I just replaced the distributor in my '85 GT. The car was missing was slightly bucking at certain rpms and I had hoped that by replacing the rusty distributor the problems would go away. Now to the problem.
I have found TDC using a whistle, clocked the cap at 1, jumped the AB connector and the motor just spins. I then thought perhaps the new icm that came with the distributor was bad, and swapped that out. Nope.
Any other suggestions?
Thanks in advance
m-a
[This message has been edited by marc-alan (edited 12-15-2013).]
You could be 180 degrees out. When you time it, make sure the timing mark is pointed to the 3rd point on the timing plate. Make sure the rotor is pointed at number one. And make sure you are at the top of the compression stroke. I have done it when I was 180 out. Easy to do
You could be 180 degrees out. And make sure you are at the top of the compression stroke. I have done it when I was 180 out. Easy to do
I was thinking the same thing, but the OP said he used a whistle to determine TDC. I don't think the whistle would sound on the exhaust stroke. However, he obviously still needs to have the rotation and position of the distributor/rotor at least "close" to #1.
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Originally posted by marc-alan:
I have found TDC using a whistle...
[This message has been edited by Patrick (edited 12-15-2013).]
I was thinking of replacing the new distributor with the old one and seeing what happens. I will double check to make sure I am not 180 degrees out. I thought that using a whistle to find TDC you could not be 180 degrees out.
I was thinking of replacing the new distributor with the old one and seeing what happens. I will double check to make sure I am not 180 degrees out. I thought that using a whistle to find TDC you could not be 180 degrees out.
m-a
A whistle will blow on the exhaust stroke, but the whistle won't be as loud because the air is exiting out the valve and the whistle at the same time
If you aren't using a probe, you need a compression tester which will only rise on the compression stroke.
I have used the compression tester with a remote trigger to bump the starter, but a probe is the easier way. You need to have the rotor visible and crank the engine until the rotor is at number one and the timing mark is at the indicator strip. If you are 180 out, it will not point at number one
thanks, I believe I also have a compression gauge. When it gets a bit warmer out, I will check to confirm with the compression gauge. Sure hope its that simple.
Too late now, but i always mark the distibutor position on the manifold AND where the rotor is pointed. You always can get it exactly where you had it.
I had a chance with the warm weather to confirm TDC for number 1. I also was able to confirm that there was spark. I then used a timing light and had my helper turn the motor over with the key, I found that I was within the landing for the timing mark with the engine spinning. We could here the motor try to catch a little bit, but not getting all the way there. I tried both the old distributor and the new one. Same results.
I could smell and see gas on the spark plug. What else could it be? I even checked the fuse under the dash.
I then used a timing light and had my helper turn the motor over with the key, I found that I was within the landing for the timing mark with the engine spinning.
With the A/B jumper in place?
And you're positive the timing marks on the balancer are in the right place? (TDC of #1 piston lines up with 0° on the scale?)
I had the AB jumper in place. The spark was determined by putting the pulled spark plug back in the boot and grounding the outside of the plug to the motor. I was able to see a nice white-blue spark. It was brighter with the newer distributor than the old.
It makes no sense to me at the moment, I stopped working on it today to think about it more before getting aggravated.
The spark was determined by putting the pulled spark plug back in the boot and grounding the outside of the plug to the motor. I was able to see a nice white-blue spark. It was brighter with the newer distributor than the old.
No offense, but that does not answer my question.
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Originally posted by Patrick:
No problem jumping a full 1/4" gap?
Having the spark jump a few thousandths of an inch outside of the combustion chamber means nothing. It's much more difficult to do so under compression which is why the spark needs to be able to jump a full 1/4" gap under atmospheric pressure.
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Originally posted by Patrick:
And you're positive the timing marks on the balancer are in the right place? (TDC of #1 piston lines up with 0° on the scale?)
I'm trying to determine if the outer ring of your harmonic balancer has spun, or if you have a non-Fiero replacement balancer installed... because if so, you'll never be able to set the ignition timing properly using the timing marks.
[This message has been edited by Patrick (edited 12-21-2013).]
Having never done this 1/4" gap, what is the best way to do so?
You want something metal sticking out of a spark plug boot that you can hold 1/4" away from an engine ground. I've done it by sticking the end of a screwdriver into the boot, and while holding its (well insulated) handle, rest the shaft of the screwdriver on something metal like an exhaust manifold. While the engine is being cranked, lift the screwdriver shaft 1/4" away from your ground. The spark should make a good loud "snap" as it jumps the 1/4" gap. And make sure your hand isn't too close to the screwdriver shaft, or you'll be cursing me as you involuntarily throw the screwdriver 50 feet into the neighbour's yard.
I re-read all the posts to my question. Today I finally had some warm weather and time to investigate this a bit farther. I determined I had compression in the cylinders with a compression tester. I double checked the position of the rotor to TDC at number one. I confirmed spark, my neighbors almost got a screwdriver as I got zapped (even replaced spark plugs). Using starter fluid injected into the throttle body had no effect. I am leaning towards a bad ecm...anyone have any other thoughts
My new distributor had a weak coil right out of the box, new one made it strong again. Also replace the ignition coil and it got even better. Setting the distributor at TDC without the AB jumper should get it to start so it can be timed. Did you check to be sure you haven't bumped something to create a vacuum leak or unplug something else? Firing orders correct?
Even with a bad ECM the engine should fire on starting fluid. The ignition system will operate without an ECM in place.
You can have a weak spark that will produce a spark with a simple tester outside the engine but not in the engine under compression. (Compression = more air between the spark plug terminals = more voltage needed to jump the gap.
An "Electronic Ignition Tester" is designed to only fire at the higher voltages produced by electronic ignition. Just checking for spark the old fashion way isn't always good enough.
If indeed you are not getting enough voltage to fire the plugs under compression the problem might be in the ignition coil (more likely) or in the rotor (less likely)
Cranking the engine with the spark plug wires disconnected can cause an ignition coil's insulation to fail if weak. It is not possible to test the coil's insulation with a standard low voltage meter.
If spark is reaching the plugs then the problem would be timing.
[This message has been edited by phonedawgz (edited 04-13-2014).]
You can have a weak spark that will produce a spark with a simple tester outside the engine but not in the engine under compression. (Compression = more air between the spark plug terminals = more voltage needed to jump the gap.
An "Electronic Ignition Tester" is designed to only fire at the higher voltages produced by electronic ignition. Just checking for spark the old fashion way isn't always good enough.
Are you saying that jumping a full 1/4" gap isn't enough? What's the gap in the tester you've linked to?
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Originally posted by Patrick:
You want something metal sticking out of a spark plug boot that you can hold 1/4" away from an engine ground... <snip>
With those distributors, here is what I have found. The pick up coils wires are longer than stock and get pinched by the cap in the back, make sure they get tucked inside the cap.
With those distributors, here is what I have found. The pick up coils wires are longer than stock and get pinched by the cap in the back, make sure they get tucked inside the cap.
Mine got pinched as well, appears to be a common thing! I ended up buying another pickup coil and replacing it.
