My wife's 86 coupe suddenly started pinging like heck on normal acceleration. We were trying to adjust the timing, and the timing mark jumps back and forth between approximately 4 and 12 degrees. Any ideas what is the most likely cause of the pinging, and what would make the timing mark jump *back and forth*? I'd think that if something were loose, such as the outer portion of the harmonic balancer (with the timing mark), the pickup coil or some other rotating mechanical part, that it would process in one direction, rather than going back and forth.

[This message has been edited by fierobear (edited 02-06-2008).]

The timing gear might be about to go; the duke has a plastic (!) timing gear. You can replace it with the motor still in the car, but I'm told it isn't very fun :-(. I'm not really sure how you could test this besides turning the motor over slowly by hand with the valve cover off and watching the rockers to see if they move smoothly with crankshaft rotation.

We replaced the timing gear with a new metal set when we rebuilt the engine, around a year ago.

Oh, and was that you heading south on 101 last Sunday?

[This message has been edited by fierobear (edited 02-06-2008).]

Hmm.. I imagine you replaced the distributor gear during the rebuilt too then.. I'm stumped!

Yeah that was me on 101! I thought that might be you in the GT. I was going to call but my new phone doesn't have your number in it.

[This message has been edited by Steven Snyder (edited 02-06-2008).]

quote Originally posted by Steven Snyder: Hmm.. I imagine you replaced the distributor gear during the rebuilt too then.. I'm stumped!

Yes, I put as many new or rebuilt parts onto that engine that I could. It's my wife's car, and I want it to be as reliable as possible. It had been until last week. The ignition module failed. We figured out that the rebuilt distributor had a painted, stippled and uneven and wavy surface. So we filed and sanded down the surface so it was flat, even and nearly shiny. Currently, we suspect one of the following:

1. Problem in the distributor
2. Bad replacement module
3. Pickup coil
4. ECM issue
5. Other electrical issue

edit, add: are you referring to the gear ON the distributor?

quote Yeah that was me on 101! I thought that might be you in the GT. I was going to call but my new phone doesn't have your number in it.

I thought that car looked like yours. We were on our way back from scouting Westfest locations in Solvang.

[This message has been edited by fierobear (edited 02-06-2008).]

The gear on the distributor that meshes with the cam gear. I doubt it'd fail, but if it was messed up it would cause jumpy timing.
I'd agree with your suspicions. I don't know enough about the non-DIS duke to help diagnose though :-(.

Solvang would be a cool backdrop for Westfest. You been out to WCF's new location yet in Tehachapi? It's beautiful up there too and they have some good car show spots.

Did you short the A/B pins in the ALDL (I think those are the correct pins)?

This will bring the car to base timing and then you adjust from there. The 4cyl is a rough running engine... My 87 sputtered and acted that way from the first day of ownership (9K on the odo). Dealer said there was nothing they could do. '88 engine runs smoother.

quote Originally posted by Steven Snyder: The gear on the distributor that meshes with the cam gear. I doubt it'd fail, but if it was messed up it would cause jumpy timing. I'd agree with your suspicions. I don't know enough about the non-DIS duke to help diagnose though :-(.

The cam is supposed to be a new Fiero Store hotter cam. I'd presume it's in good shape. We'll pull the distrubutor and check it.

quote Solvang would be a cool backdrop for Westfest. You been out to WCF's new location yet in Tehachapi? It's beautiful up there too and they have some good car show spots.

It's not clear whether we will get a show field *in* Solvang. I'm still working on it. But we'll be close enough (3 miles) for an easy and quick sidetrip.

I heard they were thinking about Tehachapi. They already moved? Wow! I'll have to get down there and check it out.

quote Originally posted by fierobear: It's not clear whether we will get a show field *in* Solvang. I'm still working on it. But we'll be close enough (3 miles) for an easy and quick sidetrip. I heard they were thinking about Tehachapi. They already moved? Wow! I'll have to get down there and check it out.

Yep, everything is setup at the new shop now. I checked it out a couple weekends ago. It's HUGE! The address is 20826 South Street, Tehachapi, CA. The old number forwards to the new one, but the new number is 661-822-8111. There will probably be a BBQ out there in a few weeks. Let me know if you end up making plans to head out there, it's less than a two hour drive for me so maybe I can make it out there too.

quote Originally posted by Steven Snyder: Yep, everything is setup at the new shop now. I checked it out a couple weekends ago. It's HUGE! The address is 20826 South Street, Tehachapi, CA. The old number forwards to the new one, but the new number is 661-822-8111. There will probably be a BBQ out there in a few weeks. Let me know if you end up making plans to head out there, it's less than a two hour drive for me so maybe I can make it out there too.

Less than 2 hours...you must be coming from school in L.A.?

I'd like to check out their new digs. I'll keep an eye out for the BBQ date.