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Thu Oct 22, 2015 8:25 am

Hi all!

I've got some timing issues (70 Automatic FI Fastback). About 6 weeks ago I got everything in order after having some rough idle issues. Got the ignition system in check and was good to go.
However, my idle is rough when I'm in gear at a stop light. It's not as bad in N or P but it's not great.
I'm figuring that I should start with the ignitions system again. (right?)
And then from there check out the fuel filter, etc.

Anyway, we checked the battery voltage. That was all good. Checked the distributor and points. Those were good. Went to time the car and that was a mess. To start, the timing light blew out in under 3 minutes. This is the second time I've had a light do this.
Am I hooking it up incorrectly?
The + side is hooked up to the + side of the coil, the - side is grounded on the body.
Is that wrong? How do you hook up your light?

Second issue is that while the light is working, the marks we made on the pulley are jumping all over the place when lit up. I have the Bentley manual but the picture of where TDC is at is still kind of confusing. I'm thinking that when we turn the engine by hand and set this, we're doing it wrong? I'm not sure. I just can't figure out how to get those damn marks to line up.

Any insight you can share is greatly appreciated! Rough idling sucks.

Oh, one more thing. Do spark plugs, points, timing go out that fast? It seems weird to me that this was checked and fixed recently but may be off again.

Thu Oct 22, 2015 8:37 am

Dolly_Dagger wrote:

Anyway, we checked the battery voltage. That was all good.

Define "all good." What are the numbers and at what rpm?

Quote:
Checked the distributor and points. Those were good. Went to time the car and that was a mess. To start, the timing light blew out in under 3 minutes. This is the second time I've had a light do this.
Am I hooking it up incorrectly?
The + side is hooked up to the + side of the coil, the - side is grounded on the body.
Is that wrong? How do you hook up your light?

That is right, + can be hooked to + side of the coil for power - clamp to any ground, and the inductive pickup clamped around the wire running to the spark plug at cylinder #1.

Never had a timing light blow out, either you are buying crappy timing lights or maybe you have an overvoltage situation (again another reason I want to know your voltage numbers).

Quote:
Second issue is that while the light is working, the marks we made on the pulley are jumping all over the place when lit up. I have the Bentley manual but the picture of where TDC is at is still kind of confusing. I'm thinking that when we turn the engine by hand and set this, we're doing it wrong? I'm not sure. I just can't figure out how to get those damn marks to line up.

This is potentially indicative of a more serious problem. The timing mark should appear steady under the strobe light at all speeds in the idle range. It shouldn't move until you get above idle and the advance mechanism kicks in.

If the timing mark is jumping around at idle that is indicative of the timing itself jumping around, which can be the result of a worn sloppy distributor or distributor drive gear, or perhaps some slop in the advance plate inside the distributor or loose points mounting screw, or, worst case, excessive crankshaft endplay where the timing changes as the crank moves back and forth longitudinally.

EDIT: make sure you are clamping the timing light's inductive pickup on the plug wire as close as possible to the spark plug itself to reduce the chance of it picking up stray signals as the other plugs fire.

Quote:
Oh, one more thing. Do spark plugs, points, timing go out that fast? It seems weird to me that this was checked and fixed recently but may be off again.

spark plugs no. As long as they are not fouled with fuel or oil they last a long time. I forget exactly when VW calls for them to be replaced, maybe every 12,000 miles? Check the Bentley. Points, however are another story. As you know, the rubbing block attached to the points where it rides on the cam inside the distributor is a wear point. The cam inside the distributor needs to be lubricated with points grease to help keep that wear to a minimum. As the points rubbing block wears down, the points move closer together which changes the gap between the points. When the gap between the points changes, the timing changes. A lot of people don't know/understand this. So yes it is normal that the points gap will change over time and the timing will change along with it.

So anytime you make any adjustment to the points, you will have to re-adjust the timing. It's just a part of normal maintenance on an old car with a points-type ignition system.

Thu Oct 22, 2015 9:37 am

This is all really good info...thank you

So the voltage was checked when the car was not running, so no rpms. It showed 12.75 or thereabouts.
Should I have put it in N and revved the engine? How do you test it while running?

Both lights that burned out were from O'Reilly's. Bosch digital timing lights that were $100. Is that considered cheap? I just bought another one from Auto Zone...different manufacturer but still a $100 digital light.

For the record, the generator looks pretty old. I didn't take it out and look at it though. Would that be an issue?

Thu Oct 22, 2015 9:41 am

Is the + side of the coil where the distributor is hooked up? If so, that's why the car runs bad and that's why the timing light burns out.

Battery power should be on +, distributor on -.

Thu Oct 22, 2015 9:46 am

even backwards, it should just cut the power and kill the car, not break a $100 test light. Ouch!

Thu Oct 22, 2015 9:49 am

Dolly_Dagger wrote: This is all really good info...thank you

So the voltage was checked when the car was not running, so no rpms. It showed 12.75 or thereabouts.
Should I have put it in N and revved the engine? How do you test it while running?

