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Timing issues related to PROM??

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Old May 22, 2008 | 01:03 PM
  #1  
whitedevilTA's Avatar
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Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Timing issues related to PROM??

Hi all. I had a PROM burned for my engine set up. I know nothing about what was done to the chip. For weeks I have not been able to get the timing even close, and here are two things I just recently noticed. Someone please help me with this!

1. When the esc wire is disconnected, my timing will actually ADVANCE 10 more degrees than what it was when still plugged in. Could this be a bad PROM burn??

2. Since the car will not run at the 10 degree base setting the chip is supposed to be programmed for, I get it set so it will run.....ussually around 45 degrees with esc unplugged. When I plug it back in, the timing drops to 35 degrees, and when I rev the engine, it will only advance 5 degrees, NO MORE! Even at high RPMs it does not advance any more that 5 degrees more than what it was at idle.

Car feels like an absolute dog because it's not getting any timing! Someone please help because it has to be distributor related or PROM related, and I would love to figure it out and drive my car!!!
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Old May 22, 2008 | 02:02 PM
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From: Chasing Electrons
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Re: Timing issues related to PROM??

First thing to do is to get a stock BIN and try it. That will tell you if your current BIN isn't set up correctly. Then while you have the stock BIN handy, use that from here out for improving your tune.

The reason is that no-one knows what was done to the BIN you had burned for your setup. There could be any number of problems with it. Or no problems at all. But that is an unknown. When you start with a stock BIN then you will know that it is OK to start off with.

If the stock BIN shows the same timing retard issue, switch the pickup coil wires (in the distributor that go to the ignition module). Then try it again with the stock BIN.

RBob.
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Old May 23, 2008 | 12:30 AM
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whitedevilTA's Avatar
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From: Northern CT
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: Timing issues related to PROM??

Thank you, i'll try that first thing in the AM and let you know how it goes.
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Old May 23, 2008 | 01:39 PM
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From: Northern CT
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: Timing issues related to PROM??

OK, heres the progress. Swapped the wires that go into the control module, and that was it. I got the idle set perfectly, and now the timing retards when the ESC wire is unplugged. PHEW! One problem down. Now however, the car doesn't want to rev. If I give it throttle slowly, I can see the timing advancing, but it pops and wont rev with quick bursts on the throttle. While I'm holding the timing light on it, and give it the quick revs, the light stops flashing, almost like it's not getting spark, or a misfire?? I'm using a stock coil, not sure if that matters. Not sure what to try next.

By the way, with the connector plugged back in, the car idles at 26 degrees advanced, which I'm told is normal. I also have my knock sensor unplugged for now so it doesnt interfere with the timing settings.
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Old Apr 8, 2009 | 09:47 AM
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From: Piedmont of NC
Car: '72 Jeep Commando "Mossy Edition"
Engine: AMC 304 w/ TBI
Transmission: TH-400
Axle/Gears: D30/D44 4.27:1
Re: Timing issues related to PROM??

Originally Posted by whitedevilTA
OK, heres the progress. Swapped the wires that go into the control module, and that was it. I got the idle set perfectly, and now the timing retards when the ESC wire is unplugged. PHEW! One problem down. Now however, the car doesn't want to rev. If I give it throttle slowly, I can see the timing advancing, but it pops and wont rev with quick bursts on the throttle. While I'm holding the timing light on it, and give it the quick revs, the light stops flashing, almost like it's not getting spark, or a misfire?? I'm using a stock coil, not sure if that matters. Not sure what to try next.

By the way, with the connector plugged back in, the car idles at 26 degrees advanced, which I'm told is normal. I also have my knock sensor unplugged for now so it doesnt interfere with the timing settings.
wdTA... any updates on this?

I'm fighting a similar NO timing advance on an AMC304 conversion. Definitely FRUSTRATING!
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Old Apr 14, 2009 | 08:55 PM
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From: Northern CT
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: Timing issues related to PROM??

Originally Posted by Caver Dave
wdTA... any updates on this?

I'm fighting a similar NO timing advance on an AMC304 conversion. Definitely FRUSTRATING!
I'm still playing with it unfortunately, but I put a carb on it so I might not be too much help if you have EFI. I did fix the timing problem now that the dist is a vacuum advance one haha!

How are your ignition wires? I had an old set that didn't look real bad looking at them quick, but I swapped them out for a new set of morroso EMI suppression ones and it made a WORLD of difference in the timing and the way it runs. Just a though. Good luck!
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Old Apr 14, 2009 | 09:17 PM
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From: Piedmont of NC
Car: '72 Jeep Commando "Mossy Edition"
Engine: AMC 304 w/ TBI
Transmission: TH-400
Axle/Gears: D30/D44 4.27:1
Re: Timing issues related to PROM??

Originally Posted by whitedevilTA
I'm still playing with it unfortunately, but I put a carb on it so I might not be too much help if you have EFI. I did fix the timing problem now that the dist is a vacuum advance one haha!

How are your ignition wires? I had an old set that didn't look real bad looking at them quick, but I swapped them out for a new set of morroso EMI suppression ones and it made a WORLD of difference in the timing and the way it runs. Just a though. Good luck!
Sorry to hear about the carb bro! For my application, the benefits FAR outweigh the pain of conversion!

The wires (8mm house brand) appear to be good (no obvious arcing or anything in the dark). I believe the VERY close proximity of the distributor pickup leads & EST to the ignition coil (about 1/2" away) was the issue. Once I moved the EST 5"-6" away in front of the TB, I was able to see the electronics adjust the timing and even get it to run with the bypass disconnected! Still need to do some additional testing, but it was good enough last Thursday to call resolved (well, for now).
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Old Apr 15, 2009 | 10:45 PM
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From: Northern CT
Car: 1986 Trans am
Engine: 5.3 LM7
Transmission: T56 6 speed
Axle/Gears: Dana 44 w/ 3.55's
Re: Timing issues related to PROM??

Originally Posted by Caver Dave
Sorry to hear about the carb bro! For my application, the benefits FAR outweigh the pain of conversion!

The wires (8mm house brand) appear to be good (no obvious arcing or anything in the dark). I believe the VERY close proximity of the distributor pickup leads & EST to the ignition coil (about 1/2" away) was the issue. Once I moved the EST 5"-6" away in front of the TB, I was able to see the electronics adjust the timing and even get it to run with the bypass disconnected! Still need to do some additional testing, but it was good enough last Thursday to call resolved (well, for now).
Thats good to hear! I'm glad yours runs at least! But yea, mine actually runs very good with the carb. Fires on the first crank and runs nice and smooth. I can drive it around fine and it idles perfect, but the minute I give it gas it chokes and stalls sometimes. I'm assuming it's carb related, and that I'm not getting the fuel I need when I step on it. Too bad I can't tune a carb to save my life! I have a buddy coming to play with it so wish me luck lol.
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