the box internal circuitry. If the "china" box triggers on positive spike, and the OEM triggers on neg spike, then you have changed timing and rotor phasing
Click to expand...

Interesting ... I did not know the box could effect polarity .
 
Well we ARE talking about the 3rd world.............
 
He is talking about the output of the pick up, it produces a very samalll AC signall when the reluctor passes it and it triggers on the positive peak of the sine wave if that makes sense.

Just a pic of one hope it helps.
1024px-Sine_wave_voltages.svg.png
 
^^Almost^^ Not really a sine, but more "sine like spikes." As the reluctor teeth pass, it makes a pos spike and a neg spike, I don't remember which "first" with normal polarity. The box triggers on one of them.
 
Just a pic. Think it upswings first from testing. Definatelly affecs phasing a litte bit.
 
You can set the IdleTiming firing off the Negative spike,
But as soon as you open the throttle a bit, and the timing starts to advance, then all kinds of chit begins to happen, because the box cannot interpret what is going on. With your timing light wired up; you will see the index mark jumping backwards, forwards, double-firing, and missing strobes. Meanwhile the engine sounds like crap, and is impossible to drive with a standard transmission.
There are at least two (maybe more IDK) magnetic pick-ups for our Mopes; one for a clockwise rotating reluctor, and another for one that spins in the CCW direction.On the bench, you can tell the apart by the colors of the wires. IIRC the SBMs have one Orange wire, and the other does not (might be violet). The wrong one can be made to work, simply by cutting the wires and reversing their connections.
The OP did not mention changing the pick-up, I just mention this for inquiring minds.
 
Popping in the exhaust on deceleration is possibly due to air being drawn into the headers at a faulty gasket up by the head. What happens is this; if the mixture goes rich on closed throttle, and/or the engine misfires then unburned gas gets into the headers. If it finds oxygen there, and a point of ignition, then it will ignite right there in the header, and pop when it goes out the tailpipe.. This type of popping is usually called an after-fire.
Popping in the exhaust on acceleration has a different source.
A backfire is when a flame comes out the carb. This has a third origin.
 
D_Toro.
Read your initial post again. You replaced the ECU because it was 'bad for a very long time'. What does 'bad mean? What symptoms?
I doubt it is the ECU if a replacement did not fix the problem.
The timing can change veeeeeery slightly with different ign systems, but not enough to cause popping.
Forget the nonsense about getting a MSD 6X box [ unless you have a 800 hp engine ], that will do nothing other than lighten your wallet.
I would check these things, regarding popping in the exh:
- dist cap & rotor for carbon tracking
- plug leads [ & coil lead ]. Replace if old or suspect.
- try another coil
- measure the bal resistors, cold, engine off, one end disconnected. Should read 0.5 ohm & 5 ohm.
- make sure with engine running that you are getting 12v at the ballast resistors.
- make sure the pick up wires are twisted, kept close to ground & that they are kept away from the coil [-] lead & HT leads.

Other things can cause popping in the exh; burned valves, valves not seating, worn cam lobes, carb.
 
Bewy said:
D_Toro.
Read your initial post again. You replaced the ECU because it was 'bad for a very long time'. What does 'bad mean? What symptoms?
I doubt it is the ECU if a replacement did not fix the problem.
The timing can change veeeeeery slightly with different ign systems, but not enough to cause popping.
Forget the nonsense about getting a MSD 6X box [ unless you have a 800 hp engine ], that will do nothing other than lighten your wallet.
I would check these things, regarding popping in the exh:
- dist cap & rotor for carbon tracking
- plug leads [ & coil lead ]. Replace if old or suspect.
- try another coil
- measure the bal resistors, cold, engine off, one end disconnected. Should read 0.5 ohm & 5 ohm.
- make sure with engine running that you are getting 12v at the ballast resistors.
- make sure the pick up wires are twisted, kept close to ground & that they are kept away from the coil [-] lead & HT leads.

Other things can cause popping in the exh; burned valves, valves not seating, worn cam lobes, carb.
Click to expand...
and Dana67Dart

Thanks, I'll do that. I borrowed a spare ECU from the GTX and ordered a new one for the Duster. I'll wait for the new one to arrive before trying to adjust anything since it might change again so updates only next week. O also ordered a ballast resistor and a dist cap and yes, it has some carbon accumulation in the central ball. The plug leads are new. I did order another coil, which has arrived today but will wait until I install the "definitive" ECU.
If you read my first reply I tried to resume what's (was) going on with the car. (I was adamant it was flooding in the beginning.)

It's popping on HIGH ACCELERATION and quite sure it's from the exhaust.

Thank you all for all the replies and tips, I'll keep you all updates.
 
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