Same way you test it when not running. Clip your meter leads to the battery terminals, throw the meter on the passenger seat where you can see it and start the engine. You should see some voltage above engine-off battery voltage at idle and then as you raise the engine speed you should see the voltage reading rise, to a point. I would say the max you should see out of it is around 14v. If your voltage reading goes above that you have a voltage regulator issue.

Quote:
Both lights that burned out were from O'Reilly's. Bosch digital timing lights that were $100. Is that considered cheap? I just bought another one from Auto Zone...different manufacturer but still a $100 digital light.

I certainly don't consider that cheap :shock:

Quote:
For the record, the generator looks pretty old. I didn't take it out and look at it though. Would that be an issue?

They all look pretty old because they all are pretty old. :D
Taking it out and looking at it isn't really going to tell you anything. The only thing you can really check visually besides making sure the belt is intact is checking the brushes - but worn brushes would cause lack of charging, not overcharging.

Thu Oct 22, 2015 10:08 am

Tram, I'll have to take a look at that. Thank you.

I'm glad you don't think these are cheap! I was looking online and there are some that are close to $400! I was like, wtf...it can't be possible that I have to buy one of those. That's why I wanted to check in. What a relief!

Anyway, I'll check the voltage tonight after work. Thanks for the tips!

Thu Oct 22, 2015 10:21 am

Dolly_Dagger wrote: Tram, I'll have to take a look at that. Thank you.

I'm glad you don't think these are cheap! I was looking online and there are some that are close to $400! I was like, wtf...it can't be possible that I have to buy one of those. That's why I wanted to check in. What a relief!

Anyway, I'll check the voltage tonight after work. Thanks for the tips!

First- are you sure your light is actually burning out- or is spark going away on #1? Did you try the light on another cylinder? Do this not only to test the light, but to see if you have an ignition "skip" or "miss" going on in any cylinder.

Second- if your mark is jumping around that's either indicative of a cylinder not always firing or a worn distributor breaker plate- either of which will cause rough idling issues.

I have 2 timing lights that I have had for decades, and they get a LOT of use. One, "old faithful", is a snap- on that i bought in the late 1970s. The other is a Snap On digital with a digital tach that I bought in 1992 that finally just had the circuit board fall apart a year ago.

I've never had one burn out, but I tend to power them on a 12v battery on a hand truck. Just more convenient that way.

Thu Oct 22, 2015 10:31 am

Yep, definitely burning out. The bulb turns near black and it starts smoking and smells like...burned electronics.

Thu Oct 22, 2015 10:55 am

regulator wasted and pumping 30 volts to the car? damn

Thu Oct 22, 2015 10:58 am

Erik G wrote: regulator wasted and pumping 30 volts to the car? damn

That's what I'm wondering but I figured it would have blown up the FI ECU long ago if that was the case!

Thu Oct 22, 2015 12:40 pm

I would check the voltage at the battery engine running . I would think if it was high enough to blow the timing light it would have boiled the battery by now or burnt out some bulbs in the car.

I don't know if you have been driving this car or just working on it.

Another thing , are you actually feeling a rough running engine ? I ask because my 73 SB FI auto trans sets up a vibration when in drive at a stop , as soon as I place it in park that stops also once I take my foot off the brake in drive it stops . Runs fine in park at idle.

Thu Oct 22, 2015 12:46 pm

blues90 wrote: I would check the voltage at the battery engine running . I would think if it was high enough to blow the timing light it would have boiled the battery by now or burnt out some bulbs in the car.

I don't know if you have been driving this car or just working on it.

Another thing , are you actually feeling a rough running engine ? I ask because my 73 SB FI auto trans sets up a vibration when in drive at a stop , as soon as I place it in park that stops also once I take my foot off the brake in drive it stops . Runs fine in park at idle.

I drive it almost every day and work on it as often as it needs it. Anywhere from 1-4x a week.

It's more than a vibration. It almost sounds like the engine is going to cut out at any given moment. Instead of an RPM surge, it sims like a dip and it shakes a bit during those moments. They (the dips and shaking) don't happen in a very rhythmic way but it's consistent while I'm stopped.

Also, when the timing light was blown, the car was running.

Thu Oct 22, 2015 12:49 pm

Dolly_Dagger wrote: blues90 wrote: I would check the voltage at the battery engine running . I would think if it was high enough to blow the timing light it would have boiled the battery by now or burnt out some bulbs in the car.

I don't know if you have been driving this car or just working on it.

Another thing , are you actually feeling a rough running engine ? I ask because my 73 SB FI auto trans sets up a vibration when in drive at a stop , as soon as I place it in park that stops also once I take my foot off the brake in drive it stops . Runs fine in park at idle.

I drive it almost every day and work on it as often as it needs it. Anywhere from 1-4x a week.

It's more than a vibration. It almost sounds like the engine is going to cut out at any given moment. Instead of an RPM surge, it sims like a dip and it shakes a bit during those moments. They (the dips and shaking) don't happen in a very rhythmic way but it's consistent while I'm stopped.

Also, when the timing light was blown, the car was running.

Yup, it sounds like a cylinder cutting out and then refiring.

