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Author Topic: HELP!!! Problem after Ignition Conversion!  (Read 2297 times)

Steve

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HELP!!! Problem after Ignition Conversion!
« on: June 03, 2008, 04:17:16 PM »

I have a 1968 Sport Fury convertible. The engine is a 440 HP (original and stock). I purchased the MOPAR Electronic Ignition conversion kit to eliminate points once and for all. Kit included a distributor, an ECU (orange) and a new ballast resistor. I also replaced the mechanical voltage regulator with a electronic one (stock appearance, Thanks FuryGT!!!).

Installation went without a hitch. set the timing to 5 degrees BTDC and total advance is 38 degrees. Just what it should be according to the included manual.

The problem? At high RPM's, the engine starts to shudder and misfire. Quick revs cause a backfire (scratch one muffler. One left). Hmmnnn. I replace the plugs (.040 Gap) and install new plug wires. No change

OK, my carb (original AVS) had been pretty mistreated in its earlier life and must've been dropped at least once. I have an intermittent fuel leak (drip) at the pass-side end of the secondary butterfly shaft. After engine shut-off, I look down into the secondaries and see puddles of fuel on the secondary butterfly and ripples from a fuel drip.  
Disassembly reveals fuel in areas where it shouldn't be and a slightly bent fuel metering rod.

A friend lends me a brand new edelbrock "AVS" carb. After install, still has a high rpm shudder. Hmmnnnn.

I then read an article discussing the benefits of the electronic ignition conversion I have performed. At the end of the article, it suggests replacing the coil. the reasoning is that while it may function well with point-type ignition, it may not handle electronic ignition and could cause "misfire or worse". Eureka!!! That has to be it! I run to to my local speed shop (20 miles away) and buy a Accel super stock coil. While there, I also buy a Edelbrock Performer Series carb; a model made as a direct replacement for my engine.

I get home and quickly install the new coil. I start the engine and after the engine reaches operating temp, I slowly increase the rpm's and ........................

NO CHANGE!!! WTF!!!

This symptom may or may not have existed prior to conversion as I have not driven the car outside of the occasional blast a couple hundred yards on my street.

BTW, those rare occasions on the street always ended the same; a full throttle run for a couple hundred feet and when I let off the throttle, the engine would stall. Everytime! I chalked this up to the carb. Maybe I was wrong?

I am out of ideas. I need some wisdom, gang.

Thanks,
Uncle Hulka

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Uncle Hulka

1967 Oldsmobile 4-4-2
1968 Plymouth Sport Fury Conv w/Factory 440HP
1969 Oldsmobile Cutlass S
1969 Oldsmobile Delta 88 w/Original B07 Police Package
1970 Chevelle 396

Steve

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HELP!!! Problem after Ignition Conversion!
« Reply #1 on: June 03, 2008, 04:36:18 PM »

OK   Just acknowledging this.  I even called the Canadian Authority to chime in.  Give me a minute if you are hanging around
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Steve

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HELP!!! Problem after Ignition Conversion!
« Reply #2 on: June 03, 2008, 04:42:21 PM »

OK
 
Lea and I talked about this.
 
It is possible the plug gap is too wide.  Seems to me I had set them at .038 and had no problems.
 
If you have a digital Volt Meter, check the voltage on the ballast resistor.  Make sure you have 12 and 9 VDC
 
It could be your distributor Pick up, even new, is bad.
 
Those Orange boxes have a bad reputation for being bad out of the box.  See if you can scrounge a working one somewhere and try it.
 
What kind of revs are we talking about here.  2000?  3000?
 
The carb dumping is another story.  But you have that solved.
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Leaburn Patey

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HELP!!! Problem after Ignition Conversion!
« Reply #3 on: June 03, 2008, 05:00:39 PM »

Stalling after letting off the gas is a drop in vacuum.
Idle too low? Maybe try setting up the timing a few degrees up more 7* to 10*
An leak in the intake manifold is known to stall an engine.
With the engine running at idle spray WD-40 around the edges of it at the heads.If the idle changes--you have a leak..
Did you fine tune the new carb  to your engine?? Is it electric or manual choke? Is the choke set up properly?
Double check/replace any rotten vacuum lines.
I strongly suggest using a vacuum guage when fine tuning both the timing and carb.
18 to 22 inches of vaccumm is what you should be reading.
Looks like you changed everything but disty cap and rotor.
 There may be a slight clearance issue between the old cap and the new disty.The disty nowadays is a Mallory type  not the old Mopar one of the old days.For the cost of it,get the Mopar Performance cap and rotor as a process of elimination.
I am asuuming that you already double checked the terminals of your new wires are on tight to the cap and wires.
Double check the gap in the disty between the pick up and reluctor.
High speed misfire can be caused by:
 a too wide gap in plugs.Close them to .37.
dirt or water in the fuel,or fuel filter.
Double check al the connections of your ECU connections.Did you solder and shrink tube your wires? The ECU as per instructions must be grounded well.
Hope any if this sheds light on your troubles.
 
