Question about my theory on timing chains & pinging

[yellowstang1994]

Ok guys, i've been chasing down a pinging problem for sometime now (who hasn't?) I've done what a lot of people recommended. My car basically bone stock down to the old air box I just put back on. I just replaced the ACT and ECT and while they helped my car still pings (not as much as it used to). So heres my theory. If i'm in 2nd or 3rd gear and I full throttle it, at times it doesn't ping. It mostly happens if i'm at a slow roll or stopped in 1st gear. My car is at 120k miles so I'm starting to suspect the timing chain has slack in it. If i'm pinging only in 1st gear when there is heavy load, it would make sense why I wouldn't ping in the other gears when I'm cruising and get on it (when there isn't that much load). And if the car is losing timing from the chain it would make sense that all the other sensors would have to be in tip top shape so even more timing wouldn't be lost from the thermisistors and stuff. Now besides taking the timing cover off the car and checking for slack phyically. Would I be correct in assuming that I can just take the spout out and check the timing at say 3k and 4k rpms and if it isn't the same as the 10* at idle then the timing chain most likely has slack in it?

Also while I'm here, why do a lot of guys replace the timing cover when they do their chains? Is it mandatory with an aftermarket chain for clearance? just for cosmetics? or because it is something that could potentially crack down the road?

Thanks guys!

 

[legalize420]

i dont see any reason why you would change to a new cover if the original is not cracked. the seal on the front should be replaced and you should be good to go. someone else will have to address the chain subject.

 

[rockin_rick]

While I don't know for sure, here's my theory about this:

I doubt that the timing chain slack is your problem. Assuming that timing chain slack can effect your timing (noticibly), I would think that the slack only delays the cam events slightly. This delay would then actually retard your spark and help with pinging. In addition, I would think that it would be the same delay regardless of if your at idle or WOT. During either, there is still going to be significant resistance to turning from the cam (from valve springs), and the slack of the chain is going to be on the 'return' side of the chain, not the 'pulling' or tension side. IOW - while slack may slightly effect your timing, it would be the same effect (delay) wether you are at idle or not.

I think that the main problem with pinging is the already aggressive timing in the GT's EEC and the head design. I think that stock 94-95 GT's were probably on the very edge of pinging when they came off the assembly line, and it doesn't take much to push them over the edge. Perhaps your problem is that you've got carbon buildup and that allows for even less timing (without pinging).

Rick

 

[final5-0]

I think that the main problem with pinging is the already aggressive timing in the GT's EEC and the head design. I think that stock 94-95 GT's were probably on the very edge of pinging when they came off the assembly line, and it doesn't take much to push them over the edge. Perhaps your problem is that you've got carbon buildup and that allows for even less timing (without pinging).

Rick

I'm with Rick and could not have said it better

Hey Rick .......... Good to see you back on the boards again

Grady

 

[yellowstang1994]

Thanks for the responses, it makes pretty good sense to me now. So instead of a poor guy like me changing out the heads and doing an engine rebuild, what can I do to help this? I guess seafoam? I always have a fear of that stuff because on a previous car I tried something similar and ended up messing up a few really expensive sensors.

 

[Synned]

Retard the timing + 93?

 

[Chythar]

Thanks for the responses, it makes pretty good sense to me now. So instead of a poor guy like me changing out the heads and doing an engine rebuild, what can I do to help this? I guess seafoam? I always have a fear of that stuff because on a previous car I tried something similar and ended up messing up a few really expensive sensors.

I've run Seafoam thru my Mustang several times over the years and never had a problem with it. The problem is, too much carbon buildup can hide other problems. Clearing the buildup reveals the problems.

Example: let's say you have carbon buildup on the cylinder walls. The piston ring will eventually wear down over the carbon. As long as the carbon buildup is there, the piston ring seals. Now, you use Seafoam on the engine. The carbon buildup is gone, and your piston ring no longer seals properly. Thus to mamy people, Seafoam "caused" an engine problem.

As with anything, use at your own risk.

 

[SeventyMach1]

+1 on Rick's theory. Head design & the EEC.


If you don't want new heads or you don't want to try Seafoam ..... you'd have to remove the heads and clean them up.


Not saying this will work for you ..... but my car pinged alot when I first got it. I've used Seafoam twice since and the pinging is now pretty much non-existent.