Thu Oct 22, 2015 1:01 pm

Tram wrote: Dolly_Dagger wrote: blues90 wrote: I would check the voltage at the battery engine running . I would think if it was high enough to blow the timing light it would have boiled the battery by now or burnt out some bulbs in the car.

I don't know if you have been driving this car or just working on it.

Another thing , are you actually feeling a rough running engine ? I ask because my 73 SB FI auto trans sets up a vibration when in drive at a stop , as soon as I place it in park that stops also once I take my foot off the brake in drive it stops . Runs fine in park at idle.

I drive it almost every day and work on it as often as it needs it. Anywhere from 1-4x a week.

It's more than a vibration. It almost sounds like the engine is going to cut out at any given moment. Instead of an RPM surge, it sims like a dip and it shakes a bit during those moments. They (the dips and shaking) don't happen in a very rhythmic way but it's consistent while I'm stopped.

Also, when the timing light was blown, the car was running.

Yup, it sounds like a cylinder cutting out and then refiring.

Do you think I should test compression before trying to set up the timing gun and timing it again?

Thu Oct 22, 2015 1:12 pm

Dolly_Dagger wrote: Tram wrote: Dolly_Dagger wrote: blues90 wrote: I would check the voltage at the battery engine running . I would think if it was high enough to blow the timing light it would have boiled the battery by now or burnt out some bulbs in the car.

I don't know if you have been driving this car or just working on it.

Another thing , are you actually feeling a rough running engine ? I ask because my 73 SB FI auto trans sets up a vibration when in drive at a stop , as soon as I place it in park that stops also once I take my foot off the brake in drive it stops . Runs fine in park at idle.

I drive it almost every day and work on it as often as it needs it. Anywhere from 1-4x a week.

It's more than a vibration. It almost sounds like the engine is going to cut out at any given moment. Instead of an RPM surge, it sims like a dip and it shakes a bit during those moments. They (the dips and shaking) don't happen in a very rhythmic way but it's consistent while I'm stopped.

Also, when the timing light was blown, the car was running.

Yup, it sounds like a cylinder cutting out and then refiring.

Do you think I should test compression before trying to set up the timing gun and timing it again?

I think you should pull the plugs and see what they look like- but first, test one cylinder at a time by unplugging the injector while it's running and see if there is one that makes no or very little difference in how it runs.

What kind of spark plugs are you running?

Thu Oct 22, 2015 1:41 pm

Tram wrote: I think you should pull the plugs and see what they look like- but first, test one cylinder at a time by unplugging the injector while it's running and see if there is one that makes no or very little difference in how it runs.

What kind of spark plugs are you running?

Injector as in fuel injector?

I can't remember the plugs that are in there. I'll check tonight.

Thu Oct 22, 2015 4:51 pm

Dolly_Dagger wrote: Tram wrote: I think you should pull the plugs and see what they look like- but first, test one cylinder at a time by unplugging the injector while it's running and see if there is one that makes no or very little difference in how it runs.

What kind of spark plugs are you running?

Injector as in fuel injector?

I can't remember the plugs that are in there. I'll check tonight.

Right! Easier than pulling plug wires one at a time.

Thu Oct 22, 2015 6:00 pm

The other way.I have seen timing lights burned out is either your clip on the positive coil is touching another connector.......or the coil wire has a leak right at the coil high tension lead and is shorting to the timing light + conector.

A crack in the coul housing near the HT lead or a crack in the boot on the coil wire can do this
Ray

Fri Oct 23, 2015 6:37 am

Tram wrote: Dolly_Dagger wrote: Tram wrote: I think you should pull the plugs and see what they look like- but first, test one cylinder at a time by unplugging the injector while it's running and see if there is one that makes no or very little difference in how it runs.

What kind of spark plugs are you running?

Injector as in fuel injector?

I can't remember the plugs that are in there. I'll check tonight.

Right! Easier than pulling plug wires one at a time.

Spark plugs = NGK-B5ES

With the car running, the battery voltage read 13.86-14.06.

Since I'm a total freak and was afraid to pull the injectors (how exactly do you do that? It didn't look easy), we pulled each spark plug.
I read in the Bentley manual to pull them all and then test compression.
What we did was pull them one by one so when 1 was out, 2,3,4 were still in. Will that skew the readings?

Anyway, pulled and checked all the spark plugs and tested compression. Here are my results: (sorry if this is overkill with info)

First of all, all the spark plugs had a gap that was too small. Re-gapped all of them per Bentley specs. Is that weird? Considering that I just did this in August?

Spark 1 = 120psi

Spark 2 = Initially read 90. Tightened the multimeter and eventually went up to 128.

Spark 3 = 118/119 psi

Spark 4 = Read this one three times to be sure of what the output was. It was low. 90-100psi

Do they look okay?

Spark plug 4 obviously has a low reading. I read in the Bentely manual that we should have put a little bit of oil in the hole to see if the reading changed. I should probably go back and do that, huh? (It got dark so I didn't have time)

What would you say are the next steps?

Should I stop driving the car until this is resolved?

Thank you!