 
 
 
 
 
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1973 Satelitte wagon
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Leaburn Patey

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HELP!!! Problem after Ignition Conversion!
« Reply #4 on: June 03, 2008, 05:02:08 PM »

Steve,I do remember having an ECU crap out on me.It was misfiring on higher RPMs but purr like a cat at idle with no load..

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1968 Newport Custom project BOAB
1973 Satelitte wagon
1983 Dodge 400
2006 300C HEMI!!

Steve

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HELP!!! Problem after Ignition Conversion!
« Reply #5 on: June 04, 2008, 02:34:20 AM »

First of all, thanks for the help. It is really appreciated. Where to start.....

(in no particular order)

1) The conversion kit included a new cap and rotor.

2) Without a tach, I am guessing around 3500 rpm +/- 500 (my tach/dwell meter only goes to 2000)

3) I'll close up the plug gap to .038 and see if that makes a difference.

4) I mounted the ECU to the front side of the radiator support. Thought this would keep it cool. It is securely bolted to the support, so it should be making a good connection to ground.

5) Plug wires are tight to both the cap and the plug.

6) I don't think I have a vacuum leak. Pulls 20+ lbs vacuum (I bought a vacuum gauge to aid this diagnosis. I wanted to try everything I could think of before coming to the group for help.)

7) The carb has not been fine tuned to the engine.

CORRECTION TO MY ORIGINAL POST!
I know for sure that this problem did NOT exist prior to conversion. ALSO adding the new coil did seem to help a bit (but I could be wrong). The misfire/breakup didn't seem quite as severe.

There are only a few gearheads in my area and none are into mopar, so borrowing an orange box is out. I'll have to buy one (I was going to get a black box as a spare anyway). I just hate to just keep throwing money at a problem like a stab in the dark.

Thanks again, POLARACO, for calling in the big guns!

Thanks to all for your contributions. I am sure with the knowlege here a solution will be found.

Can't sleep.
Can't eat.
Can't focus at work.
Not good.

Uncle Hulka

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Uncle Hulka

1967 Oldsmobile 4-4-2
1968 Plymouth Sport Fury Conv w/Factory 440HP
1969 Oldsmobile Cutlass S
1969 Oldsmobile Delta 88 w/Original B07 Police Package
1970 Chevelle 396

Steve

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HELP!!! Problem after Ignition Conversion!
« Reply #6 on: June 04, 2008, 04:09:51 PM »

I was just thinking.  Did you try removing the vacuum advance hose off the disty when you have it up to speed?
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Steve

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HELP!!! Problem after Ignition Conversion!
« Reply #7 on: June 05, 2008, 03:28:27 AM »

No, but here's what I think I'm going to do next:

1) close the plug gap to .035
2) Go through the entire timing process as outlined in the conversion manual.

Must say, I'm leary of the manual as there are mistakes in it. For example, the manual states that the rotors on small blocks (273, 318, etc.) rotate clockwise, while big blocks (383,440,hemi,etc.) rotate counter-clockwise. However the illustrations provided show both engines rotating clockwise!

I won't get to try this until this weekend, but I will keep you all updated of my success/failure.

Please keep your thinking caps on just in case;-)



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Uncle Hulka

1967 Oldsmobile 4-4-2
1968 Plymouth Sport Fury Conv w/Factory 440HP
1969 Oldsmobile Cutlass S
1969 Oldsmobile Delta 88 w/Original B07 Police Package
1970 Chevelle 396

Steve

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HELP!!! Problem after Ignition Conversion!
« Reply #8 on: June 05, 2008, 04:10:54 AM »

Darned GM Guys    
 
I dunno. . .I've run out of ideas on this one
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Snotty

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HELP!!! Problem after Ignition Conversion!
« Reply #9 on: June 05, 2008, 10:26:20 AM »

[/QUOTE]
 
They do rotate in opposite directions.  The directions are correct, regardless of the illustration.
 
Steve mentioned the Vacuum advance.  Good question, as well as is the diaphragm for the advance any good?  A bad diaphragm will cause what you are describing.  To test it, put a hose on the end and suck.  If you can draw any air at all the diaphragm is bad.
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Steve

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HELP!!! Problem after Ignition Conversion!
« Reply #10 on: June 05, 2008, 10:29:18 AM »

In his initial post he said it's advancing to 38 degrees.  It's a tad high, but I don't think enough to make it stumble like he's talking about
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Steve

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HELP!!! Problem after Ignition Conversion!
« Reply #11 on: June 07, 2008, 06:34:05 AM »

UPDATE

A really good friend (who happens to be an EXCELLENT diagnostician) came over last night and together we worked until after 2 AM trying to figure this problem out. I won't bore you with everything we did, but we did discover something that will ultimately help us solve this puzzle.

