A few days ago I thought I heard slight pinging

[blues90]

I checked the timing and since I have a pertronix it shouldn't change.

I found it difficult to see the timing mark through the small hole with this autozone light I have. I checked it a few years ago and don't recall having trouble seeing the timing mark . I made a tool that is like a pointer so I don't need to sight the pointer so far from the marks . I do need new glasses.

I recall some remove the gen pulley cover and aim their light through there.

I have the 5 degree mark painted and it was on 5 degrees . I just wonder if it might have something to do with the winter blend fuel .

It might have been some glass bottles I had in the cargo area and drove the car further than usual that day . Never heard the ping sound until the last stop to home about a mile away on the drive home .

[KTPhil]

What year? (needed to know the timing setting).

Yes, aiming the light through the gen cover helps, as does painting the correct notch white or yellow.

Did you check it with any distributor vacuum hoses off and plugged?


If it's a square, drive down a clean road with the lid off and all windows open. You will hear the pinging better. Or drive next to a freeway K-rail so you hear it echo off it as you drive.

[blues90]

[blues90]

Maybe I'm not being clear.

This ping just came out of no where , no warning same fuel . It doesn't feel like a lack of fuel . I don't keep on the throttle for more than a few seconds when it happens and then next stop or slowing down enough so it shifts back into 1st , then into second I try it again and say 1 3rd of the time it will ping.

I heard it twice today , then did as above and heard it . When it doesn't happen I hear no noise.

[Multi69s]

[blues90]

[blues90]

I connected the timing light and let it warm up and plugged the AAR line to the oil bath because it will not close fully yet enough where it does not affect the idle speed much at all .

I looked through the gen belt cover and when idle was 950 the timing was at 7.5 BTDC if I slowed the idle down it sat at 5 BTDC.

Now if I opened the throttle I could see it advance and even though the idle speed dropped to 950 the timing was still advanced pretty far past the 7.5 BTDC mark and very slowly would return to 5 BTDC . Took at least 2 or 3 minutes without timing it to drop back to 5 BTDC .

I know it used to drop right back to 5 BTDC right away and even making certain the throttle was fully closed . Now doing the same thing the advance is still far to much and it does not have a decell deal on the throttle juast the spring and it does return fully .

I pulled the Dist and am now ready to remove the advance plate to see what could be going on .

If I don't find anything hanging up what else could cause this. I checked for any loose tin and found nothing .

When you close the throttle the timing should return to 5 BTDC right away shouldn't it?

[KTPhil]

Yes, it should happen immediately and consistently. Sounds like you are on the right track taking the distributor apart.

I had a timing problem that I traced to my distributor:
https://www.thesamba.com/vw/forum/viewtopic.php?t=680557

I haven't taken my old one apart yet, but I will and take lots of photos (I know, doesn't help you now!). But search--- there have been a couple of great threads with photos laying out all the parts, so you can follow along. There are also hints for finding shims and spacers you may need.

For mine, I suspect a broken spring or mount, since my timing just kept increasing as rpms increased, way past the normal limit.

I would read up in Bentley and figure out what is correct for your car and transmission. Then get the correct vacuum can and set it all by the book.

[blues90]

[KTPhil]

My hesitation about using what you have stems from the late emission-driven changes in ignition that VW made, especially for automatics, and even worse, for those destined for California. I believe they monkeyed with static timing, as well as the dual vacuum advance, so a mixture may or may not work well for your engine. This was not well documented in manuals.

Do you have the EGR system? Vacuum spark limiting until in high gear? More complications to deal with!

[blues90]

[KTPhil]

OK, that narrows it down a bit... the less late model smog crap on it the better! Fewer variables and less to go wrong and interact. Be sure the EGR is blocked off (both exhaust and intake ends, and no vacuum leaks).

You must still have an ignition advance defect, and taking the unit apart, deburring, shimming, and lubing should restore it to good function.

[Donnie strickland]

You might check and see if Jim Adney has a good 505 vacuum can.
_________________
71 Elm Green FI A/T Squareback

[blues90]

[KTPhil]

Ok, so EGR is cleanly removed, good!

I say an ignition advance "defect" because it isn't consistently snapping back to the same, correct advance point. This should be repeatable and correct. So I suspect the distributor still, since this is not happening. As suggested here(?) or on the T3 list, lower the idle below 850 rpm to be sure there is no mechanical advance happening, then try the same test... see if it returns to the same point as soon as idle speed is down. If not, something is sticking or broken and needs attention.

[blues90]

[KTPhil]

How are your plug wires? Each side's pairs run close to each other and you might have cross-firing, which can make it ping or miss. Bad SP connectors can make this more likely, too.

[blues90]

[KTPhil]

I am starting to suspect a misadjusted/broken TPS or wires if it only pings when you give it gas... without the extra injections (like an accel pump on a carb) it will be running lean for a few seconds, and the lean mixture may let it ping.

Most of the manuals have an incorrect adjustment procedure. Get it close, and then listen for the 10 or so extra injector squirts (key on, engine off, slowly open the throttle and listen near the injectors).

[raygreenwood]

Really....this all goes back to your other threads. And part of this is STILL the same problem. It's not going to go away.

Understand.......You note that your AAR is not closing.

If that is true and you are driving it that way.....your fuel mixture is way the hell rich. The aar bleed air is read by the MPS as throttle open and it enriches.

If you are able to drive with that condition....and get actual pinging......the only way that can happen (if your fuel pressure is normal).....is if the MPS is adjusted seriously LEAN.

While this may sound like a good trade off at say.....idle.....it can make it seriously lean through the mid range and part throttle.

The amount of air entering through the open AAR increases at a square function as rpm rises. As the MPS reacts to the extra air...which equals lack of vacuum....which equals enrichment.....it is not linear with the increase of air through the AAR. You will have lean spots.

Also the idle increase and not falling back to set idle....is a dead bang giveaway that you have air bypassing and enriching the MPS at just above idle.

While you may very well have ignition and advance issues as well ....you MUST fix the vacuum leaks and FINALLY adjust the MPS.....before you can accurately set timing based on availabe advance curve of the centrifugal......because the vacuum leak and MPS adjustment will not allow you to have a stable and controllable idle. Ray