Timing has rogue spikes

[ThikStik]

While looking at my damper with a timing light , I can see 4 or so degrees of timing movements at idle. It does it erratically. The car has symptoms like idle hunting, and a dead miss at off idle cruising..but just sometimes. I have reason to believe its doing it at WOT. Tonight whil racing a bike, I got a robust ping, and Im thinking its all related to this timing moveing around.
Ive tried module, coil, crank sensor to no avail. I did find a peice of metal in the cam sensor's magnetic cap window, and it was the tiny locating tab that was broken off. I formed a new locating tab and retightened . I thought that that would fix it , but it hasnt. As long as this plate is tight, it would seem the cam sensor could do its job. It has stayed tight since the fix. Do you guys think its the cam sensor? Or....anything else?
Thanks

 

[MeanBuicks]

The cam sensor only sets up the sequential fuel injection and has nothing to do with spark timing.

 

[ThikStik]

Thanks Greg for the "Freindly" advice. I wonder if it could be the ESC module.

 

[ThikStik]

I put on a junkyard spark module, and its no different. A freind that has a turbo shop , and has gn experience says that he remembers all gn's having a miss on an unloaded engine. Ive got oe MAF, and it reads constant during episodes. But it seems so ignition related, at idle , the missis are very pronounced , like a plug arcing. Its never that simple. Ok...now this thread will fade and die in the ether of time.

 

[turbo2nr]

Most cars will have the timing go up and down in a 4degree (+2/-2 from target timing) or so range to keep the engine at idle. This and fueling and iac all are constantly moving up and down during idle within a small range.

The turbo Buick is not one of the best idling engine. My stock 85 T-type Riviera always had a real funny idle. Most of them do. The 86/87 TRs got better, but still a little rough IMO.

Check the ground on the engine? Ah...?? Seems like you have changed about everything. Try a new chip, or another know-to-be-good MAF?

 

[6=8]

Agreed... When I first got my 87 and took in to the dealer to have a few things fixed, I asked if they could check the idle... Seemed a bit rough to me... The service manager kind of laughed and said "They set these cars up to run lean... nothing we can do about it."

I thought it was a line of crap, and maybe it was... but 14 years later, the idle is still a bit rough but never got much worse. Recently, I found an original vacuum line with a hole in it. I replaced them all, and suprise! The idle is still rough! (But now my cruise control works again.)

When I rotate my engine manually, I measured 4 degrees of "Play" when comparing the crankshaft to camshaft rotation. I was informed this was normal for a stock setup on a previous post, and seems to confirm turbo2nr's reply.

I think your other problems are unrelated to the cam sensor itself, as it is only used to find TDC during startup, and is used to control the injector timing there after. If you still suspect problems in this area, I do have a suggestion:

Try starting the car and pulling off the connector to the cam sensor. This will enable "Batch Fire" mode and bypass the camshaft sensor for injector timing. The check engine light will come on, but you will be able to dive the car this way. (If it stalls, you will not be able to re-start it though!)

If your problems seem to go away or are significantly reduced in this mode, you may have some exremely worn timing gear! That is how I found my problem a few years back.

If this does not do much for ya, than I would chase either a ground issue or check into your crankshaft sensor since it is DIRECTLY related to ignition timing! I see you mentioned this, but you didn't say what you did to check it?

 

[ThikStik]

Thanks for info guys. I have replaced and numeous times remounted thne crank trigger. I now have the oe one on because the new AZone unit made no diff. I used a dial back timing light to try to see how much timing moves...its very hard to see with piping in the way , but it could be around 6 deg. And it always correlates with engine lowering alittle in rpm as timing goes lower...to timing recovering and rpm going up alittle. Not dramatic rpm changes , just maybe 100 rpm. It just seems like timing is causing the rpm changes. Not vice versa. I think MAF is only thing left. I cleaned ecm contacts and used another ecm at that. Grounds should be very good as much as this engine makes it out of car. Are u referring to rear head grounds?
It sounds like u guys have heard the same thing I mentioned about GN's just not idling well. With that puff miss at unloaded off idel. Oh yea 6=8, I did do that dis-connect trick to cam sensor and it was fine. I guess if it was simple, everyone would be doing this stuff.