Reinstalling the old dual point distributor made the car run AWESOMELY!!!

So, what is the problem with the new electronics? Is it the ECM (orange box)? Is it the distributor?

Although the orange boxes has a questionable reputation, Jon is not convinced that it is a bad box. He thinks the problem might be caused by low voltage. The ballast resistor and related circuitry is a curve ball to non-mopar guys. We don't know what voltages we should be seeing. I always thought that the ballast resistor limited the voltage the coil 'sees' to 9V when the engine is running and only passes 12V during the start sequence.

I want to test voltages to help determine if the box is bad or not. Can you guys please tell me where I should check and what voltage I should read?

Some things I can tell you:
1) With the electronic ignition distributor and related components installed, the engine starts to shake significantly and breaks up (misfires) at approx 3,000 RPM

2) Reinstalling the old points distributor made the engine run perfectly
 
3) The box orange  is properly grounded

4) All the connections (including splices) are good and solid

5) Timing is correct (both mechanical and vacuum)

I want to get another box and try it just to see, but no part stores have one in stock, the nearest dealership is 30 miles away and the one salvage yard around here doesn't have any. I'd rather establish without a doubt that it is the box before throwing more money at it. I just plunked down a bunch of moola for a new convertible top, pads, cables and rear glass. This on top of the conversion kit, Voltage regulator, Spark Plugs, wires and a new carburetor. My wife's patience is starting to wear out.

Hope this info helps with a diagnosis. If there are key voltages I should be checking, please let me know.

Thanks so much for your help!!!


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Uncle Hulka

1967 Oldsmobile 4-4-2
1968 Plymouth Sport Fury Conv w/Factory 440HP
1969 Oldsmobile Cutlass S
1969 Oldsmobile Delta 88 w/Original B07 Police Package
1970 Chevelle 396

Leaburn Patey

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HELP!!! Problem after Ignition Conversion!
« Reply #12 on: June 07, 2008, 08:59:58 AM »

You can get a generic ECU at Napa,Autozone,O'riell;y's that will work.
The Mopar one in my Diplomat did not last the same day.My el cheapo Wells ECU has not given me any trouble at all.
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1968 Newport Custom project BOAB
1973 Satelitte wagon
1983 Dodge 400
2006 300C HEMI!!

Steve

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HELP!!! Problem after Ignition Conversion!
« Reply #13 on: June 07, 2008, 09:55:13 AM »

1.  I said check the voltage on the ballast Resistor, both ends before.   Should read 12V and 9 VDC.  It's best done under a load.
 
2.  Check the air gap of the pickip.  I think it's .008.  You need a non-metalic feeler gauge to do it right, but a steel one will tell you if the gad is too wide.  Look for strike marks on the pick up.
 
3.  I had a bad pickup do that once.  High speed under a load, the car would sputter and break up. 
 
4.  As said, lately, those Orange boxes have been bad out of the box.  Bad repuataion.  I would go for a 20 dollar OE replacement and try that.  I know Butch has 2!  Lea had one, I had one and a 2nd died in 3 months.  Make sure the pins aren't loos in the box too.
 
5.  Double check continuity on the ESC Harness.  Wiggle around the connections.  The Chinese drink that whacky wine.
 
If everything else is right, then it has to be one of those three things.  Bad Voltage, pick up or box
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Steve

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HELP!!! Problem after Ignition Conversion!
« Reply #14 on: June 07, 2008, 04:37:20 PM »

CBarge, I will try to pick one up tomorrow. Was planning to keep a "just in case" spare on hand. Good advice.

POLARACO,
1)  Yes, you did advise checking these voltages before. However I am not clear on exactly what to do and what you mean. Should I be measuring the 'feed' side for 9V in the 'run' position and 12V in the 'start' position? NOTE:I should point out that as a test, we temporarily (and briefly) bypassed the ballast resistor. No change;same problem.

2) We disassembled and inspected the distributor for mechanical issues. None found. When we reassembled the distributor, we set the air gap to .008 (checked at all 8 points).

3) Bad pickup, eh? Hmmnnnn. One more variable thrown into the mix ;-)

4) Man, these orange boxes have a crappy reputation. I will track down a replacement ASAP!

5) Way ahead of you here, bro. Double-checked all connections including the pre-made ones. I'm done taking anything for granted.

Thanks for all the help guys. All great advice!!!



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Uncle Hulka

1967 Oldsmobile 4-4-2
1968 Plymouth Sport Fury Conv w/Factory 440HP
1969 Oldsmobile Cutlass S
1969 Oldsmobile Delta 88 w/Original B07 Police Package
1970 Chevelle 396
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